Model claims: Future heat waves to roast 60% of the planetary surface by 2075

2015 was the warmest year since modern record keeping began in 1880, according to an analysis by NASA’s Goddard Institute for Space Studies.

2015 was the warmest year since modern record keeping began in 1880, according to an analysis by NASA’s Goddard Institute for Space Studies.



February 23, 2016

Sweltering heat waves that typically strike once every 20 years could become yearly events across 60 percent of Earth’s land surface by 2075, if human-produced greenhouse gas emissions continue unchecked.

If stringent emissions-reduction measures are put in place, however, these extreme heat events could be reduced significantly. Even so, 18 percent of global land areas would still be subjected yearly to these intense heat waves, defined as three exceptionally hot days in a row.

These are among the findings of a new study by Claudia Tebaldi of the National Center for Atmospheric Research and Michael Wehner of the Lawrence Berkeley National Laboratory. The study, funded by the U.S. Department of Energy and published in the journal Climatic Change, quantifies the benefits society would reap, in terms of avoiding extreme heat events, if action is taken now to mitigate climate change.

“The study shows that aggressive cuts in greenhouse gas emissions will translate into sizable benefits, starting in the middle of the century, for both the number and intensity of extreme heat events,” Tebaldi said. “Even though heat waves are on the rise, we still have time to avoid a large portion of the impacts.”


Tebaldi and Wehner used data generated by the NCAR-based Community Earth System Model to study 20-year extreme heat events—those intense enough to have just a 1-in-20 chance of occurring in any given year. The model was developed with support from the Department of Energy and the National Science Foundation, NCAR’s sponsor.

The researchers looked at two things: how frequently today’s typical 20-year heat wave may occur in the future, as well as how much more intense future 20-year heat waves will be.

Table detailing how heat waves will change in the future

For large portions of the world’s land surface, future heat waves with a 1-in-20 chance of occurring in any given year are projected to become more extreme than heat waves with the same chance of occurring today. Stringent efforts to mitigate human-produced carbon emissions would reduce the amount of land area at risk for these intense heat waves—defined as three days of exceptionally hot temperature. Click to enlarge. (This table is freely available for media & nonprofit use.)

Besides finding that today’s 20-year heat waves could become annual occurrences across more than half of the world’s land areas by 2075, the study also concluded that heat waves with a 1-in-20 chance of occurring during a future year will be much more extreme than heat waves with the same probability of occurring today.

For example, if emissions remain unabated, a heat wave with a 1-in-20 chance of occurring in 2050 would be at least 3 degrees Celsius (5.4 degrees Fahrenheit) hotter for 60 percent of the world’s land areas. For 10 percent of land areas, a 20-year heat wave in 2050 would be at least 5 degrees C (9 degrees F) hotter.

A few degrees may not seem like much on a mild day, but during extreme heat events, they can mean the difference between life and death for vulnerable populations, Wehner said.

“It’s the extreme weather that impacts human health; this week could be 2 degrees Celsius hotter than last week, and that doesn’t matter,” he said. “Now, imagine the hottest day that you can remember and instead of 42 degrees C (107.6 degrees F) it’s now 45 degrees C (113 degrees F). That’s going to have a dangerous impact on the poor, the old and the very young, who are typically the ones dying in heat waves.”

By 2075, the situation is likely to become much more dire if greenhouse gas emissions—produced largely by the burning of fossil fuels—are not reduced. The percent of land areas subject to 20-year events that are at least 5 degrees C hotter swells from 10 to 54 percent.

However, if emissions are aggressively cut, the severity of these 20-year events could be significantly reduced over the majority of the world’s land areas, though portions of the Earth would still face dangerous heat extremes. For example, in 2075, almost a quarter—instead of more than a half—of land areas could experience 20-year heat waves that are at least 5 degrees C hotter than today’s. “But even with such dramatic reductions in carbon dioxide emissions, future heat waves will be far more dangerous than they are now,” Wehner said.

The researchers also looked at single-day extreme heat events, as well as single-day and three-day blocks when the overnight low temperature remained exceptionally warm. Past research has shown that human health is especially endangered when temperatures do not cool off significantly at night. All of these events had similar increases in frequency and intensity.


The fact that extreme heat events are expected to increase in the future as the climate changes—and the fact that emission reductions could ameliorate that increase—is not a surprise, Tebaldi said. But this study is important because it puts hard numbers to the problem.

“There is a cost attached to reducing emissions,” Tebaldi said. “Decision makers are interested in being able to quantify the expected benefits of reductions so they can do a cost-benefit analysis.”

Tebaldi and Wehner’s paper is part of a larger project based at NCAR called the Benefits of Reduced Anthropogenic Climate Change, or BRACE. For the project, researchers from across NCAR and partner organizations are working to quantify how emission reductions may affect health, agriculture, hurricanes, sea level rise, and drought.

About the article

Title: Benefits of mitigation for future heat extremes under RCP4.5 compared to RCP8.5

Authors: Claudia Tebaldi and Michael F. Wehner

Publication: Climatic Change

106 thoughts on “Model claims: Future heat waves to roast 60% of the planetary surface by 2075

    • You got it. Also, why did they also include the study of the Benefits of Mitigation of future cold extremes that are just as likely to happen as heat extremes?

    • Well apart from anything else we have just had Paris 21 where everything was decided. Why do we need this kind of alarmist claptrap anymore. Deals done, end of story.
      Now let’s go off and do something about real air and water pollution, can we?

  1. The flaming stupidity of intellectual-fecal-droppings like this is the only heat wave we have to worry about.

  2. by 2075 when the author will no longer be around to be asked how they could get their claims so very wrong , now who says climate ‘scientists’ never learn .

  3. Two thoughts:
    1) It is utterly amazing that the model output exactly what it was programmed to output, and;
    2) *cough* *cough* “bullsh_t!” *cough*
    “We’ll always have Paris…”

  4. The authors no longer care whether they are right or wrong, they just want money and attention.
    If their masters in the government can just take control of global energy supplies now, under whatever pretext, then they will have achieved the goal of absolute power.
    Whatever the future of climate really holds would then not matter one jot.

    • Sure, they no longer have to care about being shown to be complete fools, because step #1 of their process is calculating how many years from now they will retire.
      Step two is apparently deciding how big a lie to tell.

  5. More heatwaves and more extreme cold
    More drought and more flooding
    More food shortages and more greening of the planet
    More hurricanes, (ooops)
    Seems like a zero sum game right about now

  6. Say whatever you want. Project any hysterical outcome and no one cares… as long as you advocate for penalizing Western Civilization and transferring wealth from the developed world to the developing world. It’s simple actually. It’s all about the dialectic…

    • I disagree.
      Predictions are hard, especially about the future.
      But that is not even the biggest reason why all the maybe words in the world do not add up to one single fact.
      I doubt if these people could possibly be stupid enough to believe their own lies, but I may be wrong about that.

      • There are people who make up the lies – to them the ends justify the means and they are well paid for it.
        There are the people who believe the lies – they were placed into public schools and force fed propaganda sometimes masked as movies from ex vice presidents who only took one science course at Yale with a passing C grade. Maybe he aced his “Making Documentaries” 110 course regardless it qualifies as brainwashing.
        And then the rest of us that believe that science should be motivated by the truth and not politics and realize that CAGW is a global fraud perpetrated by the wealth holders against the masses.

  7. So my computer model that cannot predict short-term weather is valid to predict intermediate-term weather? I am missing something here. The only value of this seems to be continued funding.

  8. “Tebaldi and Wehner’s paper is part of a larger project based at NCAR called the Benefits of Reduced Anthropogenic Climate Change, or BRACE.”
    Well, seems like all the papers for this project are deliberately guaranteed to have a preordained conclusion (PC?). I guess we should BRACE ourselves for when they come to take our wallets.

  9. These folks never seem concerned about hypotheses of events so far in the future they can’t be checked. What are the intermediate predictions? Or do these scorching days just spring upon us in 44 years?

  10. Dang this sounds bad! I’d like to provide more funding to Claudia Tebaldi of the National Center for Atmospheric Research and Michael Wehner of the Lawrence Berkeley National Laboratory so that we can learn more about it, please.

  11. What a bunch of mother falcon, son of a pigeon, yellow-bellied sapsuckers!
    Pleas forgive my fowl language, but these kind of fear-mongering predictions really upset me.

  12. The inflation in horse droppings is getting out of control. Never mind that the models do not accurate predict that the sun might come up tomorrow, they now have to predict the earth turning into a white dwarf to get new funding.

  13. This BS not real future warm or heat. It natural cycle weather or solar cycle weak can cause little ice age or global cooling. Never know it natural cycle earth

  14. National Laboratory. The study, funded by the U.S. Department of Energy and published in the journal Climatic Change, Do these people ever feel embarrassed for this stupidity with taxpayer MONEY.

    • I can get climatic change just by driving ten miles down the road; or 18,520 meters if I go nautical miles.

  15. How timely that this appears concurrent with the new GRL paper showing how unreliable such ‘projections’ are. Discussed just two posts ago here.

    • NCAR-based Community Earth System Model neglects a temperature dependence of a latent heat of water vaporization. That introduces a 2.5% error in an energy transfer by evaporation from tropical seas.
      I asked NCAR for an analysis of an impact of this approximation. They did not supply any. I estimate that it limits the usefulness of the model to 100 time steps (usually 100 hours) at best.

  16. Sour Grapes. The Paris Agreement sets future CO2 emission levels. All countries have agreed.
    Computer models from this point forward are a waste of time. We are going to get the climate agreed in Paris.

  17. The increase in the greenhouse effect should reduce the highest temperature of the year. Look at regions with a lot of water vapor in the air. And the data also shows a drop. The drop might be hidden by the increase in sensibility of the instruments. At some stations, if you take the hourly data and find the highest value taken at the start of an hour an compare with the daily max. You will find a growing difference. Possibly because the instrument can catch any quick variation in temperature. The Stevenson screen might be smaller also. Anyway, the highest temperature of the year should go down based on science and is going down based on most of the data.

    • Your point is shown empirically in longitudinal studies of long service weather stations. Most often, the maximums have decreased slightly while minimums have increased more strongly. So less cool overnight, earlier Springtimes, later Autumns, milder winters. Not scary enough.

  18. I’ve just devised a model that clearly demonstrates that nothing out of the ordinary will happen so you can all relax now and plan for a ‘so so’ future (climate wise at any rate).

  19. From NCAR/UCAR:
    have they moved their headquarters to Alaska?
    How is it that Alaska remain one of the least populated places on earth in terms of people per square mile?
    Are we seeing flocks of retired people picking up and moving from Arizona and Florida up to Alaska?
    Why is it that retired people move to Arizona and Florida from colder climates?
    Why is it that billions of people live in the tropics, but almost no one lives at the poles?
    Why is it that NCAR/UCAR scientists lack an ounce of common sense?

    • Clearly they don’t view the opening of more land to agriculture due to warming in Canada, Greenland, and Russia to be a good thing. Nor extended growing seasons. Nor the shortening of shipping times by going through the Arctic. Nor fewer hurricanes due to less temperature contrast. Nor lower excess winter mortality.
      Since they’re advocating against warmer temperatures.

  20. Aren’t heat waves defined based on what is normal for that place and time of year?
    For example the same temperature that qualifies as a heat wave in Nome, Alaska, would not be a heat wave in Las Vegas, Nevada.

  21. It is my understanding that global warming has a much greater effect on nighttime low temperatures than on daytime high temperatures. I think mild winter nights are much more likely than hot summer days. Another possibility is that global warming will be minimal and no one will notice any difference.

    • Kevin Trenberth’s planetary model doe not permit ANY night time. Sun shines all day from 186 million miles altitude at the zenith.

  22. Model extremism is not to be outdone by extreme weather assertions, extreme psychology research, and extreme policy plays. It’s great for Hollywood scripts too.

  23. A definition based on Frich et al.’s Heat Wave Duration Index is that a heat wave occurs when the daily maximum temperature of more than five consecutive days exceeds the average maximum temperature by 5 °C (9 °F), the normal period being 1961–1990.

    This does vary a little around different countries, but still 3 c or 4 c above normal for maximum temperatures have generally never been a heatwave and needs to last for around 5 days not 1 or 2.
    Scientists expect future cooling over the next few decades so we need to get a rise of 5 c on average summer temperatures to increase the frequency of heat waves in just a 20 year period after it. We struggle to rise local temperatures over the past century by 1 c so how does 5 c sound over just 20 years? There is so much nonsense in this useless made up assumption of an article it is only worth laughing at it.
    You can’t forecast weather next month and you certainly can’t forecast it in 2075, so please just drop the nonsense.

  24. Uncertainty bands? How about turn that model on the next 5 year period and see how accurate the prognostications are?

  25. It’s worse than we thought. Much, much worse. To borrow a phrase from the new car advertising industry, “Introducing the all-new climate scare!”

  26. More rubbish from so called climate science.
    Notice how there is never any details to these wild claims, beyond its down to CO2. l would take theses claims more seriously if they detailed just how exactly are we going reach this state of affairs.
    Are they claiming that there will be a increase in blocking high pressure during the summer months to allow these heatwaves to happen.?
    Are they claiming that there will be a large scale shutdown of the jet stream to allow the air to stagnate and grow hotter. ?
    Are they saying that all the cold air at the poles will disappear so helping to shutdown the wind patterns across the globe. ?
    These peoples claims need to be exposed by science rather then just resorting to insults.

  27. At last the UK Government is taking action on the misuse of government funds on lobbying, rather than on the actual science.
    A certain Bob Ward is ‘communicating’ (aka squawking?) in the Guardian, as his funding is clearly under threat;
    Not a scientist, ‘Bob’ is the Policy and Communications Director for the Grantham Research Institute for Climate Change Economics and Policy, at the London School of Economics.
    We can hope that a metaphorical “pause” will affect them, too.
    I suggest, before he finds other work to do, Bob spins this bad news as: “Communications on Climate-Change Economics and Policy will be entering a pause owing to the policy of tackling the economic climate change in the LSE caused by the anthropogenic emissions of Tory politicians”

  28. This prediction relies on an assumption that CO2 concentrations in the atmosphere has a lineal correlation with global temperature and hence heat waves. This assumption is looking increasingly flawed
    Given the localised nature of weather patterns and LST thermometers, and our very sketchy historical record, there are always going to be ‘records broken’ (hot and cold) each year. Once such heat record (2015) broken in the UK was at Heathrow Airport. A good place to put a thermometer?
    We can expect the barrage of media reports on heat waves to continue

  29. Sixty years ago in Houston Texas I was out shopping,it was a very hot day, even for for Houston in the summer. I went into a Shop that was was pleasantly cool. A Thermometer on the wall showed the temp in the Shop to be 112 deg F. There was an overhead big blade fan, but no air conditioning. I never did find out what the outside Temp was.
    I think about that shop with some nostalgia because I now live in New Zealand where ( to me ) cold to chilly is normal summer weather, 32 degrees Cent and considered REALLY WARM. A friend commented just recently that the day was a real scorcher when it was 38 deg C.I took my cotton sweater off. I don’t think the end of civilisation is imminent. KG

  30. By 2075? Well,
    ‘come and find the place where I am lying,
    And kneel and say an Ave there for me.’ – Frederic Edward Weatherly 1910

  31. Remember all the fuss made about the heatwave in the middle east last summer.
    Well to get these conditions then the weather needs to “play ball”. Usually over the middle east in summer there is a jet stream flowing which helps to move the air along. But last summer during this heatwave for some reason this jet stream shutdown over the middle east. Which had allowed the blocking of the airflow
    over the middle east. Which allowed the air to stagnate over a number of days and so allowed the heat to build up into the heat wave. So for these claims to come true. There really would have be a noticeable shutting down of the global jet stream. So where are the signs this is happening.?

  32. The good news is that with some curing, this study would make excellent fertilizer. So, at least it’s “green”.

  33. Again – isn’t the entire premise that all this ‘roasting heat’ is supposed to be coming from increased humidity – which by definition, would result in more tropical fauna? The lushest, healthiest biospheres on the planet?

  34. These guys should keep up better with the peer-reviewed literature.
    Two relatively recent papers in Geophysical Research Letters cast doubt on their claims: and
    The first finds that models may be overestimating sensitivity to radiative forcings and the second that unreliable model simulations overestimate danger from extreme events. This paper doesn’t cite either of those. Why not?

  35. All of this on 0 theoretical fundamental quantitative equations or experimental demonstration of “trapping” of energy by spectral phenomena in excess of the equilibrium temperature determined by the planet’s spectrum as seen from the outside .

  36. Hmmm….just how many years ago did Hansen predict what would happen if CO2 reached the present level?
    Have the temps reached what he predicted?
    This isn’t trying to move the goal post. It’s trying to build a new one.

  37. Wait! Wait! I can do this, too! It’s fun! Ready?
    A new climate forecast: by 2125, people will only be able to live above 45 degrees latitude, because Global Warming will roast and bake the lower latitudes. And, come visit me when it happens.

  38. these intense heat waves, defined as three exceptionally hot days in a row.


    Tebaldi and Wehner used data generated by the NCAR-based Community Earth System Model to study 20-year extreme heat events—those intense enough to have just a 1-in-20 chance of occurring in any given year.

    Ad hoc definition and model based study… Not one reference to the type of weather creating heatwaves.
    I expect 100% of Earth surface will experience their next definition of a heatwave: day.

    • 3 days seems like a very poor choice. I like to remember 1976 in London – 15 days of very hot weather in a row.

  39. This kind of ‘paper’ really enrages me to the point of wanting to break something or hit somebody. But all your comments calm me down a little and make me realize I’m not the only one who who sees these tossers as money-grabbing, lying, wretches.
    Thank you guys.

  40. Here in Sydney, Australia, Peter Hannam, the resident alarmist environment editor at the Syndey Morning Herald, is claiming record heatwaves (40c + for the inner west. /sarc on Sheesh, that’s unusual for the inner west Peter /sarc off). Oh wait! It’s summer Peter!!!

  41. And now for the REAL problems: Pollution of soil, air, and water; extinction of flora and fauna; population growth (90 years ago there were fewer than 2 billion humans in the world, now on the way to 8 billion). These are REAL, present problems.

    • Therein lies my problem with this whole CAGW scam.
      If the GovMint Bureaucrats would simple be honest with the citizenry they would explain that their real concerns are overpopulation, limited resources and the growing demand on natural resources. Then we could all share in an honest discussion on how immediate the problem is and how we go about dealing with it.
      But no. They have been dumbing down the citizenry here in the U.S. so that they can peddle a fairy tale complete with cute fuzzy polar bears and lovable little penguins threatened by evil men, designed to scare and guilt a 50% + 1 majority into voting our GovMint the power over the people to restrict their energy use and degrade the quality of life for all but the powered elites including the bureaucrats. The best part? When pressed even they acknowledge that prescribed actions can’t stop their theorized doomsday scenario. They are just delaying tactics. A no win scenario for the citizenry oh and drop your pants and bend over you are not going to enjoy what comes next.

      • overpopulation, limited resources and the growing demand on natural resources.
        Heck, I don’t think any of those things are real problems. Modernity cures all.

        • I agree.. The puppet masters have created this CAGW scam because they don’t agree and don’t want to share their real concerns since they have no basis to win the argument. CAGW gives them the angle they need.

  42. If the CMIP projections come true, more heat waves, yes. But there is little to no indication that will actually happen in the first place.

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