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How much warmer on Earth in 2100, compared to mid-19th century?

1-2 degrees
5 (4.9%)
2-3 degrees
12 (11.8%)
3-4 degrees
25 (24.5%)
4-5 degrees
27 (26.5%)
5-6 degrees
9 (8.8%)
6-10 degrees
16 (15.7%)
10-20 degrees
0 (0%)
20-50 degrees
0 (0%)
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Not enough information
8 (7.8%)

Total Members Voted: 89

Author Topic: Magnitude of future warming  (Read 26292 times)

Tom_Mazanec

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Re: Magnitude of future warming
« Reply #150 on: June 18, 2020, 03:49:37 PM »
KiwiGriff:
If I read this right and my numbers are correct, CO2 went up 3.50 ppm May 2018 to May 2019, but only 2.27 ppm May 2019 to May 2020.
Could this reduction in increase (not a decrease) be a result of the shutdown?

dnem

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Re: Magnitude of future warming
« Reply #151 on: June 18, 2020, 05:06:26 PM »
I'm not sure if this is the most recent time Tamino has looked at it, but 2.5 years ago he concluded:

https://tamino.wordpress.com/2018/01/20/is-co2-still-accelerating/
Bottom line: CO2 is on the rise, the rise itself (velocity) has been getting faster (acceleration), and there’s no evidence at all that has changed recently.


I can't imagine there's enough data since then to definitively concluded that this has changed.

Hefaistos

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Re: Magnitude of future warming
« Reply #152 on: June 19, 2020, 01:42:49 AM »
Care to prove the keeling curve is now linear?
Or is that just your eyeballs?
...

I'm following Wolfpack's and Stephan's analyses of the CO2 at Mauna Loa, trying to detrend, and scrub the data from ENSO variability.

We clearly SEEM to have a slowdown in growth rate, and are almost on constant growth now.

https://forum.arctic-sea-ice.net/index.php/topic,2983.msg268712.html#msg268712

I have previously made a forecast somewhere on this forum that we will reach peak CO2 already by 2030. I still think it's possible due to the very strong growth of renewables. And certainly helped by corona lockdowns.
I expect to see a fall in the CO2 growth rate within a year.

Hefaistos

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Re: Magnitude of future warming
« Reply #153 on: June 19, 2020, 08:20:25 AM »
...

2) The data set you get to play with goes from 1950 - 2020. Over that time frame the CO2 and CH4 effects are only present on the end of the range but not in a way they are detectable in your chosen metrics.

You say that "the CO2 and CH4 effects are only present on the end of the range" /from 1950 - 2020/. You must be joking!
CO2 increases continously during this period of 70 years, and GMST have a strong positive trend, with some hiatuses. This should be reflected in the humidity levels, as the effect of increasing CO2 is supposed to go hand in hand with an increase in water vapour/humidity:

This is what they say at SkS:
"As water vapour is directly related to temperature, it's also a positive feedback - in fact, the largest positive feedback in the climate system (Soden 2005). As temperature rises, evaporation increases and more water vapour accumulates in the atmosphere. As a greenhouse gas, the water absorbs more heat, further warming the air and causing more evaporation. When CO2 is added to the atmosphere, as a greenhouse gas it has a warming effect. This causes more water to evaporate and warm the air to a higher, stabilized level. So the warming from CO2 has an amplified effect"
https://skepticalscience.com/water-vapor-greenhouse-gas-intermediate.htm

But the data shows no increase of water vapour, measured as specific humidity (or measured as relative humidity) in the LT. Only a small increase of specific humidity at the surface. (There is btw a bunch of interesting comments at SkS as well, e.g. #2 by someone called Victor.)

The research by Seidel and Yang that cloud feedback in the tropics is negative is also troubling, as clouds are the carriers of water vapour.

Hefaistos

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Re: Magnitude of future warming
« Reply #154 on: June 19, 2020, 08:52:54 AM »
...
One could look towards data we believe is reasonably accurate rather than relying on that we know is not.

Radiosonds have their problems, but since 1980 or so satellite data is presumably used.
We have the AQUA satellite with its Atmospheric Infrared Sounder (AIRS), and the Aura satellite, e.g.

According to NASA research, the satellite data shows less of an increase in humidity in the stratosphere, than models assume:
"Models that include water vapor feedback with constant relative humidity predict the Earth's surface will warm nearly twice as much over the next 100 years as models that contain no water vapor feedback.
Using the UARS /satellite/ data to actually quantify both specific humidity and relative humidity, the researchers found, while water vapor does increase with temperature in the upper troposphere, the feedback effect is not as strong as models have predicted. "The increases in water vapor with warmer temperatures are not large enough to maintain a constant relative humidity,""

This is what is shown in the charts in my post above.
https://forum.arctic-sea-ice.net/index.php/topic,2715.msg268929.html#msg268929
Relative humidity is consistently down on all altitudes measured.

https://www.nasa.gov/centers/goddard/news/topstory/2004/0315humidity.html
« Last Edit: June 19, 2020, 08:59:16 AM by Hefaistos »

gerontocrat

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Re: Magnitude of future warming
« Reply #155 on: January 28, 2023, 01:36:12 PM »
This Open Access article looks at what has happened this century to the upper troposphere–lower stratosphere.

It concludes ....
"Our results document a large warming of the tropical upper troposphere, and indications for structural changes in the global circulation patterns. These findings, supported by recent research... reveal an accelerated change of the global climate in the first decades of the 21st century."

This suggests to me that for the forseeable future we are likely to see major changes in world regional and seasonal climate - & not many of them good news.


Below I give a few quotes from the article & attach some very good graphs

click images to enlarge

https://www.nature.com/articles/s41598-023-28222-x
Resolving the 21st century temperature trends of the upper troposphere–lower stratosphere with satellite observations
Quote
Abstract
Historically, observational information about atmospheric temperature has been limited due to a lack of suitable measurements. Recent advances in satellite observations provide new insight into the fine structure of the free atmosphere, with the upper troposphere and lower stratosphere comprising essential components of the climate system. This is a prerequisite for understanding the complex processes of this part of the atmosphere, which is also known to have a large impact on surface climate. With unprecedented resolution, latest climate observations reveal a dramatic warming of the atmosphere. The tropical upper troposphere has already warmed about 1 K during the first two decades of the 21st century. The tropospheric warming extends into the lower stratosphere in the tropics and southern hemisphere mid-latitudes, forming a prominent hemispheric asymmetry in the temperature trend structure. Together with seasonal trend patterns in the stratosphere, this indicates a possible change in stratospheric circulation.

Results
see fig 1 attached - Vertical
Within the last two decades alone, upper-tropospheric temperatures have increased by up to 1 K in the tropics and in northern mid-latitudes (Fig. 1). Throughout the upper troposphere, these trends are significant at the 95% level. These concerning numbers support the hypothesis that corresponding MSU trend estimates are likely too small5,10,38. For the tropical upper troposphere as an example, MSU trend estimates are smaller by approximately a factor of two compared to GNSS RO ....

In the tropics and the SH, the warming extends through the tropopause into the LS, reaching up to about 20 km in SH mid-latitudes. This results in a prominent hemispheric asymmetry of LS temperature trends. A similar structure has already been described before, but for a shorter time period29. In the northern hemisphere (NH), the atmosphere is cooling above the tropopause, particularly in sub-tropical regions around 20 km. In the tropics, the transition between warming and cooling lies around 22 km, with increasingly negative trends above.

see fig 2 attached - horizontal i.e.regional
At each height level we observe distinct trend patterns. Tropical amplification, the amplified warming of the upper tropical troposphere compared to the surface40, is prominently observable, comparing the surface and the 12 km layer. Cooling in the Northern Atlantic region, a well-known feature called the warming hole41, continues, and our analysis reveals that this surface cooling is accompanied by a warming in the LS. At 24 km, an altitude where we have predominantly negative temperature trends around the globe, this warming pattern is striking. The region of warming corresponds to a region of positive ozone trends42, and is possibly induced by a decrease of the regional tropopause height43.

At 18 km, just above the tropical tropopause, and well into the stratosphere outside of the tropics, the most prominent feature is the clear hemispheric asymmetry. The LS is significantly warming in large parts of the tropics and SH, with particularly large trend values in the subtropical SH Pacific. The NH shows no significant temperature signal at most latitudes, except for polar regions with strong cooling, and the “warm blob” over the Northern Atlantic.

The hemispheric asymmetry of stratospheric trends points towards a possible connection to ozone. In the LS, ozone is the major driver for temperature trends, and ozone trends show a strong seasonality44.

see fig 3 attached - changes by latitude vs month
We provide insight into the seasonality of trends in a vertically differentiated picture. The seasonal signature of LS temperature trends in Fig. 3, at 18 km, 21 km, and 24 km, exhibits—somehow surprising—a strong negative temperature trend at SH polar regions in austral spring (October–November). This is in contrast to expected stratospheric warming due to the recovery of ozone6,18. The combined pattern of spring cooling of the Antarctic stratosphere and warming of the tropical LS could be a fingerprint of a weakening of the SH branch of the BDC29,45. This weakening is not expected from model projections, which show an acceleration of the BDC due to increasing GHG concentrations in the 21st century46. However, ozone recovery could have a counteracting effect16. The vertical resolution is key here to be able to resolve these change patterns, providing a clear advantage over layer-averaged observations.

In the NH, the opposite effect is observable. Warming in Arctic spring and at the same time cooling in the tropics are a signal for BDC acceleration in the NH.

It is important to note that for the relatively short time period of 20 years, atmospheric variability makes robust trend determination difficult. This variability can be (multi-)decadal such as the Pacific Decadal Oscillation47, or short-term such as the strong variability in polar regions. During the investigated time period, two rare SH southern stratospheric warmings (SSW) occurred in 2002 and 2019, imposing the suspicion that the related strong temperature anomalies could tamper with the trend estimates. This is, however, not the case, as the result holds even when removing the SSW time periods from the regression.

Conclusions
A detailed knowledge about temperature changes in the UTLS, including structural changes and changes in the coupling between troposphere and stratosphere, is fundamental for a better understanding of atmospheric dynamics and its impacts on global and regional climate.

The results indicate substantial changes in the UTLS during the observed time period:

The troposphere shows a warming of up to 1 K during the first two decades of the 21st century, particularly in the tropics and in northern mid-latitudes.

The tropopause region reveals a prominent hemispheric asymmetry of changes in the LS temperature patterns.

Tropospheric warming extents through the tropopause in the tropics and SH mid-latitudes, up to a height of about 20 km.

Layer-averaged observations miss important details of trend patterns, and likely underestimate temperature trends in the UTLS.

Regional trend patterns reveal that the surface cooling in the Northern Atlantic region translates into a stratospheric warming at around 24 km over the same region, whereas the rest of the stratosphere is cooling.

Seasonal variability of temperature shows a combined pattern of Antarctic cooling and tropical warming in the LS in austral spring. This could be a fingerprint of a weakening of the SH branch of the BDC.

Warming is observed in the LS in Arctic spring, and cooling in the tropical LS at the same time. This could hint towards a BDC acceleration in the NH.

Satellite observations from GNSS RO can substantially contribute to the climate monitoring in the UTLS region of the atmosphere. The high vertical resolution and insight into the fine structure of atmospheric temperature with GNSS RO is defining a new state-of-the-art representation of Earth’s upper-air climate change. We recognize this to be a major advance towards global climate monitoring.

In conclusion, our findings provide observational evidence that the temperature trends in the UTLS have been underestimated in the literature. Our results document a large warming of the tropical upper troposphere, and indications for structural changes in the global circulation patterns. These findings, supported by recent research45,48,49,50,51,52, reveal an accelerated change of the global climate in the first decades of the 21st century.
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gerontocrat

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Re: Magnitude of future warming
« Reply #156 on: February 15, 2023, 10:03:40 PM »
This paper opines that "in a majority of the latitudes, both cold and hot extremes warm more in response to future global sea surface temperature change than due to sea-ice loss"

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022GL102542
Changes in Winter Temperature Extremes From Future Arctic Sea-Ice Loss and Ocean Warming
Quote
Abstract[/b]
Observed rapid Arctic warming and sea-ice loss are likely to continue in the future, unless and after greenhouse gas emissions are reduced to net-zero. Here, we examine the possible effects of future sea-ice loss at 2°C global warming above pre-industrial levels on winter temperature extremes across the Northern Hemisphere, using coordinated experiments from the Polar Amplification Model Intercomparison Project. 1-in-20-year cold extremes are simulated to become less severe at high- and mid-latitudes in response to Arctic sea-ice loss. 1-in-20-year winter warm extremes become warmer at northern high latitudes due to sea-ice loss, but warm by less than cold extremes. We compare the response to sea-ice loss to that from global sea surface temperature (SST) change also at 2°C global warming. SST change causes less severe cold extremes and more severe warm extremes globally. Except northern high latitudes, the response to SST change is of larger magnitude than that to Arctic sea-ice loss.

Key Points
Less severe winter cold extremes in northern mid- and high-latitudes in response to future Arctic sea-ice loss

Winter hot extremes increase in severity over high latitudes due to future Arctic sea-ice loss, but warm less than cold extremes

In a majority of the latitudes, both cold and hot extremes warm more in response to future global sea surface temperature change than due to sea-ice loss

Plain Language Summary
The Arctic and neighboring regions have rapidly warmed in recent decades and the sea ice has reduced. These changes will likely continue in future, unless greenhouse gas emissions from human activities are reduced to net-zero.

Ongoing sea-ice loss can affect weather and climate across the Northern Hemisphere. We use climate models to study how extremely cold and hot temperatures in winter may change because of Arctic sea-ice loss. In a future world that is, on average, 2°C warmer than pre-industrial times, cold extremes will become less severe at high- and mid-latitudes because of Arctic sea-ice loss. Winter hot extremes also get warmer, but over fewer regions and not by as much as cold extremes. In the real world, changes in sea ice happen alongside changes in ocean temperatures.

So, we also looked at the effect of ocean temperature changes in a 2°C warmer world on winter temperature extremes. Ocean warming will lead to warmer cold and hot extremes in the Northern Hemisphere. The effect from ocean warming is larger than that from Arctic sea-ice loss, meaning that even in the few places where sea-ice loss might cause cooling, it will be overwhelmed by warming due to the ocean temperature changes.


Key Points
Less severe winter cold extremes in northern mid- and high-latitudes in response to future Arctic sea-ice loss

Winter hot extremes increase in severity over high latitudes due to future Arctic sea-ice loss, but warm less than cold extremes

In a majority of the latitudes, both cold and hot extremes warm more in response to future global sea surface temperature change than due to sea-ice loss

Plain Language Summary
The Arctic and neighboring regions have rapidly warmed in recent decades and the sea ice has reduced. These changes will likely continue in future, unless greenhouse gas emissions from human activities are reduced to net-zero. Ongoing sea-ice loss can affect weather and climate across the Northern Hemisphere. We use climate models to study how extremely cold and hot temperatures in winter may change because of Arctic sea-ice loss. In a future world that is, on average, 2°C warmer than pre-industrial times, cold extremes will become less severe at high- and mid-latitudes because of Arctic sea-ice loss. Winter hot extremes also get warmer, but over fewer regions and not by as much as cold extremes. In the real world, changes in sea ice happen alongside changes in ocean temperatures. So, we also looked at the effect of ocean temperature changes in a 2°C warmer world on winter temperature extremes. Ocean warming will lead to warmer cold and hot extremes in the Northern Hemisphere. The effect from ocean warming is larger than that from Arctic sea-ice loss, meaning that even in the few places where sea-ice loss might cause cooling, it will be overwhelmed by warming due to the ocean temperature changes.

3 Results
3.1 Responses to Sea-Ice Loss
Figure 2a shows the multi-model-mean difference in 1-in-20-year winter cold extremes between futArcSIC and pd in the Northern Hemisphere. The largest warming, of over ∼2.5°C, is projected for northern and eastern Canada near Hudson Bay. The futArcSIC and pd winter minimum temperature distributions are statistically significantly different at the 5% level, indicating amplified warming in boreal winter cold extremes due to future Arctic sea-ice loss, as global average temperature is 1.4°C higher in futArcSIC than in pd (Smith et al., 2019). A statistically significant warming of ∼2°C is also projected for Alaska. These results are generally consistent across the models (Figure S3 in Supporting Information S1), likely due the close proximity to imposed sea ice reductions in Hudson Bay, Labrador Sea, and Bering-Chukchi Seas (Smith et al., 2022).
SEE ATTACHED FIGURE
Figure 2
Changes in 1-in-20-year (a) December-January-February (DJF) minimum of daily minimum temperature and (b) DJF maximum of daily maximum temperature in the Northern Hemisphere due to future Arctic sea-ice loss. The panels show the multi-model mean across 10 Polar Amplification Model Intercomparison Project models. Stippling indicates where the temperature distributions from futArcSIC and pd are not statistically significantly different at the 5% level, based on a Kolmogorov-Smirnov test.

Figure 2b shows the multi-model-mean difference in 1-in-20-year winter warm extremes between futArcSIC and pd. Statistically significant changes are only simulated in the high latitudes, with northern Canada showing the strongest warming, of over ∼2.5°C, followed by northeastern Russia (∼2°C). These changes are generally consistent across the models (Figure S4 in Supporting Information S1). The multi-model mean indicates widespread cooling of up to −0.4°C that is not statistically significant across most parts of North America, Eurasia, and central Africa.

3.2 Responses to SST Change
Figure 4a shows that warmer SSTs associated with 2°C global mean warming increase 1-in-20-year cold temperatures over land in the Northern Hemisphere in the multi-model mean. This warming is statistically significant at the 5% level. No cooling response is shown in the multi-model mean at any location. In general, individual models agree on a strong (∼3°C) warming signal in North America, particularly in the western parts (Figure S5 in Supporting Information S1). The cold temperature response in Eurasia to future SST change is more variable, with IPSL-CM6A-LR showing strong warming in the northern parts, whereas FGOALS-f3-L shows cooling in those parts but relatively strong warming in east Asia (Figure S5 in Supporting Information S1). These differences may be affected by sampling variability.

SEE ATTACHED FIGURE
Figure 4

(a) Multi-model mean changes in 1-in-20-year December-January-February (DJF) minimum of daily minimum temperature in the Northern Hemisphere due to future sea surface temperature (SST) change. The temperature distributions from futSST and pd are statistically significantly different at the 5% level based on a Kolmogorov-Smirnov test. Panel (b) same as panel (a) but, for DJF maximum of daily maximum temperature. (c) Comparison between the multi-model mean temperature changes due to future Arctic sea-ice loss (x-axis) and the corresponding changes due to future SST change (y-axis). Navy points indicate changes in 1-in-20-year DJF minimum of daily minimum temperature, whereas orange points indicate changes in 1-in-20-year DJF maximum of daily maximum temperature. Each point represents the regional mean in one particular region. The dashed line indicates a 1:1 relationship, whereas the dotted line indicates a 2:1 relationship.

Future SST change is also projected to warm winter warm extremes significantly in all Northern Hemisphere land grid cells in the multi-model mean, as shown in Figure 4b. However, both the multi-model mean and individual model results (Figure S6 in Supporting Information S1) indicate that the warm extreme response is smaller compared to the cold extreme response in almost all places except northern Canada. Small inter-model differences are seen in the warm extreme response to SST change, with CanESM5 simulating cooling in Greenland and northeastern Russia that is not statistically significant, for example.

With previous evidence that responses to sea ice and greenhouse gas forcing are approximately linearly additive (McCusker et al., 2017), it may be reasonable to deduce the combined mean 1-in-20-year winter temperature responses to Arctic sea-ice loss and ocean warming from Figures 3 and 4. For cold extremes, even in places where Arctic sea-ice loss is simulated to intensify them (e.g., in southwestern United States, parts of Europe, central and eastern Asia, though not statistically significantly; Figure S3 in Supporting Information S1), warming due to SST change overwhelms this cooling effect, resulting in net warming (not shown).


Warming of winter warm extremes in the high latitudes due to Arctic sea-ice loss and ocean warming can increase the chances of rain on snow events. Notable events have already occurred in Arctic Canada (Rennert et al., 2009) and Russia (Forbes et al., 2016), which led to declines in ungulate (e.g., reindeer and musk oxen) populations that persisted for years and herders losing food security and transportation (Serreze et al., 2021). Our results suggest that these communities are at an increased risk of these impacts in a 2°C warmer world, compared to the present day.
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)