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By Labor Day 2040, Will We Have Endless Summer Heat?

If we don't act fast on climate change, we won't be celebrating the end of blistering heat at Labor Day anymore.
 
 
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 Who ever would’ve guessed that there would be a Labor Day card for global warming.  But that is what SomeEcards are for:

But “The Onion” of e-card companies makes a serious point:  In the not-too-distant future, people are going to be amazed that anybody ever thought Labor Day signified the unofficial end of summer.  As Climate Progress discussed in “Mother Nature is Just Getting Warmed Up” in June:

Stanford climate scientists forecast permanently hotter summers

The tropics and much of the Northern Hemisphere are likely to experience an irreversible rise in summer temperatures within the next 20 to 60 years if atmospheric greenhouse gas concentrations continue to increase, according to a new climate study by Stanford University scientists….

“According to our projections, large areas of the globe are likely to warm up so quickly that, by the middle of this century, even the coolest summers will be hotter than the hottest summers of the past 50 years,” said the study’s lead author, Noah Diffenbaugh.

And this could happen even sooner since, “actual GHG emissions over the early 21st century have exceeded those projected in the SRES scenario used here, suggesting that our results could provide a conservative projection of the timing of permanent emergence of an unprecedented heat regime.”

In a terrific presentation from last year, Climate scientist Katherine Hayhoe has a figure of what staying on the business as usual emissions path (A1F1 or 1000 ppm) would mean (derived from the NOAA-led report):

 

Yes, absent a sharp and deep reduction in national and global emissions, by century’s end, Kansas (!) could well be above 100°F for three full months.  Labor Day will mean a return to those pleasant mid-to-upper 90s!

It truly will be an endless summer over much of Texas and Arizona and the Central Valley of California.  Not only will it be hot, but it will be very, very dry very, very soon:

 

drought map 2 2030-2039

The maps use a common measure, the Palmer Drought Severity Index, which assigns positive numbers when conditions are unusually wet for a particular region, and negative numbers when conditions are unusually dry. A reading of -4 or below is considered extreme drought.

The PDSI in the Great Plains during the Dust Bowl apparently spiked very briefly to -6, but otherwise rarely exceeded -3 for the decade (see here).  So the numbers projected by National Center for Atmospheric Research (NCAR) are already near catastrophic by the 2030s.  And they are beyond catastrophic by the 2060s (see New study puts the ‘hell’ in Hell and High Water).

The NCAR study warned, “The United States and many other heavily populated countries face a growing threat of severe and prolonged drought in coming decades … possibly reaching a scale in some regions by the end of the century that has rarely, if ever, been observed in modern times.

This drying creates a vicious circle.  The heat dries out the land.  Then Dust-Bowlification exacerbates the warming because when large tracts of land are dry, the warming doesn’t go into evaporating moisture from the soil, but into heating up land.  It bakes.  That’s why, for instance, the U.S. set so many temperature records in the 1930s Dust Bowl.  And it’s why in July 2011, drought-stricken Oklahoma saw the highest average temperature of any state in the continental United States for any month since statewide average temperature records began in 1895.

It’ll be a hellish summer for much of the West by mid-century — see Climate change expected to sharply increase Western wildfire burn area — as much as 175% by the 2050.

Here’s the grim wildfire projection from a presentation made by the President’s science adviser Dr. John Holdren in Oslo last year:

If you’re wondering what the worst-case might look like, then the UK Met Office has what you are looking for: Catastrophic climate change, 13-18°F over most of U.S. and 27°F in the Arctic, could happen in 50 years, but “we do have time to stop it if we cut greenhouse gas emissions soon.”

This is the “plausible worst case scenario” for around 2060 from the Met Office that occurs in 10% of model runs of high emissions with the carbon cycle feedbacks [temperature in degrees Celsius, multiple by 1.8 for Fahrenheit]:

Now that is an endless global summer.

 

ThinkProgress / By Joe Romm | Sourced from

Posted at September 4, 2011, 9:44am

 
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