More Evidence of Warming: Hottest May and Longer Summers

Map: Brian Brettschneider, The Washington Post

Climate change is causing a change in the “balance” of the seasons according to new research by a scientist with the National Weather Service, The Washington Post reports.   Examining temperature records for the hottest and coldest 90 days of the year, over the past two 30-year periods, 1960-1989 and 1990-2019, “in most locations globally, including in the United States and Canada, have seen their summer season lengthen and the winter season shrink.”  On average, the U.S. and Canada gained a week of summer. Oh, and May of this year was the warmest ever recorded.

Why This Matters:  Some cities gained not just weeks, but more than a month of summer.  What could be so bad about more summer and less winter?  (We can just imagine the tweets were the President to get a hold of this fact)  Let us count the ways: it lengthens the time vulnerable populations are heat stressed, it could decrease water availability, it might expand the wildfire season, as well as increase pests harmful to forestry and agriculture, not to mention humans.  And if the change is this significant, the ripple effects on other species besides us humans are too numerous to count, but will no doubt be significant as well.

By The Numbers 

The 10 major U.S. cities that have seen the lengthiest increase of summer over the past 30 years are: Honolulu, 38 days; Miami, 37 days; San Francisco, 32 days; New Orleans, 25 days; Phoenix, 23 days; Tucson, 21 days; El Paso, 20 days; Houston, 18 days; and Las Vegas, 18 days.  The 10 major U.S. cities with the longest decrease in winters are: Los Angeles, 52 days; Miami, 49 days; Juneau, Alaska, 32 days; Orlando, 30 days; New Orleans, 28 days; Anchorage, 25 days; Phoenix, 25 days; Honolulu, 23 days; San Francisco, 23 days; and Philadelphia, 22 days.  This research is consistent with a similar study conducted in Australia, which is also experiencing longer summers and shorter winters.  The same is happening all over the globe in fact.  London‘s winter is now 36 days shorter than 30 years ago, and its summer is 17 days longer, for example.  In northern Canada and Alaska, the shortening of winter is particularly significant, but the shorter winters are also quite dramatic in Southern California and South Florida.   As for the warmest May, the largest temperature spike was in Siberia, where it was up 10 degrees Celsius on average levels.

Map: Brian Brettschneider, The Washington Post

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