Bombshell: Study Finds 80% Chance Russia’s 2010 July Heat Record Would Not Have Occurred Without Climate Warming

A major new study has reanalyzed the connection between global warming and the record-breaking temperatures we’ve been seeing.  Stefan Rahmstorf and Dim Coumou conclude in their PNAS paper, “Increase of extreme events in a warming world“:

the majority of monthly records like the Moscow heat wave must be considered due to the warming trend. In highly aggregated data with small variability compared to the trend, like the global-mean temperature, almost all recent records are due to climate warming.

Basically, they show that when there is a lot of variability in temperature, as there is on in individual days, finding a trend in extreme records at any single location thanks to global warming is small:  “daily data from a single weather station may not yet show a major change in temperature extremes due to global warming.”

But when you look at the monthly and especially yearly temperature data at a location, data that have considerable less fluctuation, then a warming trend is far more likely to create a new record.  And as lead author Rahmstorf explained to me, this matters because “monthly temperature records have much more impact on human society” in terms of impact on human health, mortality, and crop failures.

And, of course, the Russia’s heat wave apparently caused very high mortality.  As Reuters reported last year, “Nearly 56,000 more people died nationwide this summer than in the same period last year, said a monthly Economic Development Ministry report on Russia’s economy.”  And it caused Russia to ban grain exports for over a year after their crops shriveled (see Russian President Medvedev: “What is happening now in our central regions is evidence of this global climate change, because we have never in our history faced such weather conditions in the past”).

The PNAS study found:

For July temperature in Moscow, we estimate that the local warming trend has increased the number of records expected in the past decade fivefold, which implies an approximate 80% probability that the 2010 July heat record would not have occurred without climate warming.

Global warming increased the chance of this monster heat-wave occurring by a factor of 5.  I’d note that Tamino doing a far cruder analysis had estimated global warming had increased its chances by a factor of 8.

This is only a bombshell because NOAA did a flawed analysis just a few months ago that found no connection between global warming and the record-smashing.   Back in March, NCAR Senior Scientist Kevin Trenberth challenged NOAA’s attribution analysis, “Many statements are not justified and are actually irresponsible,” as Climate Progress reported.  It is unusual for a major study like that to be essentially refuted in such a short time in the peer-reviewed literature.

Rahmstorf told Wired that the NOAA study showed “an absence of evidence, not evidence of absence. We found the evidence.”  Here is one key figure:


NOAA had said there was no trend in the relevant temperature data.  Rahmstorf explains:

… in the NASA GISS data that we analysed, we found a similar lack of warming trend in July in Moscow when looking at the adjusted data, whilst the original data do show a strong warming (see our Fig. 5). In the GISS data, over-correction for the urban heat island removes this warming trend. The reason is poor and gappy rural data in the Moscow region and the fact that the urban heat island effect is very large in winter in Moscow, but GISS applies an annual-mean urban heat island correction. In effect the July temperatures are thus corrected down far too much. (But whether this is also the problem with the NOAA analysis, I have not been able to find out yet.) The kind of automatic adjustment applied by GISS is okay for looking at the big picture like global trends, but for a local analysis one needs to look at the raw data from the weather stations in the region.

NOAA wrote that “We conclude that the intense 2010 Russian heat wave was mainly due to natural internal atmospheric variability,” but that now clearly appears to be wrong, much as Trenberth had suggested.

The PNAS study concludes:

Our statistical method does not consider the causes of climatic trends, but given the strong evidence that most of the warming of the past fifty years is anthropogenic, most of the recent extremes in monthly or annual temperature data would probably not have occurred without human influence on climate.

Of course, the reason why people are concerned about global warming is because of what we face if we don’t restrict greenhouse gas emissions.  There the original NOAA study still carries a powerful warning: “Monster crop-destroying Russian heat wave to be once-in-a-decade event by 2060s (or sooner).”

Again, this extreme event ended Russian grain exports for year.  So the increase in extremes very much threatens food security if we don’t act soon to reverse emissions trends.

I had very interesting conversation with Rahmstorf about the metaphor of  loading the dice for extreme weather events and whether or not we are painting higher numbers on the dice, but I’ll discuss that in a few days.

This is a cautionary tale:  One needs to do these statistical “attribution” studies very carefully to fully understand how much to attribute the impact of the human-caused warming trend on extreme events.


This post has been updated.

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16 Responses to Bombshell: Study Finds 80% Chance Russia’s 2010 July Heat Record Would Not Have Occurred Without Climate Warming

  1. Tom Gray says:

    Huh, doesn’t that graphic remind you of the ones John Nielsen-Gammon, the Texas State Climatologist, did showing how off-the-charts the 2011 summer was in Texas? Striking, really.

  2. Peter Mizla says:

    All the weather anomalies probably have a strong correlation to climate change with this NOAA admission.

    The question now is how much quicker will such extreme events begin to occur globally? The pattern is now becoming established. Have the climate models been to slow in predicting earths capacity to react to Greenhouse gases?

  3. David B. Benson says:

    As a result of the ban on exports of wheat from Russia and neighboring countries in 2010 as a result of that heat wave, local producers did very well. The price still hasn’t come down this year and the total price received this year for a somewhat larger crop was again up a whopping 59% over 2007 returns.

    Oh yes, and also the Palouse is #2 wheat producing region in the USA (for the first time). Get the hint?

  4. David B. Benson says:

    It is indeed what I remembered: Tamino’s analysis suggests a 1-in-250 year event with global warming and a 1-in-1000 year event without. Too me that’s 4 times more likely.

  5. with the doves says:

    That’s an amazing graph up top.

    Thanks for the story.

  6. Dr.A.Jagadeesh says:

    Excellent post.Growing temperatures compared to past records in many countries confirm the climate change due to global warming.

    Dr.A.Jagadeesh Nellore(AP),India

  7. Spike says:

    sadly this is too late to have prevented Myles Allen from stating in the UK press that the Russian heatwave was unconnected to climate change.

  8. prokaryotes says:

    There are currently no reply features visible in the comment section.

  9. prokaryotes says:

    Now visible again, looks like the page loaded incomplete.

  10. prokaryotes says:

    Russian Heat Wave Statistically Linked to Climate Change

    A new method of crunching climate data could make it possible to put a figure on climate change’s contribution to freak weather events, something that’s been difficult to do with empirical precision.

    The debut subject: the Russian heat wave of July 2010, which killed 700 people and was unprecedented since record keeping began in the 19th century. According to the analysis, there’s an 80 percent chance that climate change was responsible.

    The new method, described by Rahmstorf and Potsdam geophysicist Dim Coumou in an Oct. 25 Proceedings of the National Academy of Sciences study, relies on a computational approach called Monte Carlo modeling. Named for that city’s famous casinos, it’s a tool for investigating tricky, probabilistic processes involving both defined and random influences: Make a model, run it enough times, and trends emerge.

    “If you roll dice only once, it doesn’t tell you anything about probabilities,” said Rahmstorf. “Roll them 100,000 times, and afterwards I can say, on average, how many times I’ll roll a six.”

    Rahmstorf and Comou’s “dice” were a simulation made from a century of average July temperatures in Moscow. These provided a baseline temperature trend. Parameters for random variability came from the extent to which each individual July was warmer or cooler than usual.

    Kevin Trenberth, head of climate analysis at the National Center for Atmospheric Research, said the new method gives statistical support to research on the weather dynamics underlying individual extreme weather events.

    In future research, Rahmstorf and Coumou plan to run Monte Carlo simulations of recent record temperatures around the world. They may put their model to the ultimate test: not just explaining what’s happened in retrospect, but forecasting the frequency of future records. “You could predict the likelihood for what happens next, not just the past,” said Rahmstorf.

  11. Colorado Bob says:

    And, of course, the Russia’s heat wave did kill 700 people ……

    MOSCOW | Mon Oct 25, 2010 3:21pm EDT

    MOSCOW (Reuters) –
    Nearly 56,000 more people died nationwide this summer than in the same period last year, said a monthly Economic Development Ministry report on Russia’s economy.

  12. Joe Romm says:

    Serves me right for quoting Wired!

  13. prokaryotes says:

    But this is part of the article…

  14. Chris Winter says:

    Anyone looking at that graph can see at a glance the preponderance of high-side anomalies.

    Also, this release is very timely, following the BEST study by just a few days.

  15. Icarus says:

    Climate change is, of course, all about trends. Here we’re discussing trends in extreme temperature records but there must be many different trends for which we have data – e.g. rainfall intensity and distribution, atmospheric water vapour, wind patterns, ice melt, permafrost thaw, hurricane strength and so on.

    Is there a website which attempts to aggregate what we know about these trends and make them publicly available? It’s fine to discuss individual events but the evidence for what’s happening to our climate is in the trends, and that’s what needs to be as widely and easily accessible as possible.