No, the Record-Setting April Heatwave Doesn't Prove Global Warming. But . . .


If you happened to be in part of the country that was hit by it, you sure noticed the warmer-than-usual temps caused by the April heat wave. It caused meteorologists across the country to ask if it was "July in April" and even got a few to mention global warming! But hold on--I am not about to suggest that a single hotter-than-usual week is evidence that the entire planet is experiencing global warming. That would be ridiculous, and that would be the same logic climate deniers use when it snows more than usual. In January. But with the high temperatures setting records around the world, it certainly means something in the greater scheme of things . . .And it does, of course. Here's Climate Progress:

We all know that you can't use a single weather event as evidence for or against climate change -- unless of course that weather event is a big snowstorm [wink] ... What people should be talking about are record highs versus record lows across the country. The figure above comes from a Weather Channel post by Jonathan Erdman, "July or April? Spring skipped?":

"To the south of this front, temperatures had soared into the 80s and, yes, 90s in many locations, shattering daily record highs. In fact, according to the National Climatic Data Center, in the seven-day period from March 29 through April 4, over 1100 daily record highs were either tied or broken in the nation!"

Now that is a heat wave!

Which is why the chart that leads this post is so important. As is this one:


The point is, is that the ratio of record highs to record lows recorded over the years is actually a good indicator of a warming climate. Over the last 40 years, we've seen a steady increase in the number of record highs compared to the number of record lows. This of course helps take into account the fact that though there is much fluctuation in temperatures from year to year--there is nonetheless a clear trend that can be observed by parsing the highest highs and lowest lows. And that, of course, is that those temperatures are rising--just look how many more record highs there have been compared to record lows over the last decade.

So those record highs from the April heatwave don't definitively prove climate change by any stretch of the imagination. But they contribute valuable data that when included in a larger set spanning the years, pretty clearly describes a trend of rising temperatures--and help comprise the strong case, that's ever-growing stronger, for global warming.

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