What's new in the Arctic ?

[Chris83]

Interesting study about the Barents Sea

(not sure this is the thread for it)

A seven-degree increase in atmospheric temperature in the northern Barents Sea.
A 3.5-degree increase in sea temperature.

(and this is locked in, whatever the scenario for CO2 emissions)



https://www.sciencenorway.no/arctic-climate-climate-change/new-study-the-northern-barents-sea-could-be-seven-degrees-warmer-in-2050/2429820

[gerontocrat]

Interesting study about the Barents Sea

(not sure this is the thread for it)

A seven-degree increase in atmospheric temperature in the northern Barents Sea.
A 3.5-degree increase in sea temperature.

(and this is locked in, whatever the scenario for CO2 emissions)

https://www.sciencenorway.no/arctic-climate-climate-change/new-study-the-northern-barents-sea-could-be-seven-degrees-warmer-in-2050/2429820

Goodbye winter sea ice in the Barents - full Atlantification.
& this must surely have a knockon effect on the sea ice in the Kara and the Atlantic Front of the Central Arctic and the Greenland Sea?

[El Cid]

I always thought that BOE could only occur if/when the Barents and Bering stay ice free all year because then the first 1/2 months won't be "wasted" to melt these out. If we started from an ice free barents and Bering then you would have a fully melting CAB by June/July at peak insolation. That would destroy it.

[kassy]

Not much ice gets recycled in the Bering area so this alone is enough. Of course they are discussing 2050 and we could already have had a BOE by then. Yes there will be knock on effects on other seas but they are already happening and the ice is much easier to melt as it gets thinner.

So for 2050 their WCS will probably be closer then the reasonable scenario.

[binntho]

Thats the graph. It shows that the time to melt 10% at 6C is about 500 years. Multiply by 10 to get 5000 years to melt 100%.

y=x is a straight line
y=1/x is a hyperbola, which is roughly the shape of that graph.

time to melt  = 1/melt rate, so if the time to melt is hyperbolic, the melt rate is linear

OK thanks for clarification. The graph shows the time it takes to melt the FIRST 10%, and you make a serious mistake by multiplying by 10. As clearly stated in the video, and as everybody who knows anything about how glaciers melt, the rate of melt will increase rapidly with time, if only due to drop in altitude.

Thist is also what the whole video is about! As the glacier melts, the equilibrium line moves ever further inland and ever more of the surface of the glacier is subject to stronger melt and less snowfall. It is a strongly non-linear process.

So thanks Richard for clarifying your mistake.

[Richard Rathbone]

Who knows what will happen in 500 years time? Its pretty silly to be crying wolf  about something that far in the future. I don't think its all that strongly non-linear anyway. If it had been Box would have shown it. The important question is whether it can accelerate in 50 years, not get a little bit faster than now in 1000 years time. Thats what he was talking about on the video. Getting a little bit faster after 1000 years. He didn't show the graph for that because it wouldn't have looked scary. To see a big non-linearity it would have to be even slower. At 0.5 degrees over the tipping point there's a lot more potential for increasing the area than there is at 6 degrees where a lot more area is melting already. But showing something that got really "fast" in 50,000 years time would be even more silly, even though it would be more non-linear.

There might be some other mechanism than surface melt that will kick in, like the slope getting too steep and collapsing. That would be a genuinely scary non-linearity. However, at the moment there are only reckoned to be a few gates where the ice can flow faster due to the underlying terrain and almost all of them are already active, which is where the increase in the past few decades has come from. However that increase in the rate may be over, and nothing Box said on that video suggests he thinks otherwise. He's talking about gentle non-linearities happening over millennia not ones that could push the sea level up by metres over a century.

[binntho]

An article in New Scientist claims to finally have an explanation for the unusually high temperatures last year and continuing into this year: "We finally have an explanation for 2023’s record-breaking temperatures".

The article is based on a recent article in the journal Science, unfortunately behind a pay-wall, but the abstract reads:

In 2023, the global mean temperature soared to almost 1.5K above the pre-industrial level, surpassing the previous record by about 0.17K. Previous best-guess estimates of known drivers including anthropogenic warming and the El Niño onset fall short by about 0.2K in explaining the temperature rise. Utilizing satellite and reanalysis data, we identify a record-low planetary albedo as the primary factor bridging this gap. The decline is apparently caused largely by a reduced low-cloud cover in the northern mid-latitudes and tropics, in continuation of a multi-annual trend. Further exploring the low-cloud trend and understanding how much of it is due to internal variability, reduced aerosol concentrations, or a possibly emerging low-cloud feedback will be crucial for assessing the current and expected future warming.

Apparently, record-low albedo over the oceans is to blame for the extra warming, and although it is not mentioned in the abstract above, apparently the findings show that the low albedo was mostly in tropical latitude and not over the main shipping lanes, which means that reduction in sulfur pollution by shipping since 2022 can only be partially to blame.

The interesting question then becomes: Why? What caused this drop in albedo and will it continue, or reverse, or maybe get worse? Is it because of some previously unknown natural climatic variability? Or is it some climate-warming-induced feedback mechanism that will only get worse?

[HapHazard]

People talk about the shipping fuel changes a lot here, but "For the global average, the effect of removing marine aerosols may have added about 0.02 °C" Dunno how/if it affects albedo though.

https://berkeleyearth.org/august-2023-temperature-update/

[El Cid]

People talk about the shipping fuel changes a lot here, but "For the global average, the effect of removing marine aerosols may have added about 0.02 °C" Dunno how/if it affects albedo though.

https://berkeleyearth.org/august-2023-temperature-update/

Yes, and that is exactly what James Hansen thinks is wrong, see any of his newsletters from the past 2-3 years, eg this one:

http://www.columbia.edu/~jeh1/mailings/2024/MayEmail.2024.05.16.pdf

"We interpret acceleration of warming since 2010 to be a consequence of decreasing aerosols,
with a significant contribution from reduction of ship aerosols due to the strict 2020 emission
limit imposed by the IMO (International Maritime Organization). Another recent social media
comment is that reduction of ship emissions is negligible compared to emission reductions by
China. That comment misses the point. It is well known that ship emissions are a tiny part of
total anthropogenic emissions and of emission changes, but ships emit into relatively pristine
ocean air and the aerosol effect is nonlinear. The inadvertent experiment provided by the IMO
emission limit is a great opportunity to improve understanding of aerosol and cloud physics.
An important issue concerns how much additional global warming lurks in our Faustian
aerosol bargain. That depends on interpretation of ongoing change. Our preliminary analysis
suggests a ship aerosol forcing an order of magnitude (factor of ~10) greater than what
follows from IPCC estimates. The 2021 IPCC report (AR6) pegs total aerosol forcing as 1.06
W/m2 in 2019, with 0.22 direct aerosol forcing and 0.84 the indirect effect on clouds. A 2021
update reduces the aerosol forcing to 0.98 W/m2 (0.21 direct, 0.77 indirect). Based on this
small aerosol forcing, Hausfather and Forster obtain a forcing of 0.079 W/m2 for 100%
implementation of 2020 IMO9 ship emission limits. Our estimate of a minimum of 0.5 W/m2
for the aerosol forcing from shipping refers to the present (~80%) reduction of sulfates from
ships. The difference with the Hausfather and Forster value is so large that it must be possible
to resolve this issue within the next few years"


Basically he's been saying for years that negative forcing by aerosols is absolutely underestimated which means that positive forcing by CO2 is underestimated and therefore if/when we start reducing aerosols an acceleration of global warming should happen. He's been talking about if for years and lo and behold acceleration  IS happening lately.

[binntho]

People talk about the shipping fuel changes a lot here, but "For the global average, the effect of removing marine aerosols may have added about 0.02 °C" Dunno how/if it affects albedo though.

https://berkeleyearth.org/august-2023-temperature-update/

Yes, and that is exactly what James Hansen thinks is wrong...

Basically he's been saying for years that negative forcing by aerosols is absolutely underestimated which means that positive forcing by CO2 is underestimated and therefore if/when we start reducing aerosols an acceleration of global warming should happen. He's been talking about if for years and lo and behold acceleration  IS happening lately.

I was not aware of what Hansen has been saying, but I would reply "obviously" to the above statement. I remember back in the 90s when the whole global warming issue was gaining traction in the general consciousness, that there was a lot of speculation about the aerosol cooling effect as an explanation for the warming hiatus between c.a. 1940 and 1975. Human-induced aerosol release during WWII would have been significantly above the interwar years, and the following decades saw very rapid increase in fossel fuel consumption and concomitant aerosol pollution.

During my formative years in the 70s the whole world started talking about "acid rain" and how it was destroying the forests of Europe and even North America. I remember how there were no sunny days anymore when vacating during summer, only some sort of white mist hiding the sun and the clouds and the distant mountains. All sunsets were marvellous, but nobody got tanned anymore!

And the world reacted, cleaning up transport fuels and filtering emissions from power stations. The amount of aerosol decreased rapidly, and Europe regained the clear skies of the childhood of our parents.

But then aerosol pollution over the Indian subcontinent and South-East Asia increased massively, but I assume (or hope?)  that it has been decreasing again recently. Or perhaps not? In Beijing, in 2001, the situation was even worse than I remembered from my childhood in Europe. Has the situation improved since then?

Anyway, if a fall in human-released aerosols is to blame for the significant extra warming in 2023 and continuing, then where and why and by how much has this form of pollution gone down in recent years? We know about the ship emissions, but that is not enough.

[oren]

An article in New Scientist claims to finally have an explanation for the unusually high temperatures last year and continuing into this year: "We finally have an explanation for 2023’s record-breaking temperatures".

The article is based on a recent article in the journal Science, unfortunately behind a pay-wall, but the abstract reads:

In 2023, the global mean temperature soared to almost 1.5K above the pre-industrial level, surpassing the previous record by about 0.17K. Previous best-guess estimates of known drivers including anthropogenic warming and the El Niño onset fall short by about 0.2K in explaining the temperature rise. Utilizing satellite and reanalysis data, we identify a record-low planetary albedo as the primary factor bridging this gap. The decline is apparently caused largely by a reduced low-cloud cover in the northern mid-latitudes and tropics, in continuation of a multi-annual trend. Further exploring the low-cloud trend and understanding how much of it is due to internal variability, reduced aerosol concentrations, or a possibly emerging low-cloud feedback will be crucial for assessing the current and expected future warming.

Apparently, record-low albedo over the oceans is to blame for the extra warming, and although it is not mentioned in the abstract above, apparently the findings show that the low albedo was mostly in tropical latitude and not over the main shipping lanes, which means that reduction in sulfur pollution by shipping since 2022 can only be partially to blame.

The interesting question then becomes: Why? What caused this drop in albedo and will it continue, or reverse, or maybe get worse? Is it because of some previously unknown natural climatic variability? Or is it some climate-warming-induced feedback mechanism that will only get worse?

Interesting. And as usual with climate news, disturbing.

[Richard Rathbone]

Not sure if this has already been posted somewhere, but its a finding that ocean acidification reduces the production of dimethyl sulphide, the main natural source for ocean aerosols. The non-linearity that Hansen refers to might be an even stronger effect as a result of this.

Open access https://www.nature.com/articles/s41612-024-00563-y

Changes in global DMS production driven by increased CO2 levels and its impact on radiative forcing

Our study highlights the importance of understanding the future changes in dimethyl-sulfide (DMS), the largest natural sulfur source, in the context of ocean acidification driven by elevated CO2 levels. We found a strong negative correlation (R2 = 0.89) between the partial pressure of carbon dioxide (pCO2) and sea-surface DMS concentrations based on global observational datasets, not adequately captured by the Coupled Model Intercomparison Project Phase 6 (CMIP6) Earth System Models (ESMs). Using this relationship, we refined projections of future sea-surface DMS concentrations in CMIP6 ESMs. Our study reveals a decrease in global sea-surface DMS concentrations and the associated aerosol radiative forcing compared to ESMs’ results. These reductions represent ~9.5% and 11.1% of the radiative forcings resulting from aerosol radiation and cloud interactions in 2100 reported by the Intergovernmental Panel on Climate Change Sixth Assessment Report. Thus, future climate projections should account for the climate implications of changes in DMS production due to ocean acidification.

[kassy]

The interesting question then becomes: Why? What caused this drop in albedo and will it continue, or reverse, or maybe get worse? Is it because of some previously unknown natural climatic variability? Or is it some climate-warming-induced feedback mechanism that will only get worse?

It comes from physics. Warmer air holds more moisture. At the simplest level this changes the saturation point. In a really overly simplistic way you could say that in a warmer world the lowest clouds would be higher. Of course it is more complicated in the real world but clouds change and we know this from both physics and paleo.

And it will get worse as temperatures go up while it increases local temperatures too. It is one of the many ways to accelerate global warming.

[Bruce Steele]

Thanks Richard for the DMS paper. Due to less ice there has been an increase in DMS in the Arctic so the projected changes in the Southern Hemisphere are a bit of a surprise. I think anytime we begin to consider biological ramifications of ocean acidification we are in a very complex place. A warming ocean sometimes counteracts the effects of acidification.
https://www.sciencedirect.com/science/article/abs/pii/S0048969724006570
So population shifts either towards picophytoplankton or towards diatoms or green algae all affect DMS production .
The troubling thing to me is acidification becomes a much worse an issue when we approach surface water undersaturation projected ~2100 and even though human fossil fuel reductions will limit anthro sulfur terrestrial and ocean sources by then the long term biological effects of anthro CO2 will live on centuries into the future.

[binntho]

The interesting question then becomes: Why? What caused this drop in albedo and will it continue, or reverse, or maybe get worse? Is it because of some previously unknown natural climatic variability? Or is it some climate-warming-induced feedback mechanism that will only get worse?

It comes from physics. Warmer air holds more moisture.

I think there is some misunderstanding here. This has nothing to do with moisture but with aerosol pollution. A recent increase in albedo is apparently caused by a decrease in the amount of low-lying cloud over tropical oceans. The reason for this drop is unclear, but if you were to read the posts above you would see that some people suspect that a reduction in global aerosol pollution could be to blame. Which is why I asked: Has there been a fall in global aereosol pollution recently?

Partial answer is yes, there has been a decrease in SOx pollution by maritime shipping due to new global standards for ship fuels. But this drop is apparently not sufficient to explain the measured increase in albedo.

Focusing on SOx only there is plenty of data upto 2022 but it is clear that pollution has been going down steadily since the mid 70s. The biggest difference is in Europe, but even Asia has seen a reduction from a peak of 66 million tons in 2005 to 45 in 2022. (Our World in Data)

Following the changes in regulation in 2020, pollution from shipping fell from 10 to 3 million tons between 2019 and 2022. This change does not seem to register in the graph below, and nor does SOx pollution seem to have been effected by COVID pandemic. The main trend is clearly down over the last 50 years, with SOx pollution being now only half of what it was at peak.

I am not aware of any global events that could cause a significant drop in SOx pollution in 2023 and 2024 which leads me to conclude that the excess warming in 2023 and 2024 is not likely to be caused by major changes in SOx pollution.

But other sources of aerosol pollution exist, and a big one is dust from Sahara being blown out over the Atlantic. I read somewhere that 2023 saw a big reduction in dust from Sahara, and I know that the recent summer had unusually wet weather in western Sahara, which would have cut down on dust pollution as well. That could be the start of a very ominous feedback cycle!

Aerosol Optical Depth image from Nasa Earth Observatory.

[El Cid]

Once again, I can refer to Hansen. I won't quote each of his newsletters but you can look it up.

Basically, he says that SOx emission effects are quite localized and therefore you cannot just look at global emissions, you need to see  the geograhical distribution of emissions. And since oceans constitute 2/3 of the area of the world, reducing suplhur there has an oversized effect. Also, most shipping routes are in the north midlatitudes where you had a huge jump in SSTs this decade, making his claim more believable: 

[psymmo7]

I think the numbers for this part of the earth's oceans back up the last point

[Bardian]

https://www.esa.int/Applications/Observing_the_Earth/Copernicus/Sentinel-1/Sentinel-1C_captures_first_radar_images

[vox_mundi]

Sink to Source: Arctic Tundra Now Emits Planet-Warming Pollution, Federal Report Finds
https://www.npr.org/2024/12/10/nx-s1-5215967/arctic-tundra-contributes-climate-warming-pollution-report-finds



Arctic tundra, which has stored carbon for thousands of years, has now become a source of planet-warming pollution. As wildfires increase and hotter temperatures melt long-frozen ground, the region is releasing greenhouse gases into the atmosphere.

The finding was reported in the National Oceanic and Atmospheric Administration's annual Arctic Report Card, released Tuesday. The new research, led by scientists from the Woodwell Climate Research Center in Falmouth, Massachusetts, signals a dramatic shift in this Arctic ecosystem, which could have widespread implications for the global climate.

https://arctic.noaa.gov/report-card/

https://arctic.noaa.gov/report-card/report-card-2024/

"The tundra, which is experiencing warming and increased wildfire, is now emitting more carbon that it stores, which will worsen climate change impacts," NOAA Administrator Rick Spinrad said in a press release. "This is yet one more sign, predicted by scientists, of the consequences of inadequately reducing fossil fuel pollution."

"It means that that CO2 will keep going up," Commane said. "We won't be able to do much about it."

This year's report comes as President-elect Donald Trump prepares to take office in January. Trump has said he wants to increase oil exploration and drilling in the Arctic and curtail government action on climate change.

[Jim Hunt]

The 2024 edition of the Arctic Report Card has been published by NOAA. A brief overview is available in this video: