When can we expect extremely high surface temperatures?

Sure glacier melt, sea level rise, extreme drought, and species loss get all the media attention — they are the Britney Spears, Paris Hilton, and Barack Obama of climate impacts. But what about good old-fashioned sweltering heat? How bad will that be? Two little-noticed studies — one new, one old — spell out the grim news.

Bottom line: By century’s end, extreme temperatures of up to 122°F would threaten most of the central, southern, and western U.S. Even worse, Houston and Washington, DC could experience temperatures exceeding 98°F for some 60 days a year.

The peak temperature analysis comes from a Geophysical Research Letters paper published two weeks ago that focused on the annual-maximum “once-in-a-century” temperature. Researchers looked at the case of a (mere) 700 ppm atmospheric concentrations of CO2, the A1b scenario, with total warming of about 3.5°C by century’s end. The key scientific point is that “the extremes rise faster than the means in a warming climate.”


The results, depicted above (in °C), are quite remarkable, especially when you consider that, instead of 700 ppm, we could easily end up closer to 1000 ppm by century’s end (see here), in which case these record temperatures could be seen closer to 2060 than 2100:

… values in excess of 50°C [122°F] in Australia, India, the Middle East, North Africa, the Sahel and equatorial and subtropical South America.

As you can see from the map, extreme temperature peaks are only slightly lower over large parts of this country. The study notes:

Such temperatures, if lasting for some days, are life threatening and receive relatively little attention in the climate change debate.

So now the question is, has anybody done an analysis of what global warming could do to intense heat waves that last very long times, weeks or months? The answer is yes, and the results of that study are more worrisome — and it also received relatively little attention.

The November 2005 study in the Proceedings of the National Academy of Sciences, “Fine-scale processes regulate the response of extreme events to global climate change,” found that “peak increases in extreme hot events are amplified by surface moisture feedbacks.” The study looked at the A2 scenario (about 850 ppm in 2100) in the second half of this century (from 2071 to 2095). It examined temperature rise projections, plus “fine-scale processes,” such as how local warming is affected by loss of snow cover and loss of soil moisture. I interviewed the lead author, Noah Diffenbaugh, of Purdue University, for my book.

Houston and Washington, DC would experience temperatures exceeding 98°F for some 60 days a year. Oklahoma would see temperatures above 110°F some 60 to 80 days a year. Much of Arizona would be subjected to temperatures of 105°F or more for 98 days out of the year–14 full weeks. We won’t call these heat waves anymore. As Diffenbaugh told me, “We will call them normal summers.”

And again, that’s not even the worst case, since it’s “only” based on 850 ppm.

The time to act is yesterday.

26 Responses to When can we expect extremely high surface temperatures?

  1. Jon says:

    Errata: 1. “122°C would threaten most of the central, southern, and western U.S.” should probably be in °F, no? 2. The link to Sterl et al. isn’t working for me, I think some of the html is missing.

    Thought provoking post.

  2. David says:

    “Even worse, Houston and Washington, DC could experience temperatures exceeding 98°F for some 60 days a year.”

    If this is supposed to alarm me (and I’m pretty sure it’s supposed to), it doesn’t. 98 is a joke. If that’s the worst nature can throw at me, bring it on. Because anyone who thinks 98 is hot is a wimp.

  3. Ronald says:

    What might be worse, if that can happen, is what will the temperatures be in the areas where we get most of our food. The growing season will go north, but then large areas will be to warm to grow regular crops. None of it will be pleasant.

  4. Joe says:

    David — you are joking right.

    First off, the worst that “human caused global warming” can throw at you is 80+ sea level rise, one third of the planet turned into desert, most species extinct, and the ocean hot, acidified virtually lifeless. But that is the subject of my second link above.

    That said, over 98°F on the coasts for most of the summer would be brutal. It would essentially mean very little outdoor activity during the summer for most of the country. And that assumes we have virtually eliminated air pollution — otherwise every single summer day will be beyond Code Red.

  5. Brewster says:

    David – that’s EXCEEDING 98F – in other words, it will generally be considerably HOTTER THAN THAT!

  6. llewelly says:

    Your link to the full paper is wrong. It should be:

    [JR: Fixed. Thanks.]

  7. charlie says:

    This is a little disingenuous.

    The first link is about EXTREME rises in surface temperature. From reading the map, it looks as most of the US is in the range of 40 to 44 degrees (or 104 to about 112). Yes that is hot, but really only 4-5 degrees hotter than the maximum temperatures already recorded in the continental US.

    Your second link ties in the idea about how long these hot temperatures would last. I can’t argue that science there, but it is a very different study than the first Dutch study.

    Yes, by 2060 60 days of 98+ degree in Washington would mean a summer of Code Reds. However, by 2060 even oil companies agree that we’ll be running out of oil, so we’ll either be walking or driving some other fuel. Plug-in hybrids, as you like to point out, don’t produce the ground level ozone which are the trigger events for Code Red days.

    I don’t find these scare tactics useful in a debate about how to move to off carbon.

  8. Bob Wallace says:

    “Yes, by 2060 60 days of 98+ degree in Washington would mean a summer of Code Reds. However, by 2060 even oil companies agree that we’ll be running out of oil….”

    There are other sources of CO2 and additional problematic greenhouse gases.

    Coal comes to mind….

  9. Bob Wallace says:

    The graph included in the article might be more effective/convincing if it were set up something like this one which shows how the US climate has changed during the last few years.

  10. Jörg Haas says:

    Joe, you should read this about the impact of the European Heat Wave in 2003. A detailed study found out that the excess mortality due to the heat wave was not 25-30.000 as previously estimated, but around 80.000 deaths.
    Have a look at

  11. Paul K says:

    We can no more expect these ridiculous temperature increases than we can expect cooler temperatures at century’s end. The idea that man made CO2 emissions might raise ppm to 1000 in this century is absurd. The long term trend indicates 700 ppm is unlikely. Why can’t you base your arguments on the widely accepted “doubling” to 560 ppm in this century?

    [JR: There is no “widely accepted ‘doubling’ to 560 ppm in this century.” You really need to read the literature or my blog. Achieving 560 ppm would require a radical departure from business-as-usual energy and emissions trends. The latest IPCC report, on which I base my entire analysis, clearly shows that we are headed toward 1000 ppm. Please identify three or more sources that support your supposedly “widely accepted” view.]

  12. John Hollenberg says:

    > The idea that man made CO2 emissions might raise ppm to 1000 in this century is absurd.

    Perhaps, but the idea that made-made CO2 emissions might trigger tripping points which cause release of CO2 from permafrost, etc. that lead to 1000 ppm is NOT absurd. We just don’t know where those tipping points are or whether we will decrease CO2 emissions in time to avoid crossing them.

  13. rpauli says:

    And most aircraft manuals specify the maximum operational temperature is 122F

    Phoenix airport has be shutdown by the heat a few times.

  14. elbarto says:

    Forget catastrophic warming for a moment, CO2 is toxic to humans at surprisingly low concentrations IE 420 ppm.

    It seems that elevated CO2 might lead to chronic health effects in humans (and probably most other animals) and we will not have time to adapt (evolve) to cope with the higher levels.

    This study seems to suggest that above ~420ppm CO2 lifetime exposure blood chemistry is altered leading to myriad chronic health effects.

    If you don’t care about ocean acidification, maybe blood acidification will get your attention…

    Joe, I don’t think you’ve posted on possible health effects of elevated CO2 before. It seems to me a significant unreported danger of changing the compostion of our atmosphere.

  15. carmack says:

    in 2060 will it snow on christmas in Cincinnati? if it rains i think i will kill myself.

  16. Nylo says:

    420ppm toxic? Do you happen to know the CO2 concentration in your room as you sleep, or the typical CO2 concentration in an office?

  17. paulm says:

    Quite frankly, Climate change is very bad news and we need people and bodies in the know to step up to the plate and put their money where their mouth is… all this ‘debate’ about GW is just fizzling while were sizzling.

    Scientist, if they think that it is happening and is as bad as it is and are not seeing a positive reaction to their alarms – should be taking drastic steps like Hansen and Gore.

    Letters stating ‘we believe etc…’ are not strong enough – shouldn’t they be threating resignations, having sit-ins, demanding audiences with leaders, placing law suites …. setting themselves on fire and jumping off tall buildings?

  18. Arne Marco says:

    elbarto: thank you for the link. I just read the doc and I am shocked. Until today I didn’t know that CO2 is so dangerous to us and that we are so close to the limits of 426 ppm. It means there is no possibility to adapt to a higher level of CO2. I think Hansen has got it very right when he says we have to move the CO2 amount in the atmosphere down to 350 ppm to secure our future …

  19. Steve H says:

    I’m not too worried that the cities of Houston and DC would be so adversely affected. Should this prediction come to realization, I would be doubtful that the cities would be inhabited, rather inundated. Looking at that map, I would have to say that Kuwait would have the most to gain in a fight against climate change. “Off Scale” is not an optimum temperature for humans.

  20. Dano says:

    I can tell you the Colo Front Range is experiencing this sort of thing now.

    And the temps are around 98ºF, which, combined with low rainfall, are causing quite a problem. Just like the models are sayin’.



  21. Paul K says:

    The current “business as usual” is exponential growth in wind and solar power including CSP and the hybridization/electrification of the automotive fleet over the next twenty-five years. 1,000 ppm is not in the cards.

    [JR: What planet do you live on where that is BAU — cause it ain’t earth?]

  22. John Hollenberg says:


    The growth of CO2 emissions and attempts by other countries to cap them do not (so far) support your rosy assessment. I think it is a bit early to relax.

  23. Paul K says:

    I live on a planet with concentrating solar thermal power (CSP) capacity expected to double every 16 months over the next five years, worldwide installed CSP capacity will reach 6,400 megawatts in 2012–14 times the current capacity. Over 90 percent of fossil fuel–generated electricity in the United States and the majority of U.S. oil usage for transportation could be eliminated using solar thermal power plants – CSP and PV plants to produce 69 percent of U.S. electricity and 35 percent of total U.S. energy, including transportation, by 2050. This rosy assessment is laid out at an out of this world website beloved by many.

  24. Ronald says:

    Way to suck up.

    everything we are doing right now to reduce CO2 release is on the edges. There is still quite a ways to go before we will have 80 percent less CO2 release in developed countries and 50 percent less in developing countries. And it’s when we actually take large percentage of energy use from companies when they really will scream bloody murder in job and money losses.

    Plugin vehicle would mean conveniance stores going out of business, and all the other jobs and businesses in the whole fuel supply chain. The people employed and owning those businesses will vote for those who will protect those businesses from any subsidies to Plugins. If oil is a trillion dollar business, they really won’t get excited about something that takes a few percent of the business, but once plugins take, say a hundred billion dollars a year, they’ll fight like heck against the next hundred billion going away. The same with coal going away.

    There’s billions and trillions of dollars to be lost by many people moving to a low and non carbon world. It won’t be easy. I give it a less than one percent chance. But that’s a wild ass quess, what do I know. It will be hard.

  25. lovewow says:

    yes.The growing season will go north, but then large areas will be to warm to grow regular crops. None of it will be pleasant.

  26. Ronald K

    There have been something like 25 peer reviewed studies that show that switching to renewable clean energy and energy efficiency will have little adverse economic impact.
    Some project a net economic gain.

    Then there is the non peer reviewed and heavily flawed and biased study by the Chamber of Commerce and National Association of Manufacturers, which shows something different.

    It is also well known that building solar and wind will create many more jobs than building coal or nuclear plants.

    Convenience store closings are not among my biggest concerns.
    They are convenient and expensive, and contribute to the high cost of being poor, since poor people spend a bigger chunk of their money in such places.