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Author Topic: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)  (Read 297341 times)

wdmn

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2600 on: January 15, 2020, 08:12:37 PM »
I apologize in advance for rehashing this. It will be my last post on the topic in this thread. I will crosspost this to the global surface temperature thread. I would ask that you respond to me there


@KenFeldman
I trust that the graph below will settle our debate, and we can stop with the gaslighting?

The graph shows 6 temperature data sets: Berkeley Earth’s, NASA’s GISTEMP, NOAA’s GlobalTemp, the UK’s HadCRUT, Cowtan & Way, and ECMWF's.

Note that the anomaly on the graph is compared to the 1981-2010 baseline.

Note that the lowest temperature anomaly for 2019 is ~0.44C in the HadCRUT dataset (dark blue line).

Note that as pasted below (taken from the CopernicusEU website where the ECMWF data is posted) 0.63°C (±0.06ºC) should be added to this value to relate it to the pre-industrial level defined in the IPCC Special Report on “Global Warming of 1.5°C”.

Using this method for the HadCRUT dataset we get 0.44 + 0.63 = 1.07 = ~1.1C above the preindustrial baseline.

Note that the highest temperature anomaly for 2019 is from the ECMWF data set, which gives a corrected value of 1.22 or ~1.2C above the pre-industrial baseline (as posted below from their website).

So all datasets place 2019 above 1C of warming over preindustrial, with the median being ~1.15C above preindustrial, though the mean would be higher since HadCRUT is the most anomalous from the other datasets.

https://climate.copernicus.eu/surface-air-temperature-december-2019

"Averaging over twelve-month periods smooths out the shorter-term variations. Globally, the calendar year 2019 was 0.59°C warmer than the 1981-2010 average. The warmest twelve-month period was from October 2015 to September 2016, with a temperature 0.66°C above average. 2016 is the warmest calendar year on record, with a global temperature 0.63°C above that for 1981-2010. 2019 has become the second warmest calendar year in this data record. The third warmest calendar year, 2017, had a temperature 0.54°C above average.

0.63°C (±0.06ºC) should be added to these values to relate recent global temperatures to the pre-industrial level defined in the IPCC Special Report on “Global Warming of 1.5°C”. Using the central estimate and rounding to one decimal place, the average temperature for 2019 is 1.2°C above the level."

Ken Feldman

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2601 on: January 15, 2020, 08:53:50 PM »
I apologize in advance for rehashing this. It will be my last post on the topic in this thread. I will crosspost this to the global surface temperature thread. I would ask that you respond to me there


@KenFeldman
I trust that the graph below will settle our debate, and we can stop with the gaslighting?

The graph shows 6 temperature data sets: Berkeley Earth’s, NASA’s GISTEMP, NOAA’s GlobalTemp, the UK’s HadCRUT, Cowtan & Way, and ECMWF's.

Note that the anomaly on the graph is compared to the 1981-2010 baseline.

Note that the lowest temperature anomaly for 2019 is ~0.44C in the HadCRUT dataset (dark blue line).

Note that as pasted below (taken from the CopernicusEU website where the ECMWF data is posted) 0.63°C (±0.06ºC) should be added to this value to relate it to the pre-industrial level defined in the IPCC Special Report on “Global Warming of 1.5°C”.

Using this method for the HadCRUT dataset we get 0.44 + 0.63 = 1.07 = ~1.1C above the preindustrial baseline.

Note that the highest temperature anomaly for 2019 is from the ECMWF data set, which gives a corrected value of 1.22 or ~1.2C above the pre-industrial baseline (as posted below from their website).

So all datasets place 2019 above 1C of warming over preindustrial, with the median being ~1.15C above preindustrial, though the mean would be higher since HadCRUT is the most anomalous from the other datasets.

https://climate.copernicus.eu/surface-air-temperature-december-2019

"Averaging over twelve-month periods smooths out the shorter-term variations. Globally, the calendar year 2019 was 0.59°C warmer than the 1981-2010 average. The warmest twelve-month period was from October 2015 to September 2016, with a temperature 0.66°C above average. 2016 is the warmest calendar year on record, with a global temperature 0.63°C above that for 1981-2010. 2019 has become the second warmest calendar year in this data record. The third warmest calendar year, 2017, had a temperature 0.54°C above average.

0.63°C (±0.06ºC) should be added to these values to relate recent global temperatures to the pre-industrial level defined in the IPCC Special Report on “Global Warming of 1.5°C”. Using the central estimate and rounding to one decimal place, the average temperature for 2019 is 1.2°C above the level."

You managed to find one dataset that disagrees with the IPCC.  And you accuse me of gaslighting?

https://www.ipcc.ch/sr15/chapter/spm/

Quote
A.1. Human activities are estimated to have caused approximately 1.0°C of global warming above pre-industrial levels, with a likely range of 0.8°C to 1.2°C. Global warming is likely to reach 1.5°C between 2030 and 2052 if it continues to increase at the current rate. (high confidence) (Figure SPM.1) {1.2}

A.1.1. Reflecting the long-term warming trend since pre-industrial times, observed global mean surface temperature (GMST) for the decade 2006–2015 was 0.87°C (likely between 0.75°C and 0.99°C) higher than the average over the 1850–1900 period (very high confidence). Estimated anthropogenic global warming matches the level of observed warming to within ±20% (likely range). Estimated anthropogenic global warming is currently increasing at 0.2°C (likely between 0.1°C and 0.3°C) per decade due to past and ongoing emissions (high confidence). {1.2.1, Table 1.1, 1.2.4}

Also, Copernicus compares it's reanalysis temperatures to the same pre-industrial study I linked to upthread.

https://climate.copernicus.eu/node/74

Quote
Change over the industrial era

The Paris Agreement established the aim of "holding the increase in the global average temperature to well below 2°C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5°C", but did not specify precisely what was meant by "pre-industrial levels". This has now been assessed in a scientific paper independent of C3S that proposes a baseline of 1720-1800 for estimating subsequent change over the industrial era. The paper also estimates that the atmosphere from 1986-2005 was on average between 0.55 and 0.80°C warmer than it was over the baseline period.

As I posted upthread, NASA GISS has a running 5 year average that puts current global temperatures at about 0.9C above pre-industrial.  The IPCC report from 2018 states that we're 1C above average.

Are NASA and GISS gaslighting?  Or are you cherry-picking the one dataset that supports your conclusions and ignoring all other results?






AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2602 on: January 15, 2020, 09:17:07 PM »
The attached figure comes from the linked article about GMSTA thru 2019.  Here I note that, the preindustrial baseline adjustment is +0.256C (this is the difference between the GISS 1951-1980 baseline and the 1880-1909 preindustrial baseline)

Title: "2019 was likely Earth’s second-hottest year on record"

https://arstechnica.com/science/2020/01/2019-was-likely-earths-second-hottest-year-on-record/


Edit, per the linked NASA article of January 15, 2020, the attached image was credited to Gavin Schmidt and GISTEMP had the 2019 GMSTA at 0.98C with a 1951-1980 baseline, which I calculate to be 1.236C with a pre-industrial baseline when applying a +0.256 adjustment factor.  I note that if my calculation is correct then per GISTEMP, 2019 was the warmest year on record (as GMSTA for 2016 was 1.23C with a pre-industrial baseline):

Title: "NASA, NOAA Analyses Reveal 2019 Second Warmest Year on Record"

https://www.nasa.gov/press-release/nasa-noaa-analyses-reveal-2019-second-warmest-year-on-record

Extract: "This past year, they were 1.8 degrees Fahrenheit (0.98 degrees Celsius) warmer than the 1951 to 1980 mean, according to scientists at NASA’s Goddard Institute for Space Studies (GISS) in New York."

Caption for the attached image: "This plot shows yearly temperature anomalies from 1880 to 2019, with respect to the 1951-1980 mean, as recorded by NASA, NOAA, the Berkeley Earth research group, the Met Office Hadley Centre (UK), and the Cowtan and Way analysis. Though there are minor variations from year to year, all five temperature records show peaks and valleys in sync with each other. All show rapid warming in the past few decades, and all show the past decade has been the warmest.

Credits: NASA GISS/Gavin Schmidt"

Edit2, see also:

https://www.ncdc.noaa.gov/sotc/briefings/20200115.pdf
« Last Edit: January 15, 2020, 11:34:27 PM by AbruptSLR »
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2603 on: January 15, 2020, 10:45:33 PM »
Research such as the linked reference, makes me concerned that decision makers will wait until GMSTA is at, or near, 2C and then will act by implementing solar geoengineering; while ignoring the risk that ice sheet-climate feedback (which is driven by gravity) may still occur even if aggressive solar geoengineering is implemented:

K.S. Krishnamohan et al. (08 January 2020), "The Climatic Effects of Hygroscopic Growth of Sulfate Aerosols in the Stratosphere", Earth's Future, https://doi.org/10.1029/2019EF001326

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019EF001326

Abstract

Solar geoengineering by deliberate injection of sulfate aerosols in the stratosphere is one of the proposed options to counter anthropogenic climate warming. In this study, we focus on the effect of a specific microphysical property of sulfate aerosols in the stratosphere: hygroscopic growth ‐ the tendency of particles to grow by accumulating water. We show that stratospheric sulfate aerosols, for a given mass of sulfates, cause more cooling when prescribed at the lower levels of the stratosphere because of hygroscopic growth. The larger relative humidity in the lower stratosphere causes an increase in the aerosol size through hygroscopic growth which leads to a larger scattering efficiency. In our study, hygroscopic growth provides an additional cooling of 23% (0.7 K) when 20 Mt‐SO4 of sulfate aerosols, an amount that approximately offsets the warming due to a doubling of CO2, are prescribed at 100 hPa. The hygroscopic effect becomes weaker at higher levels as relative humidity decreases with height. Hygroscopic growth also leads to secondary effects such as an increase in near‐IR shortwave absorption by the aerosols which causes a decrease in high clouds and an increase in stratospheric water vapor. The altitude dependence of the effects of hygroscopic growth is opposite to that of sedimentation effects or the fast adjustment effects due to aerosol‐induced warming identified in a recent study.

Plain Language Summary

The injection of sulfate aerosols into the stratosphere is one of the proposed solar geoengineering methods to reduce anthropogenic warming. There are several uncertainties associated with the effects of stratospheric aerosol injection such as aerosol microphysics, transport, removal, and other physical and chemical changes of the aerosols. In this study, we have investigated the effects of a single source of uncertainty – the hygroscopic growth which depends on the ambient relative humidity in the stratosphere. Hygroscopic growth could lead to an increase in the size of the aerosols and consequently an increase in scattering efficiency. As the relative humidity is larger in the lower stratosphere, we find that the cooling efficiency of a fixed mass of sulfates is larger when they are prescribed in the lower levels of the stratosphere. This effect of hygroscopic growth can be substantial: for 20 Mt‐SO4 that offsets the warming from a doubling of CO2, we find an additional cooling of about 20%. Our results indicate the need for an accurate parametrization of aerosol microphysical and radiative processes in climate models for an improved understanding of the effects of stratospheric aerosol injection.

Key Points
•   The effects of hygroscopic growth of sulfate aerosols in stratospheric aerosol geoengineering is investigated
•   A specified mass of sulfates is more efficient in cooling the climate when they reside in the lower stratosphere due to hygroscopic growth
•   Hygroscopic growth can provide ~20% additional cooling when sulfates are used to offset warming from a doubling of CO2
« Last Edit: January 15, 2020, 11:32:46 PM by AbruptSLR »
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wdmn

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2604 on: January 15, 2020, 11:45:54 PM »
@KenFeldman

You're making me break my word not to reply further on the topic in this thread.

My post presented 6 datasets; how did I cherrypick one dataset? In previous posts I referred to 2: GISTEMP and ECMWF, both of which were well above 1C of warming over the last 4 years.

Now you've had the gall to refer me back to Copernicus EU, even though the link you provided states the following:

The Paris Agreement established the aim of "holding the increase in the global average temperature to well below 2°C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5°C", but did not specify precisely what was meant by "pre-industrial levels". This has now been assessed in a scientific paper independent of C3S that proposes a baseline of 1720-1800 for estimating subsequent change over the industrial era. The paper also estimates that the atmosphere from 1986-2005 was on average between 0.55 and 0.80°C warmer than it was over the baseline period.

The average ERA-Interim temperature for 1981-2010 is almost the same as that for 1986-2005. The 2016 ERA-Interim anomaly of 0.62°C relative to 1981-2010 thus translates to a temperature increase of 1.3°C above the 1720-1800 pre-industrial level, with an uncertainty of more than ±0.1°C. The same is found for the JRA-55 reanalysis. Using the coldest of the estimates for 2016, that of HadCRUT4, the median rise above the 1720-1800 level is 1.2°C for 2016. Choosing instead the first fifty years for which HadCRUT4 provides values, 1850-1899, as the "pre-industrial" reference period gives a median estimate for 2016 that is 1.1°C above this "pre-industrial" level. Corresponding values for the NOAAGlobalTemp and GISTEMP datasets are 1.1°C and 1.2°C respectively, when the "pre-industrial" reference period is taken to be 1880-1899, the first twenty years for which they provide data.

Central estimates of the temperature increase of the year 2016 over the industrial era thus vary from 1.1°C to 1.3°C for the datasets considered, with further uncertainty of more than ±0.1°C."


My analysis in my previous post is in keeping with this analysis from EU Copernicus: HadCRUT is the coldest data set, 1.1C over the 1880-1899 baseline, and 1.2C over the baseline you have been referring to. My analysis gave 1.07C for HadCRUT in 2019 over the same baseline.

ASLR has just posted another analysis of GISTEMP. If we were to apply the +0.256 adjustment factor to the data on his graph we would get the same results: none of them would be below 1C of warming in either 2015, 2016, 2017 or 2019.

Finally I post the attached graph from Berkeley Earth with an 1850-1900 baseline. I'll let people draw their own conclusions about whether I'm cherrypicking one dataset (or even one pre-industrial baseline).

The game you're playing here is transparent to anyone who is paying attention.

AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2605 on: January 15, 2020, 11:46:38 PM »
Per the attached image from the linked Scripps website, it certainly looks to me like through January 15, 2020 that atmospheric CO2 concentrations at Mauna Loa are still following RCP 8.5:

https://scripps.ucsd.edu/programs/keelingcurve/wp-content/plugins/sio-bluemoon/graphs/RCP85_scenario.png
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2606 on: January 16, 2020, 12:16:57 AM »
The bottom line of the linked reference is that there is still too much uncertainty associated with ice sheet models even when considering progress made since AR5:

Edward Hanna, Frank Pattyn, Francisco Navarro, Vincent Favier, Heiko Goelzer, Michiel R. van den Broeke, Miren Vizcaino, Pippa L. Whitehouse, Catherine Ritz, Kevin Bulthuis, Ben Smith. Mass balance of the ice sheets and glaciers – Progress since AR5 and challenges. Earth-Science Reviews, 2020; 201: 102976 DOI: 10.1016/j.earscirev.2019.102976

https://www.sciencedirect.com/science/article/pii/S0012825219303848?via%3Dihub

Abstract
Recent research shows increasing decadal ice mass losses from the Greenland and Antarctic Ice Sheets and more generally from glaciers worldwide in the light of continued global warming. Here, in an update of our previous ISMASS paper (Hanna et al., 2013), we review recent observational estimates of ice sheet and glacier mass balance, and their related uncertainties, first briefly considering relevant monitoring methods. Focusing on the response to climate change during 1992–2018, and especially the post-IPCC AR5 period, we discuss recent changes in the relative contributions of ice sheets and glaciers to sea-level change. We assess recent advances in understanding of the relative importance of surface mass balance and ice dynamics in overall ice-sheet mass change. We also consider recent improvements in ice-sheet modelling, highlighting data-model linkages and the use of updated observational datasets in ice-sheet models. Finally, by identifying key deficiencies in the observations and models that hamper current understanding and limit reliability of future ice-sheet projections, we make recommendations to the research community for reducing these knowledge gaps. Our synthesis aims to provide a critical and timely review of the current state of the science in advance of the next Intergovernmental Panel on Climate Change Assessment Report that is due in 2021.

Extract: "The introduction of MICI in one ice-sheet model (DeConto and Pollard, 2016) has profoundly shaken the modelling community, as the mechanism potentially results in future sea-level rise estimates of almost an order of magnitude larger compared with other studies

Recent advances in ice-sheet models show major improvements in terms of understanding of physics and rheology and model initialization, especially thanks to the wealth of satellite data that has recently become available. However, recent model intercomparisons (Goelzer et al., 2018a; Seroussi et al., 2019) still point to large process and parameter uncertainties.

Meanwhile, in recognition of the remaining limitations of ice-sheet models, despite significant recent progress, alternative novel approaches including structured expert judgment are useful to assess the likely impact of ongoing ice-sheet melt on SLR. For example, Bamber et al. (2019) indicate that a high-emissions greenhouse warming scenario gives a not insignificant chance of a total >2 m SLR by 2100."

Edit:  I remind readers that climate uncertainty is not our friend as it represents risk.
« Last Edit: January 16, 2020, 12:38:00 AM by AbruptSLR »
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2607 on: January 16, 2020, 12:36:51 AM »
The linked editorial reminds us how fragile the Thwaites Glacier is, given that the subglacial cavity at the base of the Thwaites Ice Tongue lost about 13bn tonnes of ice within a three-year period; and the article notes that: "Thwaites will surely now deteriorate faster."

Title: "The Guardian view on an ice-sheet collapse: threatening the world’s coasts"

https://www.theguardian.com/commentisfree/2020/jan/07/the-guardian-view-on-an-ice-sheet-collapse-threatening-the-worlds-coasts

Extract: "The rate of Thwaites’s disintegration has alarmed scientists for good reason. In a handful of decades it could retreat to the point that collapse becomes inevitable and irreversible. That would lock us into a future sea level rise of far more than half a metre or so. The reason is simple: today, Thwaites is a brake on large inland glaciers. Lose Thwaites, and those it holds back will follow. Over centuries perhaps, they would add fully 2m to sea level rise.

Nearly 100 scientists and support staff recently arrived at Thwaites, a place as inhospitable as Earth can muster, for an urgent and ambitious field expedition. Among the British and American teams are scientists, engineers and technicians who have set up tents on Thwaites ice shelf, the slab of glacier that has slipped off the Antarctic bedrock on to the sea. They have now set up a hot water drill to bore through the 600m shelf into the frigid waters beneath. It is a process that takes days, with small teams working nonstop around the clock.

Why drill down? With the borehole open, the researchers will winch down a torpedo-shaped robotic submarine called Icefin. It will slip into the depths and make for the grounding line, where the base of the glacier lifts off the land. There it will inspect a grim discovery that Nasa scientists made some months back. Flying over the glacier on a plane fitted with ice-penetrating radar, they spotted a gigantic hole at the base of Thwaites. At 4km wide and 10km long, it is two-thirds the area of Manhattan. The 350m-tall cavern formed over three years when 13bn tonnes of ice melted away. Water had found its way between the glacier’s rough base and the bedrock to melt it, unnoticed, from below. Thwaites will surely now deteriorate faster.

It is a stark reminder that for all the observations and sophisticated climate models that scientists produce, nature can still serve up unwelcome surprises. The fact is that we are ill-equipped to model precisely a global system as devilishly complex as the climate. If we don’t know every detail – every process, every threshold, and the direction and strength of every feedback loop – we must always expect surprises. This might be the lesson of Thwaites glacier. In both the US and the UK – the countries behind the expedition – science is in peril. The Royal Society warns that Britain is losing top scientists amid ongoing Brexit uncertainty. In the US, the administration has set itself against science, particularly in environmental disciplines, and scores of researchers have quit their posts. If Thwaites tells us anything, it is that we need more science, not less, to survive the climate crisis. Without it, we will not understand the full threat we face, nor be well placed to mitigate its most dangerous consequences. If we want to avoid more unwelcome surprises, we must not let our guard down."
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

Tom_Mazanec

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2608 on: January 16, 2020, 10:21:10 AM »
Re: reply 2603
And sulfate geoengineering does not address ocean acidification and can also have side effects like acid rain.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2609 on: January 16, 2020, 04:26:05 PM »
The linked reference evaluates potential future GHG emissions associate with the Shale Revolution in the Gulf and Southwest regions of the USA and finds that these emissions may represent '… more than 8% of total US GHG emissions in 2017 and roughly equivalent to the emissions of 131 coal-fired power plants."

Andrew R Waxman et al. (2020), "Emissions in the stream: estimating the greenhouse gas impacts of an oil and gas boom", Environmental Research Letters, Vol. 15, Number 1, https://doi.org/10.1088/1748-9326/ab5e6f

https://iopscience.iop.org/article/10.1088/1748-9326/ab5e6f/pdf

Extract: "Our central estimate suggests that the total annual emissions impact of the regional oil and gas infrastructure buildout may reach 541 million tons of CO2 equivalent (CO2e) by 2030, which is more than 8% of total US GHG emissions in 2017 and roughly equivalent to the emissions of 131 coal-fired power plants.  A substantial fraction of the projected emissions come from petrochemical facilities (38%) and liquefied natural gas terminals (19%)."

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2610 on: January 16, 2020, 04:40:49 PM »
The linked reference concludes that: "The reconstructed global mean sea-surface temperature anomaly for KM5c is warmer than all but three of the PlioMIP2 model outputs, and the reconstructed North Atlantic data tend to align with the warmest KM5c model values. Our results demonstrate that even under low CO2 emission scenarios, surface ocean warming may be expected to exceed model projections, and will be accentuated in the higher latitudes."  To me this implies that the ECS values for the PlioMIP2 models were too low; which implies to me that the ECS values cited in AR5 were too low, even for low emission scenarios:

McClymont, E. L., Ford, H. L., Ho, S. L., Tindall, J. C., Haywood, A. M., Alonso-Garcia, M., Bailey, I., Berke, M. A., Littler, K., Patterson, M., Petrick, B., Peterse, F., Ravelo, A. C., Risebrobakken, B., De Schepper, S., Swann, G. E. A., Thirumalai, K., Tierney, J. E., van der Weijst, C., and White, S.: Lessons from a high CO2 world: an ocean view from ~ 3 million years ago, Clim. Past Discuss., https://doi.org/10.5194/cp-2019-161, in review, 2020.

https://www.clim-past-discuss.net/cp-2019-161/

Abstract.
A range of future climate scenarios are projected for high atmospheric CO2 concentrations, given uncertainties over future human actions as well as potential environmental and climatic feedbacks. The geological record offers an opportunity to understand climate system response to a range of forcings and feedbacks which operate over multiple temporal and spatial scales. Here, we examine a single interglacial during the late Pliocene (KM5c, ca. 3.205 ± 0.01 Ma) when atmospheric CO2 concentrations were higher than pre-industrial, but similar to today and to the lowest emission scenarios for this century. As orbital forcing and continental configurations were almost identical to today, we are able to focus on equilibrium climate system response to modern and near-future CO2. Using proxy data from 32 sites, we demonstrate that global mean sea-surface temperatures were warmer than pre-industrial, by ~ 2.3 ºC for the combined proxy data (foraminifera Mg/Ca and alkenones), or by ~ 3.2 ºC (alkenones only). Compared to the pre-industrial, reduced meridional gradients and enhanced warming in the North Atlantic are consistently reconstructed. There is broad agreement between data and models at the global scale, with regional differences reflecting ocean circulation and/or proxy signals. An uneven distribution of proxy data in time and space does, however, add uncertainty to our anomaly calculations. The reconstructed global mean sea-surface temperature anomaly for KM5c is warmer than all but three of the PlioMIP2 model outputs, and the reconstructed North Atlantic data tend to align with the warmest KM5c model values. Our results demonstrate that even under low CO2 emission scenarios, surface ocean warming may be expected to exceed model projections, and will be accentuated in the higher latitudes.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2611 on: January 16, 2020, 04:54:56 PM »
While the topic of the underlying mechanisms for the increase of tropical SSTA with anthropogenic radiative forcing remains a topic of active debate; the linked reference finds that the tropical SSTA will grow more rapidly than previously expected if low altitude cloud cover is reduced (with continued warming) in off-equatorial regions.  As this is what many of the CMIP6 projections with high values of ECS found; the tropical SSTA may likely increase faster than previously estimated by CMIP5/AR5.  As tropical SSTA is the primary parameter in determining whether the atmosphere flips into an equable pattern, this is not good news:

Stuecker, M.F., Timmermann, A., Jin, F. et al. Strong remote control of future equatorial warming by off-equatorial forcing. Nat. Clim. Chang. (2020) doi:10.1038/s41558-019-0667-6

https://www.nature.com/articles/s41558-019-0667-6

Abstract: "The tropical climate response to GHG forcing is spatially non-uniform. Even though enhanced equatorial and eastern Pacific warming is simulated by most climate models, the underlying mechanisms—including the relative roles of atmospheric and oceanic feedbacks—remain debated. Here, we use a climate model with idealized CO2-radiative forcing patterns to show that off-equatorial radiative forcing and corresponding coupled circulation/cloud adjustments are responsible for much of equatorial warming in response to global CO2 forcing. For equatorial forcing, the atmosphere responds by enhancing atmospheric heat export to the extra-tropics, an associated strengthening of the ascending Hadley circulation branch and strong negative equatorial cloud feedbacks. These processes together greatly dampen equatorial surface warming. Intensification of the oceanic subtropical cells and increased cold subsurface water upwelling in the eastern tropical Pacific provide an additional negative feedback for surface temperatures. In contrast, applying off-equatorial forcing, the atmosphere responds by exporting less heat from the tropics, Hadley circulation weakening and weaker negative equatorial cloud feedbacks, while the subtropical cells slow down in the ocean. Our results demonstrate a delicate balance in the coupled climate system between remote circulation adjustments and regional feedbacks that create the patterns of future climate change."
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2612 on: January 16, 2020, 05:13:31 PM »
Many climate scientists use frequentist assumptions/methods when using emergent constraints to try to quantify climate uncertainty (particularly uncertainty associated with climate sensitivity) for decision makers.  The linked reference uses to statistics to show that the use of Bayesian frameworks previously ignored uncertainties can be identified as illustrated in the attached image, where relaxing the underlining constraint assumptions results in a marked fattening and lengthening of the right tail of the associated ECS PDF.  This means much greater climate risk likely exists than decision makers have previously been lead to believe:

Daniel B. Williamson & Philip G. Sansom (2020), "How Are Emergent Constraints Quantifying Uncertainty and What Do They Leave Behind?", BAMS, https://doi.org/10.1175/BAMS-D-19-0131.1

https://journals.ametsoc.org/doi/full/10.1175/BAMS-D-19-0131.1?af=R

Abstract: "The use of emergent constraints to quantify uncertainty for policy-relevant quantities such as equilibrium climate sensitivity (ECS) has become increasingly widespread in recent years. Many researchers, however, claim that emergent constraints are inappropriate or even underreport uncertainty. In this paper we contribute to this discussion by examining the emergent constraints methodology in terms of its underpinning statistical assumptions. We argue that the statistical assumptions required to underpin existing frameworks are strong, hard to defend, and lead to an underreporting of uncertainty. We show how weakening them leads to a more transparent Bayesian framework wherein hitherto-ignored sources of uncertainty, such as how reality might differ from models, can be quantified. We present a guided framework for the quantification of additional uncertainties that is linked to the confidence we can have in the underpinning physical arguments for using linear constraints. We provide a software tool for implementing our framework for emergent constraints and use it to illustrate the methods on a number of recent emergent constraints for ECS. We find that the robustness of any constraint to additional uncertainties depends strongly on the confidence we have in the underpinning physics, allowing a future framing of the debate over the validity of a particular constraint around underlying physical arguments, rather than statistical assumptions. We also find that when physical arguments lead to confidence in the linear relationships underpinning emergent constraints, prediction intervals are only slightly widened by including additional uncertainties, and they show this across a range of emergent constraints for ECS."

Caption: "FIG. 5. Posterior probability density functions for ECS found for four different emergent constraints (colors) and four different levels of confidence in the constraint. The solid line in each case is the reference analysis."
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2613 on: January 16, 2020, 05:27:23 PM »
The linked CarbonBrief article discusses how 'Altantification' is making the Arctic Ocean saltier and warmer and warns that this behavior could act as a positive feedback mechanism that might push the Arctic region into a new state with higher Arctic Amplification.  In this regard, I note that if the WAIS were to collapse in the coming decades, the associated slowing of the MOC would accelerate this 'Atlantification' of the Arctic Ocean; which, would raise the risk of an abrupt increase in Arctic Amplification:

Title: "Explainer: How ‘Atlantification’ is making the Arctic Ocean saltier and warmer"

https://www.carbonbrief.org/explainer-how-atlantification-is-making-the-arctic-ocean-saltier-and-warmer

Extract: "One outstanding question surrounding Atlantification is the extent to which it could be pushing the Arctic towards a “tipping point” – a possibly irreversible and self-reinforcing change in the climate system.

A key possible driver of Atlantification in the Barents Sea is the disappearance of sea ice from atop the ocean. However, once sparked, Atlantification causes further melting of sea ice, which could, in turn, lead to more Atlantification."
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2614 on: January 16, 2020, 06:14:01 PM »
Quote from: AbruptSLR
This means much greater climate risk likely exists than decision makers have previously been lead to believe:

The decision makers are not listening and are not interested. At all.
COP25 was typical.
Who are we kidding? Ourselves.

Cheers.
Thank you for introducing and posting these interesting articles AbruptSLR. My mind can't hold all of the consequences mentioned. Overwhelming. Are you able to hold them?
Apologies for the off-topic post.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2615 on: January 16, 2020, 09:02:14 PM »
Quote from: AbruptSLR
This means much greater climate risk likely exists than decision makers have previously been lead to believe:


Thank you for introducing and posting these interesting articles AbruptSLR. My mind can't hold all of the consequences mentioned. Overwhelming. Are you able to hold them?
Apologies for the off-topic post.

nanning,

One can compare the stresses put on Earth Systems by anthropogenic radiative forcing, to a car speeding down the freeway that develops engine trouble; so, one can either choose to slow down, or one can try to fix the engine while continuing to speed down the freeway.  Unfortunately, in modern society, rather than slowing down the pace of our collective lives, many people want to try to fix the engine while continuing at full speed (or continuing to accelerate); which, would take a lot of both skill and luck.

So, in my opinion, there is no need for you to fully understand every characteristic of complex Earth Systems; only that you live your life with integrity at the pace that suits your life.

Best,
ASLR
« Last Edit: January 16, 2020, 10:38:41 PM by AbruptSLR »
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2616 on: January 16, 2020, 09:14:57 PM »
With a hat tip to jai, the attached image from Rahmstorf shows that GISTEMP with an 1880-1910 baseline exceeded 1.2C in 2019.  While Rahmstorf notes that it reaches this level of GMSTA without a strong El Nino event; I note that the record shows that strong La Nina events are occurring less frequently faster than strong El Nino event are occurring more frequently with continued global warming (which has previously been noted by Hansen as a significant contributing factor to relatively high climate sensitivity):
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2617 on: January 17, 2020, 01:11:20 AM »
The linked article discusses the sense of urgency that the climate scientists feel who are currently on the ice for the International Thwaites Glacier Collaboration:

Title: "Antarctica's doomsday glacier is melting. Can we save it in time?"

https://www.newscientist.com/article/mg24532650-900-antarcticas-doomsday-glacier-is-melting-can-we-save-it-in-time/#ixzz6BDCFhRrG

Extract: "A massive research effort is under way to understand Antarctica's Thwaites glacier before it is too late. If it collapses, it could trigger catastrophic sea level rise, putting London and New York at risk

“YOU are very aware that if something goes wrong, it goes very wrong very quickly,” says Joanne Johnson, speaking from her tent near Thwaites glacier in one of the remotest parts of Antarctica."
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2618 on: January 17, 2020, 08:04:38 AM »
Thanks, and that's a nice metaphor AbruptSLR. Much better than my train one. Readers of this forum in general don't take trains so the car example is better communication.
Integrity yes, but especially personal responsibilty (conscience) and empathy I'd say.
I wonder, do you emotionally connect with all this?
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2619 on: January 17, 2020, 09:32:50 AM »
Quote
“YOU are very aware that if something goes wrong, it goes very wrong very quickly,” says Joanne Johnson, speaking from her tent near Thwaites glacier in one of the remotest parts of Antarctica."
What is "very quickly"? To a geologist that might be centuries.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2620 on: January 17, 2020, 04:18:50 PM »
Quote
“YOU are very aware that if something goes wrong, it goes very wrong very quickly,” says Joanne Johnson, speaking from her tent near Thwaites glacier in one of the remotest parts of Antarctica."
What is "very quickly"? To a geologist that might be centuries.
To someone at one of the most remote places on Earth, it could be a matter of seconds. I believe the quote was about their safety.
FNORD

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2621 on: January 17, 2020, 04:22:14 PM »
...
I wonder, do you emotionally connect with all this?

I have found that when I expressed my emotions in this forum in the past it was either a waste of time, or actually counter-productive, so now I try to stick with the scientific method approach as much as practicable.
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2622 on: January 17, 2020, 04:25:30 PM »
Quote
“YOU are very aware that if something goes wrong, it goes very wrong very quickly,” says Joanne Johnson, speaking from her tent near Thwaites glacier in one of the remotest parts of Antarctica."
What is "very quickly"? To a geologist that might be centuries.
To someone at one of the most remote places on Earth, it could be a matter of seconds. I believe the quote was about their safety.

I concur that Joanne Johnson's quote was primarily about the researcher's personal safety in one of the most remote places on Earth; nevertheless, I believe that on a decadal-scale the quote is relevant to the personal safety of most everyone on the planet, should the Thwaites Glacier sustain an MICI-type of collapse; which I believe could be initiated circa 2040 +/- 5years.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2623 on: January 17, 2020, 05:14:46 PM »
Steig doesnt think the ozone hole is causing westerly speedup or southern anuular mode intensification. I asked him this at realclimate couple years ago, he replied he thought that it was not due to ozone hole, rather teleconnect from equatorialish pacific, referred me to a paper he wrote with Ding and others. I kinda agree with him after i looked at the evidence.

He might have changed his mind since, but i have seen no publication by him to that effect. emailing him might get you an answer.

sidd

sidd,

While I personally have no doubt that Steig was sincere when he expressed his opinion to you a couple of years ago; the linked reference (see also the linked associated article) marshals a large amount of data to verify that the Antarctic ozone hole is not only directly related to accelerating, and southward shifting, the westerly winds over the Southern Ocean; but that ozone depletion has been a significant/driving factor in multiple changes in the climate in the Southern Hemisphere in recent decades.  Thus, I wonder whether Steig underestimates the extent of the influence of the Antarctic ozone hole; which clearly extends all the way from the South Pole to the equatorial Pacific, and may very well have acted to accelerate the telecommunication of energy from the Tropical Pacific to the West Antarctic region.

Barnes, P.W., Williamson, C.E., Lucas, R.M. et al. Ozone depletion, ultraviolet radiation, climate change and prospects for a sustainable future. Nat Sustain 2, 569–579 (2019) doi:10.1038/s41893-019-0314-2

https://www.nature.com/articles/s41893-019-0314-2

Abstract: "Changes in stratospheric ozone and climate over the past 40-plus years have altered the solar ultraviolet (UV) radiation conditions at the Earth’s surface. Ozone depletion has also contributed to climate change across the Southern Hemisphere. These changes are interacting in complex ways to affect human health, food and water security, and ecosystem services. Many adverse effects of high UV exposure have been avoided thanks to the Montreal Protocol with its Amendments and Adjustments, which have effectively controlled the production and use of ozone-depleting substances. This international treaty has also played an important role in mitigating climate change. Climate change is modifying UV exposure and affecting how people and ecosystems respond to UV; these effects will become more pronounced in the future. The interactions between stratospheric ozone, climate and UV radiation will therefore shift over time; however, the Montreal Protocol will continue to have far-reaching benefits for human well-being and environmental sustainability."

See also:

Title: "Ozone depletion driving climate change in Southern Hemisphere"

https://phys.org/news/2019-06-ozone-depletion-climate-southern-hemisphere.html

Extract: ""It is now clear that ozone depletion is directly contributing to climate change across the Southern Hemisphere," Professor Robinson said.

"Ozone is a greenhouse gas, so the ozone hole has kept Antarctica cooler, pulling the westerly wind jet that circles the continent closer and tighter to Antarctica. This has increased the speed of the wind, making Antarctica cooler and drier, pulling other Southern Hemisphere weather zones further south."

The Southern Annular Mode describes the north-south movement of the wind belt that circles the Southern Hemisphere. Analysis of ice cores shows these winds are the furthest south they have been for a thousand years.

As climate zones have shifted southwards, rainfall patterns, sea-surface temperatures and ocean currents across large areas of the southern hemisphere have also shifted, impacting terrestrial and aquatic ecosystems in Australia, New Zealand, Antarctica, South America, Africa and the Southern Ocean.

"We are seeing changes across the Southern Hemisphere, from the pole to the tropics," Professor Robinson said. "Some areas are getting more rain and some have become drier, which has a huge effect on plants and animals, including on agriculture."

Best,
ASLR
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AbruptSLR

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2624 on: January 17, 2020, 06:22:04 PM »
Whatever one thinks about the World Economic Forum and its session being held in Davos this month; at least they have publicly that their top five global threats are all associated with the climate and/or environmental degradation; even if this information proves to be little more than 'greenwashing', at least they are making the public more aware of the reality of these threats.

« Last Edit: January 18, 2020, 11:19:31 PM by AbruptSLR »
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2625 on: January 17, 2020, 09:37:29 PM »
The linked reference demonstrates that since the early 2000s ocean bottom deformation (OBD) due to the increasing weight (mass loading) of the ocean has become large enough to be included as a correction factor to the sea level budget.  While this correction factor is currently relatively small, it does mean that consensus climate scientists have previously being ignoring some of the ice meltwater contribution to sea level rise.  Thus as MICI-types of estimates of ice sheet contribution to sea level rise start out small and then increase nonlinearly, we may all be must closer to the nonlinear portion of any possible MICI-type of ice sheet contribution to SLR than we all previously thought:

B.D. Vishwakarma et al. (16 January 2020), "Sea level budgets should account for ocean bottom deformation", Geophysical Research Letters, https://doi.org/10.1029/2019GL086492

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019GL086492

Abstract
The conventional sea level budget (SLB) equates changes in sea surface height (SSH) with the sum of ocean mass and steric change, where solid‐Earth movements are included as corrections, but limited to the impact of glacial isostatic adjustment. However, changes in ocean mass load also deforms the ocean bottom elastically. Until the early 2000s, ocean mass change was relatively small, translating into negligible elastic ocean bottom deformation (OBD), hence neglected in the SLB equation. However, recently ocean mass has increased rapidly; hence OBD is no longer negligible and likely of similar magnitude to the deep steric sea level contribution. Here, we use a mass‐volume framework, which allows the ocean bottom to respond to mass load, to derive a SLB equation that includes OBD. We discuss the theoretical appearance of OBD in the SLB equation and its implications for the global SLB.

Plain Language Summary
Sea level rise is expected to be one of the most severe consequences of anthropogenic climate change. A change in sea‐level can be approximately explained by addition of fresh water mass (mass change) and by increase in water volume (steric change; due to rising temperature and declining salinity). This constitutes the conventional sea level budget equation that explains the sea level rise from mass and steric change. However, other physical processes are also known to contribute to the observed change in the sea surface height. The Earth's surface is known to deform when subjected to changes in mass loading. Hence an increasing ocean mass should deform the ocean bottom downwards. This effect was negligible until early 2000s, when steric change was the dominant driver of sea surface height variations. However, in recent decades changes in ocean mass have overtaken steric change and is expected to continue to grow. Therefore, the resultant ocean bottom deformation (OBD) can no longer be assumed to be negligible. In this study we derive the sea level budget equation from fundamental principles to show that OBD should be included, and demonstrate that it is at least as important as deep‐ocean volume changes.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2626 on: January 17, 2020, 11:26:55 PM »
The linked GlacierHub article has interesting information about the status of the MELT project within the ITGC effort:

Title: "Photo Friday: Thwaites Glacier Bore Hole Drilled"

https://glacierhub.org/2020/01/17/photo-friday-thwaites-glacier-bore-hole-drilled/

Extract: "A team of scientists led by David Holland and Keith Nicholls––from the International Thwaites Glacier Collaboration Project (ITGC)––are using hot water to drill holes through the glacier. On January 8 the first bore hole was drilled, opening a 590 meter access point directly to the bottom of the glacier.

The goal of the project––MELT––is to better understand how the warm water is melting the glacier at the grounding line. Ultimately, researchers hope the data gleaned will allow the glacier’s potential sea-level contribution to be more accurately predicted.

With the first site finished🙂, we’ve been busy moving 🛷the equipment upstream⤴️ onto the grounded ice🧊 for our second site. Fingers crossed that the weather🌞🌨️💨 holds and we get the hole🕳️ drilled before we have to start our uplift!🛩️🛩️ @BAS_News @GlacierThwaites pic.twitter.com/KTVELd6SEa
— Hot Water on Ice (@HotWaterOnIce) January 15, 2020"
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2627 on: January 17, 2020, 11:41:11 PM »
While several months old, the linked article has some interesting information about ITGC & the Thwaites Glacier and potential consequences if it collapses quickly:

Title: "If Thwaites Glacier collapses, it would change global coastlines forever"

https://interactive.pri.org/2019/05/antarctica/thwaites-glacier-collapse.html

Extract: "Scientists fear the collapse of Thwaites Glacier could one day destabilize surrounding glaciers and eventually trigger up to 11 feet of global sea level rise.

“You could get a domino effect of icebergs falling off of the edge of an ice sheet,” said Ali Graham, a marine geophysicist on the ship from the UK’s University of Exeter.

“There's still a debate over what [this collapse] would look like,” Graham said. “We could be observing it right now and not really realize that it’s happening, and that’s pretty scary to think about.”

The ultimate goal of the five-year research collaboration is to collect data — on the glacier itself, the bedrock beneath it, and the warm water melting it — that will improve models and fill in some of the unknowns about what the glacier’s collapse might look like. And how fast it might happen once it starts.

“How quickly can you feasibly collapse something like Thwaites?” Graham said. “Is it over a century, over a thousand years, or can you do in a decade? I don't think anyone can, hand on heart, say which of those it is yet. And that's a concern.”"
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2628 on: January 18, 2020, 12:09:33 AM »
I note that most of the recently identified risks for danger climate tipping point mechanisms discussed in the linked article are associated with ice-climate feedback mechanisms:

Title: "Climate Science Discoveries of the Decade: New Risks Scientists Warned About in the 2010s"

https://insideclimatenews.org/news/27122019/climate-science-decade-2019-year-review-tipping-points-jet-stream-ocean-circulation

Extract: "A decade of ice, ocean and atmospheric studies found systems nearing dangerous tipping points. As the evidence mounted, countries worldwide began to see the risk.

The 2010s may also be remembered as the decade when scientists cast away their reluctance to advocate for political and social changes.

"My sense is that a key reason for this is the widening gap between physical reality and political reality," he said. "There is a growing sense that society is careening toward the abyss while we're collectively arguing about whether we should hit the brakes.

"Scientists who work in the climate domain are particularly, sometimes painfully, aware of the consequences that lie ahead if we continue on our current trajectory. And we're also aware that the emissions targets set forth in the Paris Agreement remain largely aspirational; we're currently still on a path to blow right past them.""
« Last Edit: January 18, 2020, 06:21:49 PM by AbruptSLR »
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2629 on: January 18, 2020, 02:56:48 PM »
Per the attached image from the linked Scripps website, it certainly looks to me like through January 15, 2020 that atmospheric CO2 concentrations at Mauna Loa are still following RCP 8.5:

Which needs to be mentioned on this site over and over and over again. Too many people here make comments about how we will be OK, using RCP 4.5 even when we have little hope of following this path.

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2630 on: January 18, 2020, 03:09:26 PM »
...
I wonder, do you emotionally connect with all this?

I have found that when I expressed my emotions in this forum in the past it was either a waste of time, or actually counter-productive, so now I try to stick with the scientific method approach as much as practicable.

And I appreciate your approach.

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2631 on: January 18, 2020, 03:17:20 PM »
Per the attached image from the linked Scripps website, it certainly looks to me like through January 15, 2020 that atmospheric CO2 concentrations at Mauna Loa are still following RCP 8.5:

Which needs to be mentioned on this site over and over and over again. Too many people here make comments about how we will be OK, using RCP 4.5 even when we have little hope of following this path.

Yes, if you look through the binoculars the wrong way, you might see a figure like that.

On a smaller scale, it's more than evident that we are NOT on RCP 8.5 any more - see the graphs provided by Ken Feldman upthread, and that we seem to have left the exponential increase in the Keeling curve as well.

Lies, damned lies, and statistics. Same goes for graphs.

That said, it doesn't imply that we'll necessarilly be ok.

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2632 on: January 18, 2020, 04:21:46 PM »
If you include land use changes then we are still on RCP8.5.


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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2633 on: January 18, 2020, 05:42:43 PM »
wdmn, can you give a reference to that figure, please!

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2634 on: January 18, 2020, 06:20:48 PM »
The question of anthropogenic radiative forcing is complex and difficult for the general public to understand and includes not only topics of uncertainties in observed radiative forcing but also of effective radiative forcing as well as projections of possible future effective radiative forcing.

For example, the first two images (from the first linked reference) shows the evolution of IPCC AR evaluations of the global-mean anthropogenic radiative forcing, effective radiative forcing and associated uncertainties for the periods from for FAR (1765-1990), SAR (1750-1992), TAR (1750-1998), AR4 (1750-2005) and AR5 (1750-2011).  While there are many this that I could say about this image, here I will only note that for the indicated total anthropogenic radiative forcing, AR4 only had a global-mean value of 1.6W/sq m (0.80 to 2.60), while AR5 had an effective global-mean value of 2.30W/sq m (1.30 to 3.50); and this change in global mean did not only come from the additional CO2 emission from 2005 to 2011, but also due to changes in the other radiative forcing components as well as changes in IPCC's understanding/representation of uncertainties.

For another example, the second image (also from the first linked reference) shows how AR5 attributed radiative forcing to the emitted radiative forcing component; which for example shows that AR5 attributed radiative forcing to emitted methane that included contributions from its chemical reactions with other components in the atmosphere, which increased the attributed global warming potential of such key emitted non-CO2 gases.

For another example, the third image (from the first linked reference) shows various PDFs associate with radiative forcing, not only from AR4 and AR5 but also associate two RCP scenarios; which help to illustrate differences in radiative forcing uncertainties assumed by consensus climate sciences at different times and in different forums.

Finally, for this post, I note that the second linked reference discusses 'New insights into natural variability and anthropogenic forcing of global/regional climate evolution'; which indicates that: 'the observed GMSAT changes from 1880 to 2017 on multi-decadal or longer timescales receive contributions of about 70% from GHGs, while AMV and PDV together account for roughly 30%', where AMV = Atlantic multi-decadal variability and PDV = Pacific decadal variability.  To me this shows that a natural variability increases with global warming so is climate sensitivity.

Title: "Radiative Forcing of Climate: The Historical Evolution of the Radiative Forcing Concept, and Forcing Agents and their Quantification, and Applications", Atmospheric Society Meteorological Monograph, 2019, doi: 10.1175/AMSMONOGRAPHS-D-19-0001.1

https://journals.ametsoc.org/doi/pdf/10.1175/AMSMONOGRAPHS-D-19-0001.1

&

Wu, T., Hu, A., Gao, F. et al. New insights into natural variability and anthropogenic forcing of global/regional climate evolution. npj Clim Atmos Sci 2, 18 (2019) doi:10.1038/s41612-019-0075-7

https://www.nature.com/articles/s41612-019-0075-7

Abstract: "Because of natural decadal climate variability—Atlantic multi-decadal variability (AMV) and Pacific decadal variability (PDV) —the increase of global mean surface air temperature (GMSAT) has not been monotonic although atmospheric greenhouse-gas (GHG) concentrations have been increasing continuously. It has always been a challenge regarding how to separate the effects of these two factors on GMSAT. Here, we find a physically based quasi-linear relationship between transient GMSAT and well-mixed GHG changes for both observations and model simulations. With AMV and PDV defined as the combination of variability over both the Atlantic and Pacific basins after the GHG-related trend is removed, we show that the observed GMSAT changes from 1880 to 2017 on multi-decadal or longer timescales receive contributions of about 70% from GHGs, while AMV and PDV together account for roughly 30%. Moreover, AMV contributes more to time-evolving GMSAT on multi-decadal and longer timescales, but PDV leads AMV on decadal timescales with comparable contributions to GMSAT trends."
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2635 on: January 18, 2020, 06:49:11 PM »
The linked article presents evidence that many companies (particularly those in the USA) are exploiting loopholes in the Clean Air Act and the Montreal Protocol to release ozone-depleting chemicals into the atmosphere; which will likely delay the healing of the Antarctic Ozone Hole by decades:

Title: "Ozone Layer Recovery Is Being Undermined by Pollution From U.S. Companies"

https://theintercept.com/2020/01/18/ozone-layer-epa-united-states-pollution/

Extract: "The international commitment to eliminating ozone-depleting chemicals has held so firm that in 2018, when some Chinese factories were discovered to be using a substance banned by the treaty known as CF11, they were met with condemnation from the U.S. and other countries. Erik Solheim, head of the United Nations Environment Program, which oversees the Montreal Protocol, called the release of the ozone-depleting substance “nothing short of an environment crime which demands decisive action.” China quickly addressed the problem.

Yet evidence has recently emerged that U.S. companies are also releasing ozone-depleting chemicals. While the ozone layer is rebounding overall, scientists have observed decreasing levels of the gas in certain areas. Chemicals used for everything from fracking to cooling appear to be the culprits, according to comments the nonprofit Environmental Investigation Agency submitted to the Environmental Protection Agency in December. The chemical pollution, some of which is coming from the U.S., EPA records show, has already delayed progress on the ozone layer. The resulting setback appears to be worse in highly populated southern latitudes, where it could cause the most damage. Continued emissions of the chemicals could delay the healing of the ozone layer by up to 30 years, according to a 2017 article published in Nature Communications.

Both the Clean Air Act and the Montreal Protocol do regulate some of these short-lived chemicals that erode the ozone layer. But they make an exception when the chemicals are byproducts or used as feedstock for making other products, a loophole that may explain why some of them are still accumulating in the atmosphere more than 30 years after the treaty took effect."
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2636 on: January 18, 2020, 07:19:00 PM »
Attached is a cartoon of the MELT project (part of ITGC) activities thru January 17 2020.  I hope that they finish all of their mapping and complete their second bore hole before inclement weather shuts them down.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2637 on: January 19, 2020, 04:19:06 AM »
If continuing climate change increases the frequency of future wildfires, who knows how much impact the combination of emitted CO2, and black carbon, will have as positive feedback mechanisms:

Title: "Australia's Wildfires Might Intensify Future Climate Crises"

https://www.wired.com/story/australias-wildfires-might-intensify-future-climate-crises/

Extract: "Wildfires release vast amounts of carbon into the atmosphere. Their broader impact is far more complicated.

There are a couple of ways increasingly severe wildfire seasons could speed up global climate change. In the months immediately following wildfires, the volume of CO2 in the world’s atmosphere increases, magnifying the heat trapped there. “Wildfires create a substantial contribution, because they happen in places like the Amazon rain forest and the peat bogs in Indonesia, which contain a lot of carbon,” says Colin Prentice, director of the Leverhulme Centre for Wildfires at Imperial College London. The ongoing Australian fire season has released more than 350 million metric tons of CO2 so far, with fires expected to keep burning over the next two months.

Fires also throw up clouds of soot into the atmosphere, which compounds the problem. “Black carbon is the most strongly light-absorbing material from fires, and it is regarded as one of the most important individual climate-warming agents,” Yafang Cheng, a researcher from the Max Planck Institute for Chemistry in Mainz, Germany, told WIRED in November 2018. These particles can float up into the upper layers of the atmosphere where they exert an even greater heating effect—and hang around for months."
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2638 on: January 19, 2020, 07:08:28 AM »
^^
Is it possible/likely that much of this black carbon from the Australian bushfires ends up on the Antarctic icesheet? Perhaps the westerlies around Antarctica are protecting the East Antarctic icesheet?
I have looked at the winds from (east) Australia to Antarctica on climatereanalyzer but wasn't able to get a clear picture.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2639 on: January 19, 2020, 07:45:17 PM »
^^
Is it possible/likely that much of this black carbon from the Australian bushfires ends up on the Antarctic icesheet? Perhaps the westerlies around Antarctica are protecting the East Antarctic icesheet?
I have looked at the winds from (east) Australia to Antarctica on climatereanalyzer but wasn't able to get a clear picture.

The first image indicates that much of the smoke from the Australian wildfires reaches South American; however, the second & third images indicate that small percentages of the black carbon in the associated wildfire periodically reaches Antarctica
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2640 on: January 19, 2020, 08:54:31 PM »
Aussie wildfires have happened for millenia - and are part of the natural cycle of many Eucalyptus trees and associaed flora. But the fires this year are just too too intense, too widespread and too long-lasting, and are breaking that natural cycle.

If the wildfires are intense enough, mature trees are killed (as seems to be the case in many of the Aussie wildfires), not just scorched. That means many years (if at all) before regrowth restores the forest as a carbon sink.

An article from 2014 that explains what should happen....

https://wildfiretoday.com/2014/03/03/eucalyptus-and-fire/
Quote
Eucalyptus and fire
Quote

“…Gum trees, as eucalypts are known, ‘are like weeds that come up on bombed-out blocks’, adds Jamie Kirkpatrick, professor of geography and environmental studies at the university. ‘They’re fantastically fast growers and great colonisers, but not great competitors.’

Eucalypts typically let through a lot of light, allowing other vegetation types such as scrub and grass to grow beneath them. They can live for maybe 700 years. But they won’t regenerate, Kirkpatrick explains, if what is growing beneath them over the years becomes too dense. Most eucalypt species, therefore — there are more than 600 in Australia — have evolved traits that allow them to survive and prosper in the fires that will clear that undergrowth.

Some, like the mighty, 100-metre-tall Eucalyptus regnans — also known as the mountain ash, stringy gum or Tasmanian oak — hold their seeds inside small, hard capsules; a fire will instantly trigger a massive drop of seeds to the newly fertilised ground.

The myriad bright green buds that sprout spectacularly from the trunks of other eucalypts in the aftermath of a big fire are another kind of regeneration mechanism, bursting through the scorched and blackened bark within weeks of a blaze.

Within five or six years, ‘a burned forest will be looking pretty good’, Kirkpatrick says. ‘And a large proportion of Tasmania’s flora fits into this fire ecology. Pea plants, wattles — their germination is stimulated by heat and smoke. Fire is really, really important in Tasmania.’

At the centre of it all, though, is the eucalypt. Because these trees do not just resist fire, they actively encourage it. ‘They withstand fire, they need fire; to some extent, they create fire,’ Bowman says. ‘The leaves, the bark, don’t decompose. They’re highly, highly flammable. And on a hot day, you can smell their oils.’

The bark and leaves of eucalypts seem almost made to promote fire. Some are known as stringy or candle-barks: long, easily lit strips hang loosely off their trunks and, once alight, whirl blazing up into the flammable canopy above, or are carried by the wind many kilometres ahead of a fire to speed its advance.”
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2641 on: January 19, 2020, 11:30:57 PM »
wdmn, can you give a reference to that figure, please!

Comes from Glen Peters' twitter (so will be in one of his articles) He's @peters_glen

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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2642 on: January 20, 2020, 05:29:34 PM »
While consensus climate scientists commonly assume that atmospheric methane has a 9-year lifetime; the linked reference finds that the coupled chemistry of carbon monoxide and hydroxyl radical with methane can extend this lifetime by about 40%.  This is yet another example of consensus climate scientists erring on the side of least drama:

Newton H. Nguyen et al. (16 January 2020), "Effects of Chemical Feedbacks on Decadal Methane Emissions Estimates", Geophysical Research Letters, https://doi.org/10.1029/2019GL085706

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019GL085706

Abstract

The coupled chemistry of carbon monoxide (CO), methane and hydroxyl radical (OH) can modulate methane's 9‐year lifetime, often being ignored in methane‐flux inversions, and the impacts of neglecting those feedbacks have not been quantified. Using a coupled‐chemistry box model, we show that neglecting methane's effect on [OH] can lead to a 25% bias in calculating methane source perturbations after only 10yr. Further, CO, such as from biomass burning, can have a comparable impact on methane concentrations as direct‐methane emissions, yet acting at much larger spatial scales and delayed by several months. Finally, we quantify the biases of including (or excluding) coupled chemistry in the context of recent methane and CO trends. Inter‐annual variations and decreasing trends in CO concentrations have substantial impacts on‐methane flux inversions. Given these non‐negligible errors, decadal‐methane‐emissions inversions should incorporate chemical feedbacks for more robust methane trend analyses and source attributions.

Plain Language Summary
Methane inversion studies commonly assume that atmospheric methane has a 9‐year lifetime, but the decay rate of methane perturbations can be extended by 40%. This effect is from interactions of other atmospheric compounds with methane's main sink, the hydroxyl radical. This is important for estimating global emissions over recent decades. We show that one of these compounds, carbon monoxide (CO), emitted from wildfires during El Niño, can lead to large increases in methane concentrations by extending the methane lifetime. Moreover, ignoring these effects can lead up to a 25% error in estimating methane emissions changes after a decade. Finally, we show that the effect of decreasing CO on methane has extended the methane lifetime and has led to some biases in calculating methane emissions. Thus, attributing causes of recent methane emissions trends are dependent on the consideration of compounds indirectly affecting the methane lifetime, which may have implications for future mitigation plans.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2643 on: January 20, 2020, 09:59:51 PM »
Most of the media is promoting the findings of the linked reference that ozone-depleting substances (ODS) caused about half of the Arctic Amplification between 1955 & 2005; because they seem to believe that the Montreal Protocol will control ODSs to the extent that Arctic Amplification will slowdown in the future.  However, it is also possible that the Arctic has reached a tipping point and that Arctic Amplification may continue even if ODSs are successfully controlled:

Substantial twentieth-century Arctic warming caused by ozone-depleting substances, Nature Climate Change (2020). DOI: 10.1038/s41558-019-0677-4 ,

https://www.nature.com/articles/s41558-019-0677-4

Abstract: "The rapid warming of the Arctic, perhaps the most striking evidence of climate change, is believed to have arisen from increases in atmospheric concentrations of GHGs since the Industrial Revolution. While the dominant role of carbon dioxide is undisputed, another important set of anthropogenic GHGs was also being emitted over the second half of the twentieth century: ozone-depleting substances (ODS). These compounds, in addition to causing the ozone hole over Antarctica, have long been recognized as powerful GHGs. However, their contribution to Arctic warming has not been quantified. We do so here by analysing ensembles of climate model integrations specifically designed for this purpose, spanning the period 1955–2005 when atmospheric concentrations of ODS increased rapidly. We show that, when ODS are kept fixed, forced Arctic surface warming and forced sea-ice loss are only half as large as when ODS are allowed to increase. We also demonstrate that the large impact of ODS on the Arctic occurs primarily via direct radiative warming, not via ozone depletion. Our findings reveal a substantial contribution of ODS to recent Arctic warming, and highlight the importance of the Montreal Protocol as a major climate change-mitigation treaty."

See also:

Title: "Ozone-depleting substances caused half of late 20th-century Arctic warming, says study"

https://phys.org/news/2020-01-ozone-depleting-substances-late-20th-century-arctic.html

Extract: ""In the coming decades, they will contribute less and less to global warming. It's a good-news story.""
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2644 on: January 20, 2020, 10:35:10 PM »
I am happy that MELT completed their second bore hole & associated investigations as part of the ITGC:
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2645 on: January 20, 2020, 11:24:06 PM »
While I believe that the MISMIP+ errs on the side of least drama, others may be interested in the findings of the linked reference:

Cornford, S. L., Seroussi, H., Asay-Davis, X. S., Gudmundsson, G. H., Arthern, R., Borstad, C., Christmann, J., Dias dos Santos, T., Feldmann, J., Goldberg, D., Hoffman, M. J., Humbert, A., Kleiner, T., Leguy, G., Lipscomb, W. H., Merino, N., Durand, G., Morlighem, M., Polllard, D., Rückamp, M., Williams, C. R., and Yu, H.: Results of the third Marine Ice Sheet Model Intercomparison Project (MISMIP+), The Cryosphere Discuss., https://doi.org/10.5194/tc-2019-326, in review, 2020.

https://www.the-cryosphere-discuss.net/tc-2019-326/
https://www.the-cryosphere-discuss.net/tc-2019-326/tc-2019-326.pdf

Abstract. We present the result of the third Marine Ice Sheet Intercomparison project, MISMIP+. MISMIP+ is intended to be a test of ice flow models which include fast sliding marine ice streams and floating ice shelves and in particular a treatment of viscous stress that is sufficient for buttressing, where upstream ice flow is restrained by a downstream ice shelf. A set of idealized experiments test the models in circumstances where buttressing contributes to a stable steady state, and where a reduction in that buttressing causes ice stream acceleration, thinning, and grounding line retreat. We find that the most important distinction between models in this particular type of simulation is in the treatment of sliding at the bed, with other distinctions – notably the difference between the simpler and more complete treatments of englacial stress, but also the differences between numerical methods – taking a secondary role.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2646 on: January 20, 2020, 11:38:33 PM »
The linked reference makes recommendations as to how AR6 should communicate climate response risks:

Sutton, R. T. and Hawkins, E.: ESD Ideas: Global climate response scenarios for IPCC AR6, Earth Syst. Dynam. Discuss., https://doi.org/10.5194/esd-2019-88, in review, 2020.

https://www.earth-syst-dynam-discuss.net/esd-2019-88/

Abstract. Policy making on climate change routinely employs socio-economic scenarios to sample the uncertainty in future forcing of the climate system, but the IPCC has not developed similar discrete scenarios to sample the uncertainty in the global climate response. Here we argue that to enable development of robust policies this gap should be addressed, and we propose a simple methodology.
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2647 on: January 21, 2020, 06:41:19 AM »
^^
From the link: GSAT means "global mean surface air temperature".
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2648 on: January 21, 2020, 04:42:01 PM »
While India and China announced that they had effectively ended HFC-23 emissions at the end of 2017; the linked reference and associated article indicates that that is not the case; which, demonstrates the importance of independently monitoring GHG emission, typically using satellites:

K. Stanley, et al. Increase in global emissions of HFC-23 despite near-total expected reductions, Nature Communications, 2020, DOI: 10.1038/s41467-019-13899-4

https://www.nature.com/articles/s41467-019-13899-4

Abstract: "Under the Kigali Amendment to the Montreal Protocol, new controls are being implemented to reduce emissions of HFC-23 (CHF 3), a by-product during the manufacture of HCFC-22 (CHClF 2). Starting in 2015, China and India, who dominate global HCFC-22 production (75% in 2017), set out ambitious programs to reduce HFC-23 emissions. Here, we estimate that these measures should have seen global emissions drop by 87% between 2014 and 2017. Instead, atmospheric observations show that emissions have increased and in 2018 were higher than at any point in history (15.9 ± 0.9 Gg yr −1). Given the magnitude of the discrepancy between expected and observation-inferred emissions, it is likely that the reported reductions have not fully materialized or there may be substantial unreported production of HCFC-22, resulting in unaccounted-for HFC-23 by-product emissions. The difference between reported and observation-inferred estimates suggests that an additional ~309 Tg CO 2-equivalent emissions were added to the atmosphere between 2015 and 2017."

See also:

Title: "Emissions of potent greenhouse gas rises, contradicting reports of huge reductions"

https://phys.org/news/2020-01-emissions-potent-greenhouse-gas-contradicting.html

Extract: "Despite reports that global emissions of the potent greenhouse gas hydrofluorocarbon (HFC) were almost eliminated in 2017, an international team of scientists, led by the University of Bristol, has found atmospheric levels growing at record values.

Scientists are concerned, because HFC-23 is a very potent greenhouse gas, with one tonne of its emissions being equivalent to the release of more than 12,000 tonnes of carbon dioxide. Starting in 2015, India and China, thought to be the main emitters of HFC-23, announced ambitious plans to abate emissions in factories that produce the gas. As a result, they reported that they had almost completely eliminated HFC-23 emissions by 2017.

In response to these measures, scientists were expecting to see global emissions drop by almost 90 percent between 2015 and 2017, which should have seen growth in atmospheric levels grind to a halt. Now, an international team of researchers has shown that concentrations increased, setting an all-time record in 2018."
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Re: Ice Apocalypse - MULTIPLE METERS SEA LEVEL RISE (narrated video)
« Reply #2649 on: January 21, 2020, 04:52:48 PM »
The linked article indicates that the United States-Mexico-Canada Agreement (USMCA) "… moves us one step closer to locking in Trump’s polluting legacy for decades to come."

Title: "The New U.S. Trade Deal Is Climate Sabotage"

https://newrepublic.com/article/156240/new-us-trade-deal-climate-sabotage

Extract: " “Trump’s Nafta 2.0 is a climate failure any way you slice it,” the Sierra Club’s Ben Beachy told me. Beyond continuing to allow companies to seek lax climate and environmental rules outside the United States, the USMCA also lets them challenge new regulations proposed by countries signed onto it before they’re finalized, establishing hurdles to any future climate policy under a new administration.

The deal also goes out of the way to protect fossil fuel companies. All of the tar sands oil that flows to the U.S. from Canada via the Keystone XL pipeline will be exempt from tariffs under the USMCA. While the deal has been praised for largely eliminating Nafta’s Investor-State Dispute Settlement provisions—which made it easy for corporations to challenge governments over laws they don’t like—there are some troubling exceptions to that policy under the USMCA: Oil and gas companies that have contracts with the Mexican government, for example, will still be allowed to challenge any potential threats to their profits posed by state policy. “It’s like saying we’re going to protect the henhouse by keeping all animals away except for foxes,” Beachy said, adding that “today’s vote moves us one step closer to locking in Trump’s polluting legacy for decades to come.” Climate and environmental groups broadly opposed the deal, including some—like the Natural Resources Defense Council—that enthusiastically backed Nafta 1.0 in the 1990s. "
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