Extreme heat illustrates climate change principle

IPCC framework for understanding climate variabilityCalifornians used to seaside breezes got a rude shock this weekend, as even cool Palo Alto soared into the triple digits. While this is just one data point in the long term studies of global warming, it contains a useful lesson in the difference between mean temperature and temperature distribution.

We often hear the quip “Hey, two degrees is no big deal” as a defensive reaction to the overwhelming evidence of climate change. Well, two degrees Celsius doesn’t seem big, but the resulting shift in the overall distribution of temperatures can lead to extreme impacts. As the IPCCC graph shows, with a normal or even Gaussian temperature distribution, shifting the mean to the right raises the likelihood of extreme weather events dramatically. Put simply, what used to be a once-in-a-hundred-years dog day of summer becomes a once-a-year heat wave like the one California is suffering through now.

In fact, the last scenario of both increasing mean and variance may be the most troubling. A January 2004 study in Nature (pdf) showed that a shift in mean alone was unlikely to explain an extremely improbable 2003 European heat wave. The paper gives some evidence that a local climate model with increased climate variability does a much better job explaining things.

While we are hesitant to draw conclusions from one particular weather event, the hot weekend got us both sweating and thinking about the future.

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  1. AW - July 25, 2006

    I’ve learned that people really don’t have much grasp of statistics, or more accurately, infinity trumping statstics. The idea that something is a “one in a million chance” or one in a trillion, or even astronomical odds against means that it’s actually highly likely to occur somehwere, just not at any given point.

    Infinity trumps careless statisticians.

  2. Tom - July 25, 2006

    Yes, lotteries would seem to prove your point.

    I might add that just because the public doesn’t understand statistics, doesn’t mean that we should pursue these types of investigations. What the Nature researchers showed is that current climate models don’t explain recent rashes of heat waves (they should be a once-in 46,000 year event) but that CO2 loaded models perform quite admirably in explaining these strange weather events.

  3. AW - July 25, 2006

    Never suggested that they shouldn’t be done. Just a caution towards attempting to make people understand how they actually affect things.
    That graphic is pretty good though. Should get some heads scratched.

  4. Nils - July 26, 2006

    Why is it in the discussions of global warming the emphasis is on the air temperatures and little is said about the energy contained in the warming oceans. The energy driving the weather in our world comes from the oceans and a small increase in ocean temperature represents a considerable amount of energy. The depth of the warm surface layer has been increasing and no one seems to be talking or researching this.

  5. mike johnston - July 26, 2006

    The oceans warming is half the equation fir the Permian extinction. Not because of the weather pattern change but due to the release of methane form the ocean bed. It is estimated that volcanic activity warmed the air/oceans by about 5 – 7 C. This eventually warmed the oceans about the same which released the sea bed methane. (it is solidified on the ocean beds). This GHG is 400 times more potent than CO2. This raised the air temp another 5 C and the result is a 10+ degree rise in temp over a 1000 year period. 95 % of the world species died.

  6. AW - July 26, 2006

    The methane ice on the seabed needs to warm up quite a bit. And since water has 1000 times the heat capacity of air, I think we’ll all be baking with other problems long before the methane is a serious issue. But once it goes, you can say so long to our nice little biosphere as we know it (even in the parched global warming state it’ll be in).

  7. pradwastes - July 26, 2006

    Methane is about 20 time as bad as CO2 for raising temperatures. The main problem that will come about as the air and water warm is more intense weather followed by problems with low-lying parts of the world. It angers me when ever I read or hear about Al Gore’s Inconvient lie. Perhaps some of these folks will change there minds when their air conditioner breaks. (like mine). Here in Southern California this has been the hottest June and will be the hottest July since 1877, when they have been keeping records.
    It is still very cold in the deeper parts of the oceans.

  8. Nils - July 27, 2006

    The methane thing is not something I understand, I do know tropical meteorology and how the weather is powered by our oceans. Getting caught in a hailstorm yesterday and having two days of thunderstorms is a reminder that we are messing with a pretty formidable force. The amound of energy stored in the ocean as increased temperature has a significant effect on the weather and not only El Nino, but world wide weather patterns. Tropical storms are dependent on the ocean surface heat energy and minor increases in temperature can have significant effects on storm strength. In years past it was not uncommon for a hurricane to mix up the warmer surface water with the deeper cooler water so that the next storm would not have the heat energy to grow. Now the warm layers seem to be deep enough that the mixing doesn’t provide significant cooling and tropical storms may follow each other.

  9. AW - July 27, 2006

    While the oceans are certainly heating up, the amount of energy required is enormous. There are about 1.3 Billion cubic kilometers of ocean out there. The need to raise them the 7-8 degrees C (maybe more) for the methane deposits to vaporize would require 1.3e9 km^3*1e15 cc/km^3 * 1 cal/deg/CC * 7 degrees = 9e24 calories. A calorie is 4.184 Joules, so 38e24 Joules. How much energy is that? Well, there’s about 1370 Watts/m^2 hitting the earth. The earth reflects some of that, but let’s say that the entire planet is water, with a pretty low albedo once the ice caps have melted. The earth projects an area of about 127.6 million square kilometers, or 127.6 trillion square meters, to the sun. 127.6e12 m^2*1.370e3 W/m^2=174.8e15 Watts hitting the planet at any given time. A Watt is a Joule per second, so we would need to have 38e24 J / 174.8e15 J/s = 2.17e10 seconds of all the sun’s energy hitting us. That suggests that we have 687 years before the oceans warm up enough to melt the methane deposits.

    I’m sure an oceanic scientist can point out some flaws, but I don’t think they can drop this by more than an order of magnitude, and the mean Albedo of the planet is actually 0.367, meaning that a third of the solar radiation is actually reflected into space… So that should increase our timescale. While that will drop as glaciers and icecaps melt, there is some minimum value that’s larger than 0. So methane deposits aren’t about to vaporize just yet. Storms getting more powerful due to warmer surface waters, that’s something else.

  10. Todd - July 28, 2006

    This graph is great. I can share this with my doubter friends and explain it. Or at least share the link. I did not read the rest of the article due to time issues for now, but I am sure it is packed with good info judging by a quick scan of the commments.
    Like many “average joes” that care about our environment and are educated but are working, have families, lives, and personal projects this info is disemminated is a format that is easily shared and discussed. Thanks for this article.

  11. Nils - August 2, 2006

    Thanks for all the math. Your figures indicate the tremendous amount of energy that the ocean can store. I am interested in the amount of energy that the oceans hold and the overall increase in that energy over the last hundred years.
    A layer of warm ocean water floats above the cool ocean water. The cooler water is about 6 degrees C. Oceanographers and Navy submarines are quite interested in the profile of the warm water and how deep the warm layer goes and so there should be a considerable store of information about the warm layer in recent years and also a body of information that was gotten earlier by oceanographers using less sophisticated equipment but it should still be indicative of the depth and temperature of the surface layer. A rough estimate of the amount of energy in the surface layer compared with what is present in modern times might be indicative of the increase in energy in the ocean surface and could be helpful in predicting future energy available in the ocean to drive the worlds weather. While hurricanes need ocean surface temperatures in the area of 84 degrees F, our day to day weather gets it’s energy largely by the latent heat of vaporization. The evaporation of the surface water cools the surface, but the deepening on the surface layer means more energy is available to vaporize more water resulting in more energy in the air. There are of course other sources of energy to drive the weather but the oceans remain the most important.

  12. pradwastes - August 3, 2006

    The ocean surface temperature off the coast of southern California has gone up to 80 degrees F. That has a big effect on sea life in the area. The methane deposits are in very deep water where it is 30 dregrees F or less and that not changed at all. Polar Ice melting raising sea level will home the point long before. It will not take long before we get hurricanes in Los Angelels. It is not just earthquakes to worry about.

  13. Joshua - July 28, 2009

    I live in Seattle where for the first time in recorded history it remained above 70 degrees all night last night. Besides that, we have been within a few degrees of record highs for the last week and it is expected to get higher in the next few days.
    Meanwhile, Spokane on the other, drier side of the mountain is actually colder. I speculate this is related to the heating of the oceans, which does contribute a large portion of the changing temperature in the weather.
    It drives me a little nutty when I hear anyone claiming that our scientists are in disagreement about climate change. Every reputable scientist is in agreement about two things: (1) Global Climate Change is real, it is happening now; and (2) Humans are accellerating, and likely causing, the heating of the atmosphere with greenhouse gas emissions.
    All the other “scientists” claiming it’s a hoax are being funded by oil companies, largely Exxon. You can track them all down, an their sham “scientific institutions” at exxonsecrets.org.
    Wake up and smell the burning pavement people! We’re all going to die if we don’t get it together. Still not sure? Think about the risks, youtube “How It All Ends” and use reason.