Support the Arctic Sea Ice Forum and Blog

Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.


Messages - jai mitchell

Pages: [1] 2 3 ... 42
1
Arctic sea ice / Re: The 2020 melting season
« on: March 26, 2020, 05:53:45 PM »
Zack Labe reports unprecedented early rates of sea ice declines.

https://twitter.com/ZLabe/status/1243211454121005057


2
Science / Re: The Science of Aerosols
« on: February 17, 2020, 06:37:40 PM »
https://carnegiescience.edu/news/do-climate-effects-air-pollution-impact-global-economy

Do The Climate Effects Of Air Pollution Impact The Global Economy?

Quote
Estimates indicate that aerosol pollution emitted by humans is offsetting about 0.7 degrees Celsius, or about 1.3 degrees Fahrenheit, of the warming due to greenhouse gas emissions,” said lead author Zheng. “This translates to a 40-year delay in the effects of climate change. Without cooling caused by aerosol emissions, we would have achieved 2010-level global mean temperatures in 1970.”

Previous research has shown that climate change provides some economic benefits to countries in cool regions—which would be warmed to temperatures that are ideal for agricultural productivity and human labor—and economic harm to countries in already hot regions.

3
Science / Re: The Science of Aerosols
« on: February 12, 2020, 08:27:19 PM »
I bet that there is a discernible strong northern hemisphere GMST signal that occurred between Jan 21st 2020 and through February 15th (and possibly longer) due to China coronavirus quarantine and lunar new year extension.

January was the warmest on record, perhaps February will be also?

4
ASLR

I was posting it yesterday but had a phone call and forgot  8)

The trouble I see is that we have no idea that the CPDW warming that is now fully documented on WAIS is (most likely) not something that a paleo analog can provide insight into.  The simple fact is that we have tweaked the Global atmospheric circ patterns far far far outside of any paleo analog.

5
What we already knew

https://www.pnas.org/content/early/2020/02/10/1902469117.short?rss=1

Early Last Interglacial ocean warming drove substantial ice mass loss from Antarctica

Fifty years ago, it was speculated that the marine-based West Antarctic Ice Sheet is vulnerable to warming and may have melted in the past. Testing this hypothesis has proved challenging due to the difficulty of developing in situ records of ice sheet and environmental change spanning warm periods. We present a multiproxy record that implies loss of the West Antarctic Ice Sheet during the Last Interglacial (129,000 to 116,000 y ago), associated with ocean warming and the release of greenhouse gas methane from marine sediments. Our ice sheet modeling predicts that Antarctica may have contributed several meters to global sea level at this time, suggesting that this ice sheet lies close to a “tipping point” under projected warming.


6
RCP 8.5 total greenhouse gas forcing
RCP 8.5 total anthropogenic forcing
50 years of expected carbon cycle emissions under 2C of warming (crowther et al 2017)

7


"Inter-model spread in feedback changes is well explained by differences in the ratio of warm-pool warming to global-mean warming across CMIP5 models, but this correlation fails to explain differences across CMIP6 models, suggesting that stronger SST-pattern dependence of extratropical clouds may dominate feedback changes in CMIP6 models."

. . . for both ensembles, the total variance in ECS is dominated by the spread in radiative response on fast timescales, rather than the spread in feedback evolution.  Using Green's functions derived from two AGCMs shows that the spread in feedbacks on fast timescales is primarily determined by model physics, whereas the spread in feedback changes is primarily governed by the SST patterns.

 ;D
pats self on back. . .

Recent analysis of these higher ECS runs indicate midlatitude clouds as the primary driver with the southern hemisphere having the largest impact.  This indicates that the higher ECS values come in after significant warming by the ocean surface, hence the reduced TCR with the majority of warming happening much later in the century.

8
Consequences / Re: Global Surface Air Temperatures
« on: January 16, 2020, 07:50:03 PM »
FYI

https://twitter.com/rahmstorf/status/1217851290727976961

Stephen Rahmstorf - head of earth system analysis at Potsdam

Global temperature now stands at 1.2 °C above the mean for 1880-1910, according to NASA data. And that without an El Niño event (the peaks in 1998 and 2016 were due to strong El Niño). Global cooling forecasts by climate skeptics because of the dim sun were nonsense. Of course.

image

9
The point of the SSP3 70 analysis is that the IAMS use such an outrageous rate of long term economic growth in the face of growing climate change that under even a moderate growth scenario of SSP3, the impacts of cliamate change become significant as a proportion of global economic output.  If the DICE model was right we would need 8 planet earth's worth of resources to produce the economy that Nordhaus proposed by 2100 under >3C of warming.

10
Consequences / Re: Climate change, the ocean, agriculture, and FOOD
« on: January 15, 2020, 07:35:46 AM »
This thread has many references and is very good.  https://twitter.com/ClimateBen/status/1205577540531838977

11
Consequences / Re: Climate change, the ocean, agriculture, and FOOD
« on: January 15, 2020, 04:40:57 AM »
https://blogs.scientificamerican.com/eye-of-the-storm/newly-identified-jet-stream-pattern-could-imperil-global-food-supplies/

Newly Identified Jet-Stream Pattern Could Imperil Global Food Supplies

A new study finds a 20-fold increase in the risk of simultaneous heat waves in major crop-producing regions when the pattern is in place

By Jeff Masters on December 9, 2019

Quote
A just-published December 9 follow-up study, Amplified Rossby waves enhance risk of concurrent heatwaves in major breadbasket regions--also led by Dr. Kornhuber--found that stuck jet stream patterns like seen in 2018 are prone to bringing simultaneous heat waves and associated drought conditions to multiple important grain-producing regions of the world. The authors wrote that these stuck jet stream patterns can cause “reductions of 4% in crop production in the affected regions, with regional decreases up to 11%. Given the importance of these regions for global food production, the identified teleconnections have the potential to fuel multiple harvest failures posing risks to global food security.” (A teleconnection is a causal connection or correlation between meteorological phenomena which occur a long distance apart).

In a press release that accompanied the most recent paper, Dr. Kornhuber said, “We found a 20-fold increase in the risk of simultaneous heat waves in major crop-producing regions when these global-scale wind patterns are in place. Until now, this was an underexplored vulnerability in the food system. During these events there actually is a global structure in the otherwise quite chaotic circulation. The bell can ring in multiple regions at once.”




Figure 1. Average crop production from 2003-2007 (in colors) for the major commodity crops maize (corn), wheat, soybean, and rice in units of kcal (based on data from Ray et al., 2012). Areas affected by heat waves and their associated droughts during stuck jet stream patterns of wave-5 (shown in brown-bordered regions) and during wave-7 (red-bordered regions) are also shown. Affected areas include the major breadbaskets in central North America, plus Western and Eastern Europe. The regions affected by wave-5 and 7 account for about a quarter of global food production. The U.S., France and Russia produce 42% of the world’s wheat; for maize, the U.S. and France alone produce 57% of the total. Credit: Kornhuber et al., 2019, Amplified Rossby waves enhance risk of concurrent heatwaves in major breadbasket regions, Nature Climate Change

12
Science / Re: The Science of Aerosols
« on: January 15, 2020, 01:21:58 AM »
this is a good and recent one, the values quoted are slightly lower than what I cited but they are based on 15 year period averages and are ocean heat content not EEI  I thought there was some recent work showing higher EEI values but don't see it at the moment.

https://www.frontiersin.org/articles/10.3389/fmars.2019.00432/full

13
Science / Re: The Science of Aerosols
« on: January 14, 2020, 11:02:19 PM »
Hefaistos,

While it might take a while to clean up our aerosols, ~1.1C of masked warming still means ~1.1C of masked warming. It means that -- best case scenario -- if we went to zero emissions tomorrow we'd still approach 2.5C of warming since preindustrial.

So, while you suggest that the longer it takes us to reduce our emissions (and so to clean up aerosols) the more time we buy ourselves, in fact, the opposite is true. The longer it takes, the more screwed we are, since that ~1.1C is already there, waiting, even if the rate of temp. rise from emissions goes down (it won't for sometime based on the last 10 years, and what's likely over the next 10) we are unlikely to avoid catastrophic levels of warming. We need to reach zero emissions as soon as possible. No matter how quickly or slowly we do that, we will find ourselves in a much warmer world.

Finally, the paper in question accounts for warming from cloud feedbacks from aerosols, but these tend to be from non-anthro sources, as already discussed in this thread.

much of those emissions are organic carbon which are primarily produced through biomass burning.  so they won't all go away.

Much will go away and of these, over time, it is projected that ch4 levels will also go down that will help reduce the overall burden.  Of course the uncertainty and (VERY LIKELY IN MY OPINION) rapid increase in carbon cycle emissions from warming soils will provide more than this uncertainty in future committed warming.

edit:

but we still have to accept that the current top of atmosphere energy imbalance is between 0.8 and 1.2 Watts per meter squared (even with the aerosol masking!).

14
Policy and solutions / Re: Tesla glory/failure
« on: January 14, 2020, 10:38:40 PM »
the short squeeze has only just begun.

15
Policy and solutions / Re: Renewable Energy
« on: January 14, 2020, 09:38:36 PM »
 ::)

wind power generation hourly curve

16
Science / Re: The Science of Aerosols
« on: January 14, 2020, 02:59:05 AM »
^^^
In regards to the paper posted above, I should note that it's unclear as to whether this study treats aerosols in the same way as AR5, i.e. this study includes "natural" aerosols such as sand and salt, whereas AR5 seems to only include anthropogenic aerosols in its -0.9 w/m2 forcing.


The AR5 forcing parameters can be found here:  http://www.pik-potsdam.de/~mmalte/rcps/  The direct aerosol forcing includes anthropogenic and natural aerosols (like mineral dust) and they include the indirect forcing in the total cloud effect forcing parameter which combined comes out to about -0.9 W/m^2. 

17
Policy and solutions / Re: Tesla glory/failure
« on: January 14, 2020, 01:44:14 AM »
I am guessing that Tesla is making a huge announcement about solid state batteries at their next summit.

18
Consequences / Re: Global Surface Air Temperatures
« on: January 13, 2020, 06:25:54 AM »
my understanding says that as China reduces their emissions of SOx from high temperature processes that El Nino's will become more prevalent.

19
the conversion of the GISS baseline of 1951-1980 to pre-industrial is +0.23C


My notes say that the GISTEMP (LOTI = Land Ocean Temperature Index) 1951-1980 baseline to preindustrial baseline adjustment factor is +0.256C.

I stand corrected, I have been looking for the value from the peer review but can't find it (I thought it was a 2012 hansen sato paper. . .)

20
Nearly every aspect of the SR1.5 was adjusted in the conservative direction to provide the largest possible carbon budge as possible.  Including reduced ECS/TCR, no inclusion of frozen soil feedbacks, severely understated carbon cycle feedbacks (only 100 GtCO2 by 2100!) and an inappropriate baseline that is higher than the actual (per Michael E. Mann).

more info here:  https://www.scientificamerican.com/article/new-climate-report-was-too-cautious-some-scientists-say/

21
The rest / Re: SpaceX
« on: January 10, 2020, 05:59:27 PM »
I am pretty sure that they de-orbit the satellites after 5-7 years but that is if they are responding to commands.  so longer and more random burnup than planned.

22
This Caldwell paper is a very good find.

Based on my reading of earlier work from his team, I can see now why E3SM has the highest ECS and TCR since they have been on the cutting edge of tropical cloud constraints.   Looks like they also have better sea ice modeling.  It is a little surprising that the higher resolution didn't increase sensitivity.

23
Policy and solutions / Re: Tesla glory/failure
« on: January 10, 2020, 02:51:20 AM »
No demand...

Quote
Seven Tesla Showrooms in Beijing Sell Over 1k MIC Model 3 In A Single Day


https://www.tesmanian.com/blogs/tesmanian-blog/mic-model-3-stores-have-sold-1-040-units-since-gf3-delivery-event

tesla is the iphone of cars. . .

24

While it may take centuries to reach full equilibrium for ECS values, the first image (from E3SM) shows that the lion's share of warming from ECS occurs in the first 100-years.  Thus, before deciding what is good news, or not, it is best to look at the direct GMSTA projections such as those shown in the second attached image from a French CMIP6 projections of GMSTA (with a pre-industrial baseline) for the different SSP scenarios; which indicates that by following either SSP5 8.5 or SSP3 7.0, GMSTA could be approaching 2.5C by 2040 (which is not good news):

That isn't quite right ASLR, the ECS graph shows a 4XCO2 Pulse not the result of any of the emission scenarios.  Not sure what arguments other than short term feedbacks and aerosol emissions reductions would incur a rapid increase in temperatures that has been observed recently.

25

If E3SMv1 is correct (& it is included in CMIP6), then TCR would be 2.93C as indicated in the attached.

indeed, if anything this shows that E3SM has a high ECS not just because of the midlatitude cloud effects but from other feedbacks that engage at much lower temperatures.

I was referring to the two outliers in the TCR VS ECS graph:  CESM2 and CNRM

26
the conversion of the GISS baseline of 1951-1980 to pre-industrial is +0.23C

The 1C value has been determined to have been reached in 2015. 

after a few more years we will find that we crossed 1.2C in 2019. 

27

The jury is still out
@ClimateOfGavin
 Jan 4
 
More
It turns out that recent trends in the southern ocean are close to zero precisely where the model differences would be expected to be large. No temperature trends => no feedback.

Quote
Worse, the CMIP models collectively diverge quite noticeably in the southern ocean from the observations (they would have predicted some warming by now). (Animation via @ed_hawkins)
[/quote]

from my post above:   Recent analysis of these higher ECS runs indicate midlatitude clouds as the primary driver with the southern hemisphere having the largest impact.  This indicates that the higher ECS values come in after significant warming by the ocean surface,

so gavin is right, the feedback has not yet kicked in.  However, he should not assume that it would have already been noticeable by now, especially considering that the surface temperature of this region is not monitored as well as NH land (it has higher uncertainty).

28
None of this accounts for Faero, which is warming that has already occurred but is being masked. The new paper given by JM above says Faero = -1.45 w/m2. What does that mean in degrees C? maybe 0.8C?

That would mean we're at 2C of warming now: 2 + 1.2 = 3.2C by 2080. So 3.2C would have occurred by the time we double co2. That's already as high as ECS assumed by AR5 and by James Hansen (referring to paleo).


roughly yes however the near term forcing from black carbon and (the gorilla in the room) CH4 will go down somewhat as emissions go down along with aerosol emissions, so there will be some mitigation of the future warming also depending on how effective the carbon sink operates going forward.  The carbon cycle alone has enough uncertainty to blow out any future warming prediction by over +/- 1.0C

29
The majority of low TCR value returns in the CMIP6 runs also have very low ECS while a few of the higher ECS ones have low TCRs as well.

Not true.  It helps to read the entire paper, not just the abstract.

[/quote]

Yes, actually it is true though the high ECS have a 'relatively' low TCR (compared to the average TCR/ECS ratio)

31
The majority of low TCR value returns in the CMIP6 runs also have very low ECS while a few of the higher ECS ones have low TCRs as well.  Recent analysis of these higher ECS runs indicate midlatitude clouds as the primary driver with the southern hemisphere having the largest impact.  This indicates that the higher ECS values come in after significant warming by the ocean surface, hence the reduced TCR with the majority of warming happening much later in the century.

However, there is some real indication now that the aerosol forcing is much worse than previously thought including this recent paper:  https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019MS001628  with a median estimate of -1.4 Watts per meter squared aerosol forcing.

Quote
The mean aerosol effective radiative forcing is −1.45 W/m2 (credible interval of −2.07 to −0.81 W/m2), which encompasses but is more negative than the −1.17 W/m2 in the 2013 Atmospheric Chemistry and Climate Model Intercomparison Project and −0.90 W/m2 in the Intergovernmental Panel on Climate Change Fifth Assessment Report.

This correlates with the higher range values from the CMIP6 TCR window and even slightly more (up to 2.5C) simply based on observational analysis (not the models)  See image below.


32
Hot off the presses

https://www.nature.com/collections/bfihgidbhc

Arctic change and mid-latitude weather
The Arctic is warming much faster than the rest of the planet, a phenomenon called Arctic amplification. The enhanced warming results in a massive loss in sea ice and snow cover, which in turn interact with the atmosphere. These changes can have consequences beyond the Arctic region and they have been related to an increased frequency and intensity of extreme weather events across the Northern Hemisphere mid-latitudes.
The possible link between Arctic change and mid-latitude climate and weather has spurred a rush of new observational and modelling studies. While there are some arguments for a causal relationship between Arctic amplification and mid-latitude weather extremes, the significance of an Arctic influence is still discussed. To reflect on this vivid debate, this Nature Research collection combines commentary and reviews articles with primary research articles published in Nature Communications, Nature, Nature Geoscience and Nature Climate Change. show less

33
Arctic sea ice / Re: When will the Arctic Go Ice Free?
« on: December 06, 2019, 02:34:17 AM »
As usual, I come to the conclusion that by far the best explanation of the behaviour of arctic ice, when it melts and how fast it melts, is found by looking at the changes in temperature ... etc."

Moving on to Notz and Stroeve 2018, it says
    "The sensitivity of Arctic sea ice as described by the linear relationship between global-mean temperature and Arctic sea-ice coverage has been found to remain constant in model simulations across a wide spectrum of temperature trajectories.  In particular, the linearity holds in all CMIP5 models until summer sea ice vanishes in individual simulations. Hence, the observed sensitivity can be extrapolated to directly estimate the response of the Arctic sea-ice cover to future warming."

After describing some complications, they go on to say:
     "Despite these uncertainties, the different estimates result in a relatively narrow range of additional warming above present that is required to obtain a near-ice free Arctic Ocean during summer, defined as the total sea-ice coverage dropping below 1 million km2."

Then they discuss specific temperatures, and variation around those, from which I derived a median estimate of 1.68 +/- 0.25C (95% CI) above the (inferred) 1850-1900 NASA GISS global average land and ocean surface temperature.  (inferred because GISSTemp doesn't start until 1880. Details to translate to 1850-1900 equivalent are trivial and don't affect the stated value).
And for those of you keeping score at home --- as of 2019 the running 5-year average GISSTemp is at +1.15 C.  In earlier post, I used observed recent GISSTemp trends compared to the 1.68 +/- 0.25C to make the year estimates for when Sept gets below 1M km2 Extent.

The 1.7C estimate fits with their statement:
     "As soon as the global-mean temperature has risen by slightly below 2 ◦C, the Arctic Ocean is expected to be on average nearly ice-free during September."

and slightly out of context, but still relevant:
     "A possible modification of these estimates might be caused by the future evolution of anthropogenic aerosols, as they are expected to become less abundant over the next few
decades. "   

     "... in climate-model simulations the expected aerosol reduction causes additional ice loss..."

    "This would imply that the estimates given here are too conservative."

And finally, they remind us that:
     "While the observed linear relationship between sea-ice coverage and global-mean temperature allows one to estimate the long-term average future evolution of the pan-Arctic ice cover, the evolution of the real ice cover will show substantial year-to-year variability because of internal variability."

-----------------
So it seems to me that binntho and crandles are both right!

https://forum.arctic-sea-ice.net/index.php/topic,1384.msg149174.html#msg149174

The Arctic is highly sensitive to aerosols:

Q. Coopman  T. J. Garrett  D. P. Finch  J. Riedi (2017), "High Sensitivity of Arctic Liquid Clouds to Long‐Range Anthropogenic Aerosol Transport", Geophysical Research Letters,  https://doi.org/10.1002/2017GL075795

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2017GL075795

Abstract: "The rate of warming in the Arctic depends upon the response of low‐level microphysical and radiative cloud properties to aerosols advected from distant anthropogenic and biomass‐burning sources. Cloud droplet cross‐section density increases with higher concentrations of cloud condensation nuclei, leading to an increase of cloud droplet absorption and scattering radiative cross sections. The challenge of assessing the magnitude of the effect has been decoupling the aerosol impacts on clouds from how clouds change solely due to natural meteorological variability. Here we address this issue with large, multi‐year satellite, meteorological, and tracer transport model data sets to show that the response of low‐level clouds in the Arctic to anthropogenic aerosols lies close to a theoretical maximum and is between 2 and 8 times higher than has been observed elsewhere. However, a previously described response of arctic clouds to biomass‐burning plumes appears to be overstated because the interactions are rare and modification of cloud radiative properties appears better explained by coincident changes in temperature, humidity, and atmospheric stability."

34
Policy and solutions / Re: Tesla glory/failure
« on: November 22, 2019, 04:57:42 PM »
I was soooo looking forward to having a real electric truck to move large volumes of dirt, chopped wood, rock and furniture. . .what a complete waste. 



Not a box on wheels but close. Much more powerful than the competition. Much more durable than the competition. Cost of operation of an EV. Possible 1 million mile life expectancy. Starting at 39,995.

As a work tool, this vehicle will be amazing.

This is a case of function over form. I love function over form. But I also love the form of this vehicle. What I need to know is the drag coefficient of this thing.

You have clearly never used a work truck.

The thing is a joke. If you still don't get it, may the lord have mercy on your silly soul.

The Semi was "unveiled" years ago and still doesn't exist. This truck thing broke on stage and is a total laughing stock.

35
Science / Re: Carbon Cycle
« on: November 19, 2019, 07:14:34 PM »
I read it when it came out, they looked at emissions and sea ice loss to find a very basic linear relationship.  They did not include the operation of aerosols on sea ice extent and so their linear relationship is very likely overly conservative.

36
Consequences / Re: Conservative Scientists & its Consequences
« on: November 10, 2019, 11:13:12 PM »
^^
Jai
Remember that the "Nobel Memorial Prize in Economic Sciences" is awarded by "The Svergies Risbank Prize in Economics in Memory of Alfred Nobel", a very conservative group that has no connection to the Nobel Committees that chooses actual Nobel Prize winners. There is no "Nobel Prize in Economics".

The name of the prize was obviously intended to deceive.
Terry

As was the entire body of work by Nordhaus and his parasitic water carrier Tol.

37
Consequences / Re: Conservative Scientists & its Consequences
« on: November 10, 2019, 06:45:45 PM »
https://www.msn.com/en-gb/news/empowering-the-planet/how-scientists-got-climate-change-so-wrong/

How Scientists Got Climate Change So Wrong
Had a scientist in the early 1990s suggested that within 25 years a single heat wave would measurably raise sea levels, at an estimated two one-hundredths of an inch, bake the Arctic and produce Sahara-like temperatures in Paris and Berlin, the prediction would have been dismissed as alarmist.

https://www.latimes.com/opinion/op-ed/la-oe-linden-nobel-economics-mistake-20181025-story.html
Op-Ed: The economics Nobel went to a guy who enabled climate change denial and delay
Given such a tepid assessment of the threat, it is little wonder that Nordhaus’ biggest cheerleaders have come from the “do nothing about it” crowd. In 1997, for instance, William Niskanen, then chairman of the ultra-conservative Cato Institute, seized on Nordhaus’ estimates to argue before Congress that it was premature to take action on climate change because “the costs of doing nothing appear to be quite small.”

https://blogs.scientificamerican.com/observations/scientists-have-been-underestimating-the-pace-of-climate-change/
Scientists Have Been Underestimating the Pace of Climate Change
Consistent underestimation is a form of bias—in the literal meaning of a systematic tendency to lean in one direction or another—which raises the question: what is causing this bias in scientific analyses of the climate system?

https://www.themonthly.com.au/issue/2019/august/1566136800/jo-lle-gergis/terrible-truth-climate-change
The terrible truth of climate change
When the IPCC’s fifth assessment report was published in 2013, it estimated that such a doubling of CO2 was likely to produce warming within the range of 1.5 to 4.5°C as the Earth reaches a new equilibrium. However, preliminary estimates calculated from the latest global climate models (being used in the current IPCC assessment, due out in 2021) are far higher than with the previous generation of models. Early reports are predicting that a doubling of CO2 may in fact produce between 2.8 and 5.8°C of warming. Incredibly, at least eight of the latest models produced by leading research centres in the United States, the United Kingdom, Canada and France are showing climate sensitivity of 5°C or warmer.

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019MS001739?af=R
UKESM1: Description and evaluation of the UK Earth System Model
Abstract
We document the development of the first version of the United Kingdom Earth System Model UKESM1. The model represents a major advance on its predecessor HadGEM2‐ES, with enhancements to all component models and new feedback mechanisms. These include: a new core physical model with a well‐resolved stratosphere; terrestrial biogeochemistry with coupled carbon and nitrogen cycles and enhanced land management; tropospheric‐stratospheric chemistry allowing the holistic simulation of radiative forcing from ozone, methane and nitrous oxide; two‐moment, five‐species, modal aerosol; and ocean biogeochemistry with two‐way coupling to the carbon cycle and atmospheric aerosols. The complexity of coupling between the ocean, land and atmosphere physical climate and biogeochemical cycles in UKESM1 is unprecedented for an Earth system model. We describe in detail the process by which the coupled model was developed and tuned to achieve acceptable performance in key physical and Earth system quantities, and discuss the challenges involved in mitigating biases in a model with complex connections between its components. Overall the model performs well, with a stable pre‐industrial state, and good agreement with observations in the latter period of its historical simulations. However, global mean surface temperature exhibits stronger‐than‐observed cooling from 1950 to 1970, followed by rapid warming from 1980 to 2014. Metrics from idealised simulations show a high climate sensitivity relative to previous generations of models: equilibrium climate sensitivity (ECS) is 5.4 K, transient climate response (TCR) ranges from 2.68 K to 2.85 K, and transient climate response to cumulative emissions (TCRE) is 2.49 K/TtC to 2.66 K/TtC.

https://www.nature.com/articles/s41586-019-1554-z
Climate and air-quality benefits of a realistic phase-out of fossil fuels
Abstract
The combustion of fossil fuels produces emissions of the long-lived greenhouse gas carbon dioxide and of short-lived pollutants, including sulfur dioxide, that contribute to the formation of atmospheric aerosols1. Atmospheric aerosols can cool the climate, masking some of the warming effect that results from the emission of greenhouse gases1. However, aerosol particulates are highly toxic when inhaled, leading to millions of premature deaths per year2,3. The phasing out of unabated fossil-fuel combustion will therefore provide health benefits, but will also reduce the extent to which the warming induced by greenhouse gases is masked by aerosols. Because aerosol levels respond much more rapidly to changes in emissions relative to carbon dioxide, large near-term increases in the magnitude and rate of climate warming are predicted in many idealized studies that typically assume an instantaneous removal of all anthropogenic or fossil-fuel-related emissions1,4,5,6,7,8,9. Here we show that more realistic modelling scenarios do not produce a substantial near-term increase in either the magnitude or the rate of warming, and in fact can lead to a decrease in warming rates within two decades of the start of the fossil-fuel phase-out. Accounting for the time required to transform power generation, industry and transportation leads to gradually increasing and largely offsetting climate impacts of carbon dioxide and sulfur dioxide, with the rate of warming further slowed by reductions in fossil-methane emissions. Our results indicate that even the most aggressive plausible transition to a clean-energy society provides benefits for climate change mitigation and air quality at essentially all decadal to centennial timescales.

Quote
Note: the last looks at the potential locked in warming under reasonable mitigation if ECS is 6C and the total aerosol forcing is -1.9Watts per meter squared.  The image below shows this committed warming -- these ECS and Aerosol forcing parameters are now becoming the middle estimate.

38
Science / Re: Carbon Cycle
« on: November 05, 2019, 08:08:11 PM »
the total carbon weight in the fungi below an old growth forest is approximately the same as the carbon weight (about 1/2 of total tree weight) of the forest above ground.

For more listen to this wonderful radiolab podcast on the subject.  https://www.wnycstudios.org/podcasts/radiolab/articles/from-tree-to-shining-tree

This seems like quite a break-through in understanding.

Study finds fungi, not plant matter, responsible for most carbon sequestration in northern forests
https://phys.org/news/2013-03-fungi-responsible-carbon-sequestration-northern.html?fbclid=IwAR3PcB6XPEY5lAmM2Pj_T829JD954qG61OWMfdyWLE_1K06tSzGkA09X0sk

Quote
Scientists have known for quite some time that northern forests sequester a lot of carbon—they pull in carbon dioxide after all, and "breath" out oxygen. But what the trees actually do with the carbon has been a matter of debate—most have suggested that it's likely carried to needles and leaves then eventually drops to the forest floor where over time decomposition causes it to leech into the soil. If that were the case, this new team of researchers reasoned, then the newest carbon deposits should appear closest to the surface of the forest floor. But this is not what they found—instead they discovered that newer deposits were more likely to be found at deeper levels in the soil. This was because, they learned, the trees were carrying much of the carbon they pulled in down to their roots (via sugars) where it was being sequestered by a type of fungi (ectomycorrhizal, aka mycorrhizal fungi) that eats the sugars and expels the residue into the soil.

In their study they found that 47 percent of soil carbon found on large island samples came about due to fungi, as did a whopping 70 percent of carbon in small island soil samples. Thus far, the team is only able to guess why there are such differences in the soils, but theorize it's likely due to differences in decomposition rates.

I wonder if the sequestering fungi associated with the tree roots are yet being directly fed by falling needles etc? Or, are they saying something else entirely?  Because I always assumed fungi to be involved in the breakdown of dead plant material - just never understood it to be transmitted so deeply in the soil....     

39
Consequences / Re: Worst consequence of AGW
« on: October 25, 2019, 08:05:53 PM »
https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1600-0889.2011.00527.x?deniedAccessCustomisedMessage=&userIsAuthenticated=false

By 2200, the PCF strength in terms of cumulative permafrost carbon flux to the atmosphere is 190 ± 64 Gt C. This estimate may be low because it does not account for amplified surface warming due to the PCF itself and excludes some discontinuous permafrost regions where SiBCASA did not simulate permafrost. We predict that the PCF will change the arctic from a carbon sink to a source after the mid‐2020s and is strong enough to cancel 42–88% of the total global land sink. The thaw and decay of permafrost carbon is irreversible and accounting for the PCF will require larger reductions in fossil fuel emissions to reach a target atmospheric CO2 concentration.

40
Science / Re: Trends in atmospheric CH4
« on: October 24, 2019, 03:47:08 AM »
massive acceleration happening.


41
Science / Re: Has climate sensitivity been under-estimated?
« on: October 09, 2019, 02:53:13 AM »
ECS vs Temperature not ECS vs CO2 concentration. 

The Paleosens paper showed that ECS increased with temperature non-linearly.

42
Science / Re: Has climate sensitivity been under-estimated?
« on: September 30, 2019, 08:27:37 PM »
the paleosens work from 2012 also showed this non-linearity of ECS  Though they simply checked over the last 800,000 years. see:  https://forum.arctic-sea-ice.net/index.php?topic=1053.1550


43
Science / Re: The Science of Aerosols
« on: September 27, 2019, 01:45:22 AM »
Study on the aerosol impact of the 2014-2015 eruption of Bárðarbunga in Iceland


https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/2015GL067070

Observations of a substantial cloud-aerosol indirect effect
during the 2014–2015 Bárðarbunga-Veiðivötn
fissure eruption in Iceland
Daniel T. McCoy1 and Dennis L. Hartmann

Quote
The estimated changes in upwelling SW and cloud albedo over the first 2 months of the eruption due to anomalies in re are shown in Figure 4. Cloud albedo was estimated to increase by up to 3% in the Norwegian Sea and Greenland Sea (Figure 4b). Local increases in upwelling SW exceeded 2 W/m^2. The zonal mean upwelling SW across the 60°N–70°N latitude band was estimated to increase by 1 W /m*2, and the cloud albedo was estimated to increase by 1.5% (Figure 4


44
Policy and solutions / Re: Batteries: Today's Energy Solution
« on: September 12, 2019, 05:39:42 AM »
Tesla's Partnership Virtual Power Plant with the South Australian Government is now oversubscribed and looking toward 'Phase 3"

https://reneweconomy.com.au/south-australia-says-tesla-virtual-power-plant-charging-ahead-84199/

45
Science / Re: The Science of Aerosols
« on: September 09, 2019, 09:38:39 PM »
Having a million difficulties trying to upload the presentation as a PDF.

I tried to take detailed notes, and stuck around for the Q&A. I may be able to answer some basic questions if anybody has any.

interesting to see what happened to arctic sea ice and the development of "the blob" in the north east pacific ocean after the 2014 eruption in iceland.

47
Policy and solutions / Re: Renewable Energy
« on: August 15, 2019, 09:13:53 PM »
Long - term storage solutions ( week / month ) are needed

A robust, redundant national high-voltage DC grid that connects the west to the east and the south to the north will greatly reduce the need for longer term energy storage.

48
Science / Re: Has climate sensitivity been under-estimated?
« on: August 08, 2019, 05:55:32 PM »
Interesting timeline of published ecs estimates at
https://www.carbonbrief.org/guest-post-why-results-from-the-next-generation-of-climate-models-matter

Perhaps worth noting that what the models show isn't necessarily what the final best estimate range is.

Quote
Early results suggest ECS values from some of the new CMIP6 climate models are higher than previous estimates, with early numbers being reported between 2.8C (pdf) and 5.8C. This compares with the previous coupled model intercomparison project (CMIP5), which reported values between 2.1C to 4.7C. The IPCC’s fifth assessment report (AR5) assessed ECS to be “likely” in the range 1.5C to 4.5C and “very unlikely” greater than 6C.

2.8-5.8 is certainly up from 2.1 to 4.7. More work needed before we know how much that pushes up the 1.5-4.5C likely range.


Perhaps it is worth noting that the range of ECS provided by the IPCC ARs that includes estimations from historic data (due to incomplete understanding of aerosol forcing parameters) and the rejection of known but not well understood future tipping points (like sea ice) fundamentally bias low their final estimation and that their final range estimation is not 'best.'

49
The rest / Re: Leftism is a greater threat than climate change
« on: August 08, 2019, 01:24:05 AM »
I really wish you wouldn't, this kind of idiocy makes us all dumber just by reading it.

Actually I don't mind it as a sign post... how dumb can people be. A fascist is a fascist regardless the "reasons" they concoct.

I am strongly beginning to think that the antisocial and comprehension/susceptibility to propaganda traits associated with fascist rightwing ideologues and climate deniers is directly related to pre-natal and in utero heavy metals exposure, especially in areas like refinery ally or the traditional coal-fired power generation areas.

50
The rest / Re: Leftism is a greater threat than climate change
« on: August 07, 2019, 10:51:16 PM »
I really wish you wouldn't, this kind of idiocy makes us all dumber just by reading it.

Pages: [1] 2 3 ... 42