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Vice-Regent

High Climate Sensitivity in the Community Earth System Model Version 2 (CESM2)

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New CESM2 runs are indicating that the most likely value for ECS is 5.3C:

A. Gettelman et al. (16 July 2019), "High Climate Sensitivity in the Community Earth System Model Version 2 (CESM2)", Geophysical Research Letters, https://doi.org/10.1029/2019GL083978

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019GL083978

Abstract: "The Community Earth System Model Version 2 (CESM2) has an equilibrium climate sensitivity (ECS) of 5.3 K. ECS is an emergent property of both climate feedbacks and aerosol forcing. The increase in ECS over the previous version (CESM1) is the result of cloud feedbacks. Interim versions of CESM2 had a land model that damped ECS. Part of the ECS change results from evolving the model configuration to reproduce the long‐term trend of global and regional surface temperature over the twentieth century in response to climate forcings. Changes made to reduce sensitivity to aerosols also impacted cloud feedbacks, which significantly influence ECS. CESM2 simulations compare very well to observations of present climate. It is critical to understand whether the high ECS, outside the best estimate range of 1.5–4.5 K, is plausible."

See also:

Title: "New Models Point to More Global Warming Than We Expected"

https://www.wunderground.com/cat6/New-Models-Point-More-Global-Warming-We-Expected

Extract: "Our planet’s climate may be more sensitive to increases in greenhouse gas than we realized, according to a new generation of global climate models being used for the next major assessment from the Intergovernmental Panel on Climate Change (IPCC). The findings—which run counter to a 40-year consensus—are a troubling sign that future warming and related impacts could be even worse than expected.

One of the new models, the second version of the Community Earth System Model (CESM2) from the National Center for Atmospheric Research (NCAR), saw a 35% increase in its equilibrium climate sensitivity (ECS), the rise in global temperature one might expect as the atmosphere adjusts to an instantaneous doubling of atmospheric carbon dioxide. Instead of the model’s previous ECS of 4°C (7.2°F), the CESM2 now shows an ECS of 5.3°C (9.5°F)."

Courtesy of AbruptSLR (ASIF)

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Keep in mind the devil is in the details. The aerosol forcing continues to muck up the situation when we are extrapolating from real world conditions. Climate models are very accurate simulations of what we should come to expect.

We know there is a massive threat from a ECS of 5.3C in the short-term and long-term prognosis because the aerosol forcing will inevitably be reduced. You may also come to understand why geoengineering is so dangerous due to three reasons. 1:) Solar-radiation management keeps the ECS value hidden indefinitely 2:) Geoengineering must be sustained for generations (more or less indefinitely) and finally 3:) Air-Capture reduces the incentive to prevent deforestation and restore a suitable amount of oxygen in the atmosphere and oceans.

These models allow us to avoid the risky overhead of geoengineering by providing insight into how our world would function at specific GHG concentrations with the aerosol forcing removed. We should opt for de-growth modes of attack versus mitigation modes of attack.

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3 hours ago, Vice-Regent said:

Keep in mind the devil is in the details. The aerosol forcing continues to muck up the situation when we are extrapolating from real world conditions. Climate models are very accurate simulations of what we should come to expect.

We know there is a massive threat from a ECS of 5.3C in the short-term and long-term prognosis because the aerosol forcing will inevitably be reduced. You may also come to understand why geoengineering is so dangerous due to three reasons. 1:) Solar-radiation management keeps the ECS value hidden indefinitely 2:) Geoengineering must be sustained for generations (more or less indefinitely) and finally 3:) Air-Capture reduces the incentive to prevent deforestation and restore a suitable amount of oxygen in the atmosphere and oceans.

These models allow us to avoid the risky overhead of geoengineering by providing insight into how our world would function at specific GHG concentrations with the aerosol forcing removed. We should opt for de-growth modes of attack versus mitigation modes of attack.

SMH. Really? you believe this?  Of course it is "worse than we thought".  If the Earth's climate were this sensitive we wouldn't be here. Life would not exist as rapid changes in the past would have ended up as either a hothouse Earth or an ice house.  This is simply propaganda. 

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7 hours ago, Vice-Regent said:

Keep in mind the devil is in the details. The aerosol forcing continues to muck up the situation when we are extrapolating from real world conditions. Climate models are very accurate simulations of what we should come to expect.

We know there is a massive threat from a ECS of 5.3C in the short-term and long-term prognosis because the aerosol forcing will inevitably be reduced. You may also come to understand why geoengineering is so dangerous due to three reasons. 1:) Solar-radiation management keeps the ECS value hidden indefinitely 2:) Geoengineering must be sustained for generations (more or less indefinitely) and finally 3:) Air-Capture reduces the incentive to prevent deforestation and restore a suitable amount of oxygen in the atmosphere and oceans.

These models allow us to avoid the risky overhead of geoengineering by providing insight into how our world would function at specific GHG concentrations with the aerosol forcing removed. We should opt for de-growth modes of attack versus mitigation modes of attack.

It's not necessarily aerosols here, it's clouds and changes to the behavior of marine stratocumulus in particular. Once the new parameterizations for marine stratocumulus are included (which tend to produce more realistic results when compared to previous versions), sensitivity jumps. It remains to be seen whether that's real or not.

Also, one has to keep in mind that TCR is probably the more relevant short term metric and it has been shown to be somewhat more insensitive with higher ECS (ergo, TCR increases more slowly with higher ECS). So even if ECS does end up being like 5C from 3C, then TCR "only" jumps from 2.0 to 2.8C.

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47 minutes ago, csnavywx said:

It's not necessarily aerosols here, it's clouds and changes to the behavior of marine stratocumulus in particular. Once the new parameterizations for marine stratocumulus are included (which tend to produce more realistic results when compared to previous versions), sensitivity jumps. It remains to be seen whether that's real or not.

Also, one has to keep in mind that TCR is probably the more relevant short term metric and it has been shown to be somewhat more insensitive with higher ECS (ergo, TCR increases more slowly with higher ECS). So even if ECS does end up being like 5C from 3C, then TCR "only" jumps from 2.0 to 2.8C.

More worryingly. A substantial aerosol forcing would reduce the already diminished TCR. It's easy to see the fragile network of dependencies in our dire situation. If we don't tread lightly we may find ourselves walking over the tipping point in the climate system and in our capacity to reduce atmospheric CO2 faster than the climate is responding.

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4 hours ago, blizzard1024 said:

SMH. Really? you believe this?  Of course it is "worse than we thought".  If the Earth's climate were this sensitive we wouldn't be here. Life would not exist as rapid changes in the past would have ended up as either a hothouse Earth or an ice house.  This is simply propaganda. 

Weathering

Carbon dioxide and the other atmospheric gases dissolve in surface waters. Dissolved gases are in equilibrium with the gas in the atmosphere. Carbon dioxide reacts with water in solution to form the weak acid, carbonic acid. Carbonic acid disassociates into hydrogen ions and bicarbonate ions. The hydrogen ions and water react with most common minerals (silicates and carbonates) altering the minerals. The products of weathering are predominantly clays (a group of silicate minerals) and soluble ions such as calcium, iron, sodium, and potassium. Bicarbonate ions also remain in solution; a remnant of the carbonic acid that was used to weather the rocks.

 

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7 hours ago, blizzard1024 said:

This peer reviewed paper has a climate sensitivity of 0.7C per doubling of CO2....

 

https://www.hindawi.com/journals/ijas/2017/9251034/

 

 

Outliers, both low and high, are rarely the most likely scenario. It is extremely rare that the most extreme ensemble member verifies. That’s the nature of scenarios that lie in the tails.

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This is a good write-up on the topic of this thread.

https://www.sciencemag.org/news/2019/04/new-climate-models-predict-warming-surge

For nearly 40 years, the massive computer models used to simulate global climate have delivered a fairly consistent picture of how fast human carbon emissions might warm the world. But a host of global climate models developed for the United Nations’s next major assessment of global warming, due in 2021, are now showing a puzzling but undeniable trend. They are running hotter than they have in the past. Soon the world could be, too.

In earlier models, doubling atmospheric carbon dioxide (CO2) over preindustrial levels led models to predict somewhere between 2°C and 4.5°C of warming once the planet came into balance. But in at least eight of the next-generation models, produced by leading centers in the United States, the United Kingdom, Canada, and France, that “equilibrium climate sensitivity” has come in at 5°C or warmer. Modelers are struggling to identify which of their refinements explain this heightened sensitivity before the next assessment from the United Nations’s Intergovernmental Panel on Climate Change (IPCC). But the trend “is definitely real. There’s no question,” says Reto Knutti, a climate scientist at ETH Zurich in Switzerland. “Is that realistic or not? At this point, we don’t know.”

That’s an urgent question: If the results are to be believed, the world has even less time than was thought to limit warming to 1.5°C or 2°C above preindustrial levels—a threshold many see as too dangerous to cross. With atmospheric CO2 already at 408 parts per million (ppm) and rising, up from preindustrial levels of 280 ppm, even previous scenarios suggested the world could warm 2°C within the next few decades. The new simulations are only now being discussed at meetings, and not all the numbers are in, so “it’s a bit too early to get wound up,” says John Fyfe, a climate scientist at the Canadian Centre for Climate Modelling and Analysis in Victoria, whose model is among those running much hotter than in the past. “But maybe we have to face a reality in the future that’s more pessimistic than it was in the past.”

Many scientists are skeptical, pointing out that past climate changes recorded in ice cores and elsewhere don’t support the high climate sensitivity—nor does the pace of modern warming. The results so far are “not sufficient to convince me,” says Kate Marvel, a climate scientist at NASA’s Goddard Institute for Space Studies in New York City. In the effort to account for atmospheric components that are too small to directly simulate, like clouds, the new models could easily have strayed from reality, she says. “That’s always going to be a bumpy road.”

Builders of the new models agree. Scientists at the National Oceanic and Atmospheric Administration’s Geophysical Fluid Dynamics Laboratory (GFDL) in Princeton, New Jersey—the birthplace of climate modeling—incorporated a host of improvements in their next-generation model. It mimics the ocean in fine enough detail to directly simulate eddies, honing its representation of heat-carrying currents like the Gulf Stream. Its rendering of the El Niño cycle, the periodic warming of the equatorial Pacific Ocean, looks “dead on,” says Michael Winton, a GFDL oceanographer who helped lead the model’s development. But for some reason, the world warms up faster with these improvements. Why? “We’re kind of mystified,” Winton says. Right now, he says, the model’s equilibrium sensitivity looks to be 5°C.

Developers of another next-generation model, from the National Center for Atmospheric Research (NCAR) in Boulder, Colorado, wonder whether their new rendering of clouds and aerosols might explain why it, too, is running hot, with a sensitivity in the low fives. The NCAR team, like other modelers, has had persistent problems in simulating the supercooled water found in clouds that form above the Southern Ocean around Antarctica. The clouds weren’t reflective enough, allowing the region to absorb too much sunlight. The new version fixes that problem.

Late in the model’s development cycle, however, the NCAR group incorporated an updated data set on emissions of aerosols, fine particles from industry and natural processes that can both reflect sunlight or goose the development of clouds. The aerosol data threw everything off—when the model simulated the climate of the 20th century, it now showed hardly any warming. “It took us about a year to work that out,” says NCAR’s Andrew Gettelman, who helped lead the development of the model. But the aerosols may play a role in the higher sensitivity that the modelers now see, perhaps by affecting the thickness and extent of low ocean clouds. “We’re trying to understand if other [model developers] went through the same process,” Gettelman says.

Answers may come from an ongoing exercise called the Coupled Model Intercomparison Project (CMIP), a precursor to each IPCC round. In it, modelers run a standard set of simulations, such as modeling the preindustrial climate and the effect of an abrupt quadrupling of atmospheric CO2 levels, and compare notes. The sixth CMIP is now at least a year late. The first draft of the next IPCC report was due in early April, yet only a handful of teams had uploaded modeling runs of future projections, says Fyfe, an author of the report’s projections chapter. “It’s maddening, because it feels like writing a sci-fi story as the first-order draft.”

The ambitious scope of this CMIP is one reason for the delay. Beyond running the standard five simulations, centers can perform 23 additional modeling experiments, targeting specific science questions, such as cloud feedbacks or short-term prediction. The CMIP teams have also been asked to document their computer code more rigorously than in the past, and to make their models compatible with new evaluation tools, says Veronika Eyring, a climate modeler at the German Aerospace Center in Wessling who is co-leading this CMIP round.

Such comparisons may help the modelers respond to the IPCC authors, who are peppering them with questions about the higher sensitivity, Gettelman says. “They’re asking us, what’s going on?” he says. “They’re pushing people. They’ve got about a year to figure this out.”

In assessing how fast climate may change, the next IPCC report probably won’t lean as heavily on models as past reports did, says Thorsten Mauritsen, a climate scientist at Stockholm University and an IPCC author. It will look to other evidence as well, in particular a large study in preparation that will use ancient climates and observations of recent climate change to constrain sensitivity. IPCC is also not likely to give projections from all the models equal weight, Fyfe adds, instead weighing results by each model’s credibility.

Even so, the model results remain disconcerting, Gettelman says. The planet is already warming faster than humans can cope with, after all. “The scary part is these models might be right,” he says. “Because that would be pretty devastating.”

 

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Can't get too excited about any one study or model. However, after 40+ years of rapid warming since aerosols stabilized, it should be clear that nature isn't going to bail us out.

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Well like many have been saying for some time. The Paleoclimate data robustly agrees with these new NCAR models. IPCC will ignore these findings at their own peril. They have yet to elucidate on a clear path for carbon dioxide removal or suggest the implementation of legislation that would allow climate engineering to become legalized. These are necessary if the IPCC emissions pathway is to be sustainable.

Obviously with the inherent risks found in geoengineering we must be more aggressive in reducing deforestation and economic growth.

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An argument can be made for the IPCC to increase the lower bound on their estimate from 1.5C back to 2.0C. 

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A pretty strong argument, imo. Not much support for anything below 2C at this point, especially after the corrections to the lower-end estimates in the recent past.

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On 8/12/2019 at 7:46 PM, blizzard1024 said:

This peer reviewed paper has a climate sensitivity of 0.7C per doubling of CO2....

 

https://www.hindawi.com/journals/ijas/2017/9251034/

 

 

Harde has published questionable papers in the past. For example, he conflates the residence time of CO2 with the adjustment time (among other problems) to show that anthroprogenic emissions only account for 4% of the post industrial ppm increase. You can read more about that here

But his misunderstanding of the carbon cycle is no reason to dismiss his 0.7C sensitivity claim outright. For that we can just look at observations. Since 1960 the surface has warmed by 0.9C with very little if any of that being convincingly attributable to naturally modulated forcing agents.  The hydrosphere has taken up heat equivalent to 0.6 W/m^2 of forcing for decades. If a natural (and non-GHG) forcing agent were a significant contributor of this uptake then given this magnitude it should have been quite easy to identify. Meanwhile the observed uptake of heat is a close match to the consensus theory which includes all known radiative forcing agents in their appropriate proportions including GHGs. As such the 0.7C sensitivity hypothesis has been convincingly falsified IMHO. Even the IPCC's lower bound of 1.5C is very likely to be too low.

So if Harde truly believes only 4% of the CO2 increase is anthroprogenic and if the sensitivity is only 0.7C then I guess that means he only attributes 0.04 * (ln(410/280) / ln(2)) * 0.7 = 0.015C of the 1.1C since the pre-industrial era to anthroprogenic CO2. That's about 1% which is an extreme (and I truly mean EXTREME) outlier to the overwhelming majority of estimates.

By the way, the journal in which he submitted this 0.7C claim is now defunct. I'm just saying...

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"Since 1960 the surface has warmed by 0.9C with very little if any of that being convincingly attributable to naturally modulated forcing agents.  The hydrosphere has taken up heat equivalent to 0.6 W/m^2 of forcing for decades. If a natural (and non-GHG) forcing agent were a significant contributor of this uptake then given this magnitude it should have been quite easy to identify. Meanwhile the observed uptake of heat is a close match to the consensus theory which includes all known radiative forcing agents in their appropriate proportions including GHGs"

 

How do you know this? Climate models? The ice core data clearly reveals that CO2 never dominated our climate system in the past 2.6 million years. So what is different now? It is a weak GHG with a small absorption band. H20 and clouds are 95% of the Earth's greenhouse effect. The whole theory, which is based on models, that CO2 drives the climate NOW is unfounded.  Explain to me how a highly non-linear chaotic system is linear in its dependence on CO2 level vs. temperature as is reflected in the ice core data?   The easy solution is that the oceans are more soluble to CO2 and other gases when they are colder by sucking CO2 in and outgas it when the Earth warms. This explains the lag in CO2 levels vs temperatures very well. Solar activity was at a 1000 year max in the late 20 century and was at a minimum during the Little Ice Age. How can anyone rule out solar variability in our modern warm period? There is some connection there. There has to be.   The hubris that folks on this board and climate scientists have about their understanding of the climate system is crazy.   The earth is NOT warming up rapidly either. Where do you get this from?  It is a slow rise well within the bounds of previous climate change in the Holocene. The Pleistocene has far larger climate swings. We live in a tranquil time of climate with slow modest warming. Many areas including where I live have not seen any changes in the last 100+ years. Take a look at average annual temperature for several U.S states(best observing network) as an example(below). If we are rapidly warming we certainly would have seen something significantly positive by now.  States like NY, ME, MI and ND  show small warming to NO changes. Any small warming is night time lows in winter where UHI dominates too.  There are many more states that I can run that show the same thing. The climate really hasn't changed much in the U.S since the 1890s based on the raw un-adjusted data.   Anyway climate sensitivity has to be low since ice core data shows that temperatures begin to fall as CO2 still climbs. If there were significant positive feedbacks ANY warming that takes places increases CO2 from the Oceans which then would kick in the so-called positive water vapor feedback which would amplify the warming leading to more CO2 from the oceans and more water vapor and so on. What is the breaking mechanism? What is being proposed is the CO2  modulates the hydrological cycle and sets a level for water vapor. Where are the equations for this? I have never seen this. Climate models are woefully inadequate. They don't handle clouds or convection which have a major role in the Earth's energy budget.  If you put your faith in this, your nuts. To destroy the energy sector which sets the high standard of living we enjoy is suicide as a species. That is where we are headed. Environmentalism is not helping the planet, it is destroying it by keeping third world countries poor by not allowing access to cheap energy from fossil fuels.  Poor people live miserable short lives in third world countries and are desperate so they destroy their environment by hunting and unsustainable farming methods. Environmentalists has brought tons of wind farms which have wrecked loads of wild areas in the northeast U.S and other places.  They kill birds and bats. Its horrible.  People suffer and the environment is wrecked.  

network_MECLIMATE__station_ME0000__type_avg-high__threshold_-99__syear_1893__eyear_2019__dpi_100.png.2c61c5692051d3a7d37771da54cdf694.pngnetwork_MECLIMATE__station_ME0000__type_avg-low__threshold_-99__syear_1893__eyear_2019__dpi_100.png.c23041c6912240722d27aff5cee43301.pngnetwork_MNCLIMATE__station_MN0000__type_avg-high__threshold_-99__syear_1893__eyear_2019__dpi_100.png.08a2dc5bad8829a4031d09dc56d0878b.pngnetwork_MNCLIMATE__station_MN0000__type_avg-low__threshold_-99__syear_1893__eyear_2019__dpi_100.png.547cc6689ac5162fd7aa1d286193a6d4.pngnetwork_NDCLIMATE__station_ND0000__type_avg-high__threshold_90__syear_1893__eyear_2019__dpi_100.png.0accadef5558f78e3f78ce5dcac5d4e0.pngnetwork_NDCLIMATE__station_ND0000__type_avg-low__threshold_90__syear_1893__eyear_2019__dpi_100.png.e2dd6f8f11a6acea84f007bbd91953df.pngnetwork_NYCLIMATE__station_NY0000__type_avg-high__threshold_-99__syear_1893__eyear_2019__dpi_100.png.9627b6accf612e5d6fdd3dc4042976b2.pngnetwork_NYCLIMATE__station_NY0000__type_avg-low__threshold_-99__syear_1893__eyear_2019__dpi_100.png.77740a72ca0ad1000c67ae79c9768085.png

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"Since 1960 the surface has warmed by 0.9C with very little if any of that being convincingly attributable to naturally modulated forcing agents.  The hydrosphere has taken up heat equivalent to 0.6 W/m^2 of forcing for decades. If a natural (and non-GHG) forcing agent were a significant contributor of this uptake then given this magnitude it should have been quite easy to identify. Meanwhile the observed uptake of heat is a close match to the consensus theory which includes all known radiative forcing agents in their appropriate proportions including GHGs"
 
How do you know this? Climate models? The ice core data clearly reveals that CO2 never dominated our climate system in the past 2.6 million years. So what is different now? It is a weak GHG with a small absorption band. H20 and clouds are 95% of the Earth's greenhouse effect. The whole theory, which is based on models, that CO2 drives the climate NOW is unfounded.  Explain to me how a highly non-linear chaotic system is linear in its dependence on CO2 level vs. temperature as is reflected in the ice core data?   The easy solution is that the oceans are more soluble to CO2 and other gases when they are colder by sucking CO2 in and outgas it when the Earth warms. This explains the lag in CO2 levels vs temperatures very well. Solar activity was at a 1000 year max in the late 20 century and was at a minimum during the Little Ice Age. How can anyone rule out solar variability in our modern warm period? There is some connection there. There has to be.   The hubris that folks on this board and climate scientists have about their understanding of the climate system is crazy.   The earth is NOT warming up rapidly either. Where do you get this from?  It is a slow rise well within the bounds of previous climate change in the Holocene. The Pleistocene has far larger climate swings. We live in a tranquil time of climate with slow modest warming. Many areas including where I live have not seen any changes in the last 100+ years. Take a look at average annual temperature for several U.S states(best observing network) as an example(below). If we are rapidly warming we certainly would have seen something significantly positive by now.  States like NY, ME, MI and ND  show small warming to NO changes. Any small warming is night time lows in winter where UHI dominates too.  There are many more states that I can run that show the same thing. The climate really hasn't changed much in the U.S since the 1890s based on the raw un-adjusted data.   Anyway climate sensitivity has to be low since ice core data shows that temperatures begin to fall as CO2 still climbs. If there were significant positive feedbacks ANY warming that takes places increases CO2 from the Oceans which then would kick in the so-called positive water vapor feedback which would amplify the warming leading to more CO2 from the oceans and more water vapor and so on. What is the breaking mechanism? What is being proposed is the CO2  modulates the hydrological cycle and sets a level for water vapor. Where are the equations for this? I have never seen this. Climate models are woefully inadequate. They don't handle clouds or convection which have a major role in the Earth's energy budget.  If you put your faith in this, your nuts. To destroy the energy sector which sets the high standard of living we enjoy is suicide as a species. That is where we are headed. Environmentalism is not helping the planet, it is destroying it by keeping third world countries poor by not allowing access to cheap energy from fossil fuels.  Poor people live miserable short lives in third world countries and are desperate so they destroy their environment by hunting and unsustainable farming methods. Environmentalists has brought tons of wind farms which have wrecked loads of wild areas in the northeast U.S and other places.  They kill birds and bats. Its horrible.  People suffer and the environment is wrecked.  
network_MECLIMATE__station_ME0000__type_avg-high__threshold_-99__syear_1893__eyear_2019__dpi_100.png.2c61c5692051d3a7d37771da54cdf694.pngnetwork_MECLIMATE__station_ME0000__type_avg-low__threshold_-99__syear_1893__eyear_2019__dpi_100.png.c23041c6912240722d27aff5cee43301.pngnetwork_MNCLIMATE__station_MN0000__type_avg-high__threshold_-99__syear_1893__eyear_2019__dpi_100.png.08a2dc5bad8829a4031d09dc56d0878b.pngnetwork_MNCLIMATE__station_MN0000__type_avg-low__threshold_-99__syear_1893__eyear_2019__dpi_100.png.547cc6689ac5162fd7aa1d286193a6d4.pngnetwork_NDCLIMATE__station_ND0000__type_avg-high__threshold_90__syear_1893__eyear_2019__dpi_100.png.0accadef5558f78e3f78ce5dcac5d4e0.pngnetwork_NDCLIMATE__station_ND0000__type_avg-low__threshold_90__syear_1893__eyear_2019__dpi_100.png.e2dd6f8f11a6acea84f007bbd91953df.pngnetwork_NYCLIMATE__station_NY0000__type_avg-high__threshold_-99__syear_1893__eyear_2019__dpi_100.png.9627b6accf612e5d6fdd3dc4042976b2.pngnetwork_NYCLIMATE__station_NY0000__type_avg-low__threshold_-99__syear_1893__eyear_2019__dpi_100.png.77740a72ca0ad1000c67ae79c9768085.png


All you have to do is look at studies on the PETM to see where we are headed. It’s really quite simple.


.

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1 hour ago, Bhs1975 said:

 


All you have to do is look at studies on the PETM to see where we are headed. It’s really quite simple.


.

 

Root for a technological breakthrough that slows  emissions before we get to that point.

https://phys.org/news/2019-02-high-co2-destabilize-marine-layer.html

At high enough atmospheric carbon dioxide (CO2) concentrations, Earth could reach a tipping point where marine stratus clouds become unstable and disappear, triggering a spike in global warming, according to a new modeling study.

This event—which could raise surface temperatures by about 8 Kelvin (14 degrees Fahrenheit) globally—may occur at CO2 concentrations above 1,200 parts per million (ppm), according to the study, which will be published by Nature Geoscience on February 25. For reference, the current concentration is around 410 ppm and rising. If the world continues burning fossil fuels at the current rate, Earth's CO2 level could rise above 1,200 ppm in the next century.

I think and hope that technological changes will slow carbon emissions so that we do not actually reach such high CO2 concentrations. But our results show that there are dangerous climate change thresholds that we had been unaware of," says Caltech's Tapio Schneider, Theodore Y. Wu Professor of Environmental Science and Engineering and senior research scientist at the Jet Propulsion Laboratory, which Caltech manages for NASA. Schneider, the lead author of the study, notes that the 1,200-ppm threshold is a rough estimate rather than a firm number.

 

 

The study could help solve a longstanding mystery in paleoclimatology. Geological records indicate that during the Eocene (around 50 million years ago), the Arctic was frost free and home to crocodiles. However, according to existing climate models, CO2 levels would need to rise above 4,000 ppm to heat the planet enough for the Arctic to be that warm. This is more than twice as high as the likely CO2 concentration during this time period. However, a warming spike caused by the loss of stratus cloud decks could explain the appearance of the Eocene's hothouse climate.

Stratus cloud decks cover about 20 percent of subtropical oceans and are prevalent in the eastern portions of those oceans—for example, off the coasts of California or Peru. The clouds cool and shade the earth as they reflect the sunlight that hits them back into space. That makes them important for regulating Earth's surface temperature. The problem is that the turbulent air motions that sustain these clouds are too small to be resolvable in global climate models.

To circumvent the inability to resolve the clouds at a global scale, Schneider and his co-authors, Colleen Kaul and Kyle Pressel of the Pacific Northwest National Laboratory, created a small-scale model of a representative atmospheric section above a subtropical ocean, simulating the clouds and their turbulent motions over this ocean patch on supercomputers. They observed instability of the cloud decks followed by a spike in warming when CO2 levels exceeded 1,200 ppm. The researchers also found that once the cloud decks vanished, they did not reappear until CO2 levels dropped to levels substantially below where the instability first occurred.

"This research points to a blind spot in climate modeling," says Schneider, who is currently leading a consortium called the Climate Modeling Alliance (CliMA) in an effort to build a new climate model. CliMA will use data assimilation and machine-learning tools to fuse Earth observations and high-resolution simulations into a model that represents clouds and otherimportant small-scale featuresbetter than existing models. One use of the new model will be to determine more precisely the CO2 level at which the instability of the cloud decks occurs.

 

 

 

 

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13 hours ago, Bhs1975 said:

 


All you have to do is look at studies on the PETM to see where we are headed. It’s really quite simple.


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No it's not. There is a lot of uncertainty as to how much CO2 was in the atmosphere plus even bigger was the positioning of the continents was different than today or the last few million years. There was no Gulf Stream or warm current to the North Atlantic. This is really important to the climate system since warmth and moisture that far north leads to snowfall at high latitudes.  With the continents closer together the Pacific Ocean was even more massive than today and the continents were closer. Glaciations were not present which made the Earth warmer than today. Once the continents drifted enough to close off the Isthmus of Panama  2.6 million years ago the Gulf stream formed and the "present" glacial to interglacial cycles began and the Earth began to cool. This tells us that its the glaciation and especially ice albedo effect that dominate the climate system. Look at the temperature reconstructions from ocean core forams and you can see this downward trend after 2.6 million years ago.  

Five_Myr_Climate_Change_Rev.jpg.6cde26507509778cd2752318cbc1f4c7.jpg

Furthermore, large continental glaciers also means less water vapor in the atmosphere and it is much drier. More and more precipitation falls out as snow and builds the glacier. So water vapor levels drop and hence the world cools more. CO2 passively follows the Earth's temperature. It never drove the climate before. Why does it now? 

 

 

 

 

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23 minutes ago, blizzard1024 said:

It never drove the climate before. Why does it now? 

 

 

 

 

The mechanism that has made the marginal contribution to greenhouse gas emissions that tipped the system out of balance, leading to a steady rise in the atmospheric concentration of such gases, did not exist then. The physical properties of such gases are well-established. No serious scientist has argued that the rising atmospheric concentration of greenhouse gases has no meaningful impact. The consensus in the scientific literature is strong: such gases contribute to warming and the anthropogenic contribution is the largest basis for the ongoing warming. No credible alternative explanation is present in the literature.

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It really is simple. If you add more CO2 to the atmosphere than is taken out the concentrations will go up and more heat is trapped raising the equilibrium temperature. The PETM had more than twice as much CO2 as today and therefore was about 5C warmer closely matching todays models.

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23 hours ago, blizzard1024 said:

How do you know this? Climate models? The ice core data clearly reveals that CO2 never dominated our climate system in the past 2.6 million years. So what is different now? It is a weak GHG with a small absorption band. H20 and clouds are 95% of the Earth's greenhouse effect. The whole theory, which is based on models, that CO2 drives the climate NOW is unfounded.  Explain to me how a highly non-linear chaotic system is linear in its dependence on CO2 level vs. temperature as is reflected in the ice core data?   The easy solution is that the oceans are more soluble to CO2 and other gases when they are colder by sucking CO2 in and outgas it when the Earth warms. This explains the lag in CO2 levels vs temperatures very well. Solar activity was at a 1000 year max in the late 20 century and was at a minimum during the Little Ice Age. How can anyone rule out solar variability in our modern warm period? There is some connection there. There has to be.   The hubris that folks on this board and climate scientists have about their understanding of the climate system is crazy.   The earth is NOT warming up rapidly either. Where do you get this from?  It is a slow rise well within the bounds of previous climate change in the Holocene. The Pleistocene has far larger climate swings. We live in a tranquil time of climate with slow modest warming. Many areas including where I live have not seen any changes in the last 100+ years. Take a look at average annual temperature for several U.S states(best observing network) as an example(below). If we are rapidly warming we certainly would have seen something significantly positive by now.  States like NY, ME, MI and ND  show small warming to NO changes. Any small warming is night time lows in winter where UHI dominates too.  There are many more states that I can run that show the same thing. The climate really hasn't changed much in the U.S since the 1890s based on the raw un-adjusted data.   Anyway climate sensitivity has to be low since ice core data shows that temperatures begin to fall as CO2 still climbs. If there were significant positive feedbacks ANY warming that takes places increases CO2 from the Oceans which then would kick in the so-called positive water vapor feedback which would amplify the warming leading to more CO2 from the oceans and more water vapor and so on. What is the breaking mechanism? What is being proposed is the CO2  modulates the hydrological cycle and sets a level for water vapor. Where are the equations for this? I have never seen this. Climate models are woefully inadequate. They don't handle clouds or convection which have a major role in the Earth's energy budget.  If you put your faith in this, your nuts. To destroy the energy sector which sets the high standard of living we enjoy is suicide as a species. That is where we are headed. Environmentalism is not helping the planet, it is destroying it by keeping third world countries poor by not allowing access to cheap energy from fossil fuels.  Poor people live miserable short lives in third world countries and are desperate so they destroy their environment by hunting and unsustainable farming methods. Environmentalists has brought tons of wind farms which have wrecked loads of wild areas in the northeast U.S and other places.  They kill birds and bats. Its horrible.  People suffer and the environment is wrecked.  

There is a lot of content here. For brevity's sake I'll just answer the question most relevant to my last post. I know that the established theory of climatic change is a better match to reality compared to non-GHG (or weak GHG) theories since 1960 because the observations say so. The observations over even longer stretches of time and through the paleoclimate record are more consistent with the established theory versus those that specifically ignore or downplay certain forcing agents like GHGs.

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7 hours ago, donsutherland1 said:

The mechanism that has made the marginal contribution to greenhouse gas emissions that tipped the system out of balance, leading to a steady rise in the atmospheric concentration of such gases, did not exist then. The physical properties of such gases are well-established. No serious scientist has argued that the rising atmospheric concentration of greenhouse gases has no meaningful impact. The consensus in the scientific literature is strong: such gases contribute to warming and the anthropogenic contribution is the largest basis for the ongoing warming. No credible alternative explanation is present in the literature.

You fail to understand than CO2 is a weak GHG. 

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8 minutes ago, bdgwx said:

There is a lot of content here. For brevity's sake I'll just answer the question most relevant to my last post. I know that the established theory of climatic change is a better match to reality compared to non-GHG (or weak GHG) theories since 1960 because the observations say so. The observations over even longer stretches of time and through the paleoclimate record are more consistent with the established theory versus those that specifically ignore or downplay certain forcing agents like GHGs.

There is no way that one can emphatically make this statement that understands how the atmospherics works. You have proven your ignorance.  

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7 hours ago, blizzard1024 said:

No it's not. There is a lot of uncertainty as to how much CO2 was in the atmosphere plus even bigger was the positioning of the continents was different than today or the last few million years. There was no Gulf Stream or warm current to the North Atlantic. This is really important to the climate system since warmth and moisture that far north leads to snowfall at high latitudes.  With the continents closer together the Pacific Ocean was even more massive than today and the continents were closer. Glaciations were not present which made the Earth warmer than today. Once the continents drifted enough to close off the Isthmus of Panama  2.6 million years ago the Gulf stream formed and the "present" glacial to interglacial cycles began and the Earth began to cool. This tells us that its the glaciation and especially ice albedo effect that dominate the climate system. Look at the temperature reconstructions from ocean core forams and you can see this downward trend after 2.6 million years ago.  

Five_Myr_Climate_Change_Rev.jpg.6cde26507509778cd2752318cbc1f4c7.jpg

Furthermore, large continental glaciers also means less water vapor in the atmosphere and it is much drier. More and more precipitation falls out as snow and builds the glacier. So water vapor levels drop and hence the world cools more. CO2 passively follows the Earth's temperature. It never drove the climate before. Why does it now? 

 

 

 

 

Here is an attempt at modeling using established theory of the last 3 million years of the paleoclimate record including the transition from 40kyr cycles to 100kyr cycles as depicted in the graph. It's certainly not perfect, but it is reasonably successful nonetheless IMHO.

https://advances.sciencemag.org/content/5/4/eaav7337

 

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4 minutes ago, blizzard1024 said:

You fail to understand than CO2 is a weak GHG. 

Can you define weak quantitatively? What kind of radiative forcing in W/m^2 are you thinking. What kind of sensitivity in C per W/m^2 are you thinking?

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27 minutes ago, bdgwx said:

Can you define weak quantitatively? What kind of radiative forcing in W/m^2 are you thinking. What kind of sensitivity in C per W/m^2 are you thinking?

CO2 has an absorption band in the IR between 13 and 17 microns with a peak at 15 microns. Water vapor has multiple bands in the IR in fact most of the emission spectra in the IR from the Earth resembles the H20 bands.  CO2 absorbs IR between -50c and -110C so it has little to no effect directly on the lower and middle troposphere. Also water vapor dominates the lower and middle troposphere and thins out dramatically in the upper troposphere. So CO2 does have the most influence in the upper troposphere where cold temperatures are affected. But how can a weak GHG dominate the entire choatic non-linear climate system? Water vapor and clouds are the primary GHGs.  CO2 theoretically leads to some warming in the upper troposphere which in theory would warm the lower troposphere and cool the stratosphere. But if H20 increases in the lower troposphere its emission cools the upper troposphere.  CO2 if all else remains equal leads to 1.2C of warming per doubling. But clouds, a negative water vapor feedback could easily drop the sensitivity to less than 1C.  The paleo records clearly show that CO2 is not the control knob on the climate system.  

A doubling of CO2 likely is less than 1C and possiblly even less. 

 

 

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So said chaotic and non-linear system is certain enough for you to say it isnt sensitive to CO2, but not enough for the best modeled and proposed answer to say it is?

Sent from my SM-G960U using Tapatalk

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