Climate Progress

Science has just published, “Atmospheric Warming and the Amplification of Precipitation Extremes” (subs. req’d). It concludes:

Here, we use satellite observations and model simulations to examine the response of tropical precipitation events to naturally driven changes in surface temperature and atmospheric moisture content. These observations reveal a distinct link between rainfall extremes and temperature, with heavy rain events increasing during warm periods and decreasing during cold periods. Furthermore, the observed amplification of rainfall extremes is found to be larger than predicted by models, implying that projections of future changes in rainfall extremes due to anthropogenic global warming may be underestimated.

In short, global warming is going to make extreme weather even more extreme than scientists have thought. And this conclusion is based largely on observational evidence:

The study team analyzed satellite images of rainfall over tropical oceans over nearly two decades, from 1988 to 2004….

This is something that climate models had predicted,” [coauthor Richard] Allan said. “But getting the data from observations is very important”….

For every 1.8 degree Fahrenheit (1 degree Celsius) rise in global temperature, heavy rain showers became more common, with most intense category jumping 60 percent.

Remember that on our current emissions path, we are headed towards 5°C warming in this century alone (see “Is 450 ppm politically possible? Part 0: The alternative is humanity’s self-destruction“), which suggests we are headed for a staggering increase in intense rainfall. This has huge implications for both agriculture and human health:

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Repeat after me, Joel: “Global warming makes the weather more extreme.” If even the Bush administration accepts that basic fact of climate science, shouldn’t you?

I used to like Achenbach’s cutesy science pieces, but his knowledge of climate science is about one or two decades old, as evidenced by his major story in the Washington Post today, “Global Warming Did It! Well, Maybe Not.” It is a typical ly uninformed journalistic “backlash” piece, whereby a reporter creates a straw man and then sets it on fire.

Achenbach is trying to seem reasonable by complaining that the next time we get a big hurricane, “some expert will tell us that this storm might be a harbinger of global warming.” Uhh, I hate to break this to you Joel, but global warming doesn’t need a “harbinger.” It has been here for decades.

In that sense, your article is not a harbinger of global warming denial, since deniers have been pushing back against the “global warming causes extreme weather” story for years, browbeating the media into downplaying the connection. You really should read your fellow journalist Ross Gelbspan’s long discussion of this in his great 2004 book, Boiling Point. Achenbach writes:

Weather alarmism” gives ammunition to global-warming deniers. They’re happy to fight on that turf, since they can say that a year with relatively few hurricanes (or a cold snap when you don’t expect it) proves that global warming is a myth. As science writer John Tierney put it in the New York Times earlier this year, weather alarmism “leaves climate politics at the mercy of the weather.”

You cannot be serious. The best you can do is quoting Tierney, a well-known climate doubter/denier/delayer? And deniers don’t need to look for any ammunition — they just make up stuff. You could waste a lot of time trying to figure out what you should or shouldn’t say based on a fear of how deniers might twist it or take it out of context.

This is simple stuff. As the climate changes because of human-caused greenhouse gas emissions, the weather becomes more extreme. That’s what climate change is. I understand why deniers don’t want the rest of us talking about the connection between global warming and the surge in extreme weather events that has been documented statistically by scientists — including NOAA’s National Climactic Data Center (NCDC). That would shut down most discussion of current climate impacts. But I don’t understand why Achenbach falls for that spin.

Anyway, it is now officially absurd to take the view of the deniers, Achenbach, and Tierney. Back in June, the U.S. Climate Change Science Program (aka the Bush Administration) issued Weather and Climate Extremes in a Changing Climate that acknowledged the basic climate science:

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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.

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I know we’re supposed to be going into a period of cooling, at least according to people who don’t believe in the scientific method, but for those who do, NOAA’s National Climatic Data Center reports in its “Climate of 2008 June in Historical Perspective“:

Based on preliminary data, the globally averaged combined land and sea surface temperature was the eighth warmest on record for June and the ninth warmest for January-June year-to-date period.

It is pretty darn hot in Greenland and Siberia, not like there’s anything important in those regions:

Seriously, though, a 4°C to 5°C anomaly over Siberia is bad news for anyone who worries about the 1000 billion tons of carbon locked away in the permafrost (see “Breaking News — Tundra 4: Permafrost loss linked to Arctic sea ice loss“). Speaking of sea ice:

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Global warming threatens our White Christmases with winter heatwaves. And our Halloweens with poor pumpkin crops. And our Arbor Days with record wildfires. And our immoral myopia threatens Father’s Day. At this rate, the only holiday left will be the gas tax holiday — for oil companies!

But I digress. Last year, Independence Day fireworks fizzled out for many thanks to ever worsening droughts. And the droughts have done it again this year:

Rockets’ red glare to dim this Fourth of July
Dry conditions, booming costs lead many cities to drop or ban fireworks

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[I’m not sure this Independent story is quite that big a deal, but it got Drudge all globally hot and bothered with the banner headline and pic below, so at least the deniers and delayers will all see it.]

SHOCK CLAIM:,

NO ICE AT
,

NORTH POLE
,

THIS SUMMER

,

Related Posts:

• Arctic sea ice update: 2008 poised to repeat — or beat — 2007
• Breaking News — Tundra 4: Permafrost loss linked to Arctic sea ice loss
• Forecast: 3-in-5 chance of record low Arctic sea ice in 2008

Part 1 presented the synopsis of the remarkable new U.S. Climate Change Science Program (aka the Bush Administration) report, Weather and Climate Extremes in a Changing Climate. One central point in the synopsis is

Droughts are becoming more severe in some regions, though there are no clear trends for North America as a whole…. Substantial areas of North America are likely to have more frequent droughts of greater severity.

Seems pretty clear, no? Dry areas will see more evaporation, hence less soil moisture (defined as precipitation minus evaporation), hence more drought. Further, many dry areas will see less precipitation under climate change (due to the expansion of the Hadley Cell and subtropics, see “Australia faces the “permanent dry” — as do we“).

Simply put, dry areas will get drier. The Bush report even summarizes a study I have written a lot about (see “The Century of Drought“):

For example, extreme drought increases from 1% of present day land area (by definition) to 30% by the end of the century in the Hadley Centre AOGCM’s A2 scenario.

[Note: The A2 scenario leads to atmospheric concentrations of CO2 of about 850 ppm by century’s end. On our current path, we are headed beyond 1000 ppm (see here).]

On the other hand, climate change science projects also more overall precipitation because the atmosphere will contain more water vapor [see “Global warming causes deluges and flooding, just like the Midwest is seeing (again)“]. Simply put, wet areas will get wetter.

Obviously, a country like the United States will see some areas getting wetter and some areas getting drier, so we would expect to see no clear drought trend for the country as a whole, but much worse weather extremes in different places. Bad news. At least, to some.

But suppose you are a climate change delayer enabler like, oh, I don’t know, Roger Pielke, Jr. How would you summarize the report? Well, you would list a bunch of “remarkable conclusions” that “somehow did not seem to make it into the official press release,” including (remarkably):

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The U.S. Climate Change Science Program (aka the Bush Administration) has issued a must-read report, Weather and Climate Extremes in a Changing Climate. It wouldn’t be must read or even big news if it weren’t for the fact that

• Many environmentalists stopped talking about the extreme weather/global warming link a decade ago.
• The deniers, the delayers, and of course the Roger Pielkes of the world have pushed back against any claims that climate change is driving the extreme weather we see today [as Chico Marx (dressed as Groucho) said “Who you gonna believe, me or your own eyes?“]
• The media has been brow-beaten by the deniers into downplaying the connection. The journalist Ross Gelbspan has a long discussion of this in his great 2004 book, Boiling Point — I will blog on this later.
• The Midwest is experiencing the second “500-year flood” in 13 years. [Don’t worry, big media, it’s all just a big coincidence like the deniers keep saying.]

This report is really an “I told you so” from NOAA’s National Climatic Data Center and Tom Karl in particular, who has been a real leader in this area, helping to create the still rarely-discussed Climate Extremes Index (see “Global warming causes deluges and flooding, just like the Midwest is seeing (again).”

If you don’t read the whole report, at least read the synopsis:

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Satellite images show Lake Chad one-tenth the size it was in 1972, not even 40 years ago. Lake Chad used to be the world’s sixth-largest lake, but its resources have been diverted for human use or affected by rainfall such that its been almost entirely depleted in a very short amount of time.

In the IPCC’s 2007 report on impacts, vulnerability and adaptation in Africa, there is no specific mention of Lake Chad. But staring at these satellite images one can’t help but wonder how global warming, which is expected to cause drastic changes to the hydrological cycle (drought, rainfall, water levels, etc.), especially in Africa, will accelerate or contribute to the already scarce resources that this map demonstrates is quite the stark reality.

This is a follow up to the Climate Progress exclusive from April, “The Great Ice Age of 2008 is finally over — next stop Venus!” and May. NOAA’s National Climactic Data Center reported (here):

Based on preliminary data, the globally-averaged combined land and sea surface temperature was the eighth warmest on record for May, the seventh warmest for boreal spring (March-May).

But don’t worry deniers, you can still cling to the fact that …

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