Conservative Scientists & its Consequences

[AbruptSLR]

The linked assessment report for the year 2014 indicates that climate change is progressing relatively rapidly compared to prior assessments:

http://www.noaanews.noaa.gov/stories2015/071615-international-report-confirms-2014-was-earths-warmest-year-on-record.html

See also:
https://news.vice.com/article/any-way-you-look-at-it-this-government-report-on-climate-change-is-really-bad-news

[AbruptSLR]

The linked reference discusses a path forward for hopefully reducing the uncertainty of cloud and circulation influence on equilibrium climate sensitivity:

Sandrine Bony, Bjorn Stevens, Dargan M. W. Frierson, Christian Jakob, Masa Kageyama, Robert Pincus, Theodore G. Shepherd, Steven C. Sherwood, A. Pier Siebesma, Adam H. Sobel, Masahiro Watanabe & Mark J. Webb (2015), "Clouds, circulation and climate sensitivity", Nature Geoscience, Volume: 8, Pages: 261–268, doi:10.1038/ngeo2398


http://www.nature.com/ngeo/journal/v8/n4/full/ngeo2398.html


Abstract: "Fundamental puzzles of climate science remain unsolved because of our limited understanding of how clouds, circulation and climate interact. One example is our inability to provide robust assessments of future global and regional climate changes. However, ongoing advances in our capacity to observe, simulate and conceptualize the climate system now make it possible to fill gaps in our knowledge. We argue that progress can be accelerated by focusing research on a handful of important scientific questions that have become tractable as a result of recent advances. We propose four such questions below; they involve understanding the role of cloud feedbacks and convective organization in climate, and the factors that control the position, the strength and the variability of the tropical rain belts and the extratropical storm tracks."

[sidd]

Manabe is a name to conjure with. Thanks for the link. I would dearly love to get my hands on some original Manabe and Wetherald (RIP) code from the 1960s.

The article has a link to one of Manabe's latest papers, on cloud forcings.


http://www.pnas.org/content/110/19/7568.abstract
sidd

[AbruptSLR]

The linked article indicates that plankton in the Southern Ocean release a compound named dimethylsulfoniopropionate, or DMSP, which whitens the Southern Ocean cloud (increase their albedo); however, as ocean acidification stresses the plankton this mechanism will become a positive feedback factor for global warming:

Daniel T. McCoy, Susannah M. Burrows, Robert Wood, Daniel P. Grosvenor, Scott M. Elliott, Po-Lun Ma, Phillip J. Rasch and Dennis L. Hartmann (17 Jul 2015), "Natural aerosols explain seasonal and spatial patterns of Southern Ocean cloud albedo", Science Advances, Vol. 1, no. 6, e1500157, DOI: 10.1126/sciadv.1500157

http://advances.sciencemag.org/content/1/6/e1500157.full

Abstract: "Atmospheric aerosols, suspended solid and liquid particles, act as nucleation sites for cloud drop formation, affecting clouds and cloud properties—ultimately influencing the cloud dynamics, lifetime, water path, and areal extent that determine the reflectivity (albedo) of clouds. The concentration Nd of droplets in clouds that influences planetary albedo is sensitive to the availability of aerosol particles on which the droplets form. Natural aerosol concentrations affect not only cloud properties themselves but also modulate the sensitivity of clouds to changes in anthropogenic aerosols. It is shown that modeled natural aerosols, principally marine biogenic primary and secondary aerosol sources, explain more than half of the spatiotemporal variability in satellite-observed Nd. Enhanced Nd is spatially correlated with regions of high chlorophyll a, and the spatiotemporal variability in Nd is found to be driven primarily by high concentrations of sulfate aerosol at lower Southern Ocean latitudes (35o to 45oS) and by organic matter in sea spray aerosol at higher latitudes (45o to 55oS). Biogenic sources are estimated to increase the summertime mean reflected solar radiation in excess of 10 W m–2 over parts of the Southern Ocean, which is comparable to the annual mean increases expected from anthropogenic aerosols over heavily polluted regions of the Northern Hemisphere."

See also:
http://www.csmonitor.com/Science/Science-Notebook/2015/0718/How-tiny-plankton-brighten-the-clouds-over-Southern-Ocean

[AbruptSLR]

The linked open access reference examines the coastal dynamics and creation of new submarine permafrost in shallow water of the central Laptev Sea (see the first attached image) and concludes: "For this region, it can be summarized that recent increases in coastal erosion rate and longer-term changes to benthic temperature and salinity regimes are expected to affect the depth to submarine permafrost, leading to coastal regions with shallower IBP." (see the second attached image), where IBP means: ice-bonded permafrost.

This research and conclusions may have profound implications if the abrupt collapse of the West Antarctic Ice Sheet, WAIS, in the next few decades leads to rapid increase in sea level in the Arctic Sea.  This is because more prior researchers have assumed that the IBP would be covered by a layer of somewhat protective non-ice-bonded sediment.  However, as Overduin (2015) make clear, wave driven coastal erosion (which will increase if/when the Arctic Sea Ice extent seasonally collapses) can/will expose the previously buried but new submarine IBP to relatively rapid warming from the sea water; which would likely result in a multi-decadal period (starting with the ASLR possibly around 2050) of relatively rapid methane emissions as the associated methane hydrates in the new submarine permafrost region decompose:


Overduin, P., Wetterich, S., Günther, F., Grigoriev, M. N., Grosse, G., Schirrmeister, L., Hubberten, H.-W., and Makarov, A.: Coastal dynamics and submarine permafrost in shallow water of the central Laptev Sea, East Siberia, The Cryosphere Discuss., 9, 3741-3775, doi:10.5194/tcd-9-3741-2015, 2015.

http://www.the-cryosphere-discuss.net/9/3741/2015/tcd-9-3741-2015.html
http://www.the-cryosphere-discuss.net/9/3741/2015/tcd-9-3741-2015.pdf

Abstract: "Coastal erosion and relative sea-level rise transform terrestrial landscapes into marine environments. In the Arctic, these processes inundate terrestrial permafrost with seawater and create submarine permafrost. Permafrost begins to warm under marine conditions, which can destabilize the sea floor and may release greenhouse gases. We report on the transition of terrestrial to submarine permafrost at a site where the timing of inundation can be inferred from the rate of coastline retreat. On Muostakh Island in the central Laptev Sea, East Siberia, changes in annual coastline position have been measured for decades and vary highly spatially. We hypothesize that these rates are inversely related to the inclination of the upper surface of submarine ice-bonded permafrost (IBP) based on the consequent duration of inundation with increasing distance from the shoreline. We compared rapidly eroding and stable coastal sections of Muostakh Island and find permafrost-table inclinations, determined using direct current resistivity, of 1 and 5 %, respectively. Determinations of submarine IBP depth from a drilling transect in the early 1980s were compared to resistivity profiles from 2011. Based on boreholes drilled in 1982–1983, the thickness of unfrozen sediment overlying the IBP increased from 0 up to 14 m below sea level with increasing distance from the shoreline. The geoelectrical profiles showed thickening of the unfrozen sediment overlying ice-bonded permafrost over the 28 years since drilling took place. Parts of our geoelectrical profiles trace permafrost flooded, and showed that IBP degradation rates decreased from over 0.6 m a−1 following inundation to around 0.1 m a−1 as the duration of inundation increased to 250 years. We discuss that long-term rates are expected to be less than these values, as the depth to the IBP increases and thermal and pore water solute concentration gradients over depth decrease. For this region, it can be summarized that recent increases in coastal erosion rate and longer-term changes to benthic temperature and salinity regimes are expected to affect the depth to submarine permafrost, leading to coastal regions with shallower IBP."

[AbruptSLR]

The linked articles indicate that recent measurement indicate that the oceans have been warming faster than the IPCC AR5 model projections indicate.  As the risk of abrupt sea level rise this century is most closely linked to the ocean's heat content, this is indeed bad news as it increases the thickness of the already fat-tail of the SLR pdfs:

http://www.theguardian.com/environment/climate-consensus-97-per-cent/2015/jul/20/oceans-warming-faster-than-climate-models-predicted
&
https://www.skepticalscience.com/oceans-warming-faster-than-models-predicted.html

Extract: "As I have said many times on this blog, if you want to know how much “global warming” is happening, you really have to be able to measure “ocean warming”. That is because more than 90% of the excess energy coming to the Earth from greenhouse gases goes into the ocean waters. My colleagues and I have a new publication, which better characterizes this heating and also compares climate model predictions with actual measurements. It turns out models have under-predicted ocean warming over the past few decades."

Caption for the two attached images: "Figure 1 (a) Upper (0–700 m) OHC, calculated using 40 Coupled Model Intercomparison Project, Phase 5 (CMIP5) models (historical run) (gray lines; black line is the ensemble mean). The CMIP5 results are compared with the observation-based estimate using the strategies presented in this study (red line) and National Oceanographic Data Center (NODC) mapping (dashed blue line). Two major volcanic eruptions are marked by the black arrows. (b) Annual global-averaged upper ocean warming rates from the CMIP5 model results (gray lines; red line is the ensemble mean) and from observations (blue line), computed from the first differences of OHC at 700 m (units: °C yr−1)."

See also:
http://english.cas.cn/newsroom/research_news/201506/t20150617_148976.shtml

[jai mitchell]

Permafrost and Carbon Cycle Underestimates in the IPCC

http://skepticalscience.com/are-we-overestimating-global-carbon-budget.html

What this all adds up to is that carbon cycle feedbacks caused by human interventions could be much worse than the IPCC has calculated. If we continue to follow the worst-case emissions scenario – adding about 1,700 billion tonnes of carbon from fossil fuels by 2100 – nature could contribute an additional 400 billion tonnes or more.

Note:  Permafrost is not considered to be part of the carbon cycle.  It is treated as a separate source.  The carbon cycle refers to terrestrial and aquatic carbon sinks and their shift from accumulating carbon towards releasing carbon. 

Finally, an additional study published this year in Nature by more than 90 scientists, all Amazon rainforest experts, found that the rate at which the forest has been acting as a sink of carbon dioxide has begun to decline over the past 25 years. The rate of tree growth has been flat lately, but the data show that trees are dying more quickly. The trend suggests that the Amazon Basin may soon turn from a sink of carbon into a source of carbon as the dead trees start to decompose.

[TeaPotty]

Still in shock over devastating research published by James Hansen & 16 Climate scientists. I resent scientists reflexively downplaying, and there has already been plenty of it. How many times can one be proven wrong (too conservative) before their ego stops getting in the way?

[AbruptSLR]

While the linked reference does not specifically discuss the probable climate change implications of the projected major impact of future ocean acidification on the phytoplankton community, the quote at the end of this most makes it clear that they are aware of the possible carbon cycle implications.  Some of these implications may include: (a) possible decreases in dimethylsulfoniopropionate, or DMSP, emissions which would decrease cloud albedo (particularly in the Southern Ocean); (b) reduced CO₂ absorption by the ocean; and (c) the probable decrease in the size of phytoplankton, which would make it more difficult for the dead plankton to sink to the ocean floor, which would reduce the amount of carbon sequestered by the ocean.

Stephanie Dutkiewicz, J. Jeffrey Morris, Michael J. Follows, Jeffery Scott, Orly Levitan, Sonya T. Dyhrman & Ilana Berman-Frank  (2015), "Impact of ocean acidification on the structure of future phytoplankton communities", Nature Climate Change, doi:10.1038/nclimate2722


http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2722.html


Abstract: "Phytoplankton form the foundation of the marine food web and regulate key biogeochemical processes. These organisms face multiple environmental changes, including the decline in ocean pH (ocean acidification) caused by rising atmospheric pCO2. A meta-analysis of published experimental data assessing growth rates of different phytoplankton taxa under both ambient and elevated pCO2 conditions revealed a significant range of responses. This effect of ocean acidification was incorporated into a global marine ecosystem model to explore how marine phytoplankton communities might be impacted over the course of a hypothetical twenty-first century. Results emphasized that the differing responses to elevated pCO2 caused sufficient changes in competitive fitness between phytoplankton types to significantly alter community structure. At the level of ecological function of the phytoplankton community, acidification had a greater impact than warming or reduced nutrient supply. The model suggested that longer timescales of competition- and transport-mediated adjustments are essential for predicting changes to phytoplankton community structure."


See also:

http://www.biosciencetechnology.com/news/2015/07/ocean-acidification-may-cause-dramatic-changes-phytoplankton

Extract: "“I’ve always been a total believer in climate change, and I try not to be an alarmist, because it’s not good for anyone,” said Dutkiewicz, who is the paper’s lead author. “But I was actually quite shocked by the results. The fact that there are so many different possible changes, that different phytoplankton respond differently, means there might be some quite traumatic changes in the communities over the course of the 21st century. A whole rearrangement of the communities means something to both the food web further up, but also for things like cycling of carbon.”"

[Sigmetnow]

Still in shock over devastating research published by James Hansen & 16 Climate scientists. I resent scientists reflexively downplaying, and there has already been plenty of it. How many times can one be proven wrong (too conservative) before their ego stops getting in the way?

I can only imagine that with the better (i.e., satellite) data and the increasing number of "unbelievably bad for the future" findings like Hansen et al's being released, there will soon (maybe this year?) be a tipping point where the idea of "the changes might not be that bad, or that soon" will seem as ridiculous as "no such thing as climate change" is today.  I guess I'm thinking of the general public, as well as the scientists.

[AbruptSLR]

The linked reference indicates that current GCM (ie IPCC) projections for probably losses of the Amazonian rainforest are too conservative, and that more losses than previously projected can be expected.

Juan P. Boisier, Philippe Ciais, Agnès Ducharne & Matthieu Guimberteau (2015), "Projected strengthening of Amazonian dry season by constrained climate model simulations", Nature Climate Change, Volume: 5, Pages: 656–660, doi:10.1038/nclimate2658


http://www.nature.com/nclimate/journal/v5/n7/full/nclimate2658.html

Abstract: "The vulnerability of Amazonian rainforest, and the ecological services it provides, depends on an adequate supply of dry-season water, either as precipitation or stored soil moisture. How the rain-bearing South American monsoon will evolve across the twenty-first century is thus a question of major interest. Extensive savanization, with its loss of forest carbon stock and uptake capacity, is an extreme although very uncertain scenario. We show that the contrasting rainfall projections simulated for Amazonia by 36 global climate models (GCMs) can be reproduced with empirical precipitation models, calibrated with historical GCM data as functions of the large-scale circulation. A set of these simple models was therefore calibrated with observations and used to constrain the GCM simulations. In agreement with the current hydrologic trends, the resulting projection towards the end of the twenty-first century is for a strengthening of the monsoon seasonal cycle, and a dry-season lengthening in southern Amazonia. With this approach, the increase in the area subjected to lengthy—savannah-prone—dry seasons is substantially larger than the GCM-simulated one. Our results confirm the dominant picture shown by the state-of-the-art GCMs, but suggest that the ‘model democracy’ view of these impacts can be significantly underestimated."

[jai mitchell]

It should be noted here that in the executive order 12866 study on the social cost of carbon, the Amazon Rainforest dieback is considered a "tipping point" that leads to the use of the 95th percentile value of cost of carbon per ton. 

https://www.whitehouse.gov/sites/default/files/omb/inforeg/for-agencies/Social-Cost-of-Carbon-for-RIA.pdf

This is the earlier version, the later version with significant technical adjustments to the various IAMs nearly doubles the value of the cost of carbon.

https://www.whitehouse.gov/sites/default/files/omb/inforeg/social_cost_of_carbon_for_ria_2013_update.pdf

This, of course, is based on the IPCC AR4 median values of impacts.  More recent evidence shows that these will be significantly understated.  In addition, they hold a 3% intergenerational discounting mechanism which would not stand up against a lawsuit.  if anything they should be implementing a negative discount rate.

A negative discount rate would raise these values by 2 orders of magnitude!

[AbruptSLR]

Recent studies have concluded that currently 3 out of 4 heatwaves and extreme heat events are caused by anthropogenic global warming.  Thus as discussed in the linked articles, unless prompt measures are taken to limit the potential growth of air conditioning (& refrigeration) in both the developed and the developing world; then this trend could become an increasingly positive feedback mechanism for anthropogenic forcing:

https://www.washingtonpost.com/blogs/worldviews/wp/2015/07/22/europe-to-america-your-love-of-air-conditioning-is-stupid/

Extract: ""The bottom line is that America's a big, rich, hot country," Cox told The Post. "But if the second, fourth, and fifth most populous nations -- India, Indonesia, and Brazil, all hot and humid -- were to use as much energy per capita for air-conditioning as does the U.S., it would require 100 percent of those countries' electricity supplies, plus all of the electricity generated by Mexico, the U.K., Italy, and the entire continent of Africa," he added."

Also see:
https://www.indybay.org/newsitems/2015/05/02/18771787.php

[BornFromTheVoid]

/r/science AMA (open questions and answers) today on reddit.com/r/science features (Stephen Hawking early today) then Stephan Lewandowsky and Klaus Oberauer.

I'll add a link directly to the AMA when it's posted up later.

[BornFromTheVoid]

Here's the link https://www.reddit.com/r/askscience/comments/3erfrl/askscience_ama_series_im_stephan_lewandowsky_here/

[AbruptSLR]

Duff typically provides thermal insulation to help slow permafrost degradation; however, per the following linked article Arctic wildfires, such as those burning now in Alaska, can quickly reduce the thickness of the duff layer thus subjecting the underlying permafrost to more rapid degradation, resulting in an acceleration of associated GHG emissions.  Such a positive feedback mechanism is not included in any Earth Systems Model that I am aware of (& certainly was not considered in any of the AR5 projections):

http://kvpr.org/post/beneath-alaskan-wildfires-hidden-threat-long-frozen-carbons-thaw

[AbruptSLR]

As climate change stresses our global food supplies not only are we more likely to use more refrigeration to preserve food and more fossil fuels to raise and transport food but we are also very likely to use more and more fertilized globally.  However, as the linked article indicates we are already underestimating the indirect nitrous oxide emissions associated with fertilizers in our GHG accounting, and we are not modeling the positive feedback to climate changes for this mechanism:

Peter A. Turner, Timothy J. Griffis, Xuhui Lee, John M. Baker, Rodney T. Venterea, and Jeffrey D. Wood (2015), "Indirect nitrous oxide emissions from streams within the US Corn Belt scale with stream order", PNAS, doi: 10.1073/pnas.1503598112


http://www.pnas.org/content/early/2015/07/21/1503598112.abstract


Abstract: "N2O is an important greenhouse gas and the primary stratospheric ozone depleting substance. Its deleterious effects on the environment have prompted appeals to regulate emissions from agriculture, which represents the primary anthropogenic source in the global N2O budget. Successful implementation of mitigation strategies requires robust bottom-up inventories that are based on emission factors (EFs), simulation models, or a combination of the two. Top-down emission estimates, based on tall-tower and aircraft observations, indicate that bottom-up inventories severely underestimate regional and continental scale N2O emissions, implying that EFs may be biased low. Here, we measured N2O emissions from streams within the US Corn Belt using a chamber-based approach and analyzed the data as a function of Strahler stream order (S). N2O fluxes from headwater streams often exceeded 29 nmol N2O-N m−2⋅s−1 and decreased exponentially as a function of S. This relation was used to scale up riverine emissions and to assess the differences between bottom-up and top-down emission inventories at the local to regional scale. We found that the Intergovernmental Panel on Climate Change (IPCC) indirect EF for rivers (EF5r) is underestimated up to ninefold in southern Minnesota, which translates to a total tier 1 agricultural underestimation of N2O emissions by 40%. We show that accounting for zero-order streams as potential N2O hotspots can more than double the agricultural budget. Applying the same analysis to the US Corn Belt demonstrates that the IPCC EF5r underestimation explains the large differences observed between top-down and bottom-up emission estimates."

Significance: "N2O emissions from riverine systems are poorly constrained, giving rise to highly uncertain indirect emission factors that are used in bottom-up inventories. Using a non–steady-state flow-through chamber system, N2O fluxes were measured across a stream order gradient within the US Corn Belt. The results show that N2O emissions scale with the Strahler stream order. This information was used to estimate riverine emissions at the local and regional scales and demonstrates that previous bottom-up inventories based on the Intergovernmental Panel on Climate Change default values have significantly underestimated these indirect emissions."

See also:
http://www.mprnews.org/story/2015/07/27/nitrous-oxide-study

Extract: "Previous estimates show nitrous oxide contributes to roughly 6 percent of global greenhouse gas emissions, he said.
The study's results will help inform strategies for reducing nitrous oxide emissions, he added. For example, researchers found that smaller streams and those closer to agricultural land were stronger emission sources.
"More work will need to be done to figure out what really drives the differences between all of these stream orders, so that's where we hope to go next," Turner said.
Researchers will also look at agricultural areas elsewhere in the world, such as China and India, which also use nitrogen fertilizers."

[AbruptSLR]

The linked article cites research out of Utah University that shows that forest are taking longer than expected to recover from increasingly frequent droughts, so they are storing less CO₂ than previously expected:

http://www.reuters.com/article/2015/07/30/us-climatechange-forests-science-idUSKCN0Q41YX20150730

Extract: "The world's forests are taking longer than expected to recover from increasingly frequent droughts, meaning their ability to store climate-changing carbon dioxide is smaller than previously thought, Utah University researchers said on Thursday.
If forests are absorbing less carbon dioxide, then the effects of climate change will be worse than past models had predicted, the Utah study published in the journal Science said.
"This really matters because in the future droughts are expected to increase in frequency and severity due to climate change," William Anderegg, the study's lead author, said in a statement."

[AbruptSLR]

The linked reference indicates that after updating observed data the match with models for RCP8.5 are within range of the explanations based on timing of decadal oscillations (including sequestering heat in the oceans):

Kevin Cowtan, Zeke Hausfather, Ed Hawkins, Peter Jacobs, Michael E. Mann, Sonya K. Miller, Byron A. Steinman, Martin B. Stolpe, Robert G. Way (July 29 2015), "Robust comparison of climate models with observations using blended land air and ocean sea surface temperatures", Geophysical Research Letters, DOI: 10.1002/2015GL064888

http://onlinelibrary.wiley.com/doi/10.1002/2015GL064888/full
http://www.meteo.psu.edu/holocene/public_html/Mann/articles/articles/grl53276.pdf

Abstract: "The level of agreement between climate model simulations and observed surface temperature change is a topic of scientific and policy concern. While the Earth system continues to accumulate energy due to anthropogenic and other radiative forcings, estimates of recent surface temperature evolution fall at the lower end of climate model projections. Global mean temperatures from climate model simulations are typically calculated using surface air temperatures, while the corresponding observations are based on a blend of air and sea surface temperatures. This work quantifies a systematic bias in model-observation comparisons arising from differential warming rates between sea surface temperatures and surface air temperatures over oceans. A further bias arises from the treatment of temperatures in regions where the sea ice boundary has changed. Applying the methodology of the HadCRUT4 record to climate model temperature fields accounts for 38% of the discrepancy in trend between models and observations over the period 1975-2014."


Caption for first image: "Figure 3: Difference between global mean blended temperature and air temperature, for different variants of the blending calculation, averaged over 84 historical + RCP8.5 simulations. Blended temperatures show less warming than air temperatures; hence the sign of the difference is negative for recent decades. Results are shown for the four permutations of masked versus global and absolute temperatures versus anomalies (with variable sea ice in each case). Two additional series for the absolute and anomaly methods with fixed ice show that fixing the sea ice boundary eliminates the effect of using anomalies. The final series shows the HadCRUT4 method, which shows similar behaviour to the other anomaly methods."

Caption for second image: "Figure 4. Comparison of 84 RCP8.5 simulations against HadCRUT4 observations (black), using either air temperatures (red line and shading) or blended temperatures using the HadCRUT4 method (blue line and shading). The shaded regions represent the 90% range (i.e. from 5-95%) of the model simulations, with the corresponding lines representing the multi-model mean. The upper panel shows anomalies derived from the unmodified RCP8.5 results, the lower shows the results adjusted to include the effect of updated forcings from Schmidt et al. [2014]. Temperature anomalies are relative to 1961-1990."

Caption for third image: "Figure 5: Comparison of models to observations using the IPCC method and the correct method. Thin lines are annual mean temperatures, thick lines are the trends on the period since 1975. (The data in this case are not global, but restricted to where HadCRUT4 has coverage.)

From Tamino:
https://tamino.wordpress.com/2015/07/30/getting-model-data-comparison-right/

From Cowtan:
http://www-users.york.ac.uk/~kdc3/papers/robust2015/background.html

From Sou:
http://blog.hotwhopper.com/2015/07/surface-temperature-is-not-so-different.html

[Sigmetnow]

More on the lessening carbon sink effect of some forests, from Scientific American

Northern Forests Falter in Combating Climate Change
Forests in Eurasia are not sucking as much CO2 out of the sky as they used to

Now, new research shows that one of the planet’s largest and most important carbon sinks, the forests of northern Eurasia, may be pulling in carbon at a slower rate than in the past. What is even more worrying is the possibility that regions that were absorbing carbon may emerge as sources of carbon emissions as the permafrost melts.

In northern Eurasia, the annual net sink rate increased from the 1960s to the 2000s, but since then, the rate at which carbon is sequestered by the region has leveled and even showed signs of weakening, said Michael Rawlins, an assistant professor in the University of Massachusetts’ Department of Geosciences.

In a study published in Biogeosciences, Rawlins and his team compared estimates of the rate of carbon sequestration occurring in this region from nine models, and they all suggested a weakening carbon sink. In time, the emissions are projected to overtake the ability of forests to contain them and, as he put it, “it is thought that the region will switch from a net carbon sink to a net carbon source sometime this century.”
...
Other areas are also witnessing alterations to the carbon cycle that could aggravate global warming. A large part of the land carbon sink is in the tropics, and a recent paper in Nature found that the Amazon carbon sink has accumulated carbon at a slower rate in recent years.

http://www.scientificamerican.com/article/northern-forests-falter-in-combating-climate-change/

[Lennart van der Linde]

A-Team already posted this piece by Jason Box in de Greenland-folder, but it's appropriate here too:
http://www.huffingtonpost.com/jason-e-box/ice-melt-fast_b_7927186.html

[TerryM]

A-Team already posted this piece by Jason Box in de Greenland-folder, but it's appropriate here too:
http://www.huffingtonpost.com/jason-e-box/ice-melt-fast_b_7927186.html

A must read by the good doctor!
What worries me most is that each new and unexpected finding seems to point toward either rapid sea level rise or at minimum acts to undermine our confidence in prior, more conservative extrapolations.
I'm unaware of any community, other than the good folks in Southern Carolina, taking any action to mitigate against even the previous, conservative rates of sea level rise.
Why are near sea level buildings in California built to withstand 100 year earthquakes while they ignore sea level rise that will certainly take place well within that time frame? I've seen giant subdivisions built in areas that I've seen under 20' of water. The homes are all "earthquake proof", but no one paid attention to flash flood paths.
Will the ocean view edifices now being constructed survive 'The Big One', only to be swept out to sea when a storm roils the 1 meter higher ocean 50 years from now?
No one complains about the costs of retrofitting an older home to conform with earthquake codes, but no one insists that new construction be sited far enough away from the coast to survive even the most conservative estimates of sea level rise.
Terry

[OldLeatherneck]

A-Team already posted this piece by Jason Box in de Greenland-folder, but it's appropriate here too:
http://www.huffingtonpost.com/jason-e-box/ice-melt-fast_b_7927186.html

A must read by the good doctor!
What worries me most is that each new and unexpected finding seems to point toward either rapid sea level rise or at minimum acts to undermine our confidence in prior, more conservative extrapolations.
I'm unaware of any community, other than the good folks in Southern Carolina, taking any action to mitigate against even the previous, conservative rates of sea level rise.
Why are near sea level buildings in California built to withstand 100 year earthquakes while they ignore sea level rise that will certainly take place well within that time frame? I've seen giant subdivisions built in areas that I've seen under 20' of water. The homes are all "earthquake proof", but no one paid attention to flash flood paths.
Will the ocean view edifices now being constructed survive 'The Big One', only to be swept out to sea when a storm roils the 1 meter higher ocean 50 years from now?
No one complains about the costs of retrofitting an older home to conform with earthquake codes, but no one insists that new construction be sited far enough away from the coast to survive even the most conservative estimates of sea level rise.
Terry

Jason Box has the intestinal fortitude (cojones) to tell it like it is, unlike so many of his cohorts hiding in the comfort of their tenured positions, hidden in the ivy-covered walls of academia. Yet, I don't always fault those academicians, whose careers can be ended on the whim of an angry politician. (Can't think of any politicians in the US, Canada or Australia who would do such a thing.)

[TerryM]

OLN


Some of the 'academics' have shown far more courage than I could have mustered under similar provocation.
It takes one hell of a man to stand up to two governments, as well as his own university's hierarchy, just because he felt that the public had a right to know.
I won't post his name as I don't think he's unique amongst his peers.


Terry

[Sigmetnow]

The Point of No Return: Climate Change Nightmares Are Already Here

The worst predicted impacts of climate change are starting to happen — and much faster than climate scientists expected.

A survey of scientists by meteorologist Eric Holthaus.

http://www.rollingstone.com/politics/news/the-point-of-no-return-climate-change-nightmares-are-already-here-20150805

[Bruce Steele]

I was surprised to see this article in the press and it was picked up in Australia also. I know several of the scientists quoted as I have been active in this arena for several years. Here is the abstract.

  Abstract• References• Author information• Supplementary information
Carbon dioxide removal (CDR) from the atmosphere has been proposed as a measure for mitigating global warming and ocean acidification. To assess the extent to which CDR might eliminate the long-term consequences of anthropogenic CO2 emissions in the marine environment, we simulate the effect of two massive CDR interventions with CO2 extraction rates of 5 GtC yr−1 and 25 GtC yr−1, respectively, while CO2 emissions follow the extended RCP8.5 pathway. We falsify two hypotheses: the first being that CDR can restore pre-industrial conditions in the ocean by reducing the atmospheric CO2 concentration back to its pre-industrial level, and the second being that high CO2 emissions rates (RCP8.5) followed by CDR have long-term oceanic consequences that are similar to those of low emissions rates (RCP2.6). Focusing on pH, temperature and dissolved oxygen, we find that even after several centuries of CDR deployment, past CO2 emissions would leave a substantial legacy in the marine environment.
 
https://www.pik-potsdam.de/news/press-releases/co2-removal-cannot-save-the-oceans-2013-if-we-pursue-business-as-usual

The thing that is somehow not said is that the carbon sent into the deep ocean will return to the atmosphere on a thousand year timeframe. The longer we continue ,the higher the atmospheric levels will be maintained on very long timescales. ( compared to the election cycle ) 
A long range view would be that the ocean only moderates the rate of atmospheric CO2 increase rather than it being a long term sink.

[TerryM]

Sounds as though the oceans are screwed no matter what remedial efforts are implemented. Somehow I feel that catastrophic sea level rise & global warming levels are equally outside any efforts that might be made to bring us back to pre-industrial levels.
It's somewhat comforting to be an old man with only a short future to contemplate.
Terry

[Bruce Steele]

Terry, This study is dependent on our maintaining  8.5 BAU for several more decades so things might not go quite so bad if we do turn things around and begin a long term trend toward reduced CO2 emissions.  It should however point a spotlight on IPCC models that use carbon capture to mitigate current excesses. Better hurry and figure out how to sink 25 GtC per annum. Snark 
   

[AbruptSLR]

The linked reference (with an open access pdf) presents new observation-based model findings of permafrost carbon fluxes when accounting for deep carbon deposits and thermokarst activity.  What I find to be particularly disturbing is the pulse of CH4 emissions circa 2050 from thermokarst lakes (TKLs) under RCP8.5, as indicated in both the attached images.  I find this 2050 CH4 emissions disturbing because we will likely stay on the RCP 8.5 scenario until about 2035-2040; so the 2050 pulse of high methane emissions are locked in:

Schneider von Deimling, T., Grosse, G., Strauss, J., Schirrmeister, L., Morgenstern, A., Schaphoff, S., Meinshausen, M., and Boike, J.: Observation-based modelling of permafrost carbon fluxes with accounting for deep carbon deposits and thermokarst activity, Biogeosciences, 12, 3469-3488, doi:10.5194/bg-12-3469-2015, 2015.

http://www.biogeosciences.net/12/3469/2015/bg-12-3469-2015.html

Abstract. High-latitude soils store vast amounts of perennially frozen and therefore inert organic matter. With rising global temperatures and consequent permafrost degradation, a part of this carbon stock will become available for microbial decay and eventual release to the atmosphere. We have developed a simplified, two-dimensional multi-pool model to estimate the strength and timing of future carbon dioxide (CO2) and methane (CH4) fluxes from newly thawed permafrost carbon (i.e. carbon thawed when temperatures rise above pre-industrial levels). We have especially simulated carbon release from deep deposits in Yedoma regions by describing abrupt thaw under newly formed thermokarst lakes. The computational efficiency of our model allowed us to run large, multi-centennial ensembles under various scenarios of future warming to express uncertainty inherent to simulations of the permafrost carbon feedback.

Under moderate warming of the representative concentration pathway (RCP) 2.6 scenario, cumulated CO2 fluxes from newly thawed permafrost carbon amount to 20 to 58 petagrams of carbon (Pg-C) (68% range) by the year 2100 and reach 40 to 98 Pg-C in 2300. The much larger permafrost degradation under strong warming (RCP8.5) results in cumulated CO2 release of 42 to 141 Pg-C and 157 to 313 Pg-C (68% ranges) in the years 2100 and 2300, respectively. Our estimates only consider fluxes from newly thawed permafrost, not from soils already part of the seasonally thawed active layer under pre-industrial climate. Our simulated CH4 fluxes contribute a few percent to total permafrost carbon release yet they can cause up to 40% of total permafrost-affected radiative forcing in the 21st century (upper 68% range). We infer largest CH4 emission rates of about 50 Tg-CH4 per year around the middle of the 21st century when simulated thermokarst lake extent is at its maximum and when abrupt thaw under thermokarst lakes is taken into account. CH4 release from newly thawed carbon in wetland-affected deposits is only discernible in the 22nd and 23rd century because of the absence of abrupt thaw processes. We further show that release from organic matter stored in deep deposits of Yedoma regions crucially affects our simulated circumpolar CH4 fluxes. The additional warming through the release from newly thawed permafrost carbon proved only slightly dependent on the pathway of anthropogenic emission and amounts to about 0.03–0.14 °C (68% ranges) by end of the century. The warming increased further in the 22nd and 23rd century and was most pronounced under the RCP6.0 scenario, adding 0.16 to 0.39 °C (68% range) to simulated global mean surface air temperatures in the year 2300.

[AbruptSLR]

The linked reference provides observational evidence that declines in Arctic sea ice extent is associated with an increase in methane emissions from northern wetlands.  While it may seem obvious to many that this is one of the positive feedback mechanisms for Arctic Amplification; such observational evidence hopefully makes it more likely that state-of-the-art programs likely ACME will be correctly calibrated to capture this coupled behavior:

Frans-Jan W. Parmentier, Wenxin Zhang, Yanjiao Mi, Xudong Zhu, Jacobus van Huissteden, Daniel J. Hayes, Qianlai Zhuang, Torben R. Christensen & A. David McGuire (2015), "Rising methane emissions from northern wetlands associated with sea ice decline", Geophysical Research Letters, DOI: 10.1002/2015GL065013


http://onlinelibrary.wiley.com/doi/10.1002/2015GL065013/abstract

Abstract: "The Arctic is rapidly transitioning towards a seasonal sea ice-free state, perhaps one of the most apparent examples of climate change in the world. This dramatic change has numerous consequences, including a large increase in air temperatures, which in turn may affect terrestrial methane emissions. Nonetheless, terrestrial and marine environments are seldom jointly analyzed. By comparing satellite observations of Arctic sea ice concentrations to methane emissions simulated by three process-based biogeochemical models, this study shows that rising wetland methane emissions are associated with sea ice retreat. Our analyses indicate that simulated high-latitude emissions for 2005-2010 were, on average, 1.7 Tg CH4 yr-1 higher compared to 1981-1990 due to a sea ice-induced, autumn-focused, warming. Since these results suggest a continued rise in methane emissions with future sea ice decline, observation programs need to include measurements during the autumn to further investigate the impact of this spatial connection on terrestrial methane emissions."

[Sigmetnow]

Gavin Schmidt tweeted:

@ClimateOfGavin: Some confusion today with people misunderstanding source of weather/climate predictability on different timescales (1/4) @mattwridley

@ClimateOfGavin: Short-term weather prediction (1-10 days) is based on specific tracking of individual weather systems & is fundamentally dynamical. (2/4)

@ClimateOfGavin: Seasonal outlooks (1-6 mon) rely on predictability/persistence of ocean temperatures & skilled only in averages, not specific weather (3/4)

@ClimateOfGavin: "Decadal prediction" (1-10 yrs) uses (small) predictability in initialized ocean state to estimate ocean dynamical regimes. Skill is not gr8

@ClimateOfGavin: Long-term *climate* prediction is based on impact of external drivers (CO2, solar, volcanoes, aerosols etc.) & can't forecast dynamics.

@ClimateOfGavin: There is no demonstrated connection between skill at seasonal or decadal predictions (IC problem) & climate (BC problem).

https://twitter.com/climateofgavin/status/630068874109714432

[Sigmetnow]

I can see it now:  Climate change deniers are gonna freak, believing that the lying, government-paid astronomers have falsified sunspot data just to prove the deniers' favorite theory wrong. 

Corrected sunspot history suggests climate change not due to natural solar trends

The sunspot number is the only direct record of the evolution of the solar cycle over multiple centuries. The apparent upward trend of solar activity between the 18th century and the late 20th century has now been identified as a major calibration error in the Group Sunspot Number. Now that this error has been corrected, solar activity appears to have remained relatively stable since the 1700s.

http://astronomynow.com/2015/08/08/corrected-sunspot-history-suggests-climate-change-not-due-to-natural-solar-trends/

[AbruptSLR]

The UN has just upwardly revised their global population projections; which according to the attached image from the linked summary report, gives a 50%-50% chance of having a global population of 11.2 billion people by 2100.  Obviously, upwardly revising these estimates imply that their prior estimates were too conservative, and the actual risk of high anthropogenic is greater than previously recognized:

http://esa.un.org/unpd/wpp/Publications/Files/Key_Findings_WPP_2015.pdf

See also:
http://www.newsweek.com/worlds-population-top-11-billion-2100-361388

[Sigmetnow]

Climate Scientists Reddit "Ask Me Anything" session on Eric Holthaus article (@1074 above).

5 Things We Learned From the 'Point of No Return' Climate Solutions AMA

4. Climate scientists have a sense of humor.
When asked if the AMA participants had any "crazy ideas [for] promoting climate change," Dr. Alin responded, "A cooking show from the future. Premise: now that we only have jellyfish in our oceans, what tasty treats can we make out of them anyway?"

http://www.rollingstone.com/politics/news/5-things-we-learned-from-the-point-of-no-return-climate-solutions-ama-20150814

Also, this analysis:
http://climatefeedback.org/evaluation/rolling-stone-eric-holthaus-point-of-no-return-climate-change-nightmares/

[Laurent]

On the trail of the Arctic’s carbon time bomb
https://www.newscientist.com/article/mg22730344-500-on-the-trail-of-the-arctics-carbon-time-bomb/

“Arctic fires may be creating new methane sources that could be the new fuse on the Arctic carbon bomb”

[AbruptSLR]

The linked reference indicates that studies that assume linearity of climate sensitivity likely underestimate the risk of high warming.

Jonah Bloch-Johnson, Raymond T. Pierrehumbert and Dorian S. Abbot (June 2015), "Feedback temperature dependence determines the risk of high warming", Geophysical Research Letters, DOI: 10.1002/2015GL064240

http://onlinelibrary.wiley.com/doi/10.1002/2015GL064240/abstract

Abstract: "The long-term warming from an anthropogenic increase in atmospheric CO2 is often assumed to be proportional to the forcing associated with that increase. This paper examines this linear approximation using a zero-dimensional energy balance model with a temperature-dependent feedback, with parameter values drawn from physical arguments and general circulation models. For a positive feedback temperature dependence, warming increases Earth's sensitivity, while greater sensitivity makes Earth warm more. These effects can feed on each other, greatly amplifying warming. As a result, for reasonable values of feedback temperature dependence and preindustrial feedback, Earth can jump to a warmer state under only one or two CO2 doublings. The linear approximation breaks down in the long tail of high climate sensitivity commonly seen in observational studies. Understanding feedback temperature dependence is therefore essential for inferring the risk of high warming from modern observations. Studies that assume linearity likely underestimate the risk of high warming."

Edit: While I originally "soft-balled" the presentation of this study because it reiterates previous research warning about the probably non-linear nature of climate sensitivity once we get above a mean global surface temperature increase of 2C above pre-industrial, I would now like to state the following obvious, correlated, implications of this research: (a) as we are now in multi-decadal period of synergistic positive reinforcement from such systems as the PDO and the AMO super-imposed on the positive trend of global warming, it is very likely that we will exceed a 2C increase circa 2030-2040 no matter what CoP21 achieves & so the positive feedback of warming global temperatures on increasing ESS is somewhat locked in; (b) if indeed ECS is current between 4.1 & 4.5C instead of between 3 & 3.3C then we can expect the locked-in positive feedback to result in far stronger non-linearity than commonly acknowledged; and (c) if Hansen et al. (2015) is correct that ASLR could trigger a temporary surge of planetary energy imbalance then we could easily be currently setting the stage for a shift in the global atmospheric-oceanic equilibrium point after about 2100 that after this century large parts of the EAIS and of the GIS could be set-up for long-term rapid degradation.

[jai mitchell]

Agree ASLR,  We have locked in massive warming at 400ppmv  I have estimated to be +2.3C locked in at these levels.

Once the arctic becomes a carbon source instead of a sink we will have additional feedbacks that will continue to drive the carbon cycle into a positive feedback loop. 

In related news, I have been in conversation with personnel at NODC who are putting together the AMJ quarter's ocean heat content analysis.  They are having trouble putting it together.  I expect that their readings show such an incredible heat gain that they are trying to find out how to reconcile with current theories and satellite surface height data. 

The slowdown of the Chinese economy, the reduction in Sulfate Aerosols in this region coupled with the massive surge in El Nino temps is why I expect this to be happening.  I have asked for preliminary data but it looks that they are going to be about 4 weeks late in publishing.

to see some of my work on this go here:  http://www.dailykos.com/story/2015/05/22/1386904/-Rapid-Warming-is-Here

[AbruptSLR]

Agree ASLR,  We have locked in massive warming at 400ppmv  I have estimated to be +2.3C locked in at these levels.

Once the arctic becomes a carbon source instead of a sink we will have additional feedbacks that will continue to drive the carbon cycle into a positive feedback loop. 

In related news, I have been in conversation with personnel at NODC who are putting together the AMJ quarter's ocean heat content analysis.  They are having trouble putting it together.  I expect that their readings show such an incredible heat gain that they are trying to find out how to reconcile with current theories and satellite surface height data. 

The slowdown of the Chinese economy, the reduction in Sulfate Aerosols in this region coupled with the massive surge in El Nino temps is why I expect this to be happening.  I have asked for preliminary data but it looks that they are going to be about 4 weeks late in publishing.

to see some of my work on this go here:  http://www.dailykos.com/story/2015/05/22/1386904/-Rapid-Warming-is-Here

I think that this HotWhopper article offers some insights:

http://blog.hotwhopper.com/2015/07/bob-tisdales-latest-conspiracy-theory.html

See also:
Cheng, Lijing, Jiang Zhu, and John Abraham. "Global upper ocean heat content estimation: recent progress and the remaining challenges." Atmospheric and Oceanic Science Letters (2015): 101. doi: 10.3878/AOSL20150031.

[AbruptSLR]

Many modelers are projecting an increase of the frequency and intensity of El Nino events compared to La Nina events (see references below, and the attached image of a summary of Nino 3.4 forecasts for January 2016).  However, what many people ignore is that such an increase in the El Nino events will mean an accelerated increase in global mean surface temperature rise; which effectively means that ECS will be greater than for GCM projections that average out the ENSO influence:

Sung, M.-K., An, S.-ll, Kim, B.-M. & Kug, J.-S.: Asymmetric impact of Atlantic Multidecadal Oscillation on El Niño and La Niña characteristics, Geophysical Research Letters, Volume 42, Issue 12, Pages 4998–5004, 2015.

Cai, W., Borlace, S., Lengaigne, M., Rensch, P.V., Collins, M., Vecchi, G., Timmermann, A., Santoso, A., McPhaden, M., Lixin Wu, Matthew H. England, Guojian Wang, Eric Guilyardi & Fei-Fei Jin, (2014), "Increasing frequency of extreme El Niño events due to greenhouse warming", Nature Climate Change, doi:10.1038/nclimate2100

[AbruptSLR]

I previously posted this in the Antarctic folder; however, I thought that people who read this thread might like to know that increased insect activity (see link & extract below) with continued global warming, and CO2 concentrations, will act as a positive feedback factor that is currently ignored by most climate change models:

http://www.newscientist.com/article/dn27064-hungry-insects-may-halve-forest-carbon-sink-capacity.html?cmpid=RSS

Extract: "Previous studies showed increased carbon dioxide levels upped the rate of photosynthesis in trees by approximately 50 per cent.
Bugs, however, could lessen this capacity dramatically, according to a new study. "Insects may change in response to elevated carbon dioxide levels and limit or compromise the capacity of forests to serve as carbon sinks," says Richard Lindroth, an ecologist at the University of Wisconsin-Madison."

[AbruptSLR]

Many modelers are projecting an increase of the frequency and intensity of El Nino events compared to La Nina events (see references below, and the attached image of a summary of Nino 3.4 forecasts for January 2016).  However, what many people ignore is that such an increase in the El Nino events will mean an accelerated increase in global mean surface temperature rise; which effectively means that ECS will be greater than for GCM projections that average out the ENSO influence:

Sung, M.-K., An, S.-ll, Kim, B.-M. & Kug, J.-S.: Asymmetric impact of Atlantic Multidecadal Oscillation on El Niño and La Niña characteristics, Geophysical Research Letters, Volume 42, Issue 12, Pages 4998–5004, 2015.

Cai, W., Borlace, S., Lengaigne, M., Rensch, P.V., Collins, M., Vecchi, G., Timmermann, A., Santoso, A., McPhaden, M., Lixin Wu, Matthew H. England, Guojian Wang, Eric Guilyardi & Fei-Fei Jin, (2014), "Increasing frequency of extreme El Niño events due to greenhouse warming", Nature Climate Change, doi:10.1038/nclimate2100

The attached four NOAA images show that not only will increasingly frequent strong El Nino's directly contribute to accelerated global warming; but that the increasing fluctuations from wet to dry conditions will stress the plant life (particularly tropical rainforests) in different parts of the world (indicated in the images); which will increase associated emissions of both carbon dioxide and of methane (from the dead vegetation).

As many/most GCM projections in AR5 do not adequately forecast such changes associated with the ENSO cycle, this indicates that for this positive feedback mechanism AR5 errs on the side of least drama.

[AbruptSLR]

The linked Working Paper 411 from the Center for Global Development indicates that without the rapid implementation of a carbon pricing plan we could lose an area of tropical rainforest equal to the size of India by 2050.  This is yet another positive feedback factor that is under-estimated by AR5 (and I note that is research finding likely does not include the full impact of increasingly frequent strong El Nino events this century):

http://www.cgdev.org/sites/default/files/future-forests-complete-8-21-jo.pdf

The Future of Forests: Emissions from Tropical Deforestation with and without a Carbon Price, 2016–2050

Abstract: "We project the future of tropical deforestation from 2016-2050 with and without carbon pricing policies, based on 18 million observations of historical forest loss spanning 101 tropical countries.  Our spatial projections of future deforestation incorporate topography, accessibility, protected status, potential agricultural revenue, and a robust observed inverted-U-shaped trajectory of forest cover loss with respect to remaining forest cover. We project that in the absence of new forest conservation policies, 289 million hectares of tropical forest will be cleared from 2016-2050—an area about the size of India and one-seventh of Earth’s tropical forest area in the year 2000. We project that this tropical deforestation will release 169 GtCO2 to the atmosphere from 2016-2050— one-sixth of the remaining carbon that can be emitted if the rise in Earth’s temperature is to be likely held below 2 °C. We estimate that a universally applied carbon price of $20/tCO2 from 2016- 2050 would avoid 41 GtCO2 of emissions from tropical deforestation while a carbon price of $50/tCO2 would avoid 77 GtCO2. These prices correspond to average costs to land users of $9/tCO2 and $21/tCO2 respectively. By comparison if all tropical countries implemented anti-deforestation policies as effective as those in the Brazilian Amazon post-2004 then 60 GtCO2 of emissions would be avoided. Our analysis corroborates the conclusions of previous studies that reducing tropical deforestation is a sizable and low-cost option for mitigating climate change. In contrast to previous studies, we project that the amount of emissions that can be avoided at low-cost by reducing tropical deforestation will increase rather than decrease in future decades. Encouragingly, 89% of potential low-cost emission reductions are located in the 47 tropical countries that have already signaled their intention to reduce emissions from deforestation in exchange for performance-based finance."

[AbruptSLR]

The following link leads to a thread in the Science folder that discusses the risks that CO2 venting from the Southern Ocean may be higher than expected:

http://forum.arctic-sea-ice.net/index.php/topic,888.0.html

This thread cites references such as the following that indicates that the Southern Ocean is progressively becoming less and less of a CO2 sink:


Corinne Le Quéré, Christian Rödenbeck, Erik T. Buitenhuis, Thomas J. Conway, Ray Langenfelds, Antony Gomez, Casper Labuschagne, Michel Ramonet, Takakiyo Nakazawa, Nicolas Metzl, Nathan Gillett, Martin Heimann, (2007),"Saturation of the Southern Ocean CO₂ Sink Due to Recent Climate Change", Science, Vol. 316, no. 5832  pp. 1735-1738, DOI: 10.1126/science.1136188

http://www.cccma.ec.gc.ca/papers/ngillett/PDFS/1735.pdf

http://www.sciencemag.org/content/316/5832/1735

Abstract: "Based on observed atmospheric carbon dioxide (CO2) concentration and an inverse method, we estimate that the Southern Ocean sink of CO2 has weakened between 1981 and 2004 by 0.08 petagrams of carbon per year per decade relative to the trend expected from the large increase in atmospheric CO2. We attribute this weakening to the observed increase in Southern Ocean winds resulting from human activities, which is projected to continue in the future. Consequences include a reduction of the efficiency of the Southern Ocean sink of CO2 in the short term (about 25 years) and possibly a higher level of stabilization of atmospheric CO2 on a multicentury time scale."

[AbruptSLR]

In Replies 1088 and 1090 I indicated that increasingly frequent strong El Ninos would contribute to more rapid global warming in the future than we have experienced in the recent modern era; however, I failed to mention the additional positive feedback caused by frequent strong El Nino events on ECS.  The first image (from Sherwood et al 2014) shows how increasing tropical evaporation (which is common in the Tropical Pacific during El Nino events) can shift shallow atmospheric convective cells into a deep convective cell pattern.  These deep convective cells can carry water vapor from the Tropical Pacific high into the troposphere thus creating high clouds about the ITCZ that create a greenhouse effect; while simultaneously moving dry upper atmosphere down to lower elevations where the dry air dissipates shallow cloud that would otherwise be a negative feedback by reflecting sunlight.

The second image shows how the ITCZ shifts across the equator from the boreal summer to the boreal winter, thus shifting the high and shallow cloud pattern with the seasons and also as strong El Ninos develop.  This allows more sunlight shine down on the Tropical Pacific waters causing still more evaporation which acts as a long-term positive feedback for increasing the ECS value.


Caption for the second figure: "The ITCZ moves farther away from the equator during the Northern summer than the Southern one due to the North-heavy arrangement of the continents."

Finally, I provide the linked reference (with a free pdf) that indicates that El Nino like behavior occurred for at least the past 12 million years (including period when the Earth was warmer than now); which supports the idea that El Nino-like behavior will continue into the foreseeable future, thus contributing to sustained high ECS values:

Yi Ge Zhang, Mark Pagani, Zhonghui Liu, (2014), "A 12-Million-Year Temperature History of the Tropical Pacific Ocean", Science 4 April 2014: Vol. 344 no. 6179 pp. 84-87, DOI:10.1126/science.1246172

http://people.earth.yale.edu/sites/default/files/2014_zhang_science.pdf

Abstract: "The appearance of permanent El Nino–like conditions prior to 3 million years ago is founded on sea-surface temperature (SST) reconstructions that show invariant Pacific warm pool temperatures and negligible equatorial zonal temperature gradients. However, only a few SST records are available, and these are potentially compromised by changes in seawater chemistry, diagenesis, and calibration limitations. For this study, we establish new biomarker-SST records and show that the Pacific warm pool was ~4°C warmer 12 million years ago. Both the warm pool and cold tongue slowly cooled toward modern conditions while maintaining a zonal temperature gradient of ~3°C in the late Miocene, which increased during the Plio-Pleistocene. Our results contrast with previous temperature reconstructions that support the supposition of a permanent El Nino–like state."

[AbruptSLR]

The linked article is essentially saying that climate sensitivity is likely higher than previously accepted by most scientists, and that through our continued high carbon emissions we have reduced our chances of avoiding significant climate change related damage:


http://cleantechnica.com/2015/08/26/world-must-almost-completely-decarbonize-in-next-35-years-to-tackle-climate-change/


“The scientific underpinning for the 2°C policy target being a ‘safe’ level of climate change is now weaker than it was a decade ago,” the report says.
“The scientific case for a 1.5°C limit is more consistent with our current level of understanding, bolstering the case for even more urgent action.”

[AbruptSLR]

Anyone going to the Fall AGU meeting can get updates on the progress of ACME such as the following:

Yuying Zhang (2015) "Application of ARM Cloud Radar Simulator to GCMs: Plan, Issues, and Preliminary Results", AGU Fall Meeting presentation board

http://fallmeeting.agu.org/2015/abstract/application-of-arm-cloud-radar-simulator-to-gcms-plan-issues-and-preliminary-results/

Abstract: "It has been challenging to directly compare ARM ground-based cloud radar measurements with climate model output because of limitations or features of the observing process. To address this issue, an ongoing effort in ARM is to implement ARM cloud radar simulator, similar to satellite simulators that have been widely used in the global climate modeling community, to convert model data into pseudo-ARM cloud radar observations. The simulator mimics the instrument view of a narrow atmospheric column (as compared to a large GCM grid-cell) thus allowing meaningful comparison between model output and ARM cloud observations. This work is being closely coordinated with the CFMIP (the Cloud-Feedback Model Intercomparison Project) Observation Simulator Package (COSP, www.cfmip.net; Bodas-Salcedo et al. 2011) project. The goal is to incorporate ARM simulators into COSP with the global climate modeling community as the target user.
This poster provides details about the implementation plan, discusses potential issues with ground-based simulators for both ARM radars, and presents preliminary results in evaluating the DOE Accelerated Climate Model for Energy (ACME) simulated clouds with ARM radar observations through applying the ARM radar simulator to ACME. Future plans on this project are discussed.
This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344."



See also:

Betz, E. (2015), Researchers roll clouds into climate modeling, Eos, 96, doi:10.1029/2015EO027283. Published on 2 April 2015.

https://eos.org/research-spotlights/researchers-roll-clouds-into-climate-modeling

[jai mitchell]

Have we already lost the coastal cities of New York and Boston?

[AbruptSLR]

Have we already lost the coastal cities of New York and Boston?

I would say yes; however, I have talked to several decision makers on this topic and they all resort to the somewhat magical line of thinking adopted by the NRC 2013 (ala Alley) that so long as the abrupt SLR does not exceed a rate of 1m in three decades, then they will have time to build adequate defenses to protect NYC & Boston.  Unfortunately, this magical line of thinking does not consider increases in storm surge and the difficulties of getting major coastal construction approved (and financed) in a timely manner.


National Research Council, NRC, (2013), Abrupt Impacts of Climate Change Anticipating Surprises, The National Academies Press, Washington D.C.

[AbruptSLR]

The linked pdf provides a nice summary regarding climate change models:

http://www.usclivar.org/sites/default/files/documents/2015/Variations2015Summer-1_0.pdf


Edit: See the article by Marvel et al (2015) starting on page 25

[jai mitchell]

not to mention the slowdown of the AMOC leading to sudden rises in eastern sea levels.

it won't take much to wash out boston.  I didn't ask about miami because we lost that decades ago.