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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3200 on: May 19, 2020, 02:15:20 PM »
The linked reference concludes that global warming has increased the likelihood of forming Category 3 tropical storms, or even higher by eight percent a decade.  As weather variability is a function of climate sensitivity, this is evidence that climate sensitivity is not low:
James P. Kossin,  Kenneth R. Knapp, Timothy L. Olander, and Christopher S. Velden (May 18, 2020), "Global increase in major tropical cyclone exceedance probability over the past four decades", PNAS, https://doi.org/10.1073/pnas.1920849117

https://www.pnas.org/content/early/2020/05/12/1920849117

Significance
Tropical cyclones (TCs), and particularly major TCs, pose substantial risk to many regions around the globe. Identifying changes in this risk and determining causal factors for the changes is a critical element for taking steps toward adaptation. Theory and numerical models consistently link increasing TC intensity to a warming world, but confidence in this link is compromised by difficulties in detecting significant intensity trends in observations. These difficulties are largely caused by known heterogeneities in the past instrumental records of TCs. Here we address and reduce these heterogeneities and identify significant global trends in TC intensity over the past four decades. The results should serve to increase confidence in projections of increased TC intensity under continued warming.

Abstract
Theoretical understanding of the thermodynamic controls on tropical cyclone (TC) wind intensity, as well as numerical simulations, implies a positive trend in TC intensity in a warming world. The global instrumental record of TC intensity, however, is known to be heterogeneous in both space and time and is generally unsuitable for global trend analysis. To address this, a homogenized data record based on satellite data was previously created for the period 1982–2009. The 28-y homogenized record exhibited increasing global TC intensity trends, but they were not statistically significant at the 95% confidence level. Based on observed trends in the thermodynamic mean state of the tropical environment during this period, however, it was argued that the 28-y period was likely close to, but shorter than, the time required for a statistically significant positive global TC intensity trend to appear. Here the homogenized global TC intensity record is extended to the 39-y period 1979–2017, and statistically significant (at the 95% confidence level) increases are identified. Increases and trends are found in the exceedance probability and proportion of major (Saffir−Simpson categories 3 to 5) TC intensities, which is consistent with expectations based on theoretical understanding and trends identified in numerical simulations in warming scenarios. Major TCs pose, by far, the greatest threat to lives and property. Between the early and latter halves of the time period, the major TC exceedance probability increases by about 8% per decade, with a 95% CI of 2 to 15% per decade.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3201 on: May 19, 2020, 02:29:42 PM »
Hausfather retweets that Berkeley Earth projects a 60% chance that 2020 will be the warmest year on record based on Jan, Feb, March and April 2020 records:
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3202 on: May 19, 2020, 06:14:45 PM »
People are frequently confused by the radiative forcing associated with methane emissions, as the linked article and related reference make it clear that most likely AR5 underestimated the GWP for methane:

Title: "How Potent Is Methane?"

https://www.factcheck.org/2018/09/how-potent-is-methane/

Extract: "Shine says that if work from his group and others holds up, it’s possible the IPCC’s sixth report could revise methane’s GWP100 upward to 35 or higher. That number, like all the others before it, will be in flux as climatologists learn more and make refinements. It’s also likely to include a fair amount of uncertainty. GWP values for methane typically come with uncertainties between 30 percent and 40 percent, according to the IPCC."

See also:

M. Etminan, G. Myhre, E. J. Highwood and K. P. Shine (27 December 2016), "Radiative forcing of carbon dioxide, methane, and nitrous oxide: A significant revision of the methane radiative forcing", Geophysical Research Letters, https://doi.org/10.1002/2016GL071930

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2016GL071930

Abstract
New calculations of the radiative forcing (RF) are presented for the three main well‐mixed greenhouse gases, methane, nitrous oxide, and carbon dioxide. Methane's RF is particularly impacted because of the inclusion of the shortwave forcing; the 1750–2011 RF is about 25% higher (increasing from 0.48 W m−2 to 0.61 W m−2) compared to the value in the Intergovernmental Panel on Climate Change (IPCC) 2013 assessment; the 100 year global warming potential is 14% higher than the IPCC value. We present new simplified expressions to calculate RF. Unlike previous expressions used by IPCC, the new ones include the overlap between CO2 and N2O; for N2O forcing, the CO2 overlap can be as important as the CH4 overlap. The 1750–2011 CO2 RF is within 1% of IPCC's value but is about 10% higher when CO2 amounts reach 2000 ppm, a value projected to be possible under the extended RCP8.5 scenario.

Plain Language Summary
“Radiative forcing” is an important method to assess the importance of different climate change mechanisms, and is used, for example, by the Intergovernmental Panel on Climate Change (IPCC). Increased concentrations of greenhouse gases, such as carbon dioxide, methane and nitrous oxide, are the major component of the human activity that led the IPCC, in its 2013 Assessment, to conclude that “it is extremely likely that human influence is the dominant cause of warming since the mid‐20th century.” In this letter, we report new and detailed calculations that aimed to update the simpler methods of computing the radiative forcing that have been used in IPCC assessments, and elsewhere. The major result is that radiative forcing due to methane is around 20‐25% higher than that found using the previous simpler methods. The main reason for this is the inclusion of the absorption of solar radiation by methane, a mechanism that had not been included in earlier calculations. We examine the mechanisms by which this solar absorption causes this radiative forcing. The work has significance for assessments of the climate impacts of methane emissions due to human activity, and for the way methane is included in international climate agreements.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3203 on: May 19, 2020, 07:59:51 PM »
Just a reminder that the GHG from coastal permafrost can occur abruptly due to projected erosion associated with future climate change:

G. Tanski, D. Wagner, C. Knoblauch, M. Fritz, T. Sachs and H. Lantuit (15 October 2019), "Rapid CO2 Release From Eroding Permafrost in Seawater", Geophysical Research Letters, https://doi.org/10.1029/2019GL084303

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019GL084303

Abstract
Permafrost is thawing extensively due to climate warming. When permafrost thaws, previously frozen organic carbon (OC) is converted into carbon dioxide (CO2) or methane, leading to further warming. This process is included in models as gradual deepening of the seasonal non‐frozen layer. Yet, models neglect abrupt OC mobilization along rapidly eroding Arctic coastlines. We mimicked erosion in an experiment by incubating permafrost with seawater for an average Arctic open‐water season. We found that CO2 production from permafrost OC is as efficient in seawater as without. For each gram (dry weight) of eroding permafrost, up to 4.3 ± 1.0 mg CO2 will be released and 6.2 ± 1.2% of initial OC mineralized at 4 °C. Our results indicate that potentially large amounts of CO2 are produced along eroding permafrost coastlines, onshore and within nearshore waters. We conclude that coastal erosion could play an important role in carbon cycling and the climate system.

Plain Language Summary
The permanently frozen soils of the Arctic, known as permafrost, store large amounts of organic carbon, which accumulated over millennia due to slow decomposition in the cold Arctic regions. With climate warming this frozen organic carbon reservoir thaws and microbes recycle it quickly into greenhouse gases, which in turn support further warming. A slow and continuous thaw is currently used in models to project future greenhouse gas release from permafrost. Yet along the rapidly eroding coastlines of the Arctic Ocean, which make up 34% of the Earth's coastlines, whole stretches of the coast simply collapse, sink or slide into the ocean, including the previously frozen organic carbon. We simulated greenhouse gas release in response to coastline collapse in a laboratory experiment by simply mixing permafrost with seawater. We show that large amounts of carbon dioxide are being produced during the Arctic open‐water season. Our study indicates that eroding permafrost coasts in the Arctic are potentially a major source of carbon dioxide. With increasing loss of sea ice, longer open‐water seasons, and exposure of coasts to waves, we highlight the importance of coastal erosion for potential carbon dioxide emissions.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3204 on: May 19, 2020, 08:15:22 PM »
The linked E3SM presentation finds that use of their machine learning algorithm resulted in an accuracy improvement of 50-90% as compared to current consensus algorithms in ESMs.  The presentation also indicates that wildfires in tropical regions are particularly important for ESMs to simulate correctly w.r.t. climate projections:

Title: "Wildfire modeling with E3SM and machine learning techniques"

https://e3sm.org/wp-content/uploads/2020/05/200514_Q_Zhu_reduced.pdf
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Stephan

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3205 on: May 19, 2020, 08:50:48 PM »
Yet along the rapidly eroding coastlines of the Arctic Ocean, which make up 34% of the Earth's coastlines, whole stretches of the coast simply collapse, sink or slide into the ocean, including the previously frozen organic carbon.
Is there any number available, how many kilometers of arctic coastline is affected by erosion caused by thawing of permafrost soil? I guess at least some portion of arctic coastline is bare rocks having not much soil available for erosion processes.
It is too late just to be concerned about Climate Change

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3206 on: May 19, 2020, 10:09:37 PM »
Yet along the rapidly eroding coastlines of the Arctic Ocean, which make up 34% of the Earth's coastlines, whole stretches of the coast simply collapse, sink or slide into the ocean, including the previously frozen organic carbon.
Is there any number available, how many kilometers of arctic coastline is affected by erosion caused by thawing of permafrost soil? I guess at least some portion of arctic coastline is bare rocks having not much soil available for erosion processes.

If you click on the link in the original post it leads to an open access paper.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3207 on: May 19, 2020, 10:13:34 PM »
The linked open access reference describes how stable gas hydrates can trigger submarine landslides that can release methane into the atmosphere:

Judith Elger et al, Submarine slope failures due to pipe structure formation, Nature Communications (2018). DOI: 10.1038/s41467-018-03176-1

https://www.nature.com/articles/s41467-018-03176-1

Abstract: "There is a strong spatial correlation between submarine slope failures and the occurrence of gas hydrates. This has been attributed to the dynamic nature of gas hydrate systems and the potential reduction of slope stability due to bottom water warming or sea level drop. However, 30 years of research into this process found no solid supporting evidence. Here we present new reflection seismic data from the Arctic Ocean and numerical modelling results supporting a different link between hydrates and slope stability. Hydrates reduce sediment permeability and cause build-up of overpressure at the base of the gas hydrate stability zone. Resulting hydro-fracturing forms pipe structures as pathways for overpressured fluids to migrate upward. Where these pipe structures reach shallow permeable beds, this overpressure transfers laterally and destabilises the slope. This process reconciles the spatial correlation of submarine landslides and gas hydrate, and it is independent of environmental change and water depth."
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3208 on: May 20, 2020, 04:39:46 PM »
While the impact of decreased albedo from Antarctic green snow algae may be limited to marine regions of the Antarctic Peninsula for some time to come; nevertheless, it shows a net increasing trend (see the linked open access reference and associated linked article):

Gray, A., Krolikowski, M., Fretwell, P. et al. Remote sensing reveals Antarctic green snow algae as important terrestrial carbon sink. Nat Commun 11, 2527 (2020). https://doi.org/10.1038/s41467-020-16018-w

https://www.nature.com/articles/s41467-020-16018-w

Abstract: "We present the first estimate of green snow algae community biomass and distribution along the Antarctic Peninsula. Sentinel 2 imagery supported by two field campaigns revealed 1679 snow algae blooms, seasonally covering 1.95 × 106 m2 and equating to 1.3 × 103 tonnes total dry biomass. Ecosystem range is limited to areas with average positive summer temperatures, and distribution strongly influenced by marine nutrient inputs, with 60% of blooms less than 5 km from a penguin colony. A warming Antarctica may lose a majority of the 62% of blooms occupying small, low-lying islands with no high ground for range expansion. However, bloom area and elevation were observed to increase at lower latitudes, suggesting that parallel expansion of bloom area on larger landmasses, close to bird or seal colonies, is likely. This increase is predicted to outweigh biomass lost from small islands, resulting in a net increase in snow algae extent and biomass as the Peninsula warms."

See also:

Title: "Climate change will turn coastal Antarctica green, say scientists"

https://phys.org/news/2020-05-climate-coastal-antarctica-green-scientists.html

Extract: "Scientists have created the first ever large-scale map of microscopic algae as they bloomed across the surface of snow along the Antarctic Peninsula coast. Results indicate that this 'green snow' is likely to spread as global temperatures increase."
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3209 on: May 20, 2020, 05:42:13 PM »
The attached Berkeley Earth graphic (retweeted by Hausfather) of the global surface temperature anomaly distribution for the period from January thru April 2020 emphasizes the very high anomalies in Siberia; which is bad for permafrost degradation.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3210 on: May 20, 2020, 06:33:07 PM »
The linked reference indicates that the regional climate sensitivities for CMIP6 are relatively close to those for CMIP5.  To me this suggests that the global climate sensitivities calculated by the various CMIP6 models may well be reasonable when considering the uncertainties associated with the modeled climate feedback mechanisms:

Sonia I. Seneviratne and Mathias Hauser (13 May 2020), "Regional climate sensitivity of climate extremes in CMIP6 vs CMIP5 multi‐model ensembles", Earth's Future, https://doi.org/10.1029/2019EF001474

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019EF001474

Abstract
We analyse projected changes in climate extremes (extreme temperatures and heavy precipitation) in the multi‐model ensembles of the 5th and 6th Coupled Model Intercomparison Projects (CMIP5 and CMIP6). The results reveal close similarity between both ensembles in the regional climate sensitivity of the projected multi‐model mean changes in climate extremes, i.e. their projected changes as a function of global warming. This stands in contrast to widely reported divergences in global (transient and equilibrium) climate sensitivity in the two multi‐model ensembles. Some exceptions include higher warming in the South America monsoon region, lower warming in Southern Asia and Central Africa, and higher increases in heavy precipitation in Western Africa and the Sahel region in the CMIP6 ensemble. The multi‐model spread in regional climate sensitivity is found to be large in both ensembles. In particular, it contributes more to inter‐model spread in projected regional climate extremes compared to the inter‐model spread in global climate sensitivity in CMIP6. Our results highlight the need to consider regional climate sensitivity as a distinct feature of Earth System Models and a key determinant of projected regional impacts, which is largely independent of the models' response in global climate sensitivity.

Plain Language Summary
Many articles analyse and compare global climate sensitivity in climate models, i.e. how their global warming differs at a given level of CO2 concentrations. However, global warming is only one quantity affecting impacts. To assess human‐ and ecosystem‐relevant impacts, it is essential to evaluate the regional climate sensitivity of climate models, i.e. how their regional climate features differ at a given level of global warming. We analyse here regional climate sensitivity in the new multi‐model ensemble that will underlie the conclusions of the 6th Assessment Report of the Intergovernmental Panel on Climate Change (IPCC). This ensemble of model projections is called the ``6th Coupled Model Intercomparison Project”, or CMIP6. We find that differences in regional climate sensitivity between models in CMIP6 often contribute more to the uncertainty of regional extremes projections than the uncertainty in global mean warming between models. Overall, the regional climate sensitivity features in the CMIP6 model projections ensemble are very similar to those of the prior ensemble (CMIP5), although the model ensembles have been highlighted to differ in their global climate sensitivity over the 21st century.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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Ken Feldman

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3211 on: May 20, 2020, 10:20:42 PM »
The linked reference indicates that improved modeling of future thermokarst behavior in northeast Siberia indicates that:

"... by 2100 thaw-affected carbon could be up to three-fold (twelve-fold) under RCP4.5 (RCP8.5), of what is projected if thermokarst-inducing processes are ignored."

AR5 projections ignored this significant positive feedback mechanism.

Nitzbon, J., Westermann, S., Langer, M. et al. Fast response of cold ice-rich permafrost in northeast Siberia to a warming climate. Nat Commun 11, 2201 (2020). https://doi.org/10.1038/s41467-020-15725-8

https://www.nature.com/articles/s41467-020-15725-8

Abstract: "The ice- and organic-rich permafrost of the northeast Siberian Arctic lowlands (NESAL) has been projected to remain stable beyond 2100, even under pessimistic climate warming scenarios. However, the numerical models used for these projections lack processes which induce widespread landscape change termed thermokarst, precluding realistic simulation of permafrost thaw in such ice-rich terrain. Here, we consider thermokarst-inducing processes in a numerical model and show that substantial permafrost degradation, involving widespread landscape collapse, is projected for the NESAL under strong warming (RCP8.5), while thawing is moderated by stabilizing feedbacks under moderate warming (RCP4.5). We estimate that by 2100 thaw-affected carbon could be up to three-fold (twelve-fold) under RCP4.5 (RCP8.5), of what is projected if thermokarst-inducing processes are ignored. Our study provides progress towards robust assessments of the global permafrost carbon–climate feedback by Earth system models, and underlines the importance of mitigating climate change to limit its impacts on permafrost ecosystems."

Note that they didn't include the findings from the RCP2.6 model runs in the abstract.

Quote
Under the RCP2.6 scenario, all landscape types (LB, HD, YD) remained stable throughout the simulation period, with the exception of water-logged YD where shallow surface water bodies formed. We thus restrict the following analysis of the landscape evolution to the warming scenarios RCP4.5 and RCP8.5.

kassy

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3212 on: May 21, 2020, 01:51:20 PM »
Isn´t 2.6 the one were we actively collectively do something about it? Not everyone is on board.

Þetta minnismerki er til vitnis um að við vitum hvað er að gerast og hvað þarf að gera. Aðeins þú veist hvort við gerðum eitthvað.

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3213 on: May 21, 2020, 03:44:07 PM »
Isn´t 2.6 the one were we actively collectively do something about it? Not everyone is on board.

The linked 2015 reference discusses how much negative emissions were estimated to be needed back then to follow RCP 2.6:

Gasser, T., Guivarch, C., Tachiiri, K. et al. Negative emissions physically needed to keep global warming below 2 °C. Nat Commun 6, 7958 (2015). https://doi.org/10.1038/ncomms8958
https://www.nature.com/articles/ncomms8958

Abstract
To limit global warming to <2 °C we must reduce the net amount of CO2 we release into the atmosphere, either by producing less CO2 (conventional mitigation) or by capturing more CO2 (negative emissions). Here, using state-of-the-art carbon–climate models, we quantify the trade-off between these two options in RCP2.6: an Intergovernmental Panel on Climate Change scenario likely to limit global warming below 2 °C. In our best-case illustrative assumption of conventional mitigation, negative emissions of 0.5–3 Gt C (gigatonnes of carbon) per year and storage capacity of 50–250 Gt C are required. In our worst case, those requirements are 7–11 Gt C per year and 1,000–1,600 Gt C, respectively. Because these figures have not been shown to be feasible, we conclude that development of negative emission technologies should be accelerated, but also that conventional mitigation must remain a substantial part of any climate policy aiming at the 2-°C target.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3214 on: May 21, 2020, 04:01:22 PM »
The linked reference discusses how machine learning can be used to identify abrupt and extreme climate events in large data sets.  When the authors applied their strategy to the RCP 8.5 scenario of the CMIP5 data set they found that over half of the simulations exhibited abrupt shifts on a timescale of 10 years:

Sebastian Bathiany, Johan Hidding, and Marten Scheffer (2020), "Edge detection reveals abrupt and extreme climate events", Journal of Climate, https://doi.org/10.1175/JCLI-D-19-0449.1

https://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-19-0449.1?af=R

Abstract
The most discernible and devastating impacts of climate change are caused by events with temporary extreme conditions (“extreme events”) or abrupt shifts to a new persistent climate state (“tipping points”). The rapidly growing amount of data from models and observations poses the challenge to reliably detect where, when, why and how these events occur. This situation calls for data-mining approaches that can detect and diagnose events in an automatic and reproducible way. Here, we apply a new strategy to this task by generalising the classical machine-vision problem of detecting edges in 2d images to many dimensions (including time). Our edge detector identifies abrupt or extreme climate events in spatiotemporal data, quantifies their abruptness (or extremeness), and provides diagnostics that help understand the causes of these shifts. We also publish a comprehensive toolset of code which is documented and free to use. We document the performance of the new edge detector by analysing several datasets of observations and models. In particular, we apply it to all monthly 2d-variables of the RCP8.5 scenario of the Coupled Model Intercomparison Project (CMIP5). More than half of all simulations show abrupt shifts of more than 4 standard deviations on a timescale of 10 years. These shifts are mostly related to the loss of sea ice and permafrost in the Arctic. Our results demonstrate that the edge detector is particularly useful to scan large datasets in an efficient way, for example multi-model or perturbed-physics ensembles. It can thus help reveal hidden “climate surprises” and assess the uncertainties of dangerous climate events.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3215 on: May 21, 2020, 04:09:26 PM »
The linked reference discusses observed changes in the Barents Sea cooling mechanism that within a few years could cause the MOC to slow more than it already is.

Skagseth, Ø., Eldevik, T., Årthun, M. et al. Reduced efficiency of the Barents Sea cooling machine. Nat. Clim. Chang. (2020). https://doi.org/10.1038/s41558-020-0772-6

https://www.nature.com/articles/s41558-020-0772-6

Abstract: "Dense water masses from the Barents Sea are an important part of the Arctic thermohaline system. Here, using hydrographic observations from 1971 to 2018, we show that the Barents Sea climate system has reached a point where ‘the Barents Sea cooling machine’—warmer Atlantic inflow, less sea ice, more regional ocean heat loss—has changed towards less-efficient cooling. Present change is dominated by reduced ocean heat loss over the southern Barents Sea as a result of anomalous southerly winds. The outflows have accordingly become warmer. Outflow densities have nevertheless remained relatively unperturbed as increasing salinity appears to have compensated the warming inflow. However, as the upstream Atlantic Water is now observed to freshen while still relatively warm, we speculate that the Barents Sea within a few years may export water masses of record-low density to the adjacent basins and deep ocean circulation."
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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sidd

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3216 on: May 21, 2020, 08:33:21 PM »
That Bathiany paper on multidimensional edge detection is very nice.

I havent had to time to read in careful detail yet, but i can see that i shall use their technique soon for a problem or two i am working on.

sidd

Ken Feldman

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3217 on: May 22, 2020, 12:30:59 AM »
Isn´t 2.6 the one were we actively collectively do something about it? Not everyone is on board.

The linked 2015 reference discusses how much negative emissions were estimated to be needed back then to follow RCP 2.6:

Gasser, T., Guivarch, C., Tachiiri, K. et al. Negative emissions physically needed to keep global warming below 2 °C. Nat Commun 6, 7958 (2015). https://doi.org/10.1038/ncomms8958
https://www.nature.com/articles/ncomms8958

Abstract
To limit global warming to <2 °C we must reduce the net amount of CO2 we release into the atmosphere, either by producing less CO2 (conventional mitigation) or by capturing more CO2 (negative emissions). Here, using state-of-the-art carbon–climate models, we quantify the trade-off between these two options in RCP2.6: an Intergovernmental Panel on Climate Change scenario likely to limit global warming below 2 °C. In our best-case illustrative assumption of conventional mitigation, negative emissions of 0.5–3 Gt C (gigatonnes of carbon) per year and storage capacity of 50–250 Gt C are required. In our worst case, those requirements are 7–11 Gt C per year and 1,000–1,600 Gt C, respectively. Because these figures have not been shown to be feasible, we conclude that development of negative emission technologies should be accelerated, but also that conventional mitigation must remain a substantial part of any climate policy aiming at the 2-°C target.

Yes, negative emissions will be required.  That's been known for decades.  There are many ways to achieve negative emissions without new technologies.

Stopping deforestation and allowing forests to regrow could sequester 120 PgC between 2016 and 2100.  120 billion tons in 84 years is 1.4 billion tons per year, or about half of what is required.

https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.13876

Quote
Negative emissions from stopping deforestation and forest degradation, globally
Richard A. Houghton, Alexander A. Nassikas
21 August 2017

 Abstract

Forest growth provides negative emissions of carbon that could help keep the earth's surface temperature from exceeding 2°C, but the global potential is uncertain. Here we use land‐use information from the FAO and a bookkeeping model to calculate the potential negative emissions that would result from allowing secondary forests to recover. We find the current gross carbon sink in forests recovering from harvests and abandoned agriculture to be −4.4 PgC/year, globally. The sink represents the potential for negative emissions if positive emissions from deforestation and wood harvest were eliminated. However, the sink is largely offset by emissions from wood products built up over the last century. Accounting for these committed emissions, we estimate that stopping deforestation and allowing secondary forests to grow would yield cumulative negative emissions between 2016 and 2100 of about 120 PgC, globally. Extending the lifetimes of wood products could potentially remove another 10 PgC from the atmosphere, for a total of approximately 130 PgC, or about 13 years of fossil fuel use at today's rate. As an upper limit, the estimate is conservative. It is based largely on past and current practices. But if greater negative emissions are to be realized, they will require an expansion of forest area, greater efficiencies in converting harvested wood to long‐lasting products and sources of energy, and novel approaches for sequestering carbon in soils. That is, they will require current management practices to change.

Biochar use for agriculture can improve soil quality, reduce the amount of fertilizers needed (and the amount of NO2 emitted, the third most important greenhouse gas behind CO2 and CH4) and is a negative emission technology.

https://www.mdpi.com/2073-445X/8/12/179

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Potentials, Limitations, Co-Benefits, and Trade-Offs of Biochar Applications to Soils for Climate Change Mitigation
by Alexandre Tisserant * and Francesco Cherubini
Published: 23 November 2019

 Abstract
Biochar is one of the most affordable negative emission technologies (NET) at hand for future large-scale deployment of carbon dioxide removal (CDR), which is typically found essential to stabilizing global temperature rise at relatively low levels. Biochar has also attracted attention as a soil amendment capable of improving yield and soil quality and of reducing soil greenhouse gas (GHG) emissions. In this work, we review the literature on biochar production potential and its effects on climate, food security, ecosystems, and toxicity. We identify three key factors that are largely affecting the environmental performance of biochar application to agricultural soils: (1) production condition during pyrolysis, (2) soil conditions and background climate, and (3) field management of biochar. Biochar production using only forest or crop residues can achieve up to 10% of the required CDR for 1.5 ∘C pathways and about 25% for 2 ∘ C pathways; the consideration of dedicated crops as biochar feedstocks increases the CDR potential up to 15–35% and 35–50%, respectively. A quantitative review of life-cycle assessment (LCA) studies of biochar systems shows that the total climate change assessment of biochar ranges between a net emission of 0.04 tCO 2 eq and a net reduction of 1.67 tCO 2 eq per tonnes feedstock. The wide range of values is due to different assumptions in the LCA studies, such as type of feedstock, biochar stability in soils, soil emissions, substitution effects, and methodological issues. Potential trade-offs between climate mitigation and other environmental impact categories include particulate matter, acidification, and eutrophication and mostly depend on the background energy system considered and on whether residues or dedicated feedstocks are used for biochar production. Overall, our review finds that biochar in soils presents relatively low risks in terms of negative environmental impacts and can improve soil quality and that decisions regarding feedstock mix and pyrolysis conditions can be optimized to maximize climate benefits and to reduce trade-offs under different soil conditions. However, more knowledge on the fate of biochar in freshwater systems and as black carbon emissions is required, as they represent potential negative consequences for climate and toxicity. Biochar systems also interact with the climate through many complex mechanisms (i.e., surface albedo, black carbon emissions from soils, etc.) or with water bodies through leaching of nutrients. These effects are complex and the lack of simplified metrics and approaches prevents their routine inclusion in environmental assessment studies. Specific emission factors produced from more sophisticated climate and ecosystem models are instrumental to increasing the resolution and accuracy of environmental sustainability analysis of biochar systems and can ultimately improve the characterization of the heterogeneities of varying local conditions and combinations of type feedstock, conversion process, soil conditions, and application practice.

And RCP2.6, like the other RCPs, overestimated how much coal would be burned and how quickly renewable energy would replace fossil fuels.



Stopping methane leaks would have an almost immediate impact on warming, as it's lifetime in the atmosphere is around a decade and it has a warming potential around 35 times that of CO2.  With the curtailment of fracking in the US due to the oversupply of oil and natural gas this spring, we should see decreases this year.  The oil industry may never recover to its 2019 levels of production.

https://iopscience.iop.org/article/10.1088/1748-9326/ab2577

Quote
Timelines for mitigating the methane impacts of using natural gas for carbon dioxide abatement
Magdalena M Klemunand Jessika E Trancik
Published 16 December 2019

Abstract

Reducing carbon dioxide (CO2) emissions through a reliance on natural gas can create a hidden commitment to methane (CH4) leakage mitigation. While the quantity of CH4 leakage from natural gas has been studied extensively, the magnitude and timing of the CH4 mitigation required to meet climate policy goals is less well understood. Here we address this topic by examining the case of US electricity under a range of baseline natural gas leakage rate estimates and emissions equivalency metrics for converting CH4 to CO2-equivalent emissions. We find that CH4 emissions from the power sector would need to be reduced by 30%–90% from today's levels by 2030 in order to meet a CO2-equivalent climate policy target while continuing to rely on natural gas. These CH4 emissions reductions are greater than the required CO2 reductions under the same policy. Alternatively, expanding carbon-free sources more rapidly could meet the 2030 target without reductions in natural gas leakage rates. The results provide insight on an important policy choice in regions and sectors using natural gas, between emphasizing a natural gas supply chain clean-up effort or an accelerated transition toward carbon-free energy sources.


Ken Feldman

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3218 on: May 22, 2020, 01:12:35 AM »
More on the importance of controlling methane emissions.

https://www.eurekalert.org/pub_releases/2019-09/pues-cmi092019.php

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News Release 20-Sep-2019
Controlling methane is a fast and critical way to slow global warming, say experts

In independent studies, two Princeton University research teams recently identified surprisingly large sources of methane, a powerful greenhouse gas, being leaked into the atmosphere. Pound for pound, methane causes a far greater warming effect in the atmosphere than does carbon dioxide -- 86-fold more heating over 20 years, and 35-fold more over the course of a century.

In one study, a team headed by Mark Zondlo, associate professor of civil and environmental engineering at Princeton, looked at an area around western Pennsylvania rich with natural gas wells and found that a small number of these wells are "superemitters" of methane. The other study came from the research group of Denise Mauzerall, a Princeton professor jointly appointed in civil and environmental engineering and the Woodrow Wilson School of Public and International Affairs. By equipping fishing boats with sensors and sailing around offshore oil and gas rigs in the North Sea, the researchers found that these facilities leak substantially more methane than previously reported.

Fortunately, both fracking (which is what is common in Pennsylvania these days) and off-shore oil are among the highest cost forms of oil production, and thus are suffering most from the oversupply and Covid-19 recession impacting the oil industry.

https://oilprice.com/Energy/Crude-Oil/Oil-May-Never-Fully-Recover-From-This-Crisis.html

Quote
Oil May Never Fully Recover From This Crisis
By Irina Slav - May 21, 2020

Quote
Ten years ago, oil was one of the first industries to emerge from the crisis relatively unscathed, with demand strong and prices in the $80s. Now, it is likely to be among the last ones to recover from the double blow of demand destruction by the pandemic and the excess supply resulting from excessive production. And it may never recover fully.

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3219 on: May 22, 2020, 07:30:34 AM »
This post is not meant to start a discussion here.

<snip>
Yes, negative emissions will be required.  That's been known for decades.  There are many ways to achieve negative emissions without new technologies.

Stopping deforestation and allowing forests to regrow could sequester 120 PgC between 2016 and 2100.  120 billion tons in 84 years is 1.4 billion tons per year, or about half of what is required.

All of our antropogenic fossil fuel generated CO₂ is outside of the carbon cycle.
Massively destroying forests and later letting trees regrow is somehow solving this? That doesn't add up.

And it is not just the wrecked carbon cycle but other global cycles as well.
"It is preoccupation with possessions, more than anything else, that prevents us from living freely and nobly" - Bertrand Russell
"It is preoccupation with what other people from your groups think of you, that prevents you from living freely and nobly" - Nanning
Why do you keep accumulating stuff?

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3220 on: May 22, 2020, 11:16:52 AM »
This post is not meant to start a discussion here.

<snip>
Yes, negative emissions will be required.  That's been known for decades.  There are many ways to achieve negative emissions without new technologies.

Stopping deforestation and allowing forests to regrow could sequester 120 PgC between 2016 and 2100.  120 billion tons in 84 years is 1.4 billion tons per year, or about half of what is required.

All of our antropogenic fossil fuel generated CO₂ is outside of the carbon cycle.
Massively destroying forests and later letting trees regrow is somehow solving this? That doesn't add up.

And it is not just the wrecked carbon cycle but other global cycles as well.

The linked reference (and associated linked article) uses IPCC's consensus assumptions for climate sensitivity (which to me err on the side of least drama) to confirm that even after potentially implementing interventions such as renewable energy, energy efficiency, and electrification of the transportation sector, that industrial-scale (on the order of 2700 Gt of carbon storage) implementation of carbon capture and storage (CCS) will also be required to stay below 2C.  However, if the IPCC's consensus assumptions on climate sensitivity are wrong, then the likelihood of successfully implementing such an industrial approach are much, much lower than assumed by the linked reference.


"Global geologic carbon storage requirements of Q2 climate change mitigation scenarios" by Christopher Zahasky and Samuel Krevor, published 21 May 2020 in Energy & Environmental Science.

https://pubs.rsc.org/en/content/articlelanding/2020/ee/d0ee00674b#!divAbstract

Abstract
Integrated assessment models have identified carbon capture and storage (CCS) as an important technology for limiting climate change. To achieve 2 °C climate targets, many scenarios require tens of gigatons of CO2 stored per year by mid-century. These scenarios are often unconstrained by growth rates, and uncertainty in global geologic storage assessments limits resource-based constraints. Here we show how logistic growth models, a common tool in resource assessment, provide a mathematical framework for stakeholders to monitor short-term CCS deployment progress and long-term resource requirements in the context of climate change mitigation targets. Growth rate analysis, constrained by historic commercial CO2 storage rates, indicates sufficient growth to achieve several of the 2100 storage targets identified in the assessment reports of the Intergovernmental Panel on Climate Change. A maximum global discovered storage capacity of approximately 2700 Gt is needed to meet the most aggressive targets, with this ceiling growing if CCS deployment is delayed.

See also:

Title: "World can likely capture and store enough carbon dioxide to meet climate targets"

https://phys.org/news/2020-05-world-capture-carbon-dioxide-climate.html

Extract: "The capture and storage of carbon dioxide (CO2) underground is one of the key components of the Intergovernmental Panel on Climate Change's (IPCC) reports on how to keep global warming to less than 2°C above pre-industrial levels by 2100.

Carbon capture and storage (CCS) would be used alongside other interventions such as renewable energy, energy efficiency, and electrification of the transportation sector.

&

Title: "World can likely capture and store enough carbon dioxide to meet climate targets"

http://www.imperial.ac.uk/news/197635/world-likely-capture-store-enough-carbon/


“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

bluice

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3221 on: May 22, 2020, 04:08:08 PM »

Stopping deforestation and allowing forests to regrow could sequester 120 PgC between 2016 and 2100.  120 billion tons in 84 years is 1.4 billion tons per year, or about half of what is required.

Yes. And stopping shooting other people would end all wars.

Meanwhile in the real world:

"Between 2015 and 2020, the rate of deforestation was estimated at 10 million hectares per year, down from 16 million hectares per year in the 1990s. The area of primary forest worldwide has decreased by over 80 million hectares since 1990."

http://www.fao.org/state-of-forests/en/

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3222 on: May 22, 2020, 08:34:01 PM »

Stopping deforestation and allowing forests to regrow could sequester 120 PgC between 2016 and 2100.  120 billion tons in 84 years is 1.4 billion tons per year, or about half of what is required.

Yes. And stopping shooting other people would end all wars.

Meanwhile in the real world:

"Between 2015 and 2020, the rate of deforestation was estimated at 10 million hectares per year, down from 16 million hectares per year in the 1990s. The area of primary forest worldwide has decreased by over 80 million hectares since 1990."

http://www.fao.org/state-of-forests/en/

See also:

Title: "Deforestation boosts Brazil greenhouse gas emissions as global emissions fall"

https://news.trust.org/item/20200521161743-sy45x/

Extract: "Brazil could produce 10-20% more climate-warming gases in 2020 due to deforestation and farming as compared to the most recent data from 2018, a new study said on Thursday, while emissions globally have dropped this year as the new coronavirus pandemic paralyzes society."
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

Ken Feldman

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3223 on: May 22, 2020, 11:07:05 PM »
This post is not meant to start a discussion here.

<snip>
Yes, negative emissions will be required.  That's been known for decades.  There are many ways to achieve negative emissions without new technologies.

Stopping deforestation and allowing forests to regrow could sequester 120 PgC between 2016 and 2100.  120 billion tons in 84 years is 1.4 billion tons per year, or about half of what is required.

All of our antropogenic fossil fuel generated CO₂ is outside of the carbon cycle.
Massively destroying forests and later letting trees regrow is somehow solving this? That doesn't add up.

And it is not just the wrecked carbon cycle but other global cycles as well.

It's as important to correct our problems with land use change as it is to stop using fossil fuel. It's not an either/or situation. WE HAVE TO DO BOTH! The energy transition is well underway and renewables are rapidly replacing fossil fuel electricity.  The next two decades will see electric powered vehicles replace gas/diesel vehicles.  So anthropogenic emissions will decrease rapidly.

Reforestation is part of addressing the land use changes that also cause greenhouse gas emissions. Better agricultural practices (biochar and sustainable grazing, seaweed farming, etc...) are being employed more frequently.

Deforestation remains a problem, especially (but not only in) Brazil.  Pressure has to be applied to Brazil to stop the deforestation of the Amazon, and efforts to restore the forest will take decades.

In the meantime, there are five other forested continents, and there are efforts underway to reforest them.

https://www.upworthy.com/africans-are-building-a-great-green-wall-of-trees-across-the-continent-to-stop-the-sahara-from-expanding

Quote
Africans are building a Great Green Wall of trees across the continent to slow down the Saharan
Tod Perry
05.20.20

Twenty-one African countries have come together in an attempt to stop the Sahara desert from encroaching further south. Their mission: plant a 4,750-mile-long wall of trees.

When completed, the Great Green Wall will extend from sea to sea and reclaim 247 million acres. It'll stretch from Senegal in the west to Djibouti in the east, and will be three times the size of the Great Barrier Reef. The massive reforestation project will sequester 250 million tons of carbon.

https://www.earth.com/news/recovery-project-launched-to-restore-one-million-trees-in-australia/

Quote
04-22-2020
Recovery project launched to restore one million trees in Australia

By Chrissy Sexton

In honor of Earth Day’s 50th Anniversary, two nonprofit organizations have announced a five-year project to help Australia recover from devastating wildfires. One Tree Planted is teaming up with the Foundation for National Parks and Wildlife (FNPW) to plant one million trees in Bushfire Recovery Nurseries.

https://www.treehugger.com/environmental-policy/pakistan-turns-unemployed-workers-tree-planters.html

Quote
Pakistan turns unemployed workers into tree planters
Katherine Martinko

May 4, 2020

The country's ambitious reforestation project has received a surprise influx of laborers, thanks to coronavirus.

In 2018, Pakistan pledged to plant ten billion trees in an effort to slow climate change and to replenish a landscape that has been decimated by decades of deforestation, livestock grazing, and drought. It was an ambitious goal, but as the Washington Post reported at the time, "the idea of a green awakening seems to be taking root... The concept appeals to a new generation of better-educated Pakistanis, and it has sparked excitement on social media."

That program, whose name is 10 Billion Tree Tsunami, has been chugging along for the past two years, but it recently received an unexpected infusion of help from – of all things – the coronavirus. Many Pakistanis are suddenly unemployed, so the government has given them jobs as tree-planters. Unemployed day laborers have been turned into "jungle workers," planting saplings for 500 rupees a day ($3), which is roughly half of what a construction worker would normally earn. It's not a lot, but it's enough to get by, and that can mean the difference between survival and starvation. Al Jazeera reported,

    "As the coronavirus pandemic struck Pakistan, the 10 Billion Trees campaign was initially halted as part of social distancing orders put in place to slow the spread of the virus, which has infected more than 14,880 people in Pakistan, according to a tally by Johns Hopkins University. But earlier this month, the prime minister granted an exemption to allow the forestry agency to restart the programme and create more than 63,600 jobs, according to government officials."

https://www.fastcompany.com/90506965/the-eu-is-going-to-plant-3-billion-trees-by-2030

Quote
    05-20-20

The EU is going to plant 3 billion trees by 2030
It’s part of a broad plan to increase biodiversity by protecting 30% of the continent’s land and water.

 By Adele Peters

Over the next decade, the European Union plans to plant 3 billion trees. It’s one piece of a larger commitment to protect nature on the continent at a time when a million species, globally, are now at risk of extinction, and biodiversity loss also threatens future pandemics. In a new strategy document, the European Commission says it now aims to protect 30% of the region’s land and oceans, based on science that suggests that amount is necessary to preserve biodiversity.

https://www.greenbiz.com/article/rethinking-trillion-trees-act-could-help-us-economy

Quote
Rethinking the Trillion Trees Act could help the US economy
By Alex Rudee
April 28, 2020

As the spread of COVID-19 sickens thousands of Americans and pushes the U.S. economy into recession, Congress is working around the clock to provide resources to healthcare workers and relief to workers and industries facing economic hardship. That remains our collective first priority. Once the worst of this public health crisis has passed though, the United States will need an even greater stimulus package to jumpstart job growth and economic expansion. When that time comes, Congress can lead not just by addressing immediate economic needs, but also by delivering common-sense solutions for a long-term economic threat: climate change.

Federal climate policy must include not only ambitious measures to reduce greenhouse gas emissions, but also investments to remove carbon already in the atmosphere. Trees are nature’s own carbon removal engines, and restoring them to ecologically appropriate areas while protecting existing trees and forests is critical to keeping the United States on a path to avoid the most dangerous impacts of climate change. Investing in planting and sustainably managing trees could remove gigatons of carbon dioxide while creating hundreds of thousands of jobs (many more jobs per dollar spent than in carbon-intensive industries such as aviation or oil and gas, which previously have been the focus of stimulus discussions).

Many Republican policymakers have recognized the importance of trees as a climate solution. President Donald Trump committed the United States to participating in the global Trillion Trees Initiative in January. Shortly after, Rep. Bruce Westerman, R-Ark., and nine co-sponsors introduced the Trillion Trees Act in the House of Representatives. In early March, Sen. Mike Braun, R-Ind., said he would propose a version of the Trillion Trees Act in the Senate.

Even as parts of the Amazon are being converted into pastures, others are being reforested.

https://news.mongabay.com/2020/05/seed-by-seed-a-womens-collective-helps-reforest-brazils-xingu-river-basin/

Quote
Seed by seed, a women’s collective helps reforest Brazil’s Xingu River Basin
by JoAnna Haugen on 12 May 2020

    Members of the Yarang Women’s Movement in Brazil have collected 3.2 tons of seeds over the past decade.
    The native seeds are sold to rural landowners and organizations to help replenish forests that have been degraded.
    The Yarang Women’s Movement is part of a seed network collective responsible for replanting nearly 6,000 hectares (14,800 acres) of land in Brazil’s Xingu River Basin.
    Unpredictable changes in weather patterns have made the seed-collecting process more challenging in recent years.


vox_mundi

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3224 on: May 23, 2020, 12:05:37 PM »
Mississippi Delta Marshes In State of Irreversible Collapse: Study
https://phys.org/news/2020-05-mississippi-delta-marshes-state-irreversible.html

Given the present-day rate of global sea-level rise, remaining marshes in the Mississippi Delta are likely to drown, according to a new Tulane University study.

A key finding of the study, published in Science Advances, is that coastal marshes experience tipping points, where a small increase in the rate of sea-level rise leads to widespread submergence.

The loss of 2,000 square miles (5,000 km2) of wetlands in coastal Louisiana over the past century is well documented, but it has been more challenging to predict the fate of the remaining 6,000 square miles (15,000 km2) of marshland.

The study used hundreds of sediment cores collected since the early 1990s to examine how marshes responded to a range of rates of sea-level rise during the past 8,500 years.

"Previous investigations have suggested that marshes can keep up with rates of sea-level rise as high as half an inch per year (10 mm/yr), but those studies were based on observations over very short time windows, typically a few decades or less," said Torbjörn Törnqvist, lead author and Vokes Geology Professor in the Tulane Department of Earth and Environmental Sciences.

"We have taken a much longer view by examining marsh response more than 7,000 years ago, when global rates of sea-level rise were very rapid but within the range of what is expected later this century."

The researchers found that in the Mississippi Delta most marshes drown in a few centuries once the rate of sea-level rise exceeds about one-tenth of an inch per year (3 mm/yr). When the rate exceeds a quarter of an inch per year (7.5 mm/yr), drowning occurs in about half a century

"The scary thing is that the present-day rate of global sea-level rise, due to climate change, has already exceeded the initial tipping point for marsh drowning," Törnqvist said. "And as things stand right now, the rate of sea-level rise will continue to accelerate and put us on track for marshes to disappear even faster in the future."

Open Access: Torbjörn E. Törnqvist, et.al. Tipping points of Mississippi Delta marshes due to accelerated sea-level rise, Science Advances (2020)
https://advances.sciencemag.org/content/6/21/eaaz5512
“There are three classes of people: those who see. Those who see when they are shown. Those who do not see.” ― Leonardo da Vinci

Insensible before the wave so soon released by callous fate. Affected most, they understand the least, and understanding, when it comes, invariably arrives too late

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3225 on: May 24, 2020, 12:01:28 AM »
The linked article (extracted from the cited book) makes some good points about uncertainty and the burden of proof in the climate change debate:

Title: "Risk, doubt, and the burden of proof in the climate debate"

https://www.greenbiz.com/article/risk-doubt-and-burden-proof-climate-debate

Extract: "Excerpted from "Industrial-Strength Denial: Eight Stories of Corporations Defending the Indefensible, from the Slave Trade to Climate Change" by Barbara Freese, published by the University of California Press. © 2020 by the Regents of the University of California. The above is an affiliate link and we may get a small commission if you purchase from the site.
...

Whoever does not bear the burden of proof gets the benefit of the doubt and thus has an incentive to exaggerate or manufacture doubt."
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3226 on: May 25, 2020, 12:04:33 AM »
The linked open access reference indicates that rising CO2 is causing plants to lose less water throughout the Northern Hemisphere, including densely vegetated regions in the tropics and the midlatitudes. This process causes temperatures in these places to warm even more than they would from climate change alone.  Overall, the study estimates that the plant effect may account for nearly 10% of the Arctic’s warming each year. And it could explain as much as 28% of the warming across the Northern Hemisphere’s lower latitudes.  Furthermore, this feedback mechanism has was not includes in previous consensus climate model projections:

Park, S., Kim, J. & Kug, J. The intensification of Arctic warming as a result of CO2 physiological forcing. Nat Commun 11, 2098 (2020). https://doi.org/10.1038/s41467-020-15924-3

https://www.nature.com/articles/s41467-020-15924-3

Abstract: "Stomatal closure is one of the main physiological responses to increasing CO2 concentration, which leads to a reduction in plant water loss. This response has the potential to trigger changes in the climate system by regulating surface energy budgets—a phenomenon known as CO2 physiological forcing. However, its remote impacts on the Arctic climate system are unclear. Here we show that vegetation at high latitudes enhances the Arctic amplification via remote and time-delayed physiological forcing processes. Surface warming occurs at mid-to-high latitudes due to the physiological acclimation-induced reduction in evaporative cooling and resultant increase in sensible heat flux. This excessive surface heat energy is transported to the Arctic ocean and contributes to the sea ice loss, thereby enhancing Arctic warming. The surface warming in the Arctic is further amplified by local feedbacks, and consequently the contribution of physiological effects to Arctic warming represents about 10% of radiative forcing effects."
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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Tom_Mazanec

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3227 on: May 25, 2020, 10:25:02 AM »
AbruptSLR, it looks from your posts that Science is saying to us "No time left for you" tos get AGW under control.
As the Guess Who would say:

SHARKS (CROSSED OUT) MONGEESE (SIC) WITH FRICKIN LASER BEAMS ATTACHED TO THEIR HEADS

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3228 on: May 25, 2020, 03:51:01 PM »
While the thoughtful planting of trees is a good idea, the linked article points-out that the thoughtless mass planting of trees can do more harm than good.

Title: "Planting Trees Won’t Stop Climate Change"

https://slate.com/technology/2020/05/trees-dont-stop-climate-change.html

Extract: "The passion for planting trees comes partly from the fact that, in some places, they sequester carbon. This has been broadly interpreted to mean that festooning the Earth with trees will solve the problem of climate change, which is why tree-planting programs are so popular with carbon polluters seeking to avoid cleanup costs. President Donald Trump, for example, instantly embraced the One Trillion Tree Initiative launched in January by the World Economic Forum, pledged U.S. participation, and then gushed about it in his State of the Union address: “To protect the environment, days ago, I announced that the United States will join the One Trillion Tree Initiative, an ambitious effort to bring together government and the private sector to plant new trees in America and around the world.”

Planting trees can be beneficial, especially in countries where predatory logging and other land abuse has destroyed soil stability and deprived people of shade, clean water, fish, and fruit. But such initiatives are the exception. Mass plantings are apt to do more harm than good. And it’s nearly impossible to distinguish decent projects from bad ones."
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3229 on: May 25, 2020, 11:02:38 PM »
People need to realize that not only are the probability of cascading climate net positive feedback mechanisms increasing, but also the risk of cascading climate impacts as cited in the linked reference:

Judy Lawrence, Paula Blackett and Nicholas A. Cradock-Henry (30 April 2020), "Cascading climate change impacts and implications", Climate Risk Management, https://doi.org/10.1016/j.crm.2020.100234

https://www.sciencedirect.com/science/article/pii/S2212096320300243

Abstract: "Climate change is expected to have adverse impacts and implications for a range of human-environment systems. However, our understanding of the extent to which these impacts may propagate as cascades, compounding to form multiple impacts across sectors, is limited. Cascades result from interdependencies between systems and sub-systems of coupled natural and socio-economic systems in response to changes and feedback loops. The combined effects of interacting stressors may affect the ability of individuals, governments, and the private sector to adapt in time, before widespread damage occurs. We discuss the origins of cascading impacts thinking and present the results of an investigation of cascading impacts and implications in New Zealand. A participatory and collaborative approach was used through workshops and semi-structured interviews with sector informants, including engineers, local government staff, and financial risk managers and analysts from the financial services sectors. Qualitative data collection was combined with network and systems analysis to examine increased frequency of high-intensity rainfall events, sea-level rise and drought, across urban water infrastructure and the financial services, and the implications of cascading climate change impacts for governance. Results demonstrate that closer consideration of the combined effects of linked stressors can facilitate a better understanding of the scope and scale of climate change impacts. By using critical systems thinking in characterising and assessing how climate change impacts cascade across domains, we show the implications of cascades for their governance and reveal where climate change adaptation interventions might be focused. The research methods and insights into cascades provide a conceptual and practical basis for further development, which can inform the design of additional studies in other domains and jurisdictions."
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3230 on: May 25, 2020, 11:57:43 PM »
The linked article, and associated reference, project that the rate change of deep ocean 'climate velocity' will accelerate about 11 times before the end of the century:

Title: "The deep ocean is warming slowly—but dramatic changes are ahead"

https://phys.org/news/2020-05-deep-ocean-slowlybut.html

Extract: "The research, led by University of Queensland Ph.D. student Isaac Brito-Morales, looked at how ocean life was responding to climate change.

"We used a metric known as climate velocity which defines the likely speed and direction a species shifts as the ocean warms," Mr Brito-Morales said.

"We calculated the climate velocity throughout the ocean for the past 50 years and then for the rest of this century using data from 11 climate models.

"This allowed us to compare climate velocity in four ocean depth zones—assessing in which zones biodiversity could shift their distribution the most in response to climate change."

The researchers found climate velocity is currently twice as fast at the surface because of greater surface warming, and as a result deeper-living species are less likely to be at risk from climate change than those at the surface.

"However by the end of the century, assuming we have a high-emissions future, there is not only much greater surface warming, but also this warmth will penetrate deeper," Mr Brito-Morales said.

"In waters between a depth of 200 and 1000 metres, our research showed climate velocities accelerated to 11 times the present rate."

See also:

Climate velocity reveals increasing exposure of deep-ocean biodiversity to future warming, Nature Climate Change (2020). DOI: 10.1038/s41558-020-0773-5

www.nature.com/articles/s41558-020-0773-5

Abstract: "Slower warming in the deep ocean encourages a perception that its biodiversity is less exposed to climate change than that of surface waters. We challenge this notion by analysing climate velocity, which provides expectations for species’ range shifts. We find that contemporary (1955–2005) climate velocities are faster in the deep ocean than at the surface. Moreover, projected climate velocities in the future (2050–2100) are faster for all depth layers, except at the surface, under the most aggressive GHG mitigation pathway considered (representative concentration pathway, RCP 2.6). This suggests that while mitigation could limit climate change threats for surface biodiversity, deep-ocean biodiversity faces an unavoidable escalation in climate velocities, most prominently in the mesopelagic (200–1,000 m). To optimize opportunities for climate adaptation among deep-ocean communities, future open-ocean protected areas must be designed to retain species moving at different speeds at different depths under climate change while managing non-climate threats, such as fishing and mining."

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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3231 on: May 26, 2020, 03:18:09 AM »
The linked article was published in a magazine focused on explaining ethics in the news and culture called: "The Prindle Post".  I think that it does a good job of explaining the role of scientific reticence in increasing risks from climate change:

Title: "Why Isn’t Everybody Panicking? Scientific Reticence and the Duty to Scare People"

https://www.prindlepost.org/2020/01/why-isnt-everybody-panicking-scientific-reticence-and-the-duty-to-scare-people/

Extract: "There is an epistemic failure occurring: people in the affluent, industrialized world do not, in general, appear to know how bad the climate crisis is, and do not, in general, appear to appreciate how much worse things will get if we continue to burn fossil fuels and pollute the atmosphere.
...
Doubtless, part of the knowledge difficulty, the epistemic deficit, is a form of cognitive dissonance. It is hard to imagine the scale of the problem. “Climate induced societal collapse is now inevitable in the near term” writes Professor of Sustainability Jem Bendell, “it may be too late to avert environmental catastrophe.” Part of the problem is that this does in fact sound like a crazy dystopian fiction.

This failure of the imagination is related to the problem of scientific reticence, which some have recently argued is having an adverse effect on policy action, and is even a dereliction of an ethical duty to seriously entertain possible, but extreme, scenarios. Scientific reticence arises both methodologically and stylistically. It takes the form of a tendency to understate the risks of global warming.
...
In their paper What Lies Beneath, which explores the failures and blind spots of climate science’s understanding of the effects of global warming, Spratt and Dunlop write: “It is now becoming dangerously misleading, given the acceleration of climate impacts globally. What were lower-probability, higher-impact events are now becoming more likely.

Scientific reticence has hindered communication to the public of the true dangers of global warming. This may in turn have directly (and indirectly) hindered action, which in turn has worsened the problem. Given that the findings of climate science research have existential implications for us, it could be argued that not entertaining the worst potential outcomes is a dereliction of moral duty as well as our duty to science.

There is a view that it is dangerous to frighten people too much, that the relevant information and worst risks worth considering are enough to scare the public into a sense of fatalism. Indeed, the news is bad, and at this critical time, resignation may be the last nail in the coffin (so to speak).
...
People aren’t scared enough about global warming. It is, as Wallace-Wells says, worse than people think – and though it may not be as bad as his picture, the trend so far points in that direction.”

See also:

https://www.prindleinstitute.org/about/about-prindle/
« Last Edit: May 26, 2020, 03:31:27 AM by AbruptSLR »
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3232 on: May 26, 2020, 03:29:49 AM »

People aren’t scared enough about global warming. It is, as Wallace-Wells says, worse than people think – and though it may not be as bad as his picture, the trend so far points in that direction.”

It is much worse than Wallace-Wells, so this article is guilty of hopium.
There is a principle which is a bar against all information, which cannot fail to keep a man in everlasting ignorance. That principle is contempt prior to investigation. - Herbert Spencer

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3233 on: May 26, 2020, 06:49:05 AM »
The linked article, and associated reference, project that the rate change of deep ocean 'climate velocity' will accelerate about 11 times before the end of the century:

Title: "The deep ocean is warming slowly—but dramatic changes are ahead"

https://phys.org/news/2020-05-deep-ocean-slowlybut.html


I'd love to see the precise defintion of climate velocity. This quote doesn't give it:  "We used a metric known as climate velocity which defines the likely speed and direction a species shifts as the ocean warms,..."

And also which species will be most affected.

The research article is paywalled.

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3234 on: May 26, 2020, 09:25:28 AM »
"The research article is paywalled."
Here you go Hefaistos: https://sci-hub.tw/10.1038/s41558-020-0773-5
"It is preoccupation with possessions, more than anything else, that prevents us from living freely and nobly" - Bertrand Russell
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3235 on: May 27, 2020, 02:43:17 AM »
Don't forget that the oceans are also running low on oxygen, as discussed in the linker article:

Title: "Climate change: Oceans running out of oxygen as temperatures rise"

https://www.bbc.com/news/science-environment-50690995

Extract: "As more carbon dioxide is released enhancing the greenhouse effect, much of the heat is absorbed by the oceans. In turn, this warmer water can hold less oxygen. The scientists estimate that between 1960 and 2010, the amount of the gas dissolved in the oceans declined by 2%.

That may not seem like much as it is a global average, but in some tropical locations the loss can range up to 40%."
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3236 on: May 27, 2020, 04:35:48 AM »
The linked reference presents research based on Short-Range weather forecasts that support the HadGEM3‐GC3.1 model projection that ECS is on the order of 5.5C.

K. D. Williams, A. J. Hewitt and A. Bodas‐Salcedo (23 March 2020), "Use of Short‐Range Forecasts to Evaluate Fast Physics Processes Relevant for Climate Sensitivity", JAMES, https://doi.org/10.1029/2019MS001986

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019MS001986

Abstract:
The configuration of the Met Office Unified Model being submitted to CMIP6 has a high climate sensitivity. Previous studies have suggested that the impact of model changes on initial tendencies in numerical weather prediction (NWP) should be used to guide their suitability for inclusion in climate models. In this study we assess, using NWP experiments, the atmospheric model changes which lead to the increased climate sensitivity in the CMIP6 configuration, namely, the replacement of the aerosol scheme with GLOMAP‐mode and the introduction of a scheme for representing the turbulent production of liquid water within mixed‐phase cloud. Overall, the changes included in this latest configuration were found to improve the initial tendencies of the model state variables over the first 6 hr of the forecast, this timescale being before significant dynamical feedbacks are likely to occur. The reduced model drift through the forecast appears to be the result of increased cloud liquid water, leading to enhanced radiative cooling from cloud top and contributing to a stronger shortwave cloud radiative effect. These changes improve the 5‐day forecast in traditional metrics used for numerical weather prediction. This study was conducted after the model was frozen and the climate sensitivity of the model determined; hence, it provides an independent test of the model changes contributing to the higher climate sensitivity. The results, along with the large body process‐orientated evaluation conducted during the model development process, provide reassurance that these changes are improving the physical processes simulated by the model.

Plain Language Summary

Climate sensitivity is a leading order measure of the climate system. The latest Met Office model has a higher climate sensitivity than its predecessor and many other models, so warrants additional tests. Here we follow a published method to test in weather forecast mode, model changes contributing to the higher climate sensitivity. The model changes increasing the climate sensitivity are found to improve the short‐range weather forecast and reduce the error growth over the first few hours of the forecast which is a measure of the error in the local physical processes. This increases our confidence that the model changes contributing to the higher sensitivity are improving the physical realism of the model.

See also:

Title: "Short-term tests validate long-term estimates of climate change"

https://www.nature.com/articles/d41586-020-01484-5

Extract: "The authors found that the 6-hour-forecast errors were smaller for the revised model than for a version of the model without the cloud-microphysics revisions. Hence, instead of being able to discount estimates of high sensitivity, as Rodwell and I had done, their result provides some of the best current evidence that climate sensitivity could indeed be 5 °C or greater."
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3237 on: May 27, 2020, 07:10:55 PM »
Even though the ASIF keep close tabs on daily/hourly observations of Arctic sea ice extent (SIE); nevertheless, it is useful to note that the linked reference provides data points about the dramatic decline in Arctic SIE over the past 4 decades through 2019:

Yadav, J., Kumar, A. & Mohan, R. Dramatic decline of Arctic sea ice linked to global warming. Nat Hazards (2020). https://doi.org/10.1007/s11069-020-04064-y

https://link.springer.com/article/10.1007/s11069-020-04064-y

Abstract
Arctic sea ice has declined rapidly over the past four decades at the rate of − 4.7% per decade leading to an imbalance in the oceanic heat flux. The study reported that the July 2019 was the warmest month in the Arctic, leading to a substantial sea ice loss in the last 41 years. Consequently, during this month, the lowest sea ice extent (SIE, 7.5 million km2) and sea ice volume (8900 km3) were recorded. The decadal trend of sea ice decline in September 2019 has reached to ca. − 13% per decade. The latest record shows that average SIE during summer 2019 (5.65 million km2) has set a new lowest record after 2012 (5.32 million km2), since the sea ice formation process has been largely hampered during the summer months. The study reveals that the land–ocean warming processes intensifying the sea ice loss and also leading in disruption of the global ocean circulation.
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3238 on: May 27, 2020, 07:16:12 PM »
The linked reference discusses the 40-year record high surface melting that occurred on the Larsen C Ice Shelf during February 2020.  If such events happen with increased frequency, and/or magnitude, in near future then it is possible that the Larsen C Ice Shelf could break apart abruptly in the coming years:

Bevan, S., Luckman, A., Hendon, H., and Wang, G.: 2020 Larsen C Ice Shelf surface melt is a 40-year record high, The Cryosphere Discuss., https://doi.org/10.5194/tc-2020-130, in review, 2020.

https://www.the-cryosphere-discuss.net/tc-2020-130/

Abstract. Along with record-breaking summer air temperatures at two Antarctic Peninsula meteorological stations in February 2020, the Larsen C ice shelf experienced an exceptionally long and extensive 2019/2020 melt season. We use a 40-year time series of passive and scatterometer satellite microwave data, which is sensitive to the presence of liquid water in the snow pack, to reveal that the extent and duration of melt observed on the ice shelf in the austral summer of 2019/2020 was the greatest on record. We find that unusual perturbations to southern hemisphere modes of atmospheric flow, including a persistently positive Indian Ocean Dipole in the spring and a very rare southern hemisphere sudden stratospheric warming in September 2019, preceded the exceptionally warm Antarctic Peninsula summer. It is likely that tele-connections between the tropics and southern high latitudes were able to bring sufficient heat via the atmosphere and ocean to the Antarctic Peninsula to drive the extreme Larsen C Ice Shelf melt. The record breaking melt of 2019/2020 brought to an end the trend of decreasing melt that had begun in 1999/2000, and will re-initiate earlier thinning of the ice shelf by depletion of the firn air content.
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3239 on: May 27, 2020, 07:25:30 PM »
The linked reference provides evidence that the combination of climate change and deforestation has led to a feedback loop that has/is decreasing the amount of isoprene (BVOC) emitted by Amazonia.  This is not good new as BVOC emissions promote low altitude cloud formation that both provide the Amazon rainforest with precipitation, but also that provide a negative feedback for radiative forcing.

A.M. Yáñez‐Serrano et al. (23 May 2020), "Amazonian Biogenic Volatile Organic Compounds under Global Change", Global Change Biology, https://doi.org/10.1111/gcb.15185

https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.15185?af=R

Abstract
Biogenic volatile organic compounds (BVOCs) play important roles at cellular, foliar, ecosystem, and atmospheric levels. The Amazonian rainforest represents one of the major global sources of BVOCs, so its study is essential for understanding BVOC dynamics. It also provides insights into the role of such large and biodiverse forest ecosystem in regional and global atmospheric chemistry and climate. We review the current information on Amazonian BVOCs and identify future research priorities exploring biogenic emissions and drivers, ecological interactions, atmospheric impacts, depositional processes, and modifications to BVOC dynamics due to changes in climate and land cover. A feedback loop between Amazonian BVOCs and the trends of climate and land‐use changes in Amazonia is then constructed. Satellite observations and model simulation time series demonstrate the validity of the proposed loop showing a combined effect of climate change and deforestation on BVOC emission in Amazonia. A decreasing trend of isoprene during the wet season, most likely due to forest biomass loss, and an increasing trend of the sesquiterpene to isoprene ratio during the dry season, suggest increasing temperature stress induced emissions due to climate change.
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3240 on: May 27, 2020, 07:42:08 PM »
The linked reference confirms that the CMIP6 models project a significant decline of the AMOC this century, and I note that the CMIP6 projections to not consider the impacts of significant freshwater hosing events that might occur this century such as a partial collapse of the WAIS and/or a flux of relatively freshwater from the Beaufort Gyre.  A slowing of the AMOC slows the MOC; which results in increased SSTAs in the tropical regions that leads to more evaporation that leads to more high altitude cloud formations that leads to higher ECS values in the coming decades:

W. Weijer et al. (24 May 2020), "CMIP6 Models Predict Significant 21st Century Decline of the Atlantic Meridional Overturning Circulation", Geophysical Research Letters, https://doi.org/10.1029/2019GL086075

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019GL086075?af=R

Abstract
We explore the representation of the Atlantic Meridional Overturning Circulation (AMOC) in 27 models from the CMIP6 multi‐model ensemble. Comparison with RAPID and SAMBA observations suggests that the ensemble mean represents the AMOC strength and vertical profile reasonably well. Linear trends over the entire historical period (1850‐2014) are generally neutral, but many models exhibit an AMOC peak around the 1980's. Ensemble‐mean AMOC decline in future (SSP) scenarios is stronger in CMIP6 than CMIP5 models. In fact, AMOC decline in CMIP6 is surprisingly insensitive to the scenario at least up to 2060. We find an emergent relationship among a majority of models between AMOC strength and 21st century AMOC decline. Constraining this relationship with RAPID observations suggests that the AMOC might decline between 6 and 8 Sv (34‐45%) by 2100. A smaller group of models projects much less AMOC weakening of only up to 30%.

Plain Language Summary
The Atlantic Meridional Overturning Circulation (AMOC) is a circulation pattern in the Atlantic Ocean that is an important component of the climate system, due to its ability to redistribute and sequester heat and carbon. An accurate representation of the AMOC is a critical test for climate models and essential for building confidence in their projections. Here we investigate the AMOC in 27 climate models that contributed simulations to the Coupled Model Intercomparison Project phase 6 (CMIP6). We find that many models reproduce the observed AMOC quite well, but there are still several models in which the AMOC is too weak or too strong. Most models suggest a slight upward trend in the AMOC from 1850 to the 1980's. Simulations representing different scenarios for future socioeconomic development suggest a stronger AMOC decline compared to previous assessments. Using direct measurements of the AMOC since 2004 and an emerging across‐model relationship between AMOC decline in the 21st century and their present‐day mean state, we find that the majority of CMIP6 models point to an end of century AMOC weakening of 34%‐45% of its present‐day strength. A smaller group of models projects much less weakening of only up to 30% of its present state.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3241 on: May 27, 2020, 07:50:56 PM »
The linked reference indicates that with regard to a parameterization for secondary ice production (SIP) in clouds associate with the break-up (BR) from collisions between ice particles:

"The BR mechanism is currently not represented in most weather prediction and climate models; including this process can have a significant impact on the Antarctic radiation budget and thus in projections of the future regional climate."

If is not good to have the Antarctic radiation budget poorly modelled by consensus climate projections, so decision makers may be subjected to some unpleasant surprises in the coming decades, both w.r.t. climate sensitivity (from cloud feedback) and/or from Antarctic ice mass loss:

Sotiropoulou, G., Vignon, E., Young, G., Morrison, H., O'Shea, S. J., Lachlan-Cope, T., Berne, A., and Nenes, A.: Secondary ice production in summer clouds over the Antarctic coast: an underappreciated process in atmospheric models, Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-328, in review, 2020.

https://www.atmos-chem-phys-discuss.net/acp-2020-328/

Abstract. The correct representation of Antarctic clouds in atmospheric models is crucial for accurate projections of the future Antarctic climate. This is particularly true for summer clouds which play a critical role in the surface melting of the ice-shelf in the vicinity of Weddell Sea. However these clouds are often poorly represented, as ice crystal number concentrations (ICNCs) are undepredicted by atmospheric models, even when primary ice formation is constrained with aerosol measurements. Rime-splintering, thought to be the dominant secondary ice production (SIP) mechanism at temperatures between −8 and −3 °C, is also very weak in summer Antarctic conditions. Including a parameterization for SIP due to break-up (BR) from collisions between ice particles in the Weather and Research Forecasting model bridges the gap between observations and simulations, suggesting that BR could account for the enhanced ICNCs in the pristine Antarctic atmosphere. These results are insensitive to uncertainties in primary ice production. The BR mechanism is currently not represented in most weather prediction and climate models; including this process can have a significant impact on the Antarctic radiation budget and thus in projections of the future regional climate.
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3242 on: May 28, 2020, 03:43:53 AM »
The linked scientific article indicates that atmospheric ozone loss associated with global warming can (& has in the past) lead to mass extinction:

Title: "No asteroids needed: ancient mass extinction tied to ozone loss, warming climate"

https://www.sciencemag.org/news/2020/05/no-asteroids-or-volcanoes-needed-ancient-mass-extinction-tied-ozone-loss-warming

Extract: "Scientists have long believed—at least before humanity became a force for extinction—that there were just two ways to wipe out life on Earth: an asteroid strike or massive volcanic eruptions. But 2 years ago, researchers found evidence that in Earth’s worst extinction—the end-Permian, 252 million years ago—volcanoes lofted Siberian salt deposits into the stratosphere, where they might have fed chemical reactions that obliterated the ozone layer and sterilized whole forests. Now, spores from the end-Devonian make a compelling case that, even without eruptions, a warming climate can deplete the ozone layer, says Lauren Sallan, a paleobiologist at the University of Pennsylvania. “Because the evidence is so strong, it will make people rethink other mass extinction events.”"
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3243 on: May 28, 2020, 09:17:52 PM »
Antarctic Ice Sheets Capable of Retreating Up to 50 Meters per Day
https://phys.org/news/2020-05-antarctic-ice-sheets-capable-retreating.html



The ice shelves surrounding the Antarctic coastline retreated at speeds of up to 50 metres per day at the end of the last Ice Age, far more rapid than the satellite-derived retreat rates observed today, new research has found.

The study, led by the Scott Polar Research Institute at the University of Cambridge, used patterns of delicate wave-like ridges on the Antarctic seafloor to calculate how quickly the ice retreated roughly 12,000 years ago during regional deglaciation.

The ridges were produced where the ice sheet began to float, and were caused by the ice squeezing the sediment on the seafloor as it moved up and down with the movement of the tides. The images of these landforms are at unprecedented sub-metre resolution and were acquired from an autonomous underwater vehicle (AUV) operating about 60 metres above the seabed. The results are reported in the journal Science.

... Using drones, satellites and AUVs, the researchers were able to study ice conditions in the Weddell Sea in unprecedented detail.

Their goals were to investigate the present and past form and flow of the ice shelves, the massive floating sections of ice that skirt about 75% of the Antarctic coastline, where they act as a buttress against ice flow from inland.

The team identified a series of delicate wave-like ridges on the seafloor, each only about one metre high and spaced 20 to 25 metres apart, dating to the end of the last great deglaciation of the Antarctic continental shelf, roughly 12,000 years ago. The researchers have interpreted these ridges as formed at what was formerly the grounding line—the zone where grounded ice sheet begins to float as an ice shelf.

The researchers inferred that these small ridges were caused by the ice moving up and down with the tides, squeezing the sediment into well-preserved geological patterns, looking a little like the rungs of a ladder, as the ice retreated. Assuming a standard 12-hour cycle between high and low tide, and measuring the distance between the ridges, the researchers were then able to determine how fast the ice was retreating at the end of the last Ice Age.

They calculated that the ice was retreating as much as 40 to 50 metres per day during this period, a rate that equates to more than 10 kilometres per year. In comparison, modern satellite images show that even the fastest-retreating grounding lines in Antarctica today, for example in Pine Island Bay, are much slower than these geological observations, at only about 1.6 kilometres per year.

"The deep marine environment is actually quite quiet offshore of Antarctica, allowing features such as these to be well-preserved through time on the seafloor," said Dowdeswell. "We now know that the ice is capable of retreating at speeds far higher than what we see today. Should climate change continue to weaken the ice shelves in the coming decades, we could see similar rates of retreat, with profound implications for global sea level rise."

J.A. Dowdeswell el al., "Delicate seafloor landforms reveal past Antarctic grounding-line retreat of kilometers per year," Science (2020).
https://science.sciencemag.org/cgi/doi/10.1126/science.aaz3059

"Tracking the rapid pace of a retreating ice sheet," Science (2020)
https://science.sciencemag.org/cgi/doi/10.1126/science.abc3583
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3244 on: May 29, 2020, 05:51:30 PM »
The linked reference presents research based on Short-Range weather forecasts that support the HadGEM3‐GC3.1 model projection that ECS is on the order of 5.5C.

K. D. Williams, A. J. Hewitt and A. Bodas‐Salcedo (23 March 2020), "Use of Short‐Range Forecasts to Evaluate Fast Physics Processes Relevant for Climate Sensitivity", JAMES, https://doi.org/10.1029/2019MS001986

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019MS001986

Abstract:
The configuration of the Met Office Unified Model being submitted to CMIP6 has a high climate sensitivity. Previous studies have suggested that the impact of model changes on initial tendencies in numerical weather prediction (NWP) should be used to guide their suitability for inclusion in climate models. In this study we assess, using NWP experiments, the atmospheric model changes which lead to the increased climate sensitivity in the CMIP6 configuration, namely, the replacement of the aerosol scheme with GLOMAP‐mode and the introduction of a scheme for representing the turbulent production of liquid water within mixed‐phase cloud. Overall, the changes included in this latest configuration were found to improve the initial tendencies of the model state variables over the first 6 hr of the forecast, this timescale being before significant dynamical feedbacks are likely to occur. The reduced model drift through the forecast appears to be the result of increased cloud liquid water, leading to enhanced radiative cooling from cloud top and contributing to a stronger shortwave cloud radiative effect. These changes improve the 5‐day forecast in traditional metrics used for numerical weather prediction. This study was conducted after the model was frozen and the climate sensitivity of the model determined; hence, it provides an independent test of the model changes contributing to the higher climate sensitivity. The results, along with the large body process‐orientated evaluation conducted during the model development process, provide reassurance that these changes are improving the physical processes simulated by the model.

Plain Language Summary

Climate sensitivity is a leading order measure of the climate system. The latest Met Office model has a higher climate sensitivity than its predecessor and many other models, so warrants additional tests. Here we follow a published method to test in weather forecast mode, model changes contributing to the higher climate sensitivity. The model changes increasing the climate sensitivity are found to improve the short‐range weather forecast and reduce the error growth over the first few hours of the forecast which is a measure of the error in the local physical processes. This increases our confidence that the model changes contributing to the higher sensitivity are improving the physical realism of the model.

See also:

Title: "Short-term tests validate long-term estimates of climate change"

https://www.nature.com/articles/d41586-020-01484-5

Extract: "The authors found that the 6-hour-forecast errors were smaller for the revised model than for a version of the model without the cloud-microphysics revisions. Hence, instead of being able to discount estimates of high sensitivity, as Rodwell and I had done, their result provides some of the best current evidence that climate sensitivity could indeed be 5 °C or greater."

To state the obvious, the findings of this research implies that ECS is currently about 5.5C, and that the activation of any feedback tipping points going forward (such as an abrupt slowing of the MOC, a collapse of the Amazon rainforest, etc.) would increase ECS in coming decades.
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3245 on: May 30, 2020, 12:56:48 AM »
Hopefully, the research about Thwaites in the linked article will be published soon so that we can read about what they learned by sending a AUV far beneath the Thwaites ice shelf:

Title: "Venturing beneath the Antarctic ice with an autonomous vessel"

https://www.createdigital.org.au/venturing-beneath-antarctic-ice-with-autonomous-vessel/

Extract: "It is fast by the standards of glaciers — with a surface speed over 2 km per year — but it is also fast-melting, which is what is so worrying about it. The Earth’s warming climate has already ensured that Thwaites Glacier, as it is officially called, contributes four per cent of the world’s annual sea level rise.

The Autonomous Underwater Vehicle (AUV) Facility Coordinator at the University of Tasmania’s Australian Maritime College, King has spent the past four years working on nupiri muka, a fully autonomous vessel designed to venture deep beneath the Antarctic ice, gather data, then return to report its findings to researchers.

“The AUV team and the AUV and all the equipment were all mobilised on to their icebreaker,” he said of KOPRI.

“You’ve got this layer of ice that’s hundreds to thousands of metres thick and you don’t know anything about the water underneath it, then the water underneath that is really the critical component. So, when you offer up an ability to take the sensors and actually deliver them to the hotspot, it’s an amazing piece of technology, and you can see why the risk is certainly worth the reward.”"

“We spent two months with them down south and were given an opportunity to deploy our AUV down in the Thwaites Glacier area.”
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3246 on: May 30, 2020, 03:35:09 AM »
The linked reference indicates that PAMIP is working in a coordinated way with CMIP6 to improve future modeling of the causes and consequences of polar amplification.  The more we know about the various building blocks of climate sensitivity (including polar amplification) the sooner we will know how much confidence to have in the relatively high values of ECS projected by CMIP6:

Smith, D. M., Screen, J. A., Deser, C., Cohen, J., Fyfe, J. C., García-Serrano, J., Jung, T., Kattsov, V., Matei, D., Msadek, R., Peings, Y., Sigmond, M., Ukita, J., Yoon, J.-H., and Zhang, X.: The Polar Amplification Model Intercomparison Project (PAMIP) contribution to CMIP6: investigating the causes and consequences of polar amplification, Geosci. Model Dev., 12, 1139–1164, https://doi.org/10.5194/gmd-12-1139-2019, 2019.

https://www.geosci-model-dev.net/12/1139/2019/

Abstract
Polar amplification – the phenomenon where external radiative forcing produces a larger change in surface temperature at high latitudes than the global average – is a key aspect of anthropogenic climate change, but its causes and consequences are not fully understood. The Polar Amplification Model Intercomparison Project (PAMIP) contribution to the sixth Coupled Model Intercomparison Project (CMIP6; Eyring et al., 2016) seeks to improve our understanding of this phenomenon through a coordinated set of numerical model experiments documented here. In particular, PAMIP will address the following primary questions: (1) what are the relative roles of local sea ice and remote sea surface temperature changes in driving polar amplification? (2) How does the global climate system respond to changes in Arctic and Antarctic sea ice? These issues will be addressed with multi-model simulations that are forced with different combinations of sea ice and/or sea surface temperatures representing present-day, pre-industrial and future conditions. The use of three time periods allows the signals of interest to be diagnosed in multiple ways. Lower-priority tier experiments are proposed to investigate additional aspects and provide further understanding of the physical processes. These experiments will address the following specific questions: what role does ocean–atmosphere coupling play in the response to sea ice? How and why does the atmospheric response to Arctic sea ice depend on the pattern of sea ice forcing? How and why does the atmospheric response to Arctic sea ice depend on the model background state? What have been the roles of local sea ice and remote sea surface temperature in polar amplification, and the response to sea ice, over the recent period since 1979? How does the response to sea ice evolve on decadal and longer timescales?

A key goal of PAMIP is to determine the real-world situation using imperfect climate models. Although the experiments proposed here form a coordinated set, we anticipate a large spread across models. However, this spread will be exploited by seeking “emergent constraints” in which model uncertainty may be reduced by using an observable quantity that physically explains the intermodel spread. In summary, PAMIP will improve our understanding of the physical processes that drive polar amplification and its global climate impacts, thereby reducing the uncertainties in future projections and predictions of climate change and variability.


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Hefaistos

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3247 on: May 30, 2020, 02:28:57 PM »

To state the obvious, the findings of this research implies that ECS is currently about 5.5C, ...

There is nothing obvious about those unbelievably high ECS values of the current generation of GCM's, the CMIP6 models.

The following highly critical  paper evaluates the differences between CMIP5 and CMIP6 model generations.
From the abstract: "...Here we show that the closely related effective climate sensitivity has increased substantially in Coupled Model Intercomparison Project phase 6 (CMIP6), with values spanning 1.8–5.6 K across 27 GCMs and exceeding 4.5 K in 10 of them. This (statistically insignificant) increase is primarily due to stronger positive cloud feedbacks from decreasing extratropical low cloud coverage and albedo. Both of these are tied to the physical representation of clouds which in CMIP6 models lead to weaker responses of extratropical low cloud cover and water content to unforced variations in surface temperature. "

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019GL085782

Attached figure from the same paper shows that almost all differences between the two model generations are attributable to the way that the models are handling clouds and water vapor. Low cloud water content and coverage decrease more strongly with global warming, causing enhanced planetary absorption of sunlight—an amplifying feedback that ultimately results in more warming.

The factual development is on the other hand that global cloud cover has been slowly increasing over the last decades, not decreasing.

We can't even say for sure that clouds are a positive feedback. (Most of the 27 evaluated models have a +ve feedbakc , but 2 have a -ve feedback). The basic physics says that clouds are a negative feedback. NOAA says:   "The cloud radiative effect (CRE) on the Earth’s present-day radiation budget can be inferred from satellite data by comparing upwelling radiation in cloudy and non-cloudy regions. The figure at right shows that cloud conditions exert a global and annual SW CRE of approximately -50 W/m2 and a mean LW CRE of approximate 30 W/m2. The net global mean CRE is approximately -20 W/m2 implying a strong net cooling effect of clouds on the current climate. Given the large magnitude of SW and LW CRE, clouds have the potential to cause significant climate feedback."
The issue of cloud feedback is much more complex than that, but the starting point is actually a -ve feedback.

From the papers' Conclusions: "While some high ECS models closely match the observed record (e.g., Gettelman et al., 2019), others do not (e.g., Golaz et al., 2019). Do the former models achieve their results via unreasonably large negative aerosol forcings and/or substantial pattern effects (Kiehl, 2007; Stevens et al., 2016)? It is worth noting that cloud feedbacks are enhanced in CMIP6 primarily over the Southern Ocean, a region of efficient ocean heat uptake (Armour et al., 2016). This implies that the enhanced surface SW heating is less likely to manifest as surface warming during transient climate change than if the heating were focused elsewhere (Frey et al., 2017). This cloud feedback pattern could make it easier for high ECS models to simulate the observed surface temperature record without requiring a large negative aerosol radiative forcing or large historical era pattern effects."

This conclusion raises the issue that the unbelievably high ECS models are manipulated in a false way as a means to achieve a goal, namely the high ECS value.
What's obvious, is that these latest "bottom up" models still are unable to properly handle the feedback of clouds and water vapor.

https://www.gfdl.noaa.gov/cloud-radiative-effect/

Figure byline: "Figure S7. Contributions of forcing and feedbacks to ECS in each model and for the multi-
model means. Contributions from the tropical and extratropical portion of the feedback are shown
in light and dark shading, respectively. Black dots indicate the ECS in each model, while upward
and downward pointing triangles indicate contributions from non-cloud and cloud feedbacks,
respectively. Numbers printed next to the multi-model mean bars indicate the cumulative sum
of each plotted component. Numerical values are not printed next to residual, extratropical
forcing, and tropical albedo terms for clarity. Models within each collection are ordered by ECS."
« Last Edit: May 30, 2020, 02:35:59 PM by Hefaistos »

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3248 on: May 30, 2020, 05:34:38 PM »
The linked (open access) reference discusses pervasive, and disturbing, shifts in forest dynamics in a warming world:

Nate G. McDowell et al. (29 May 2020), "Pervasive shifts in forest dynamics in a changing world", Science, Vol. 368, Issue 6494, eaaz9463, DOI: 10.1126/science.aaz9463

https://science.sciencemag.org/content/368/6494/eaaz9463.full

Abstract
Forest dynamics arise from the interplay of environmental drivers and disturbances with the demographic processes of recruitment, growth, and mortality, subsequently driving biomass and species composition. However, forest disturbances and subsequent recovery are shifting with global changes in climate and land use, altering these dynamics. Changes in environmental drivers, land use, and disturbance regimes are forcing forests toward younger, shorter stands. Rising carbon dioxide, acclimation, adaptation, and migration can influence these impacts. Recent developments in Earth system models support increasingly realistic simulations of vegetation dynamics. In parallel, emerging remote sensing datasets promise qualitatively new and more abundant data on the underlying processes and consequences for vegetation structure. When combined, these advances hold promise for improving the scientific understanding of changes in vegetation demographics and disturbances.

Caption: "Fig. 3 Drivers, disturbances, and demographics are changing both historically and into the future.
A graphical summary of the literature evidence of changing drivers and disturbances (left-hand column) and subsequent demographic rates (right-hand column). Shown are the chronically changing drivers (A and B) CO2 and (C and D) VPD and temperature, as well as the more transient disturbances of (E and F) drought (low precipitation), (G and H) deforestation, (I and J) wildfire, (K and L) wind, and (M and N) insect outbreaks. Each driver or disturbance’s corresponding demographic responses (shown as carbon fluxes per unit area over time) are shown in the corresponding right-hand panels.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #3249 on: May 30, 2020, 05:54:08 PM »
The three attached images were captured today from the UK Met Office Climate Dashboard (see link).  They all indicate disturbing trends in GHG concentrations, and Earth System responses to increasing radiative forcing

https://www.metoffice.gov.uk/hadobs/monitoring/dashboard.html
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson