How Global Warming Affects Weather: Why Can’t We Get the Story Right?

By Chris Mooney | June 20, 2011 10:48 am

Joe Romm is upset by this recent John Broder piece on climate and extreme weather, entitled “Scientists See More Deadly Weather, but Dispute the Cause.” So am I. There are such better ways to tell this complex, but still important story.

There are three fundamental points here that every story on this topic should get across:

1) No single weather event is  caused by climate change; climate is defined as the sum total of weather, so the effect of a climate change on weather is only detectable in the aggregate statistics.

2) For some types of severe weather, such as tornadoes, the science doesn’t currently allow us to say that global warming is making them worse. So that shouldn’t be stated.

3) Nevertheless, global warming represents a key change operating in background of all weather—there’s more overall heat. This is certain to have a wide array of consequences—like a greater risk of heat waves, and more intense precipitation events–and indeed, some of those are already being detected.

Is that hard?

For another good explanation see here.


Comments (20)

  1. TA

    What should also be mentioned is that there are more people than ever before, densely packed, but also using more land than ever before, with property values that are higher than they ever have been before.

    So, even if the extreme weather events remain constant for the next 100 years, the real world effect will always be ‘the worst ever’.

  2. Zathras

    Seems to me that there is a simple description of climate vs. weather:

    Climate = signal (the overall temperature/heat)
    Weather = noise laid on top of that signal (local weather forecast)

    Which is why climate is only discernable in retrospect.
    Are my definitions correct/incorrect/oversimplified?

  3. Nullius in Verba


    That’s a definition that is sometimes used. There are several, depending on what aspects you are interested in studying.

    In general, the difference between weather and climate is frequency. The state of the atmosphere varies in a very complicated way, but one way of simplifying it is to think of it as a sum of components, each of which varies on a narrowly defined timescale. There’s a part that varies from minute to minute, another that varies over hours, a third (very strong) one varies over a day. There are changes over weeks, months, the whole year, years, decades, centuries, millenia, etc.

    For example, sunny intervals vary on scales from minutes to hours, storms occur over hours to days, high and low pressure systems move over days to weeks, blocking high’s can last for months, the El Nino/La Nina cycles and the Northern and Southern Annular Modes over months to years, the larger climate oscillations – the Atlantic Meridional Oscillation (AMO), Pacific Multidecadal Oscillation (PDO), etc. – vary over decades. The interstadials (the Bond and Dansgaard-Oeschger events) occur over a 1500 year cycle. Ice ages occur on 40,000 and 100,000 year cycles. And there have been longer-term changes still.

    Both natural and artificial influences drive change on all timescales. To put it simply, climate is the low frequency components of that variation, and weather is the high frequency components. There isn’t any objective dividing line between the two – it depends on context. Some people take the threshold as 30 years (mainly because when they first started talking about it, they had about 30 years of good data), but some take five to ten years and some take only intervals longer than centuries. Usually it depends on what you want to know – for practical purposes, times based on the human lifespan or the rate at which agricultural practices can change are often used.

    The signal/noise paradigm is often useful because in signal processing we often want to enhance a low-frequency signal buried in noise that is spread across all frequencies. If we cut off the highest frequencies (by smoothing or averaging), it affects the noise far more than the signal (because the noise is stronger at those frequencies), and so reduces the error. Many of the same techniques used for doing this are also useful in studying climate.

    And yes, that’s why climate is only discernable in retrospect.

  4. Susan Anderson

    I believe we need to be careful not to buy into the campaign to eliminate all extreme events from the data. Extreme events are large “signals” if you will, indicators of a trend.

    Unfortunately, this distracting debate is intended to do just that – distract. If we are talking about measurement, eliminating the outliers can be useful, but in this case it is a mistake, because we are dealing with reality.

    Extreme events, in fact, are the ones that get our attention because they endanger lives and livelihoods. Non-technical people, people who don’t “believe” in science, are reached by nature’s power. While I agree it is a bad idea to exploit these events it is also a mistake to ignore them.

    A dataset without extremes is incomplete. Perspective is useful, but blindness is idiocy. We need a better sense of time and space. History is still relevant but forgetting is becoming the mode du jour.

  5. Joe Romm was “upset” with the headline, not the piece. Andy Revkin captured the hilarity in a tweet:

    Kind of amusing to see Joe “Stunner” Romm ( point finger at “Crappy Headline” elsewhere:

  6. How hard can it be to explain?
    Just ask how many of Mark McGwire’s home runs were caused by steroids…

  7. Matt

    It appears that many people feel that the term “global warming” is a negative term and an attack on their values; and, as such, it causes more political turbulence than it should. Maybe framing it in terms of ‘climate stabilization’ would put it in a more positive light.

  8. Nullius in Verba

    “It appears that many people feel that the term “global warming” is a negative term and an attack on their values”

    The term “global warming” is fine. Whether it is taken negatively depends on what you mean by it. If you simply mean that the global average temperature anomaly has increased during the 20th century, then there’s no problem. If you use it to mean specifically the increase due to emission of CO2, or the projected future increase over the next century due to CO2, then many people regard it as an unproven/unquantified hypothesis. (It makes a positive contribution to the temperature, but whether the net result is or will be either positive or significant is a different question.) If by “global warming” you mean the campaign to forcibly restrict CO2 emissions by means of laws, regulations, taxes, subsidies, compensation, or other uses of state power in order to prevent all or part of the hypothesised future rise, then yes, many people see it as an attack on their values. But in that case I don’t think changing its name will help.

  9. Sean McCorkle

    The “loaded dice” metaphor at SkepticalScience is a good one, but the general public often has difficulties applying statistics in real life (risk analysis, lotteries, etc). With human tendencies to see patterns where there are none in random events on one hand, and motivated denial of reality on the other hand, a nuanced message is going to tough to get across.

    It makes a positive contribution to the temperature, but whether the net result is or will be either positive or significant is a different question.

    ? The net result is positive: global average temperature has increased. The CO2 increase is sufficient to explain that.

  10. Nullius in Verba


    f(x,y) = ax+by+c, where a,b,c are unknown constants.
    It is known that f(x,y) increased and x increased. It is not known what happened to y.

    Prove that the increase in f(x,y) was “caused” by the increase in x.

  11. NikFromNYC

    Cold fusion featured in the LA Times in ’89 before it was debunked. Environmentalists were aghast at the possibility of cheap clean energy:

    “It’s like giving a machine gun to an idiot child.” – Paul Ehrlich (mentor of John Cook of the SkepticalScience blog, author of “Climate Change Denial”)
    “Clean-burning, non-polluting, hydrogen-using bulldozers still could knock down trees or build housing developments on farmland.” – Paul Ciotti (LA Times)
    “It gives some people the false hope that there are no limits to growth and no environmental price to be paid by having unlimited sources of energy.” – Jeremy Rifkin (NY Times)
    “Many people assume that cheaper, more abundant energy will mean that mankind is better off, but there is no evidence for that.” – Laura Nader (sister of Ralph)

    CLIMATEGATE 101: “For your eyes only: Don’t leave stuff lying around on ftp sites – you never know who is trawling them. The two MMs have been after the CRU station data for years. If they ever hear there is a Freedom of Information Act now in the UK, I think I’ll delete the file rather than send to anyone….Tom Wigley has sent me a worried email when he heard about it – thought people could ask him for his model code. He has retired officially from UEA so he can hide behind that.” – Phil “Hide The Decline” Jones to Michael “Hockey Stick” Mann

    Here I present The Quick Glance Guide to Global Warming:

    -=NikFromNYC=- Ph.D. in Carbon Chemistry (Columbia/Harvard)

  12. Sean McCorkle

    What does that example have to do with AGW? I could see maybe a function of one variable, time.

    Also, don’t confuse mathematics, a discipline of proofs, with science, where things are rarely, if ever, proven. “Not yet falsified” is about as close as it gets in the real world.

  13. Edmh

    Looking at the recent sunspot announcements, we should be concerned about increasing extreme weather events. They are more likely to be linked to GLOBAL COOLING, which is currently just starting its progress and is likely to continue cold for a generation, if not longer.

    Will global warming alarmists ever wake up to this.

    North-western USA temperatures have been low this year with massive snowfalls etc. These lower temperatures and warmer air form the Gulf of Mexico generate increased differentials and thus give rise to the more extreme weather / tornado events that we have seen recently.

    As Global Cooling proceeds the differential – Poles to the Equator grows and one can expect more weather extremes not less.

    A warmer climate is likely to be more BENIGN but a colder climate is TRULY DEADLY.

    From Brian H | June 1, 2011 at 6:22 am |
    At a rough guess, the odds of warming being benign are about 80%, and of cooling being benign about 0.01%. The odds of warming occurring are about 10%, and of cooling occurring about 60%. The ratio of the riskiness is thus [(1-.8)(.1)]/[(.6)(1-.9999)] = .02/.00006 = 333. So it makes 333X more sense to prepare for cooling disaster than for warming.

  14. Nullius in Verba


    f is temperature anomaly, x is CO2, y is everything else.

    OK, it’s “not yet falsified” that the 20th century warming was due to the warm phase of the PDO, that CO2 contributed less than the noise, and we have nothing to worry about. Isn’t that good news?

  15. Sean McCorkle


    OK, it’s “not yet falsified” that the 20th century warming was due to the warm phase of the PDO, that CO2 contributed less than the noise,

    If one looks, one can discern features of the PDO signal superimposed on the steady temperature climb of the last century, but it certainly doesn’t explain that climb – the temperatures near 2010, during which time the PDO index oscillated close to zero, are far higher than the mini-peak around 1945 or so, when the PDO was quite high.

    There, falsified that for you.

    f is temperature anomaly, x is CO2, y is everything else.

    You’re leaving out the most important parameter, time. f(t) is more informative for comparisons and potential tests. f(t) is measured, so is x(t), and they have similar profiles (unlike your PDO).

    Don’t dismiss “not yet falsified”; Its important in the context of other proposed hypotheses which have been falsified. Many hypothesis have been tried, many have failed. AGW survives.

  16. Chris – this is author/columnist, David Lawrence Dewey.

    I have been writing about global warming since 1997 well before Al Gore came along.

    I have found that most people do not know the real facts and deniers of global warming are using the carbon tax issue as the means to argue man has NOT caused the premature warming of the planet.

    My column, Global Warming – Is It Too Late? – provides much data.

    Here is a time laspe video which shows how much of the Arctic has melted from 1980 through August 2010. If this does not convince people that MAN is the primary cause of the premature warming of our planet…. I don’t what will.

    Also this…

    “Temp Leads Carbon” Crock”

    A recent report published this week by scientists observing SUN activity have found that the sun has been in a period of “inactivity”, less warmth for the last several years. This is important to know because if the sun had been in its’ normal heat dispersion, temperatures which are already above normal worldwide would be much greater.

    Here is additional data:

    Analysis of ice core samples done by totally independent researchers from the National Geographic Society have isolated man made carbon gasses in the ice at ever increasing levels since the 1900’s and especially since 1980.


    Oceans are dying, worst than expected say experts:

    The reason why politicians have basically sat on their behinds and not passed the correct laws because they have been in the pockets of the corporations that have been helping man cause global warming. Until people all over the world truly grasp what is happenning to our planet caused by man, and then start to unite and stand up to the politicians to pass the correct laws, passing tarriffs on imported goods so that companies will be forced to bring the manufacturing back to the U.S. and create jobs, until the government and yes in this case we need government intervention, force the auto maunfacturers to TRULY build fuel efficient and no polluting CO2 emission cars,( they have had the technology for years – they have simple been partners with the oil companies since every major auto maker owns OIL stock )- when Americans STOP buying the junk made overseas at Wally World, Kmart and Target and start buying American made, yes it may cost more, however, everytime ten American buys crap made in China or where ever, it has cost ONE American his manufacturing job. China has become the world’s worst polluter now. This has been proven…we have already lost over 5 million manufacturing jobs in this country during the last year of Clinton and during the 8 years of Bush. Until Americans truly start to see what has really occured while they slept, and then start to accept what they MUST change in their behavior and start standing up to politicians regardless of party to do the RIGHT THING, things are only going to get worse, they already have with what is occuring worldwide with floods, droughts etc. The handwriting is on the wall – it does not take a genius to figure it out.

    Americans MUST take off the blinders and start seeing the truth of their actions, accept they must change and then do something about it instead of simply complaining about everything, but mainly they just might have to change their lifestyles, which many people are too selfish to do.

    YES, man MUST change and immediately to reverse what man has done to planet earth, if mankind does not, we WILL destroy ourselves. That is the truth and people must start to accept that now!

    In addition, I am not too happy with President Obama. He has not come forward to the American people or the world and tell it like it is concerning global warming. He has fallen prey to corporate influence as other Presidents have concerning ignoring the facts and President Bush was the worst. It is interesting in a latest poll that 67% of Republicans do not believe man has caused global warming. I find this interesting because it has been Republicans that have fought EPA regulations for years, again backing the corporations, and folks its all about GREED !

    Does mankind want to go down at the generations that destroyed our planet.

    Drop me an email Chris !

    People – we only have one planet to live on – we must stop destroying her !

  17. Nullius in Verba


    Temperature is related to the integral of the PDO. The zero of the index is arbitrary – it’s just chosen to centre the recent data. The PDO (hypothetically) controls how much extra heat enters the ocean surface layer (e.g. PDO might affect cloudiness, which would affect the Earth’s albedo and how much energy it receives from the sun) and heat is cumulative. PDO was more positive, meaning heat was accumulating in the system, from 1920 to 1945, and from 1975 to 2000. The PDO being negative reduces the heat input to close to zero, and the temperature stays constant.

    If you require every wiggle to match, then I will observe – as many have before – that temperature anomaly did not rise between 1940 and 1980, while CO2 did. “There, falsified that for you.”

    The PDO idea is a hypothesis. The wiggle match is also obvious “correlation implying causation” and not a proof of anything. (Much like the “CO2 matches temperature rise” claim.) But if your standard of science is “not disproved yet”, then I have millions of claims that meet that standard. You can’t say that just because CO2 can be made to fit temperature rise for some particular choice of the unknown parameters, that it therefore “explains” it. It’s a different question.

    Incidentally, given that I just said that CO2 contributes positively to the temperature, I hadn’t disagreed with AGW – for one particular interpretation of the term. In this particular case, AGW survives anyway; so why argue?

  18. Sean McCorkle

    Temperature is related to the integral of the PDO

    The data is online; integrating it over that range doesn’t yield a secular increase anywhere near that seen in the global temperature rise over that time. By far, any long term trend in the integral over that range is completely dominated by the ups and downs in the 40s and 50s.

    But I will meet you partway on this: while the increase in CO2 explains the secular rise in temperature (the main feature of the temperature profile over the last century), it doesn’t explain the smaller features which do concur nicely with PDO variations, so its clearly involved in modulating the temperature in addition to the CO2. Its just not playing a major role.

    But if your standard of science is “not disproved yet”, then I have millions of claims that meet that standard.

    Thats always the case in science. Thats why we have things like Occam’s Razor, among other princiciples, to cut them out.

  19. Nullius in Verba


    What origin did you use?

  20. Sean McCorkle

    what origin? for the integration? first point


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About Chris Mooney

Chris is a science and political journalist and commentator and the author of three books, including the New York Times bestselling The Republican War on Science--dubbed "a landmark in contemporary political reporting" by and a "well-researched, closely argued and amply referenced indictment of the right wing's assault on science and scientists" by Scientific American--Storm World, and Unscientific America: How Scientific Illiteracy Threatens Our Future, co-authored by Sheril Kirshenbaum. They also write "The Intersection" blog together for Discover blogs. For a longer bio and contact information, see here.


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