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Climate Change and Extreme Summer Weather Events – The Future is still in Our Hands


Summer 2018 saw an unprecedented spate of extreme weather events, from the floods in Japan, to the record heat waves across North America, Europe and Asia, to wildfires that threatened Greece and even parts of the Arctic. The heat and drought in the western U.S. culminated in the worst California wildfire on record. This is the face of climate change, I commented at the time.

Some of the connections with climate change here are pretty straightforward. One of the simplest relationships in all of atmospheric science tells us that the atmosphere holds exponentially more moisture as temperatures increase. Increased moisture means potentially for greater amounts of rainfall in short periods of time, i.e. worse floods. The same thermodynamic relationship, ironically, also explains why soils evaporate exponentially more moisture as ground temperatures increase, favoring more extreme drought in many regions. Summer heat waves increase in frequency and intensity with even modest (e.g. the observed roughly 2F) overall warming owing to the behavior of the positive “tail” of the bell curve when you shift the center of the curve even a small amount. Combine extreme heat and drought and you get more massive, faster-spreading wildfires. It’s not rocket science.

But there is more to the story. Because what made these events so devastating was not just the extreme nature of the meteorological episodes but their persistence. When a low-pressure center stalls and lingers over the same location for days at a time, you get record accumulation of rainfall and unprecedented flooding. That’s what happened with Hurricane Harvey last year and Hurricane Florence this year. It is also what happened with the floods in Japan earlier this summer and the record summer rainfall we experienced this summer here in Pennsylvania. Conversely, when a high-pressure center stalls over the same location, as happened in California, Europe, Asia and even up into the European Arctic this past summer, you get record heat, drought and wildfires.

Scientists such as Jennifer Francis have linked climate change to an increase in extreme weather events, especially during the winter season when the jet stream and “polar vortex” are relatively strong and energetic. The northern hemisphere jet stream owes its existence to the steep contrast in temperature in the middle latitudes (centered around 45N) between the warm equator and the cold Arctic. Since the Arctic is warming faster than the rest of the planet due to the melting of ice and other factors that amplify polar warming, that contrast is decreasing and the jet stream is getting slower. Just like a river traveling over gently sloping territory tends to exhibit wide meanders as it snakes its way toward the ocean, so too do the eastward-migrating wiggles in the jet stream (known as Rossby waves) tend to get larger in amplitude when the temperature contrast decreases. The larger the wiggles in the jet stream the more extreme the weather, with the peaks corresponding to high pressure at the surface and the troughs low pressure at the surface. The slower the jet stream, the longer these extremes in weather linger in the same locations, giving us more persistent weather extremes.

Something else happens in addition during summer, when the poleward temperature contrast is especially weak. The atmosphere can behave like a “wave guide”, trapping the shorter wavelength Rossby waves (those that that can fit 6 to 8 full wavelengths in a complete circuit around the Northern Hemisphere) to a relatively narrow range of latitudes centered in the mid-latitudes, preventing them from radiating energy away toward lower and higher latitudes. That allows the generally weak disturbances in this wavelength range to intensify through the physical process of resonance, yielding very large peaks and troughs at the sub-continental scale, i.e. unusually extreme regional weather anomalies. The phenomenon is known as Quasi-Resonant Amplification or “QRA”, and (see Figure below).

Many of the most damaging extreme summer weather events in recent decades have been associated with QRA, including the 2003 European heatwave, the 2010 Russian heatwave and wildfires and Pakistan floods (see below), and the 2011 Texas/Oklahoma droughts. More recent examples include the 2013 European floods, the 2015 California wildfires, the 2016 Alberta wildfires and, indeed, the unprecedented array of extreme summer weather events we witnessed this past summer.

The increase in the frequency of these events over time is seen to coincide with an index of Arctic amplification (the difference between warming in the Arctic and the rest of the Northern Hemisphere), suggestive of a connection (see Figure below).

Last year we (me and a team of collaborators including RealClimate colleague Stefan Rahmstorf) published an article in the Nature journal Scientific Reports demonstrating that the same pattern of amplified Arctic warming (“Arctic Amplification”) that is slowing down the jet stream is indeed also increasing the frequency of QRA episodes. That means regional weather extremes that persist longer during summer when the jet stream is already at its weakest. Based on an analysis of climate observations and historical climate simulations, we concluded that the “signal” of human influence on QRA has likely emerged from the “noise” of natural variability over the past decade and a half. In summer 2018, I would argue, that signal was no longer subtle. It played out in real time on our television screens and newspaper headlines in the form of an unprecedented hemisphere-wide pattern of extreme floods, droughts, heat waves and wildfires.

In a follow-up article just published in the AAAS journal Science Advances, we look at future projections of QRA using state-of-the-art climate model simulations. It is important to note that that one cannot directly analyze QRA behavior in a climate model simulation for technical reasons. Most climate models are run at grid resolutions of a degree in latitude or more. The physics that characterizes QRA behavior of Rossby Waves faces a stiff challenge when it comes to climate models because it involves the second mathematical derivative of the jet stream wind with respect to latitude. Errors increase dramatically when you calculate a numerical first derivative from gridded fields and even more so when you calculate a second derivative. Our calculations show that the critical term mentioned above suffers from an average climate model error of more than 300% relative to observations. By contrast, the average error of the models is less than a percent when it comes to latitudinal temperature averages and still only about 30% when it comes to the latitudinal derivative of temperature.

That last quantity is especially relevant because QRA events have been shown to have a well-defined signature in terms of the latitudinal variation in temperature in the lower atmosphere. Through a well-established meteorological relationship known as the thermal wind, the magnitude of the jet stream winds is in fact largely determined by the average of that quantity over the lower atmosphere. And as we have seen above, this quantity is well captured by the models (in large part because the change in temperature with latitude and how it responds to increasing greenhouse gas concentrations depends on physics that are well understood and well represented by the climate models).

These findings, incidentally have broader implications. First of all, climate model-based studies used to assess the degree to which current extreme weather events can be attributed to climate change are likely underestimating the climate change influence. One model-based study for example suggested that climate change only doubled the likelihood of the extreme European heat wave this summer. As I commented at the time, that estimate is likely too low for it doesn’t account for the role that we happen to know, in this case, that QRA played in that event. Similarly, climate models used to project future changes in extreme weather behavior likely underestimate the impact that future climate changes could have on the incidence of persistent summer weather extremes like those we witnessed this past summer.

So what does our study have to say about the future? We find that the incidence of QRA events would likely continue to increase at the same rate it has in recent decades if we continue to simply add carbon dioxide to the atmosphere. But there’s a catch: The future emissions scenarios used in making future climate projections must also account for factors other than greenhouse gases. Historically, for example, the use of old coal technology that predates the clean air acts produced sulphur dioxide gas which escapes into the atmosphere where it reacts with other atmospheric constituents to form what are known as aerosols.

These aerosols caused acid rain and other environmental problems in the U.S. before factories in the 1970s were required to install “scrubbers” to remove the sulphur dioxide before it leaves factory smokestacks. These aerosols also reflect incoming sunlight and so have a cooling effect on the surface in the industrial middle-latitudes where they are produced. Some countries, like China, are still engaged in the older, dirtier-form of coal burning. If we continue with business-as-usual burning of fossil fuels, but countries like China transition to more modern “cleaner” coal burning to avoid air pollution problems, we are likely to see a substantial drop in aerosols over the next half century. Such an assumption is made in the Intergovernmental Panel on Climate Change (IPCC)’s “RCP 8.5” scenario—basically, a “business as usual” future emissions scenario which results in more than a tripling of carbon dioxide concentrations relative to pre-industrial levels (280 parts per million) and roughly 4-5C (7-9F) of planetary warming by the end of the century.

As a result, the projected disappearance of cooling aerosols in the decades ahead produces an especially large amount of warming in middle-latitudes in summer (when there is the most incoming sunlight to begin with, and, thus, the most sunlight to reflect back to space). Averaged across the various IPCC climate models there is even more warming in mid-latitudes than in the Arctic—in other words, the opposite of Arctic Amplification i.e. Arctic De-amplification (see Figure below). Later in the century after the aerosols disappear greenhouse warming once again dominates and we again see an increase in QRA events.

So, is there any hope to avoid future summers like the summer of 2018? Probably not. But in the scenario where we rapidly move away from fossil fuels and stabilize greenhouse gas concentrations below 450 parts per million, giving us a roughly 50% chance of averting 2C/3.6F planetary warming (the so-called “RCP 2.6” IPCC scenario) we find that the frequency of QRA events remains roughly constant at current levels.

While we will presumably have to contend with many more summers like 2018 in the future, we could likely prevent any further increase in persistent summer weather extremes. In other words, the future is still very much in our hands when it comes to dangerous and damaging summer weather extremes. It’s simply a matter of our willpower to transition quickly from fossil fuels to renewable energy.

54 Responses to “Climate Change and Extreme Summer Weather Events – The Future is still in Our Hands”

  1. 1
    Nic Lewis says:

    You say “The same thermodynamic relationship, ironically, also explains why soils evaporate exponentially more moisture as ground temperatures increase, favoring more extreme drought in many regions.”

    Isn’t the increase in overall evaporation with surface temperature limited to far below the CC exponential rate of increase due to energetic constraints related to how much extra heat the atmosphere can lose as temperature increases?

    “While we will presumably have to contend with many more summers like 2018 in the future”

    I know this may not apply to many countries, but in the UK I’ve found most people regard 2018 as the best summer for several decades!

  2. 2
    Brian Dodge says:

    Does the energy being blocked by QRA events from being transported poleward have effects that persist into the next seasonal cycle? Would these effects create positive feedbacks, making summertime extreme events more likely in the year following a year like 2018?
    Or does the trapped equatorial energy in a QRA year persist to make the Temperature gradient higher, poleward energy transport higher, and QRA less likely the following year? Are the 2007 and 2012 negative NH sea ice transients only coincidentally correlated with QRA events in 2006 and 2011?
    Does the trapped energy from QRA raise temperature and exponentially increase water vapor feedback in the Tropics?
    How do QRA dynamics interact with the ENSO sloshing of energy in the Pacific Ocean?

  3. 3
    Carrie says:

    So if science and maths can produce this information for China out to 2050 in regard to meeting the 1.5C Paris Treaty goals:

    2. Objectives and requirements for nuclear power in China to realize the global 1.5 °C temperature rise target

    Power sector plays a very important role in the context of the 1.5 °C target. Model analyses show that by 2050, the power generation would have increased to over 14,000 TW h, with per capita 10,320 kW h in China, and 80% of power will be generated with renewable energy sources and nuclear energy (Jiang et al., 2018). […]

    Moreover, the share of coal power and gas power will reach 5.3% and 7.1% by 2050, respectively, which in 2015 was 71% and 3%, respectively (Jiang et al., 2018). The data show that the power mix will change, which means that powerful policies need to be immediately made to achieve that target.

    Furthermore, to achieve this target, the installed capacity of various power generation modes needs to be significantly changed.
    https://www.sciencedirect.com/science/article/pii/S1674927817301181

    Then why is that the IPCC 1.5C Report cannot take the very same approach globally and present some real world QUANTITIES where anyone in any nation in any language could understand their meaning especially grasping the MASS SCALE of the changes required to meet those UNFCCC Goals?

    It would not very difficult to create a software program to then produce “estimates” of how either individual nations or regional areas would need / must look like 30 years from now regarding total fossil fuel use and the growth in alternatives energy sources.

    The urgency for immediate actions would become self-evident to most people and even to the media and politicians.

    It surely also give a powerful indication to all those people and retirement funds who are the major investors in coal mining, oil and gas wells and fossil fuel trading of when and why their portfolios in those companies will all but disappear down the toilet during the 2030s and beyond.

    eg global coal production in 2018 vs coal production in 2030, 2040 and 2050. These numbers are not difficult to calculate when creating a Net Zero Carbon Emissions Scenario using today’s existing scientific know how and energy data.

    It’s a lot easier to produce than doing climate science. The Politcians refuse to get their government to do it, the governments refuse to let the UNFCCC do it, therefore the climate scientists producing IPCC 1.5C Reports and others had better do it and get it published as Peer-Reviewed Science papers.

    No one else credible enough is going to do it for you. Please enough “confusing rhetoric” and “motherhood statements”. Some quantified truths can’t hurt.

  4. 4
    Tony Weddle says:

    When you mention that “stabilizing greenhouse gas concentrations below 450ppm” to give us half a hope of avoiding 2C, are you referring to CO2e? I seem to recall your saying, in a SciAm or HuffPost article, that we’d need to stabilise the proportion to about 405ppm CO2 to have a chance, so how does that estimate fit with this new one. Perhaps it’s CO2e?

    By the way, saying it’s “very much in our hands” presupposes that humans can, in general, stop exhibiting its characteristic species behaviour quickly enough to make a difference. Is there any science behind that belief?

  5. 5

    Mike, thanks for a succinct wrap-up on this topic. It updates and synthesizes a number of things that I hadn’t seen brought together previously.

    Question: The paragraph beginning “scientists like Jennifer Francis…” is a nice summation of the concept of the SIE-atmospheric circulation link. Originally, the idea was met with some skepticism, including by (IIRC) Kevin Trenberth, who stressed the lack of a well-developed physical mechanism to explain the putative linkage between either Arctic SIE (as, IIRC, originally proposed) or Arctic temperature (as described here) and the slowing of the jet stream. How would you characterize the current state of play in this debate? Is the objection being met, and if so, to what extent are critics accepting the physical mechanism(s) being proposed?

    Or, put differently, to what extent is the analogic presentation you present (“Just like a river traveling over gently sloping territory…”) conjectural, or demonstrated?

    Brian Dodge, #2–

    Does the energy being blocked by QRA events from being transported poleward have effects that persist into the next seasonal cycle?

    That’s an interesting question in the light of the 2018 summer melt season. We came into it with very low extent–record or near-record low, in fact (at various times it was one or the other). Then we had a relatively modest summer melt, leading to a minimum that was in the area of 6th-lowest, depending on the exact metric chosen. Weather is always a huge factor in how the melt season plays out, but it’s pretty easy conceptually to connect a slow melt to a decrease in heat advected into the Arctic.

    If that’s the case–and of course I’m speculating–then more QRAs might mean a slowing of sea ice loss, and a lengthening of the time scale over which the associated feedbacks worsen. I’m guessing such an effect would not be very large, though, so if it’s any sort of silver lining at all, it wouldn’t be one to get hugely excited about.

    And, speaking of sea ice, it’s currently 3rd-lowest for this date, per the ADS (formerly JAXA) data, which now has so many names attached to it that I’m not sure what it’s actually supposed to be called these days.

    https://ads.nipr.ac.jp/vishop/#/extent/&time=2018-11-01%2000:00:00

  6. 6
    nigelj says:

    Carrie @3 suggests the IPCC dont have a precise quantified country by country plan on renewable energy and mix of electricity generation, and suggests if they wont do it climate scientists should.

    Yes good comment, but already done to a large extent, at least for electricity generation. Mark Jacobson has done a comprehensive and highly detailed study on renewable electricity generation, a country by country plan. Its a properly published study. Hes not a climate scientist and its not really a job that has to be done by a climate scientist, but he has a lot of environmental engineering expertise from memory.

    Jacobsons latest work:

    https://cleantechnica.com/2018/02/08/new-jacobson-study-draws-road-map-100-renewable-energy/

    http://thesolutionsproject.org/why-clean-energy/

    https://www.worldgbc.org/news-media/100-renewable-energy-all-worldwide-possible-qa-with-mark-z-jacobson

    I think the problem is this information is out there, but gets lost / buried in all the political and media noise and rubbish.

  7. 7

    Clausius-Clapeyron would give 11% increase in saturation vapour pressure per degree C warming, but it requires energy to evaporate. The GCMs show an increase of evaporation rate on average of only about 2% per degree C, and even this (smaller) extra energy dissipation rate as latent heat is at the expense of a reduction in sensible heat dissipation. The sum of latent and sensible heat fluxes remains virtually unchanged and this makes sense as the greenhouse effect delivers no more ability to do work.

  8. 8
    Mike Roberts says:

    I know this may not apply to many countries, but in the UK I’ve found most people regard 2018 as the best summer for several decades!

    Completely unecessary remark from Nic Lewis, in the opening comment, but one that we’ve come to expect from sceptics, who totally miss the point.

  9. 9
    patrick says:

    Thank you very much for this post and for your timely work on emerging signals and notable and extreme weather events. There’s an extensive post on the Weather Underground’s “Cat 6” feature (Jeff Masters, Nov. 2) recognizing and citing your work, starting with this post.

    “During the summer of 2018, the future of climate change became the present. …”

    https://www.wunderground.com/cat6/Climate-Change-Likely-Increase-Frequency-Extreme-Summer-Weather-Stuck-Jet-Stream-Patterns

  10. 10
    Hank Roberts says:

    https://communemag.com/dystopias-now/

    Kim Stanley Robinson

    ======================
    It’s important to remember that utopia and dystopia aren’t the only terms here. You need to use the Greimas rectangle and see that utopia has an opposite, dystopia, and also a contrary, the anti-utopia. For every concept there is both a not-concept and an anti-concept. So utopia is the idea that the political order could be run better. Dystopia is the not, being the idea that the political order could get worse. Anti-utopias are the anti, saying that the idea of utopia itself is wrong and bad, and that any attempt to try to make things better is sure to wind up making things worse, creating an intended or unintended totalitarian state, or some other such political disaster. 1984 and Brave New World are frequently cited examples of these positions. In 1984 the government is actively trying to make citizens miserable; in Brave New World, the government was first trying to make its citizens happy, but this backfired. As Jameson points out, it is important to oppose political attacks on the idea of utopia, as these are usually reactionary statements on the behalf of the currently powerful, those who enjoy a poorly-hidden utopia-for-the-few alongside a dystopia-for-the-many. This observation provides the fourth term of the Greimas rectangle, often mysterious, but in this case perfectly clear: one must be anti-anti-utopian….
    ====================================

  11. 11
    David Young says:

    Well “simple physics” can tell us many things including many that are speculative at best. One could argue for example that Arctic amplification decreases the pole to equator temperature gradient and thus extreme weather in mid latitudes. And indeed US tornado activity does seem to decreasing over the global warming period. But I would rate this argument rather weak because it lacks quantification.

    The problem with most of what is said above is that the data is noisy and the models questionable for reconciling often opposing effects.

  12. 12
    Michael Roderick says:

    I did not really understand the start of this argument in the second paragraph.

    The saturated vapour pressure of water increases with Temperature at around 7% per degC of warming as suggested. Climate models also project the relative humidity to remain roughly constant so the vapour content of the air increases with warming as stated.

    However, the situation with evaporation is more complex than this simple relationship. Evaporation is a flux and depends on the spatial difference between the vapour pressure at the surface and in the adjacent air as well as a transfer coefficient. This means that evaporation does not necessarily follow the increase in atmopheric moisture at 7% per degC. As noted in post 7 by my colleague, Graham Farquhar, climate models project global evaporation to increase a lot slower at around 2% per degC. Nearly all of the increase in global evaporation is from the ocean. In fact, over land, the same climate models project virtually no change in evaporation. Part of the reason is that over land, elevated CO2 increases the water use efficiency of plant photosynthesis and plant water use is projected to remain more or less unchanged.

  13. 13
    Mr. Know It All says:

    Good article.
    I think it would be good to see a simple drawing showing what a normal Jet looks like without QRA, and what the Jet looks like with QRA; over say North America and/or Europe.
    Also, the graphs at the bottom are a little fuzzy – got a link to better ones?

    Agree with 12 Michael above on the ~7% increase in moisture per 2C warming. From the psychrometric chart at Sugar Engineers, you get the following temperature and humidity ratios at saturation; temps in deg F, humidity in pounds of moisture per pound of dry air, all at 100% RH (saturation), in steps of 2F (1.11C).
    Source: https://sugartech.co.za/psychro/

    78 F, 0.0207804 lb H2O/lb dry air
    80 F, 0.0222416 lb/lb delta = 7.03% increase in moisture over 78F
    82 F, 0.0237957 lb/lb delta = 6.98% over 80 F
    84 F, 0.0254482 lb/lb delta = 6.94% over 82 F
    86 F, 0.0272052 lb/lb delta = 6.90% over 84 F
    88 F, 0.0290727 lb/lb delta = 6.86% over 86 D
    Total delta moisture content of saturated air from 78F to 88F = 39.9%
    The specific volume (cubic feet per pound) goes from 14 at 78F to 14.44 at 88F, an increase of only 3.1%. Enthalpy goes from 41.5 BTU/lb at 78F to 53.1 at 88F, an increase of 28%.

    I’ll bet the USDA has done research into soil evaporation versus increasing temps, perhaps with varying CO2 concentrations.

  14. 14
    Priscilla Gilman says:

    Thanks. Informative and much appreciated.

  15. 15
    Carrie says:

    Science kind of works like : If this, then that.

    To arrive at Net Zero GHG emissions as “that” must entail laying out a reverse timeline of this and this and this and this and this recurring. And that is precisely what climate scientists, and the IPCC and the UNFCCC are responsible for quantifying scientifically. The how is someone else’s problem but the WHAT and the WHEN is 100% on the heads of Climate Scientists like Mann and Schmidt and anyone who touches an IPCC report.

    Denial of one’s collective responsibility – and who are more expert than the climate scientists collectively – does not absolve one of that moral responsibility to speak the truth in a way even an 8 year old could understand.

    But what happens when this “this” and that “this” gets relegated out of the “scientific equations” that arrive at “then that”?

    https://www.youtube.com/watch?v=T3Kx7MkKgVk

    aka science should never be allowed to operate in a vacuum disconnected from the whole of Life.

  16. 16
  17. 17

    KIA, #13–

    Confusing. You say you agree with #12 that the increase should slower the 7% per 2 C increase, then post a table that indicates a rate of increase that’s inconstant but close to 7% per 2 Fahrenheit degree step, which would obviously greater by a factor of 9/5. (And I see that the calculator offers SI units, too.) Appreciate your effort, but huh?

    Care to explain?

  18. 18

    #16, Hank–

    Good one.

    Yes, we’ve been ‘making dirt’ at home for years, and just got it going at our church, too–a surprisingly toilsome exercise. (Not the dirt-making; the organization/communication necessary to enable it–committees!)

  19. 19
    Mr. Know It All says:

    17 Kevin

    I looked into the increase in moisture content to verify that the statement in the article that warmer air holds exponentially more moisture was correct. “Exponentially more moisture” sounds like a lot – in fact post 12 is correct – it CAN hold ~7% more per deg C, as claimed in post 12. I picked temps I thought might occur in hurricanes – probably varies versus altitude.

    Post 12 said 7% per deg C, not per 2 deg C. 1 deg C is 1.8F, not far from the 2F that I used. I just prefer English units. I was just confirming that, according to the psychrometric chart, his 7% moisture increase per deg C temperature increase is correct (at saturation). He’s correct.

    The 2% is a different topic – evaporation. I say nothing about that except that the USDA has probably done experiments on it in their test chambers.

  20. 20
    Carrie says:

    The Future is still in Our Hands
    — mike @ 31 October 2018

    Erm, I’ll try another tack.

    So mike, given CO2ppm has been rising at +2 ppm for years and is not at or over 2.5 ppm growth and stil rising, and given the known future projections of FF use by professional global energy orgs out to 2040 show no real decrease in total FF Carbon energy use (putting aside all the other destructive drivers ongoing not being addressed) what YEAR will the Future be totally out of Our Hands (based on existing science based numbers we already know) to stop runaway non-stop irreversible for CENTURIES temp increases and climate change effects?

    2025?
    2030?
    2035?
    2040?
    other?

    I ask because that is the Scientific Based Knowledge people need to have in their heads and hands now, today.

  21. 21
    Carrie says:

    The Future is still in our hands? I am far from convinced it is.

    It’s far more logical, rational and evidence based to see our future is really in the hands of others far more powerful pathological than us – the average person on any street in any nation.

    Ken Livingstone is an English politician, he served as the Mayor of London between 2000 and 2008. He is also a former MP and a former member of the Labour Party.

    Brazil’s shift from progressive socialism to the far-right: Why did this happen?

    Bolsonaro has inherited a country in chaos, but the fear is that he is likely to make it worse and it will not just be the people of Brazil who will suffer but the whole world. It is his policy towards the environment and climate change that may become the biggest threat to life across the planet.

    If he goes ahead with an earlier plan to merge the ministries of agriculture and environment this would mean the interests of large agricultural companies would come before tackling climate change. Bolsonaro’s failure to accept the significance of climate change for our future may cost his grandchildren their lives by the end of the century.

    The president constantly attacks environmental agencies and has said he wishes to open up the Amazon rainforest with a massive hydroelectric programme of dams. Building dams in the Amazon will mean major new highways and much of the rainforest would be destroyed. He will support big business rather than preserving Brazil’s bio diversity and is committed to allowing the market to exploit Brazil’s vast natural resources. This will be devastating for the indigenous tribes still living in the Amazon region. Lula’s government stood strongly against demands to extract vast natural resources which would have had a devastating impact on climate change globally.

    I find it breathtaking to think that politicians in power, not just in Brazil, but in many places around the world, are prepared to take decisions which could see a mass extinction of humanity by the end of the century. Here in Britain, our government has just launched a new policy of extracting shale gas by fracking after having reduced spending on green energy projects. Norway is pressing ahead with oil exploitation and Germany is increasing its coal mining.

    Climate scientists across the world have warned that we have only twelve years left to reduce carbon emissions or see a huge surge in global warming. As things stand the widespread commitment of governments to limit the increase in global warming to 1.5 centigrade has no chance of being achieved because of their failure to act decisively and immediately.

    This year, thousands have lost their lives in weather-related disasters – storms, floods, hurricanes and forest fires. And all of this after just a one degree increase in temperature. Based on the timid policies to tackle climate change around the world we are clearly heading for at least a three degree increase and possibly even four or five degrees by the end of the century. Such an increase would see the collapse of human civilisation. And yet still we see all around the world governments actually making things worse with Trump undermining his Environmental Protection Agency, allowing industry to move into national parks and cutting pollution controls.

    It’s not just presidents like Bolsonaro who are putting the lives of his children and grandchildren at risk. The directors and chief executives of those companies continuing to pump more and more carbon into our atmosphere are also putting the lives of their own children and grandchildren at risk. I find it hard to believe that people can be so short-sighted and focused only on their own short term interests.

    https://www.rt.com/op-ed/443266-bolsonaro-right-left-brazil/

    Do any of you have “any pull” in Brazil, Saudi Arabia, Russia, the EU or the United States or in Voting at the UNFCCC? Please raise your hands!

    Nobody listens to me, maybe they will listen to you? Not!

  22. 22

    KIA, #17–

    Thanks for clarifying.

    I wonder if you could use some clarification on one point, however. You say:

    “Exponentially more moisture” sounds like a lot – in fact post 12 is correct – it CAN hold ~7% more per deg C, as claimed in post 12.

    You do realize that a ~7% increase per degree C of warming describes an exponential function, right? (The implication would be that for every 10-degree increase, water vapor would approximately double.)

  23. 23
    Mr. Know It All says:

    22 – Kevin

    Yes, I realize it – it’s obvious if you look at a psychrometric chart. I just wanted to quantify it and confirm the 7% figure. In my post 13, I calculated a 39.9% increase from 78 to 88 deg F.

    https://duckduckgo.com/?q=psychrometric+chart&t=h_&ia=images&iax=images

  24. 24
    Carrie me over the Mountain says:

    re 20/21 Carrie

    Climate scientists across the world have warned that we have only twelve years left to reduce carbon emissions or see a huge surge in global warming.

    Is that true? Which climate scientists have been saying that – do you know?

  25. 25

    Carrie, #21–

    Do any of you have “any pull” in Brazil, Saudi Arabia, Russia, the EU or the United States or in Voting at the UNFCCC? Please raise your hands!

    Nobody listens to me, maybe they will listen to you? Not!

    Well, thanks for the encouragement to keep on fighting to elect and support more climate-friendly leaders. I’m sure all the other activists and voters who contributed to the Democrats winning the total House vote by over 9% will agree with me that it’s terribly helpful of you.

  26. 26
    Carrie says:

    Democrats winning the total House vote by over 9% …. Huh? What? Will this ever stop? Nope. Not when there are so many amercians infesting forums and social media groups and news media comments boxes. The following look suspiciously like 4.5% to me.
    https://www.nytimes.com/interactive/2018/11/06/us/elections/results-house-elections.html

    So much for CNN Polling predicting a +13% to the Democratic party. And others +8% to +10%. Imagine actually expecting the news media to report real accurate news for a change? I think they’d all die of shock in the USA if that ever happened.

    The best thing about hanging out on chinese social media and forums? No Americans, except the sane rational ones. Second best is genuine dialogue, sharing and discussions absent all the haughty egos and wild ideologies.

    It’s like hanging out with Sgt Friday … just the facts ma’am.

  27. 27
    Carrie says:

    Oh I found which climate scientists said there was only a 12 year window left to implement rapid ghg reductions or shit hit fans forever.

    We have 12 years to limit climate change catastrophe, warns UN
    Urgent changes needed to cut risk of extreme heat, drought, floods and poverty, says IPCC
    https://www.theguardian.com/environment/2018/oct/08/global-warming-must-not-exceed-15c-warns-landmark-un-report

    Is the IPCC the extremists now? That’s a turn-about given how “conservative” their prognosis have been for so long.

    —–
    26 October 2017
    James Hansen
    I am writing Scientific Reticence and the Fate of Humanity in response to a query from the editor of Atmospheric Chemistry and Physics who handled
    Ice Melt, Sea Level Rise and Superstorms.1

    That paper, together with Young People’s Burden,2 makes the case for a low global warming target and the urgency of phasing out fossil fuel emissions. We argue that global warming of 2°C, or even 1.5°C, is dangerous, because these levels are far above Holocene temperatures and even warmer than best estimates for the Eemian, when sea level reached 6-9 meters (20-30 feet)
    higher than today.

    The editor noted that the Ice Melt paper was not highly cited or mainstream in climate impact discussions, and he was concerned because he thought it important for peer-reviewed extreme scenarios to be included in the upcoming IPCC AR6 cycle3. It might be added that both papers received VERY extensive peer review, all of which is available on the journals’ web sites.

    I responded that I was not surprised by the minimal of citations. A public affairs person handling media contacts for the Ice Melt paper reported that a leading science reporter decided not to write about the paper, and later declined to write about the Burden paper, because 5 of the 6 experts he
    contacted advised against reporting on it. If the top people in a field are negative and do not cite a paper, it is license for others to ignore it, perhaps even a warning to younger researchers.

    Scientific reticence may play a role here – I should be able to recognize that as well as anyone.

    However, my specific interpretation in terms of the famous elephant story is not as obvious. One would think that top experts in the field should have enough perspective to avoid that malady. Perhaps they even have a basis that should be presented for believing that a 2°C global warming
    limit provides a safe guardrail. It would be good to learn the basis for that in view of all the contrary evidence that we present in the two papers.
    http://www.columbia.edu/~jeh1/mailings/2017/20171026_ScientificReticence.pdf

    And so on it goes, where a year later and nothing much comes of this. Maybe Hansen has been deposited plonked into the Peter Wadhams basket by his peers.

  28. 28
    Mr. Know It All says:

    26 – Carrie

    In the James Hansen Paper, did he indicate how long it would take for the sea level to rise 20 or 30 feet? Are we talking 100 years? 1000 years?

    Not living in the USA, you may not realize that it is not possible to get an accurate political poll here. If you say you are voting R, or you support DJT, then you will be attacked, called horrible names, etc, by the fascist left, so a lot of people just lie or don’t answer polls. The fascist left does not believe in free speech – even on this website we’ve seen calls for capital punishment for those who express different opinions. However:

    It will please you to know that Stormy Daniels is working the polls.
    What? There is no election – it’s over.
    That is correct, but she is still working the poles.
    :)

  29. 29

    KIA 28: If you say you are voting R, or you support DJT, then you will be attacked, called horrible names, etc, by the fascist left

    BPL: Fascism is right-wing, not left-wing. No matter how many times you or Jacob Goldman say “Fascist Left,” it will still be a meaningless phrase.

    I’m also struck by the irony of you whining about being called horrible names, and then calling all your opponents fascists. Hypocrite much?

  30. 30
    Piotr says:

    Re: Michael Roderick (12):
    “over land, elevated CO2 increases the water use efficiency of plant photosynthesis and plant water use is projected to remain more or less unchanged.”

    I am not so sure:

    1. “increased water efficiency” applies only to the plants that are water limited.
    And it does not mean that they will be transpiring less water – they will just use
    the same amount water to get more CO2 and therefore more growth (CO2-fertilization) in the regular season.

    – add to this the INCREASED transpiration if their growing season getslonger – because they will transpire in times of the year when previously they didn’t (having shut down for the winter).

    2. As for plants that are not water-limited (say, rain forest) they transpire to maximize the uptake of dissolved nutrients from poor soil and/or for evaporative cooling. At least for the latter – there will more evaporation needed in the warmer world.

    Which means that the evaporation from land WILL increase – both from the longer growing season of the boreal froests and the need for increased evaporative cooling in rain forests.

    Well, unless your argument counts on Bolsonaro – if he follows his electoral promises of destroying Amazon rain forest – then there will be be less transpiration from whatever would cover the land after the destruction. But at the expense of massive increases in CO2 emissions (burning of biomass and increased erosion of the soils).

  31. 31
    Piotr says:

    Re: Graham Farquhar (7):” Clausius-Clapeyron would give 11% increase in saturation vapour pressure per degree C warming, but it requires energy to evaporate.The GCMs show an increase of evaporation rate on average of only about 2% per degree C”

    Graham, did I understand you right- warming atmosphere by 1C would make space to hold 11% more water vapour, but because evaporation requires energy – the real increase is only 2% per 1 deg. warming?

    If yes, then wouldn’t some of the extra energy from global warming be enough? I’ll show you my-back-of-the-envelope-calculations:

    – Current total mass of water vapour in atm: 13*10^18g
    – Enthalpy of vaporization at 20C – 44,200 J/mol=2456 J/g
    – Surface area of Earth =510 mln km2= 5.1*10^14 m2

    So an 11% increase in the water vapour per m2 of Earth would require: 0.11*13*10^18g *2456 J/g /5.1*10^14 m2 = 6.89*10^6 J/m2
    If spread over a month this comes to 2.6 W/m2. To put this into perspective – the current total anthropogenic effective radiative forcing over the Industrial Era is 2.3W/m2.

    Wouldn’t this suggest than the anthropogenic heating of Earth in a mere 5 weeks -would provide enough energy to evaporate enough water vapour to cause 11% increase in water vapour, corresponding to a 1C warming? And since the Earth temp is not going up by 1C per 5 weeks, then the energy required for evaporation is not the limiting factor here?
    Where have I gone wrong?

    Piotr

  32. 32
    Carrie says:

    28
    Mr. Know It All says:
    13 Nov 2018 at 11:19 PM

    26 – Carrie

    In the James Hansen Paper, did he indicate how long it would take for the sea level to rise 20 or 30 feet? Are we talking 100 years? 1000 years?

    —-

    In the abstract hansen covers the basics:
    https://www.atmos-chem-phys.net/16/3761/2016/acp-16-3761-2016.pdf

    The millennial (500–2000-year) timescale of deep-ocean ventilation affects the timescale for natural CO2 change and thus the timescale for paleo-global climate, ice sheet, and sea level changes, but this paleo-millennial timescale should not be misinterpreted as the timescale for ice sheet response to a rapid, large, human-made climate forcing. These climate
    feedbacks aid interpretation of events late in the prior interglacial, when sea level rose to + 6–9 m with evidence of extreme storms while Earth was less than 1◦C warmer than today

    The modeling, paleoclimate evidence, and ongoing observations together imply that 2◦C global warming above the preindustrial level could be dangerous. Continued high fossil fuel emissions this century are predicted to yield […..] and (5) non-linearly growing sea level rise, reaching several meters over a timescale of 50–150 years.

    These predictions, especially the cooling in the Southern Ocean and North Atlantic with markedly reduced warming or even cooling in Europe, differ fundamentally from existing climate change assessments. We discuss observations and modeling studies needed to refute or clarify these assertions.

    later “We conclude that, in the common meaning of the word danger, 2◦C global warming is dangerous.”

    why? because in the past at temps 1C above industrial “Sea level reached
    +6–9 m in the Eemian, a time that we have concluded was probably
    no more than a few tenths of a degree warmer than today.

    So my reading of this is that several meters in 5-150 years

    and +6 meters in +150-500 years

    and +9 meters circa +500 years

    and Dangerous , now, today in the next 20 years long before 2050 — for “humanity” overall, for ecology wildlife more feedback driving more temps and more extreme weather events progressively increasing as the old climate becomes more unstable and unpredictable — Hansen suggested a return to 350 ppm CO2 or under … back to Holocene levels.

    As to the US … I’d rather pretend it didn’t exist. Nothing about it is helpful to anyone long term. Frankly I think you are all ‘collectively mad’ – pro or con agw/cc matters, repub democrat, pro-gun anti-gun, religious / atheist none of these matter to that norm. The USA is a train wreck waiting to happen imo.

  33. 33

    Carrie, @26–

    With some time gone by, that oracle of the internet, Wikipedia, puts the Democrat margin of victory in popular House vote at 7.6%.

    https://en.wikipedia.org/wiki/United_States_House_of_Representatives_elections,_2018

    I think my larger point stands: people worked hard to rebuke Trump and the GOP agenda and, more importantly, to bring some sanity back into the US federal government. And their work was rewarded.

    IMO, you should lay of the faux-fatalist despair and let people do the hard work of making change in the real world without being sniped at. (Though I’m sure most of them were mercifully unaware of your scoffing anyway.)

  34. 34
    Jimbrock says:

    How does melting ice increase warming in the Arctic? Unless you are talking about albedo effects only, there is a cooling effect from the heat of fusion.

  35. 35
    Carrie says:

    PS for 33 Kevin McKinney

    Put a Democrat in the WH as president. Put 100 democrat senators there too, and 435 democrats in the House …. the United States of America would still be laughing stock of the world, would still be a duplicitous warmongering collection of paranoid schitzos, a cultural shit fight killing each other 24/7 and would still be refusing to act rationally to fight climate change.

    Trump, republicans and democrats are not the problem … AMERICANS ARE THE PROBLEM … collectively you are all quite mad and delusional… and above all, INCOMPETENT.

  36. 36
    Carrie says:

    And whether it is some toothless god-fearing born again gun slinger from Arkansas or a M Mann from MIT or a KMcK or an LA atheist makes no difference. Frankly y’all nuts in some way shape and form, thus disconnected from reality and the rest of the civilized world.

  37. 37
    Carrie says:

    Seems to me that too often some of the comments (the future i still in OUR hands) by climate scientists incl. Michael Mann, sound little different than those presented at by and for the American Petroleum Institute in the 50s and the 60s

    such as this classic outtake here:
    https://forum.arctic-sea-ice.net/index.php?action=dlattach;topic=861.0;attach=111694;image

    No rush fellas. We have all the time in the world to get “our hands dirty”

  38. 38

    #35, Carrie–

    No.

  39. 39
    Piotr says:

    Re: Carrie (38) “Seems to me that too often some of the comments (the future i still in OUR hands) by climate scientists incl. Michael Mann, sound little different than those presented at by and for the American Petroleum Institute in the 50s and the 60s […] No rush fellas. We have all the time in the world to get “our hands dirty”

    Well, my impression is exactly opposite to yours – where you see demobilising:
    “No rush fellas. We have all the time in the world to get “our hands dirty” –
    I see the opposite – the call for action – there is “still” time do influence climate and our future. The alternative would be to say the future in NO LONGER in our hands, so there is no point in getting “our hands dirty”.

    See the evolution of George W. Bush who went smoothly from – it’s too early to act because the science is not settled, to – it’s too late to act, because we no longer can stop the climate change.

    they say “the future is still in Our Hands”
    not to imply “We have all the time in the world to get “our hands dirty”” – but the opposite – we “still” have a chance to do something about the climate so no point throwing up your hands in the air and sayinb “its t

  40. 40
    zebra says:

    #34 Jimbrock,

    It depends on what you mean by “warming”. I often point out that we are not communicating as clearly as we could.

    If ice is melting, then the system is increasing in energy. “Global Warming” is often misunderstood, often intentionally by Denialists, to refer only to the surface temperature, when as a physics phenomenon it clearly must include phase changes.

    So, increased energy causes the ice to melt, but the temperature of the ice and water doesn’t change. That’s an effect from, not a cause of, “warming”.

    And yes, after the ice melts there is more absorption of solar radiation, as well as from the atmosphere. It is also true that less ice increases energy loss from the water. What the net effect is, when you incorporate advection through atmospheric weather patterns and oceanic current transport, is something you have to do a serious model to understand and quantify.

    Maybe someone can reference such a specific study for you; I’m not familiar with any.

  41. 41
    MA Rodger says:

    Piotr @31,
    You quote from Graham Farquhar @7 – ”Clausius-Clapeyron would give 11% increase in saturation vapour pressure per degree C warming, but it requires energy to evaporate.The GCMs show an increase of evaporation rate on average of only about 2% per degree C” – and suggest AGW provides plenty enough “energy to evaporate enough water vapour to cause 11% increase in water vapour, corresponding to a 1C warming,” and thus you surmise energy cannot be the limiting factor.

    There are actully two quite different phenomena being compared with these 11% and 2% values.
    Firstly, the physics of Clausius-Clapeyron suggests AGW would result in the atmosphere’s relative humidity remaining constant with rising temperature and thus in specific humidity increasing exponentially, although I was under the impression it was ~7% per degree Celsius. This relationship appears in the models and also is supported by measurement.
    Secondly, “increased evaporation” results not from an increase in the column H2O content but from an increase in intensity of the hydrologic cycle as global temperatures rise. This is the increase that is constrained by energy requirements, a situation evident in models and probably also in measurements when all the lumpiness is smoothed out. A paper-to-hand that describes this energy constraint on the hydrologic cycle is Allen & Ingram (2002). It puts this rise at 3.4%, “much less than the 6.5% per kelvin implied by the Clausius–Clapeyron relation.”

  42. 42
    Dan says:

    #35 “Trump, republicans and democrats are not the problem … AMERICANS ARE THE PROBLEM … collectively you are all quite mad and delusional… and above all, INCOMPETENT.”

    ^Goodness what pure rubbish. Lumping all together as one and the same (complete with the obligatory use of all capital letters; quite a dead giveaway) is truly an indicator of a serious failure of critical thinking and intellectual laziness. To be unable to separate those who are part of the problem and those who are working (either collectively or individually) to address it is truly pathetic.

  43. 43
    Carrie says:

    Kevin: “In a nation of lies, those who tell the truth are criminals.”

    Piotr: “The future is someone’s hands, but it is not in ours.”

  44. 44
    Piotr says:

    Carrie (43):
    Huh? I have never said what you “quote”: “Piotr: “The future is someone’s hands, but it is not in ours.”” – neither literally, NOR EVEN implicitly.

    1. I did not state ANY my opinion, on whether the future is or is not in our hands, MUCH LESS STATING that our future is in …”someone else’s hands”. And out of curiosity – have I said whose these hands might be? I’d be interested to know. ;-)

    2. What I DID say is that there is an alternative interpretation of the words that you attack:

    if “climate scientists incl. Michael Mann” say: “the future is still in our hands”

    it does not have to necessarily mean that they dismiss the urgency of a strong action now (your: “No rush fellas. We have all the time in the world to get “our hands dirty”)

    but in fact the OPPOSITE is more probable: that “the future is STILL in our hands” means “if we act now, we can STILL make a difference, AS OPPOSED to saying – it’s too late: the climate is NO LONGER in our hands, so let’s enjoy our consumption while we can.”

    And since I don’t recall Michael Mann claiming that we can safely delay action on climate change (“No rush fellas. We have all the time in the world to get “our hands dirty””) – it seems you cast contemptuous accusations toward others based on YOUR own MISREADING of other people’s words and intentions.

    A suspicion made stronger by the fact that in the same thread you have just tried to discredit me by attributing to me words that I have neither said nor even implied. And by your contemptuous treatment of other people you disagree with.
    One might have been be a anomaly, taken together – looks more and more like a pattern.

    Piotr

  45. 45
    Piotr says:

    Re: (41) MA Rodger:
    “Secondly, “increased evaporation” results not from an increase in the column H2O content but from an increase in intensity of the hydrologic cycle as global temperatures rise. This is the increase that is constrained by energy requirements”
    I am not sure what you are saying here:

    1. You: “increased evaporation results not from an increase in the column H2O” – except, I didn’t say it did. If anything it is the _opposite_ (the increased column H2O results FROM increased evaporation (or reduced precipitation, which comes to the same))

    2. You: [“increased evaporation” results] from an increase in intensity of the hydrologic cycle as global temperatures rise. This is the increase that is constrained by energy requirements”

    If I warm atmosphere by 1C, I would make 7% (or Grahams 11%) more room for water vapour. All I need it to do fill this room ONCE: to move enough water from (mainly) ocean into the atmosphere. All energy required here is the enthalphy of evaporation of this ONE-TIME evaporation amount of water. And there is more than enough of this energy in the system/and/or AGW.

    Hydrologic cycle does not really come into play here – it has been slightly disturbed once when I needed to bring this extra water vapour into atm. (as for a couple of weeks evaporation needed to be larger than precipitation). but once it is done, it operates as previously, E=P. So I still don’t see what Graham’s
    lack of “required energy to evaporate” may mean.

    And a related question – if the increase in H20 content per 1C in the models is LESS than predicted theoretical maximum of 7% (or Grahams’s 11%) then this means that the model’s relative humidity DROPS with increasing global temperature.
    So the Gavin’s “first approximation” grom his water vapour text in 2005 on realclimate:
    -“To first approximation, the water vapour adjusts to maintain constant relative humidity”, “A closer look reveals that for a warming (in the GISS model at least) relative humidity increases slightly in the tropics, and decreases at mid latitudes”
    is not correct? And would’t there be a negative feedback as the lower relative humidity reduces condensation, which then prevents any farther decrease in relative humidity?
    Piotr

  46. 46
    Carrie says:

    42 Dan, ah don’t worry about it. I was not expecting agreement, besides:

    “Being right too soon is socially unacceptable.” Robert A. Heinlein

    in 43 Carrie, my replies were in “….” :)

  47. 47
    MA Rodger says:

    Piotr @45,

    Regarding the first part of your “related question”, my understanding is that, put simplistically the level of relative humidity at a global scale has dropped a little (so it has not remained constant) but this is a land/ocean thing. (See for instance Byrne & O’Gorman 2018) The land temperatures are rising faster than the ocean temperatures but there is a limited supply of water to evaporate on land. This may be a different expression of your quoted comment from “Gavin’s … water vapour text in 2005 on realclimate”“A closer look reveals that for a warming (in the GISS model at least) relative humidity increases slightly in the tropics, and decreases at mid latitudes..” The land at mid-latitudes is usually quite dry and of the deserty sort. So concerning the first part of your “related question”, it is correct that globally relative humidity has dropped very slightly. I would not consider constant relative humidity as being a “theoretical” finding. It derives from measurements of relative humidity in the extre-tropics where there is an annual temperature cycle but flat relative humidity. So it is more hypothesis than theory.
    The second part of your “related question” is far less straightforward and so I here will go no further than to say that the phenomenon you call “a negative feedback” is an interesting one: its effects are presumably small and possibly something that would diminish or disappear when AGW reaches equilibrium, giving a little boost to the tag end of a warming episode.

    Beyond these points,I believe we are mainly in agreement with one outstanding issue in that you say “I still don’t see what Graham’s lack of “required energy to evaporate” may mean.”
    The reference to Alan & Ingram (2002) @41 does describe it. Another explanation may be helpful.
    Air at the surface loaded with H2O to perhaps 100% relative humidity is drawn upward into cooler higher altitudes resulting in rain because the 100% humidity would otherwise be exceeded as the air packet cools. But with the rain dropping from the sky, the latent heat of evaporation is released warming these cooler altitudes. If there is too much rain, the increase in latent heat released will warm these upper altitudes to the point where the warming reduces the amount of surface air being drawn upwards. So it is a matter of how quickly these upper altitudes can get rid of any extra latent heat that determines the level of rainfall. Thus an energy constraint.

  48. 48
    Rles says:

    #28, Mr I Know It All
    In reply. Only 1 of the 2 major parties in the US embraces Fascists in their organization, and that is the conservative right wing Republican Party. Your post here does not change which President and which political party condones Fascism.

  49. 49
    Piotr says:

    Re: MA Rodger (47)
    Thanks for clarifying the “related questions”. As for the main issue – I am still not convinced. Specifically -your example: “If there is too much rain, the increase in latent heat released will warm these upper altitudes to the point where the warming reduces the amount of surface air being drawn upwards.”

    First – there won’t be too much of that “too much rain” as it is a self-limiting process – as both removing of some the water vapour into rain AND the latent heat released from it – would both quickly reduce the humidity oversaturation to 100%.

    Second – yes, the latent heat from condensation warms the upper air making it less dense, and therefore possibly limiting the ability of the vertical draft of surface water, but the very same condensation removes water vapour from air making it denser, and thus having the OPPOSITE effect.

    Third and most important – in the main part of the answer you argue that’s the ability to draft the surface air into higher altitudes is the limiting factor for less than 100% humidity, but in the other part (the related question) you indicate that it is the availability of water to evaporate over land, particularly over deserts is the cause for the gap.

    I agree with THE LATTER explanation (because of points 1 and 2 and of Occam’s razor), but this mean it would be the _availability of the water to evaporate_ on land, and NOT the lack of “energy to evaporate it”, as Graham stated, which is the reason for the total water vapour in atm. not keeping up with temperature increase.

  50. 50
    MA Rodger says:

    Piotr @49,
    I’ll not dwell further on the matter except to say that the use of logic is not the best of appraoches in situations where models can show counter-logical processes at work.
    I did provide one rather old reference to these energy constraints on precipitation @41. For completeness, here are some other newer ones which I felt were less helpful for a casual reader.
    Wentz et al (2007) “How Much More Rain Will Global Warming Bring?”
    O’Gorman et al (2011) “Energetic Constraints on Precipitation Under Climate Change”
    Stephens et al (2012) “An update on Earth’s energy balance in light of the latest global observations”
    Pendergrass & Hartmann (2014) “The Atmospheric Energy Constraint on Global-Mean Precipitation Change”
    Hegerl et al (2015) “Challenges in Quantifying Changes in the Global Water Cycle”