Friday, August 7, 2015

Los Angeles Has Warmed 3 Degrees Over the Last Century, But Baton Rouge Has Gotten Cooler

Climate data offers a lot of interesting details that go well beyond the tired believe it/don't believe it headlines in the press.    The EPA recently published a chart showing average temperature growth across the U.S. since 1900.  Interestingly, many of the areas warming up the most are colder and drier, while the hot, humid Gulf Coast hasn't warmed at all, and has even gotten cooler in some spots.

Los Angeles has seen average temperatures rise three degrees over this time period according to the EPA.  But annual deviations often exceed this level, which means it's possible to not to sense global warming is occurring at all.  For example, the average temperature in LA was 64 degrees in 2012, same as it was in 1930.   But it shot up to 68 degrees in 2014.   Though this was less than the all-time peak of 69 degrees reached twice over thirty years ago, but hasn't been reached since. However, from 1880 to 1914, LA only averaged 64 degrees or higher once.  While from 1980 to 2014, it never averaged less than 64 degrees.

With long-term average annual increases not much larger than the standard deviation in annual temperature, it's very easy to think there is no warming.  Moreover, it makes dire predictions less credible, because while extremes could occur, there will also be individual years a century from now that are no warmer than today, even in a climate that's warmed by a few degrees.

In addition to the deviations among years, deviations among places are also important to acknowledge.  While it's an anomaly, Alabama has actually gotten cooler over the last 100 years.   The humid Southeast has been far less impacted by increased CO2 than the arid Mountain West.   While there is no doubt humans are on average warming the planet, climate science would be far more credible if it focused more on the variances in today's impacts, and less on questionable predictions.

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