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Messages - Hefaistos

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1
The forum / Re: Arctic Sea Ice Forum Humor
« on: July 08, 2020, 03:08:33 PM »
Free-hand Extrapolation of the melting curve of Arctic 08072020: ;D ;)

"Free-hand Extrapolation" - you're too honest! Should have said it's a 27th degree polynomial fitted with a strange attractor.

2
Science / Re: Solar cycle
« on: July 08, 2020, 01:03:00 PM »
The solar forcing implemented in the new generation of CMIP6 models seem to forecast a Maunder minimum. Solar cycles declining all the way to 2100.

Figure from attached pdf page 9.

3
Another paper about the ongoing strengthening of the AMOC:

"Pending recovery in the strength of the meridional overturning circulation at 26°N"

by Moat et al, in Ocean Science, forthcoming  (still in peer review)

Abstract. The strength of the Atlantic meridional overturning circulation (AMOC) at 26°N has now been continuously measured by the RAPID array over the period Apr 2004 - Sept 2018. This record provides unique insight into the variability of the large-scale ocean circulation, previously only measured by sporadic snapshots of basin-wide transports from
hydrographic sections. The continuous measurements have unveiled striking variability on timescales of days to a decade, driven largely by wind-forcing, contrasting with previous expectations about a slowly-varying, buoyancy forced large-scale ocean circulation. However, these measurements were primarily observed during a warm state of the Atlantic Multidecadal
Variability (AMV) which has been steadily declining since a peak in 2008-2010. In 2013-2015, a period of strong buoyancyforcing by the atmosphere drove intense watermass transformation in the subpolar North Atlantic and provides a unique opportunity to investigate the response of the large-scale ocean circulation to buoyancy forcing. Modelling studies suggest that the AMOC in the subtropics responds to such events with an increase in overturning transport, after a lag of 3-9 years. At 45°N, observations suggest that the AMOC may already be increasing. ..."

https://www.researchgate.net/publication/338658885_Pending_recovery_in_the_strength_of_the_meridional_overturning_circulation_at_26_N

Figure 3 The total AMOC at 10-day resolution (a), can be decomposed into a seasonal cycle (b), interannual variability (c)...

4
The linked reference confirms that the AMOC is projected to continue slowing with continued global warming:

Wei Liu  et al. (26 Jun 2020), "Climate impacts of a weakened Atlantic Meridional Overturning Circulation in a warming climate", Science Advances, Vol. 6, no. 26, eaaz4876, DOI: 10.1126/sciadv.aaz4876

https://advances.sciencemag.org/content/6/26/eaaz4876

Abstract
While the Atlantic Meridional Overturning Circulation (AMOC) is projected to slow down under anthropogenic warming, the exact role of the AMOC in future climate change has not been fully quantified. Here, we present a method to stabilize the AMOC intensity in anthropogenic warming experiments by removing fresh water from the subpolar North Atlantic. This method enables us to isolate the AMOC climatic impacts in experiments with a full-physics climate model. Our results show that a weakened AMOC can explain ocean cooling south of Greenland that resembles the North Atlantic warming hole and a reduced Arctic sea ice loss in all seasons with a delay of about 6 years in the emergence of an ice-free Arctic in boreal summer. In the troposphere, a weakened AMOC causes an anomalous cooling band stretching from the lower levels in high latitudes to the upper levels in the tropics and displaces the Northern Hemisphere midlatitude jets poleward.

Some in this thread have suggested that the recent observed cooling of the lower levels of the troposphere is an indication that climate sensitivity is relatively low; however, the quoted reference indicates that instead it is an indication that the AMOC is slowing (see the bolded text in the abstract); which to me is an indication that in coming decades TCR will be much higher (near 2.93C) than assumed by consensus climate science.

What if the AMOC instead is in a strengthening cycle? This is suggested be several recent papers. How do you then explain the decreasing tropospheric temperatures?

"Surface predictor of overturning circulation and heat content change in the subpolar North Atlantic"
Desbruyères et al, 2019, Ocean Sci., 15, 809–817

Abstract
The Atlantic Meridional Overturning Circulation (AMOC) impacts ocean and atmosphere temperatures on a wide range of temporal and spatial scales. Here we use observational datasets to validate model-based inferences on the usefulness of thermodynamics theory in reconstructing AMOC variability at low frequency, and further build on this reconstruction to provide prediction of the near-future (2019–2022) North Atlantic state. An easily observed surface quantity – the rate of warm to cold transformation of water masses at high latitudes – is found to lead the observed AMOC at 45∘ N by 5–6 years and to drive its 1993–2010 decline and its ongoing recovery, with suggestive prediction of extreme intensities for the early 2020s. We further demonstrate that AMOC variability drove a bi-decadal warming-to-cooling reversal in the subpolar North Atlantic before triggering a recent return to warming conditions that should prevail at least until 2021. Overall, this mechanistic approach of AMOC variability and its impact on ocean temperature brings new key aspects for understanding and predicting climatic conditions in the North Atlantic and beyond."

From the Conclusions:
"In this paper we have provided observationally based evidence of a tight causal relationship between low-frequency changes in the rate of surface-forced water mass transformation in the eastern SPG /Subpolar Gyre/, the variability in the overturning circulation at 45∘ N, and ocean heat content trends in the SPG. The 5-year delay between surface property changes in the SPG and downstream circulation changes suggests good skills for short-term predictability in the region from the sole use of ocean surface and air–sea interface measurements. Here, a strong intensification of the overturning and associated heat transport from 2010 is found to persist until the early 2020s, driving a new significant reversal of climatic condition in the SPG as temperatures rapidly rise from their last minimum of 2017. "

Enjoy the full text:
https://os.copernicus.org/articles/15/809/2019/

Caption Figure 4. The AMOC and SFOC time series. (a) Annual anomalies in the maximum AMOC (blue) and the maximum SFOC (red) at 45 N (in Sv), with the latter shifted 5 years forward (lag of maximum correlation). The reference (time-mean) period is 1996–2013. Thick lines show 7-year low-pass-filtered time series. The right-hand side axis displays the corresponding heat transport anomalies. The original time line for SFOC is given in the top x axis. (b) The 7-year low-pass-filtered time series of anomalies in the maximum SFOC at 45 N (red – shifted 5 years forward), the maximum SFOC at the OSNAP line (green – shifted 4 years forward) decomposed into contributions from the eastern (thin) and western (dashed) basins, and the maximum SFOC at the GIS sills (yellow – shifted 3 years forward). Shading indicates the ensemble standard errors for each variable.

Caption  Figure 5. OHC time series. Detrended anomalies in OHC within
the upper SPG (0–1000 m; 10–70W, 45–65 N; black, in joules)
and MHT -driven OHC anomalies north of 45 N (blue, in joules).
Shading indicates the ensemble standard errors for each variable.
The SFOC -driven OHC prediction for 2017–2022 is shown in red,
with its associated error based on the historical predictive skills of
SFOC (Eq. 6). The green patch indicates the “cold blob” era driven
by extreme air–sea flux events (Josey et al., 2018).

5

Here is another reminder that the quoted research indicates that the AMOC is currently slowing (particularly since 2015); which is a major risk factor for high values of TCR in coming decades:


ASLR, your statement (bolded by me) is not correct.
AMOC is stable during the period from 2015 to 2019, even showing a slight increase.
Please see the charts i posted in reply #3424 and reply #3425:

The RAPID arrays show:
At 26N, a slight increase
At Upper Mid Ocean, stable
Florida Straits, stable
Ekman at 26N, a slight increase
OVIDE section, a slight increase

What's the evidence you can provide that "AMOC is currently slowing (particularly since 2015)"?

https://forum.arctic-sea-ice.net/index.php/topic,2205.msg271113.html#msg271113

I believe that Smeed et al got it right in their recent paper, when they write:
"Our results show that the previously reported decline of the AMOC (Smeed et al., 2014) has been arrested, but the length of the observational record of the AMOC is still short relative to the time scales of importantdecadal variations that exist in the Atlantic. Understanding is therefore constantly evolving. What we identify as a changed state of the AMOC in this study may well prove to be part of a decadal oscillation superposed on a multidecadal cycle."

In other words, what we're seeing is natural variations, and there is currently no evidence of a declining AMOC, specifically not since 2015.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/2017GL076350

6
Per the linked open access reference:

"The AMOC has been observed to slow down over the past decade in the Rapid Climate Change (RAPID) array at 26.5°N in the North Atlantic, although this AMOC slowdown can be part of natural climate variability, considering the relatively short observational period."

Wei Liu et al. (26 Jun 2020), Climate impacts of a weakened Atlantic Meridional Overturning Circulation in a warming climate", Science Advances, Vol. 6, no. 26, eaaz4876< DOI: 10.1126/sciadv.aaz4876

https://advances.sciencemag.org/content/6/26/eaaz4876

That whole paper is built on computer simulations with a GCM model and applying only the RCP8.5 scenario.
That alone disqualifies the results, as we aren't following the RCP8.5 due to the strong development of renewables.

Secondly, the paper enforces a very strong decline in the AMOC, a decline that has no support in the actual data that we have today, see chart.
Caption: "Fig. 1 AMOC strength and global mean surface air temperature in CCSM4 historical and RCP8.5 simulations and sensitivity experiment AMOC_fx. (A) From 1850 to 1980, the AMOC strength is adopted from CCSM4 historical simulation (purple, ensemble mean; light purple, ensemble spread). After 1980, the AMOC strength from CCSM4 historical and RCP8.5 simulations (AMOC_fx) is shown as green (purple) curve for ensemble mean and light green (light purple) shading for ensemble spread. The AMOC strength is defined as the maximum of the annual mean stream function below 500 m in the North Atlantic."

Furthermore, the paper uses AMOC data up until 2017 which are claimed to show a slight slowdown of the AMOC. Developments since then seem to contradict that.
As Smeed et al write:
"Our results show that the previously reported decline of the AMOC (Smeed et al., 2014) has been arrested, but the length of the observational record of the AMOC is still short relative to the time scales of importantdecadal variations that exist in the Atlantic. Understanding is therefore constantly evolving. What we identify as a changed state of the AMOC in this study may well prove to be part of a decadal oscillation superposed on a multidecadal cycle."


https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1002/2017GL076350

7
Consequences / Re: Temperature signals from Covid-19
« on: July 01, 2020, 01:35:59 PM »
We have a pronounced negative temperature anomaly signal during the second quarter of 2020.
We expected a positive anomaly signal due to the reduced aerosols as a result of world-wide lockdowns.

So why do we get the opposite?

Attached is a temperature chart, including a forecast for the next week as well.

8
The theme of AMOC slowdown is also covered in this post:

https://forum.arctic-sea-ice.net/index.php/topic,2205.msg240256.html#msg240256

The chart gives no support at all for a slowdown.

"A time series of AMOC transport (MOCρ ) at the OVIDE section (eastern subpolar gyre: Portugal to Cape Farewell) for 1993–2017, constructed from altimetry and hydrography. The gray line is from altimetry combined with a time-mean of Argo velocities; the green curve is low-pass filtered using a 2-year running mean. The black curve is from altimetry and Argo. Red circles are estimates from OVIDE hydrography with associated errors given by the red lines. The mean of the gray curve is given by the black dashed line (Updated from Mercier et al., 2015)."

9
I find it disturbing that the linked reference indicates that many consensus climate scientists primarily attribute the North Atlantic warming hole (or Cold Blob) to a slow-down of that AMOC; while in fact both the Cold Blob and the slow-down of the AMOC is primarily related to meltwater hosing from Greenland.  This indicates to me that many consensus climate science models should be upgraded to include freshwater hosing from meltwater:

Keil, P. et al. (2020) Multiple drivers of the North Atlantic warming hole, Nature Climate Change, doi:10.1038/s41558-020-0819-8

https://www.nature.com/articles/s41558-020-0819-8

Abstract: "Despite global warming, a region in the North Atlantic ocean has been observed to cool, a phenomenon known as the warming hole. Its emergence has been linked to a slowdown of the Atlantic meridional overturning circulation, which leads to a reduced ocean heat transport into the warming hole region. Here we show that, in addition to the reduced low-latitude heat import, increased ocean heat transport out of the region into higher latitudes and a shortwave cloud feedback dominate the formation and temporal evolution of the warming hole under greenhouse gas forcing. In climate model simulations of the historical period, the low-latitude Atlantic meridional overturning circulation decline does not emerge from natural variability, whereas the accelerating heat transport to higher latitudes is clearly attributable to anthropogenic forcing. Both the overturning and the gyre circulation contribute to the increased high-latitude ocean heat transport, and therefore are critical to understand the past and future evolutions of the warming hole."

See also:

Title: "Scientists shed light on human causes of North Atlantic’s ‘cold blob’"

https://www.carbonbrief.org/scientists-shed-light-on-human-causes-of-north-atlantics-cold-blob

Extract: "Previous research has linked the warming hole to a weakening of an ocean current in the North Atlantic, which brings heat up from the tropics.

Now a new study – published in Nature Climate Change – suggests that a number of other factors are also involved. These include “changes in the high latitude ocean circulation” and the cool sea surface creating “more low-level clouds”, the lead author tells Carbon Brief."

There is a lot of talk about a slowdown of the AMOC, and a lot of CMIP modelling takes it as a given thing in their future scenarios.

However, the evidence for a slowdown of AMOC is rather weak, as it relies on data that are disputed.
The causes of the eventual slowdown are also disputed.

No evidence of a slowdown are to be seen in recent data. Here as measured at different places.
(data taken from KNMI site)

10
Consequences / Re: COVID-19
« on: June 29, 2020, 11:41:16 AM »
A thorough analysis of C-19 in Sweden by a competent statistician, Nic Lewis, he concludes:

"Notwithstanding that a month ago antibodies were only detected in 6.3% of the Swedish population, the declining death rate since mid-May strongly suggests that the herd immunity threshold had been surpassed in the three largest regions, and in Sweden as a whole, by the end of April.

In the absence of a change in trends, it seems likely that the epidemic will peter out after a thousand or so more deaths, implying an overall infection fatality rate of 0.06% of the population (0.04% excluding COVID-19 deaths of people in care homes). This is broadly comparable to excess deaths from influenza infections over two successive above-average seasons, such as 2016–17 plus 2017–18."

https://www.nicholaslewis.org/the-progress-of-the-covid-19-epidemic-in-sweden-an-analysis/

11

Something is going wrong at Moyhu as for instance, the first attached image from the linked Moyhu website shows that no month in 2020 has been the warmest on record.

http://www.moyhu.org.s3.amazonaws.com/data/freq/ncep.html

Yet, NOAA, NASA and Copernicus (see the second attached image where Hausfather uses Copernicus data thru the end of May 2020 to project that 2020 will be the warmest year on record) all indicate that all months thru May 2020 were the warmest on record.

Thus until Moyhu's data falls in line with the observed NOAA, NASA and Copernicus observed data, I am inclined to ignore all data from Moyhu.

There seems to be some issues with the NCEP V1 data, or the feed.
It has been discussed on the Moyhu blog, also by Karsten Haustein (sign. KarSteN):

https://moyhu.blogspot.com/2020/05/ncepncar-reanalysis-surface-temperature.html
https://moyhu.blogspot.com/2020/06/ncepncar-reanalysis-may-2020-surface.html

Karsten Haustein discusses issues with the NCEP reanalysis in depth here:
http://www.karstenhaustein.com/reanalysis/info.php

12
Geron,
your examples are valid, but not relevant.
Gravity always pulls downward.
The Nile always flows only in one direction.
Planets and stars always move in the same way.
By plain observation you can spot reliable patterns.

But what about cloud feedbacks? Some of the clouds have positive feedback, some have negative.
Cloud feedback tend to be negative in the tropics, positive elsewhere.
Aerosols play an important role, but how, and where, and for which types of clouds?
Convective processes and cloud feedbacks happen on smaller scales (grid sizes) than the models can handle. And even if they had this data, there isn't enough computational capacity available.
You don't even have observations on the relevant scale.
Without observations you have no valid data.
Without theories that cover all relevant cloud and aerosol processes, you have no valid model.
Without computational capacity your deficient data and model built on incomplete theories will indeed produce only GIGO.

There is a research initiative to resolve these issues, The World Climate Research Programme (WCRP) Grand Challenge on Clouds, Circulation, and Climate Sensitivity.
They write in a white paper: "Limited understanding of clouds is the major source of uncertainty in Climate Sensitivity, but also contributes substantially to persistent biases in modelled circulation systems..."
"The spread of climate sensitivity estimates is unacceptably large, mostly as a result of uncertain changes in clouds. This uncertainty can be thought of as the ‘cloud problem’. The cloud problem contributes to an inability to usefully constrain the upper bound, and the relative reliability, of differing estimates of climate sensitivity."

https://wcrp-climate.org/component/content/article/61-gc-clouds-circulation?catid=30&Itemid=267

13
...
Seems relevant to ask, have these CMIP models with unbelievably high ECS values got their fundamental physics reg. clouds and water vapor right?

First, no model is perfect but some models are useful (& thus should not be ignored). 

Models that can be characterized as GIGO should be ignored.
...

Of course if the CMIP models are assuming that feedback from aerosol emissions are less negative than that feedback actually is then then the CMIP5 projections might be matching the recently observed record by using two wrongs to make a right; while the high-end CMIP6 projections might not match the observed record as well but may be projecting the future better if/when anthropogenic aerosol emissions are reduced (such as they have been for the first five months of 2020 when the month GMSTA values have been at record highs).  Thus, when uncertainty is involved who is to say what constitutes garbage in-garbage out (GIGO) w.r.t. modeling; however, the climate risks associated with the high-end CMIP6 projections are so high as to justify the adoption of the Precautionary Principle.

New research paper published that evaluates CMIP6 models.
"Context for interpreting equilibrium climate sensitivity and transient climate response from the CMIP6 Earth system models" by Meehl et al. Science Advances  24 Jun 2020, Vol. 6, no. 26,
From the Abstract
"....Here we review and synthesize the latest developments in ECS and TCR values in CMIP, compile possible reasons for the current values as supplied by the modeling groups, and highlight future directions. Cloud feedbacks and cloud-aerosol interactions are the most likely contributors to the high values and increased range of ECS in CMIP6."

Accompanying presentation of the research:
"Increased warming in latest generation of climate models likely caused by clouds
New representations of clouds are making models more sensitive to carbon dioxide"
Jun 24, 2020 - by Laura Snider

"“Cloud-aerosol interactions are on the bleeding edge of our comprehension of how the climate system works, and it’s a challenge to model what we don’t understand,” Meehl said. “These modelers are pushing the boundaries of human understanding, and I am hopeful that this uncertainty will motivate new science.”"

Can you really model something that you don't understand? Yes, you can. But it will definitely be GIGO.

https://advances.sciencemag.org/content/6/26/eaba1981
DOI: 10.1126/sciadv.aba1981

https://news.ucar.edu/132741/increased-warming-latest-generation-climate-models-likely-caused-clouds

14

The problem in the statement above is the word "actual". What is actual?

From the same climate-lab-book page link provided (so clear and obvious that it would be hard to miss. Surprising that it was not mentioned when presenting the evidence):
 
"The simulation data uses spatially complete coverage of surface air temperature whereas the observations use a spatially incomplete mix of air temperatures over land and sea surface temperatures over the ocean. It is expected that this factor alone would cause the observations to show smaller trends than the simulations."

How well do the various models perform if the above factor was applied to observational temperature or use of a more spatially complete data set? e,g. Cowtan and Way (although not perfect widely accepted to be a more accurate record of global temperature increase. Remember - here we're trying to evaluate the accuracy of the models over a relatively short time period (not track global temperatures over a long time period).

Good question!
Moyhu has a nice portal where you can follow various temperature data. It's updated each day.
I plotted six series with land and ocean temps in the attached chart.
Cowtan and Way - dark green
HadCrut - red
GISS - light brown
NOAA - dark brown
BEST - light green
Temp LS Mesh - lila

CW updating is lagging.
All series are showing the same development, with small variations.
To answer your question, no, it wouldn't change the evaluation. Models are running hot irrespective of which temperature data you use.

https://moyhu.blogspot.com/p/latest-ice-and-temperature-data.html

Here is a description of the method for creating Temp LS Mesh, which is a similar attempt to CW to create more spatially complete data by applying statistical methods.

https://moyhu.blogspot.com/2019/10/new-femloess-method-of-integrating.html
https://moyhu.blogspot.com/p/a-guide-to-global-temperature-program.html

15
...

Edit: Also, I note that if AR6 does decide to us weighting factors on ECS projections then they should also downweight the Russian (INM CM4/5) projection of ECS.

INM CM4 and CM5 models are among the ones that track actual temperature developments best. So might be a good idea to keep them - maybe they are the ones that will be demonstrated to have gotten the hydro cycle, as well as the cloud feedback right?
In the first attached 'spaghetti' chart, the INM CM4 is one of the blue ones near the bottom of the spaghetti bowl. Rather close to the actual HadCrut temperatures compared to many high-flying models.
In the second attached chart models are compared in terms of contributions to ECS from different factors.
In the third attached chart models are compared in terms of cloud feedback contributions.

The high-flying models have more to prove in terms of tracking actual temperatures, than their more realistic competitors. So what's the argument, ASLR, why should they be "downweighted", as you propose? Because they don't err on the side of maximum ECS drama?

https://www.climate-lab-book.ac.uk/comparing-cmip5-observations/
https://link.springer.com/article/10.1134/S000143381004002X

16
...
I believe that such evidence indicates that in coming decades we can expect more ice-climate feedback mechanisms than assumed in any CMIP6 model (including in E3SM1).

Ad hoc calvings is a natural phenomenon. It's also snowing a lot over Greenland and the surface mass balance goes up with maybe 600 gigatonnes each winter season.
Espen estimates this calving to be around 200 sq.km. How many tonnes might such a berg be? 1 gigaton? 10 gigatonnes? In any case, it's a rather negligible event in the bigger picture.

Such regular calvings are just part of the natural seasonal variations and no evidence of any drama in terms of "more ice-climate feedback mechanisms than assumed in any CMIP6 model (including in E3SM1)"

17
Science / Re: 2020 Mauna Loa CO2 levels
« on: June 21, 2020, 04:23:08 AM »
1. Clearly, we are not having exponential growth anymore, we're on a linear growth path.
I do not agree. The rates are slightly increasing. The later you look the steeper is the slope.

I averaged 100-month increase rates of Mauna Loa CO2:

1959-1967: + 0.77 ppm/year
1967-1975: + 1.10 ppm/year
1975-1984: + 1.50 ppm/year
1984-1992: + 1.52 ppm/year
1992-2000: + 1.59 ppm/year
2000-2009: + 1.99 ppm/year
2009-2017: + 2.34 ppm/year
2012-2020: + 2.48 ppm/year

These data are not compatible with "linear growth path".

See also the annual increase (raw data) in the attached graph. y-axis: increase in ppm/year

True, but I was looking at Wolfie's detrended /ENSO scrubbed data, and they do show that we have an almost constant growth rate:
2011-2018  2.39
2013-2020  2.40

This would be significant, if correct :)

After all, we do expect CO2 to grow exponentially if temperatures are to rise linearly, as there is a logarithmic relationship between radiative forcing (which is directly proportional to the change in surface temperature at equilibrium) and the atmospheric CO2 increase.
This logarithmic relationship means that each doubling of atmospheric CO2 will cause the same amount of warming at the Earth's surface.
Thus, a linear increase in CO2 means we will have the inverse relationship. In the graph, temperatures will increase, but with decreasing amounts. (the green curve instead of the black one)

18
Science / Re: Magnitude of future warming
« 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

19
Science / Re: Magnitude of future warming
« 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.

20
Science / Re: Magnitude of future warming
« 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.

21
Science / Re: Magnitude of future warming
« on: June 18, 2020, 11:50:06 AM »
In my opinion based on following climate change since the 70s is that ECS, like the uncertainty of the preindustrial baseline, is a tool for obfuscation.

Why the doubling of co2, what is magical about that standard ?
...

Global annual mean CO2 concentration has increased by almost 50% since the start of the Industrial Revolution, from 280 ppm to 420 ppm now.
Doubling of CO2 means another 140 ppm to add. Currently we add maybe 2.2 ppm per year, and it has become a linear growth. So in 50 - 70 years with continued linear growth we will have doubled the CO2. Kind of graspable.

Testing with GCM models for the effects of a doubling of CO2 thus makes a lot of sense, per se.

22
Science / Re: 2020 Mauna Loa CO2 levels
« on: June 17, 2020, 10:45:03 PM »
I made a mistake in my de-trending chart above.  I didn't de-trend ENSO before de-trending Mauna Loa. If you want to de-trend just *anthropogenic* effects you have to make sure ENSO(lagged) integrates to zero. 

I went with multi-line regression.  I have 4 regression lines where ENSO integrates to zero(accounting for 5 month lag). Blending these together you'll notice that anthropogenic changes are only worth about an additional ~0.1 ppm/year by 2020 compared to 2007.

Thanks, Wolfie.
Two musings related to "anthropogenic changes are only worth about an additional ~0.1 ppm/year".

1. Clearly, we are not having exponential growth anymore, we're on a linear growth path.

2. What if ENSO has an anthropogenic component? Frequency, amplitudes, durations...

23
Antarctica / Re: What's new in Antarctica ?
« on: June 17, 2020, 01:35:09 PM »
Pretty cold in the Southern Ocean and over Antarctica now. Anomalies are on rather low levels both long and short term, according to the CFS Reanalyzer.

24
Science / Re: Magnitude of future warming
« on: June 17, 2020, 07:20:15 AM »
Quote
It's very disturbing that the enormous range of possible ECS's persists between these models. Currently, with AR5 and CMIP5, the range is from 1.5 - 4.5

...
I doubt that a lower bound of 1.5C will hold into AR6 as much work has been published attempting to reconcile the low results of some observational based models with other methods.
https://www.carbonbrief.org/explainer-how-scientists-estimate-climate-sensitivity


You refer to an overview article in Carbonbrief. In that article they make a central claim regarding the most influential GHG, water vapour: "As the world warms, the amount of water vapour in the atmosphere is expected to increase and, therefore, so too will the greenhouse effect. Measurements from satellites confirm that water vapour concentrations have been increasing in step with temperatures in the atmosphere over the past few decades." , with a link to:
https://www.gfdl.noaa.gov/blog_held/48-increasing-vertically-integrated-water-vapor-over-the-oceans/
At the link, there is a chart that shows very slightly increasing water vapor over the oceans, but only in the tropics.
However, the data is not that straightforward, nor is it simple to interpret. At the NOAA Physical Sciences Laboratory (PSL) you can create charts of humidity. Relative atmospheric humidity (%) at three different altitudes in the lower part of the atmosphere (the Troposphere) is generally speaking going down.
Also specific atmospheric humidity (g/kg) is down on higher altitudes, and shows the stipulated uptrend only at surface level.
https://psl.noaa.gov/cgi-bin/data/timeseries/timeseries1.pl

Conflicting evidence regarding water vapour feedback!

We also have recent research showing that the cloud feedback in the tropics is negative. Already mentioned upthread, the paper by Seidel and Yang, in Science Advances  06 May 2020: DOI: 10.1126/sciadv.aba1951
https://forum.arctic-sea-ice.net/index.php/topic,2715.msg268667.html#msg268667

Conflicting evidence also regarding cloud feedback!

There are already several critical scientific evaluations of the CMIP6 models. Zelinka et al write:
"ECS is higher on average in CMIP6 due primarily to strengthened cloud feedbacks. Tropical low cloud feedbacks and global non‐low cloud feedbacks are positive in nearly every model."
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019GL085782

What if the CMIP models didn't get their physical processes right? What if the feedback in the most important sector, the tropics, is negative, as Seidel and Yang show?

Then it is the high ECS models that should be discarded, not the low ECS ones.

25
Science / Re: Magnitude of future warming
« on: June 16, 2020, 07:08:33 AM »
Quote
GCM models are inherently unable to model convectice processes, as they operate on grid sizes that are about 1000 times bigger than the actual processes. Thus, the GCMs resort to parametrization of these processes. In other words, GIGO modelling.

The Hadley validation test shows that if they use their cloud model parameter in short term weather forecasting it improves the forecasts so that is a hint that it actually works (similar to how they used the method to disprove another model challenge earlier).

And of course there are multiple levels on which we can take this.

 You are critical of the model. Fine. But...
Do you think the neutral assumption was more true then what we calculate? Or is it more a problem of magnitudes?
Is the GIGO postulation analysis driven or just because you don´t want it to be true?

I find GIGO kind of harsh. This is complicated stuff which needs tons of computing power.

I have written at some length about this, and about the challenges facing the models before, in a number of posts. To sum up the arguments:

Model makers face 4 major challenges, as I see it:
1. GCM's lack a 'general theory' on water vapor on various latitudes and altitudes. Specifically, the tropics are challenging with the very powerful, energy intensive phase changes taking place (e.g. in the ubiquitos tropical thunderstorms).

2. There is a lack of understanding on the radiative forcing of clouds/water vapor. Is there a positive feedback, or a negative feedback between clouds and SST's? No-one knows. Recent research indicates that the feedback is negative in the tropics, but positive elsewhere. Specifically, IPCC doesn't know, and has previously just assumed that the feedback is zero. Yes, maybe better like that, than rely on GIGO models.

3. GCM's don't have the input data for the strongest GHG (water vapor/clouds) as they operate on MUCH larger grids than clouds, and the convective processes in clouds (currently a factor of more than 1000 between needed grid size, and feasible grid size). Thus, they have to rely on parameterizations for clouds and water vapor. That is a substandard practice, typical for GIGO models.

4. Computing capacity isn't big enough. Witness the GCM model E3SM, where they have severe restrictions on the length of runs they can make, and the number of runs they can afford, in terms of computing capacity and work time involved. GCMs typically use 100 km grid cells, whereas modelling of convective activity would require something like 0.1 km - 1 km cells. To reach this definition in a GCM would require in the order 10^10 times more powerful computers, as well as correspondig feed of input data. This won't happen in any foreseeable future.

All these challenges are clearly solvable, but I'd guess we need a couple of decades to get models that are more reliable as forecasting tools.

It's very disturbing that the enormous range of possible ECS's persists between these models. Currently, with AR5 and CMIP5, the range is from 1.5 - 4.5. And now we have the newer CMIP6 models, where maybe a fourth of them push for even higher ECS, up to 5.5 or so. But still, there are other CMIP6 models that maintain a ECS of 1.5 or so. Thus, the range seems to increase in the near future, in IPCC's AR6 Synthesis Report due in 2022. This is bizarre! How can we build a climate policy on such imprecise tools?!

As IPCC lacks tools for evaluating the quality and performance of models, and has decided to resort to give each model 'one vote', and together they form an ensemble of models. The hope is that the problems that different models have will be averaged out. This is a very crude approach. 

https://forum.arctic-sea-ice.net/index.php/topic,2205.msg234634.html#msg234634
https://forum.arctic-sea-ice.net/index.php/topic,2205.msg231232.html#msg231232
https://forum.arctic-sea-ice.net/index.php/topic,2205.msg232206.html#msg232206
https://forum.arctic-sea-ice.net/index.php/topic,2205.msg243866.html#msg243866
https://forum.arctic-sea-ice.net/index.php/topic,2205.msg237028.html#msg237028

26
...
Seems relevant to ask, have these CMIP models with unbelievably high ECS values got their fundamental physics reg. clouds and water vapor right?

First, no model is perfect but some models are useful (& thus should not be ignored). 

Models that can be characterized as GIGO should be ignored.

Quote
Second, per Mark Zelinka's talk in Reply #3256, the CMIP6 models (gold in the attached image) more closely match the observed mean-state liquid condensate fraction (LCF) in clouds that do the CMIP5 models (blue in the attached image).  So at least by this measure the CMIP6 models (on average) model fundamental physics better than did the CMIP5 models.

Gavin Schmidt is quite sceptical to those high ECS values, and the modelling approaches.

"...claims that climate sensitivity is much higher, or that worst cases scenarios need to be revised upwards, are premature."

and

"What is clear is that (for the first time) the discord between the GCMs and the external constraints is going to cause a headache for the upcoming IPCC report."

http://www.realclimate.org/index.php/archives/2020/06/sensitive-but-unclassified-part-ii/
http://www.realclimate.org/index.php/archives/2019/11/sensitive-but-unclassified/

27
Science / Re: Magnitude of future warming
« on: June 15, 2020, 09:49:28 AM »
This recent research finds a negative feedback for clouds in the ever important tropics.

The lightness of water vapor helps to stabilize tropical climate

Seth D. Seidel and Da Yang

Science Advances  06 May 2020:
Vol. 6, no. 19, eaba1951
DOI: 10.1126/sciadv.aba1951

Abstract
"Moist air is lighter than dry air at the same temperature, pressure, and volume because the molecular weight of water is less than that of dry air. We call this the vapor buoyancy effect. Although this effect is well documented, its impact on Earth’s climate has been overlooked. Here, we show that the lightness of water vapor helps to stabilize tropical climate by increasing the outgoing longwave radiation (OLR). In the tropical atmosphere, buoyancy is horizontally uniform. Then, the vapor buoyancy in the moist regions must be balanced by warmer temperatures in the dry regions of the tropical atmosphere. These higher temperatures increase tropical OLR. This radiative effect increases with warming, leading to a negative climate feedback. At a near present-day surface temperature, vapor buoyancy is responsible for a radiative effect of 1 W/m2 and a negative climate feedback of about 0.15 W/m2 per kelvin."

There is no settled science regarding the feedback of clouds and water vapor. In some situations/some places it's a negative feedback, in others it's a positive feedback.

GCM models are inherently unable to model convectice processes, as they operate on grid sizes that are about 1000 times bigger than the actual processes. Thus, the GCMs resort to parametrization of these processes. In other words, GIGO modelling.

28
Consequences / Re: World of 2030
« on: June 08, 2020, 11:19:21 PM »
Let's see, the worst cyclone of all time was the Bhola in 1970, which killed half a million people in Bangladesh.  Prior to that, the deadliest cyclones occurred in the 19th century.  The worst floods were all in China during the early 20th century.  The worst droughts in the U.S. occurred in the 1930s and 50s.  Of course, nothing compares to the great Chinese drought of the 1920s, which killed millions (total unknown, but estimates are as high as 10 million).  Ironically, that was followed by the great flood of 1931 mentioned previously.  Do you still believe that this was not the case back then?

Compare to the current corona pandemic. Maybe it will kill one million people.
The modern world seems to be more resilient to catastrophies.

29
Arctic sea ice / Re: "Stupid" Questions :o
« on: June 08, 2020, 11:07:25 PM »

Corona lockdowns has given massively reduced aerosols.

We expect to get increased warming because less aerosols mean less masking of radiative fluxes.

My question is how this might be detected at the TOA? Will it be a decline of emitted thermal radiation (ETR), e.g. in the form of OLR, or will it be an increase in absorbed solar radiation (ASR)? Or maybe both?

Is there any commonly accepted, scientifically specific expected increase in forcing from aerosol reduction?

I found the answer for the last question. The IPCC has -0,5 W/sq.m for aerosols.
Some recent research has twice bigger values.

My main question remains unanswered:

How might the massive reduction in aerosols due to corona lockdowns be detected at the TOA? Will it be a decline of emitted thermal radiation (ETR), e.g. in the form of OLR,
or will it be an increase in absorbed solar radiation (ASR)? Or maybe both?

30

Counter-intuitive then that the LT temperature anomalies have dropped a lot since the lockdowns started.


I think a lot is timing of ice and snow cover because these influence the anomaly most.

We do have a covid drop but we also had a pretty unexpected winter scenario so tying this plot to the covid emission drop is pretty hard.

More or less the same volume of ice has been molten out in the Arctic during the last 10 years, see attached figure from Gerontocrat. What's "unexpected"?

Still searching for the elusive effect of the reduction in aerosols. A reduction of aerosols is expected to show up quickly in temperature data and in radiative forcings!

We have had three big volcanic eruptions in the recent decades, and there has been almost no time lags involved, when aerosols increased. Mt Pinatubo in June 1991 is the latest one, and well researched. This might serve as a proxy for the current reduction in aerosols.

"Radiative Climate Forcing by the Mount Pinatubo Eruption" by Minnis et al from 1993 says in the Abstract: "The volcanic aerosols caused a strong cooling effect immediately: the amount of cooling increased through September 1991 as shortwave forcing increased relative to longwave forcing."
https://www.researchgate.net/publication/6039761_Radiative_Climate_Forcing_by_the_Mount_Pinatubo_Eruption

31
Consequences / Re: Global Surface Air Temperatures
« on: June 08, 2020, 05:38:06 AM »
Somebody able to find the error in the following? What am I missing or does this mean that we've already gone flying past Paris goal of  "pursuing" 1.5 degC above pre-industrial?

...
-  On top of this is the delayed heating of the atmosphere from the heating lag mainly caused by heat stored in the oceans. This article puts the full length of delay at 40 years ( https://skepticalscience.com/Climate-Change-The-40-Year-Delay-Between-Cause-and-Effect.html) ...

I'd like to add to the quoted paragraph that we're living on a water planet.
Hansen et al estimated a time lag of 37.5 years for 60 % of emissions to be seen as surface temperature warming.
The reason is the inertia of the oceans.
The total time lag is really big in the Thermohaline circulation, the bulk of deep water upwells in the Southern Ocean, which is currently significantly cooling, see chart. The oldest waters have a transit time of about 1000 years and most of that upwells in the North Pacific.
Thus, we presumably have a lot of cold water from the Little Ice Age (from around 1300 - 1850 AD) still in the process, and that can be expected to dampen the global warming for centuries to come.

https://en.wikipedia.org/wiki/Thermohaline_circulation

32

Counter-intuitive then that the LT temperature anomalies have dropped a lot since the lockdowns started.

Looking at the graph it usually goes down in the early part of the year. Biggest peak on these is 2016. Might be a response to the state of winter ice?

And musing on it´s interesting how these peaks are created.
What was the date for the 2016 peak?
What was the date for the 2020 peak?

I think a lot is timing of ice and snow cover because these influence the anomaly most.

We do have a covid drop but we also had a pretty unexpected winter scenario so tying this plot to the covid emission drop is pretty hard.

1. Thermal energy is strongly down in the atmosphere from February/March, according to all available/updated satellite data. (UAH6, RSS and CFSR). The decline is similar to 2016, when Earth came out of a strong El Nino. No such thing this year. Part of it might be a seasonal effect, but hardly all of it.

2. Aerosols are down a lot. How much? Haven't seen any data yet, but air traffic alone seems to be down 90 % or so. I will make a quick net estimate below, and for the sake of the argument I will guess that aerosols are down by 50%.

3. Forcing from aerosols has been estimated many times, and recent estimates are really high, at -1.14 W/sq.m:

The linked reference, and associated article, indicate that the aerosol-cloud feedback is more negative than previously assumed by consensus climate scientistsThus as aerosol emissions decrease (as they have done during the COVID-19 crisis) the Earth will warm faster than previously projected by consensus climate science (such as projected in AR5):
Otto P. Hasekamp et al. Analysis of polarimetric satellite measurements suggests stronger cooling due to aerosol-cloud interactions, Nature Communications (2019). DOI: 10.1038/s41467-019-13372-2
https://www.nature.com/articles/s41467-019-13372-2
"The resulting estimate of RFaciaci = −1.14 Wm−2−2 (range between −0.84 and −1.72 Wm−2−2) is more than a factor 2 stronger than the IPCC estimate that includes also other aerosol induced changes in cloud properties.

4. CO2 levels are at maximum ever, as well as methane. Forcing remains highest ever from CO2 and CO2eq. See attached figure from IPCC. Total forcing is 3.10 W/sq.m.
https://en.wikipedia.org/wiki/Radiative_forcing

Just a quick back of the envelop calculation to sum things up here:
Total forcing including aerosols would then be 3.10 - 1.14 = 1.96
If aerosols are down 50%, we would get an increased net forcing of 3.10 - 0.57 = 2.53
Thus, the net forcing is up from 2.0 to 2.5, or an increase with 25%.

Where is this effect to be seen? Not in the atmosphere, according to point 1.
When the masking effect of aerosols is lifted, we would expect to see an immediate effect on the thermal energy in the atmosphere. But there is no trace of such an effect, au contraire...

33
Consequences / Re: World of 2030
« on: June 07, 2020, 12:31:57 AM »
Simple question: In what year will human population peak? Right now human births outnumber deaths by ~80 million people a year. When do folks think annual human deaths will outnumber births?

I'll throw out 2034.  I recognize that represents a dramatic, unprecedented demographic shift.

Nothing unprecedented, but it will be after 2100.

https://population.un.org/wpp/Graphs/DemographicProfiles/Line/900

34
Arctic sea ice / Re: "Stupid" Questions :o
« on: June 06, 2020, 10:52:56 AM »

Corona lockdowns has given massively reduced aerosols.

We expect to get increased warming because less aerosols mean less masking of radiative fluxes.

My question is how this might be detected at the TOA? Will it be a decline of emitted thermal radiation (ETR), e.g. in the form of OLR, or will it be an increase in absorbed solar radiation (ASR)? Or maybe both?

Is there any commonly accepted, scientifically specific expected increase in forcing from aerosol reduction?

35

...
"If we know how much the aerosols cool, then we can much better quantify how the Earth is going to warm to CO2 because that aerosol-cooling effect is our biggest uncertainty."

In other words, scientists now have a window to peer into the future."

Counter-intuitive then that the LT temperature anomalies have dropped a lot since the lockdowns started. Satellite data from UAH6 and RSS MSU show the same, and also the CSFR which is a mix of various data sources shows a significant drop starting from March.
These LT temperature data are our best indicators of the thermal energy in the atmosphere.

This drop comes instead of the expected increase due to massively reduced aerosols. Or at least we would expect to see more of a constant temperature anomaly.

The drop is similar to what we had in 2016, coming out of the strong El Nino. Nothing like that provides an explanation this year.

What could the explanation be?
What is the expected increase in forcing from aerosol reduction?


36
Arctic background / Re: Aerosol reduction effects
« on: June 05, 2020, 12:45:44 AM »
The map shows regional distribution, but what about quantification? What's the temperature anomaly according to GHCN?
Also noticeable that there is almost no data for SH compared to the NH.

37
Consequences / Re: Temperature signals from Covid-19
« on: June 05, 2020, 12:27:41 AM »

No. I disagree that it is of high quality and accuracy.

Some of the problems they have struggled with relate to satellite altitudes (they slowly fall over their lifetimes, and this orbital decay biases the readings); satellite drift (their orbits shift east-west a small amount causing an error); they errantly include stratosphere temperatures in their lower atmosphere readings; and they have incorrect temperature calibration on the satellites.

And it is very sensitive/dominated by El Nino conditions. I contend that small changes over the Pacific would hide any probable Covid-19 temperature signal.

...

All these factors regarding satellite data are well-known and nothing that invalidates the data, as corrections are made and the quality of the data is continously improved.

OK, if you don't like pure sat data like UAH6 or RSS, we can look at composite data like the CFSR reanalysis product instead. It also contains a load of sat data, but mixed with other data sources.
The latest version of CFSR, based on CFSv2, is described in this paper:
https://journals.ametsoc.org/doi/10.1175/JCLI-D-12-00823.1

Attached is a chart with CSFR temperatures since 2014, with moving averages.
You claim that there is some kind of yearly pattern regarding the temperature anomalies, from your previous post:
 
Quote
"1) There is a trend during the months of the year, with anomalies typically falling in the spring (March April and then rising in the summer. (see 2017 and 2018). "

Yes, anomalies are typically higher in the beginning of the year. But they aren't falling as early as in March/April, that seems to come somewhat later, in May/June for the last years, as seen in the chart.

What's totally clear, is that we still have a negative temperature anomaly signal to deal with for the first half of 2020, in spite of the expected positive anomaly signal due to reduced aerosols. (CFSR forecasts the temperature anomaly to drop further.)
2020 shapes up to look like the "coming out of ENSO year" 2016, but possibly with a Covid signal instead of the ENSO signal. Only that the signal has the wrong sign.

38
Consequences / Re: Temperature signals from Covid-19
« on: June 04, 2020, 12:36:15 PM »
Hefaistos, I dont really have any problem with you starting this thread. It is worthwhile to explore the relationship between global temperatures and recent downturn in economic activity (because of Covid-19).

But I do have a difficulty using UAH as a metric. I know many people have reservations about Roy Spencer's data series and methods employed to generate it. There have already been several revisions/adjustments since 1979 so I find it difficult to compare say 1980 anomalies with those of UAH ver 6.0.
...

Neil, if you don't like the satellite that feeds the UAH6 with data for this reason, you can choose another satellite.
There is e.g. RSS MSU, also available at WoodForTrees, which afaik is from a different satellite(s). Here's a plot of the both together. As you can see, the data are practically identical, except for a baseline shift. (UAH6 is the lower one, I shifted it up by 0.3 to bring them to the same level).

These satellite data are the highest quality temperature data we can get, and I think it further ads to their value that they are not measured only at 2 m surface, but for the entire LT. They give a more accurate manifestation of the thermal energy in the atmosphere, than the surface-only data does.

Here is a nice and very informative wikipedia article comparing the different satellite data, and also discussing how they relate to surface data.

https://en.wikipedia.org/wiki/Microwave_Sounding_Unit_temperature_measurements

39
Consequences / Re: World of 2100
« on: June 04, 2020, 09:50:54 AM »
I think the technological singularity is within reach (that some AI passes the Turing test in a general setting)

It's more likely that some sort of AI will be on top in 2100, than the Chinese (as Freegrass suggested)

40
Consequences / Re: World of 2100
« on: June 04, 2020, 08:22:45 AM »

Impossible to know with the emergence of AI and Quantum computing...
But China will be on top I guess.

Technological singularity 2029
Full singularity 2045

https://futurism.com/kurzweil-claims-that-the-singularity-will-happen-by-2045

41
Consequences / Re: Temperature signals from Covid-19
« on: June 04, 2020, 07:27:35 AM »
When you start a new thread the opening post matters.  It's 2020 & you seem surprised that CO2 concentration is up even though emissions are down.  CO2 ACCUMULATES IN THE ATMOSPHERE! This is AGW 101. 

If you read my first post, you also might have noticed that there was a chart attached? In that chart there was a blue line, showing the rising trend of CO2 level in the atmosphere. Thanks, but I knew that :) My point was just to emphasize that we're seeing a drop in LT temperatures in spite of the increased level of CO2. Forcing is up, LT temperatures down.

Quote
The current warming rate is roughly +0.20°C per decade.  That's an alarming rate but on a monthly basis worth: +0.0017°C per month.  Global mean temps monthly variability (largely ENSO) is ~0.50°C.  That's 2 orders of magnitude higher than the background warming rate!

On the background of a trend of rising temperatures, we have a negative temperature anomaly signal in the satellite data since about February (different satellites show the same). Part of that might be a seasonal drop, although i wouldn't bet on it, as there is no stable pattern here if you look at temperature data from year to year.

Quote
We already have several threads on aerosols as well as CO2 concentration, CO2 emissions, CO2 equivalent and a thread on tracking global mean temps.

I know that this forum has quite a few threads.
But this is the thread about the eventual temperature signals from Covid-19.
This is something totally unique happening in the world, with a recession/depression hitting in no time at all, and massive drops in the aerosols, especially in the NH.
We're still looking for temperatures to rise, but what if they continue to fall? Might it be due to the economic and environmental effects of C19?

42
The rest / Re: Free Access to Journal Articles
« on: June 03, 2020, 11:52:39 PM »
Currently working:

https://sci-hub.tw

ht to Nanning

43
Another recent paper highly critical of the unbelievably high ECS values of many CMIP6 models is "Past warming trend constrains future warming in CMIP6 models" by Tokarska et al in Science Advances, March 2020

"Our results show that most models with high climate sensitivity
(outside the AR5 likely range) or high transient response overestimate
recent warming trends
, with differences that cannot be
explained by internal variability. This probably leads to future
warming projections being biased high
. Thus, the raw ensemble
median and spread of future warming in CMIP6 (and therefore
most other variables that scale to first order with global mean temperature)
are not representative of a distribution constrained by
observed trends
,"

DOI: 10.1126/sciadv.aaz9549
Open access.

Seems relevant to ask, have these CMIP models with unbelievably high ECS values got their fundamental physics reg. clouds and water vapor right?

44
Consequences / Re: Temperature signals from Covid-19
« on: June 01, 2020, 10:35:38 AM »
Come on guys the CO2 impact from COVID-19 & the impact on global temperatures is so minuscule it's noise at best.  The fact that you think will be able to track it month-by-month global mean temps affects is silly.

You realize that CO2 concentration growth year-over-year is responsible for an additional radiative forcing of like ~0.03 W/M².  Estimates have 2020 *annual* emissions down 7%.  That's doesn't even account for all anthropogenic CO2: land use changes, etc..  Regardless, that 7% drop in emissions due to COVID-19 is a drop in radiative forcing of  ~0.00021 W/M².

Also what's the obsession with satellite data?  Surface temperature data is way more accurate for global mean estimates.  You realize that satellite data goes through massive algorithms & corrections because of changes in orbits & time of day passes.

The focus should be on aerosols not CO2 concentration changes when talking about COVID-19.

Hi Wolfpack.
The title of this thread is "Temperature signals from C19". I of course don't expect any change in CO2 at all because of C19.
I said in the first post that I expect temperatures to rise, because of strongly diminished aerosols, and a continued increase in CO2. Instead they have fallen strongly, at least the sat. data.

I don't agree with you that surface temperature data is more accurate. The satellite data that measures temperatures in all of the LT give a richer measure than surface only data.

All temperature datasets we have go through algorithms/processing. You want to claim that the high precision, finely tuned and continously evaluated satellite data is somehow giving us the wrong temperatures? Something wrong in the algos?

Then please give a reference to that claim!! Because it would be sensational if it was true.
Or at least maybe you would care to present a hypothesis, what causes the satellite data to be faulty!

45
Kate Marvel has spent most of her career studying cloud feedback (which has proven to be key w.r.t. the high values of ECS projected by the high-end CMIP6 model projections) and in the linked opinion piece she acknowledges a good amount of uncertainty about projections of future climate change; which from a risk point of view is not good:

Title: "Global Warming: How Hot, Exactly, Is it Going to Get?"

https://blogs.scientificamerican.com/hot-planet/global-warming-how-hot-exactly-is-it-going-to-get/

Extract: "All climate models simulate a changing planet in response to a changing temperature. And, increasingly, we know why they disagree on that final warming. In the climate models that warm more, low, thick clouds appear to be changing in ways that reduce their sun-blocking power. In the models that warm less, these changes are smaller.

So scientists have devoted their time to measuring clouds, understanding them, and figuring out how to represent them in climate models. This work has paid off: the range of uncertainty is now changing. Unfortunately, it’s increased. Climate models that use more modern techniques to simulate clouds are now projecting more warming: five or six degrees Celsius in response to a doubling of carbon dioxide. To put those numbers in context, four and a half degrees is the difference between now and the last Ice Age.

But the past is not the future, and we have good reason to believe that there are no analogues for the future into which we are hurtling."

She is quite skeptical to the unbelievably high ECS values of the majority of CMIP6 models, though:
"I find these high numbers hard to believe, but as a scientist it’s my job to find things hard to believe. My skepticism is rooted in clues from the planet’s past. At the height of the last Ice Age, temperatures were cooler and carbon dioxide levels lower. It’s hard to reconcile these measurements with extremely high climate sensitivities."

46
...
This conclusion raises the issue that the unbelievably high ECS models are manipulated in a false way as a means to achieve a goal, namely the high ECS value.
...

Your statement indicates that you are accusing many CMIP6 climate scientists of intentionally manipulating their models to achieve false projections.

Such a conspiracy theory is not worth addressing here.

Yes, intentional or not, but that's my interpretation of what Zelinka et al says in "Causes of Higher Climate Sensitivity in CMIP6 Models" in Geophysical Research Letters.

I repeat the quote from the papers' Conclusions (my added italics/bold): "While some high ECS models closely match the observed record (e.g., Gettelman et al., 2019), others do not (e.g., Golaz et al., 2019). Do the former models achieve their results via unreasonably large negative aerosol forcings and/or substantial pattern effects (Kiehl, 2007; Stevens et al., 2016)? It is worth noting that cloud feedbacks are enhanced in CMIP6 primarily over the Southern Ocean, a region of efficient ocean heat uptake (Armour et al., 2016). This implies that the enhanced surface SW heating is less likely to manifest as surface warming during transient climate change than if the heating were focused elsewhere (Frey et al., 2017). This cloud feedback pattern could make it easier for high ECS models to simulate the observed surface temperature record without requiring a large negative aerosol radiative forcing or large historical era pattern effects."

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019GL085782

47

To state the obvious, the findings of this research implies that ECS is currently about 5.5C, ...

There is nothing obvious about those unbelievably high ECS values of the current generation of GCM's, the CMIP6 models.

The following highly critical  paper evaluates the differences between CMIP5 and CMIP6 model generations.
From the abstract: "...Here we show that the closely related effective climate sensitivity has increased substantially in Coupled Model Intercomparison Project phase 6 (CMIP6), with values spanning 1.8–5.6 K across 27 GCMs and exceeding 4.5 K in 10 of them. This (statistically insignificant) increase is primarily due to stronger positive cloud feedbacks from decreasing extratropical low cloud coverage and albedo. Both of these are tied to the physical representation of clouds which in CMIP6 models lead to weaker responses of extratropical low cloud cover and water content to unforced variations in surface temperature. "

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019GL085782

Attached figure from the same paper shows that almost all differences between the two model generations are attributable to the way that the models are handling clouds and water vapor. Low cloud water content and coverage decrease more strongly with global warming, causing enhanced planetary absorption of sunlight—an amplifying feedback that ultimately results in more warming.

The factual development is on the other hand that global cloud cover has been slowly increasing over the last decades, not decreasing.

We can't even say for sure that clouds are a positive feedback. (Most of the 27 evaluated models have a +ve feedbakc , but 2 have a -ve feedback). The basic physics says that clouds are a negative feedback. NOAA says:   "The cloud radiative effect (CRE) on the Earth’s present-day radiation budget can be inferred from satellite data by comparing upwelling radiation in cloudy and non-cloudy regions. The figure at right shows that cloud conditions exert a global and annual SW CRE of approximately -50 W/m2 and a mean LW CRE of approximate 30 W/m2. The net global mean CRE is approximately -20 W/m2 implying a strong net cooling effect of clouds on the current climate. Given the large magnitude of SW and LW CRE, clouds have the potential to cause significant climate feedback."
The issue of cloud feedback is much more complex than that, but the starting point is actually a -ve feedback.

From the papers' Conclusions: "While some high ECS models closely match the observed record (e.g., Gettelman et al., 2019), others do not (e.g., Golaz et al., 2019). Do the former models achieve their results via unreasonably large negative aerosol forcings and/or substantial pattern effects (Kiehl, 2007; Stevens et al., 2016)? It is worth noting that cloud feedbacks are enhanced in CMIP6 primarily over the Southern Ocean, a region of efficient ocean heat uptake (Armour et al., 2016). This implies that the enhanced surface SW heating is less likely to manifest as surface warming during transient climate change than if the heating were focused elsewhere (Frey et al., 2017). This cloud feedback pattern could make it easier for high ECS models to simulate the observed surface temperature record without requiring a large negative aerosol radiative forcing or large historical era pattern effects."

This conclusion raises the issue that the unbelievably high ECS models are manipulated in a false way as a means to achieve a goal, namely the high ECS value.
What's obvious, is that these latest "bottom up" models still are unable to properly handle the feedback of clouds and water vapor.

https://www.gfdl.noaa.gov/cloud-radiative-effect/

Figure byline: "Figure S7. Contributions of forcing and feedbacks to ECS in each model and for the multi-
model means. Contributions from the tropical and extratropical portion of the feedback are shown
in light and dark shading, respectively. Black dots indicate the ECS in each model, while upward
and downward pointing triangles indicate contributions from non-cloud and cloud feedbacks,
respectively. Numbers printed next to the multi-model mean bars indicate the cumulative sum
of each plotted component. Numerical values are not printed next to residual, extratropical
forcing, and tropical albedo terms for clarity. Models within each collection are ordered by ECS."

48
Arctic sea ice / Re: Arctic energy balance
« on: May 29, 2020, 02:34:52 PM »
Some valid input might be gathered from this paper:
"Trends in the CERES Dataset, 2000–13: The Effects of Sea Ice and Jet Shifts and Comparison to Climate Models"
Dennis L. Hartmann and Paulo Ceppi

From the Abstract

The Clouds and the Earth’s Radiant Energy System (CERES) observations of global top-of-atmosphere radiative energy fluxes for the period March 2000–February 2013 are examined for robust trends and variability. The trend in Arctic ice is clearly evident in the time series of reflected shortwave radiation, which closely follows the record of ice extent. The data indicate that, for every 106 km2 decrease in September sea ice extent, annual-mean absorbed solar radiation averaged over 75°–90°N increases by 2.5 W m−2, or about 6 W m−2 between 2000 and 2012.  ...."


Full paper:
https://journals.ametsoc.org/doi/10.1175/JCLI-D-13-00411.1

49
Arctic sea ice / Re: Arctic energy balance
« on: May 29, 2020, 02:15:34 PM »
Estimations of energy input/output. Many factors affect the ice. It's important to determine if the factor deserves attention. Often simple calculations can help understand the order of magnitude.


Albedo would be such a factor.

Figure byline: "Figure S6. All-sky albedo as a function of latitude for 5-year averages during the observational period and for the estimated change under a transition to ice-free conditions from a 1979 baseline state. The average value over the Arctic Ocean during 1979-1983 is shown as a grey circle on the right side of the gure, with Arctic Ocean spatial averages associated with the 3 curves also included for reference."

From "Radiative Heating of an Ice‐Free Arctic Ocean", Kristina Pistone,Ian Eisenman, Veerabhadran Ramanathan
First published: 20 June 2019
https://doi.org/10.1029/2019GL082914

50
Consequences / Re: Temperature signals from Covid-19
« on: May 27, 2020, 09:07:15 AM »
NH arctic amplification shows up during fall to winter months and the current season looks similar to last year. If we are expecting aerosols to have a large impact it doesn’t seem obvious in the temperatures. It is nice having clear skies and so little air traffic but the jury is still out on aerosol cooling effects.

Bruce, there is no factual evidence of an increase in Arctic amplification.
Yes, there is a deviation from trend, but for March and April this deviation is similar to previous years. More like a parallell offset from the baseline.

Here's a graph with the monthly plot for the latest years, and for the first 4 months of 2020, compared to the reference period.

I can't see how this could explain the big drop in temperatures during the  C19 lockdown period from March 2020.

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