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COMMENTARY

With global warming still on a tear, July on track to be hottest month ever

In the recent hot spell, Western New York got off comparatively easy. While we had some oppressive dew points in the 70s, the  temperatures were nothing out of the ordinary. Elsewhere, the heat index soared to truly dangerous levels in New York City, Washington, D.C., Boston, and much of the Midwest. Among large cities, Minneapolis peaked with a heat index of 115.

This week, a new surge of extreme heat will develop in western Europe for a few days, while areas in eastern Europe and Russia will be much cooler. Again, the immediate conditions are more weather than climate. Yet, it continues to be more apparent the extremes have a climate tie-in more often than not. The tie-in appears most readily in examining the high amplitude waves in the jet stream that allow these extremes to extend across large portions of the continents. The current upper air pattern over North America has a greater amplitude for its ridge west and trough near the Great Lakes than the average flow for summer.

The high amplitude is linked to accelerated high latitude warming in the arctic, weakening the jet stream and allowing it to “buckle” into long waves more often. As I’ve written a number of times, peer-reviewed studies show the warmth in the arctic lessens the temperature contrast between the mid and high latitudes, and that causes the weakened, buckling jet phenomenon to occur much more often than it did a few decades ago.

While not totally unprecedented, wildfires in Greenland are becoming more common.

Climate writer Andrew Freedman summarized the current arctic wildfire situation overall in the Washington Post: “... the Greenland fire fits a broader pattern that is raising alarms in the climate science community. According to the Copernicus Atmosphere Monitoring Service (CAMS), the European science organization tracked more than 100 ‘intense and long-lived wildfires’ above the Arctic Circle since June. Calculations show these fires emitted enough carbon dioxide to be the equivalent of Sweden’s total annual emissions.”

So while Western New York basks in one of the most tolerable summer climates, it is the global picture that counts most for impacts around the planet. Mean global warming leads to reduced ice mass on the Arctic Ocean, on land, and even in Antarctica (where ice melt has greatly accelerated in the last five to six years around the periphery of the continent). It leads to warmer oceans and that, combined with land meltwater from shrinking glaciers is accelerating mean sea level rise.

From NASA, here is a graph of the global temperature anomalies compared back to 1880.

With careful measurements of solar energy input and the current stage of earth’s eccentric orbit, we know the only explanation for the vast majority of this warming is human activity (solar input has not been increasing, so it’s not the sun). The current stage of our orbit would normally be inducing global cooling. These orbital eccentricities have been largely responsible for past ice ages and warming periods prior to the industrial revolution. In other words, if you subtract our 42% increase in carbon dioxide since 1880 from the burning of fossil fuels, model simulations and physics dictate the world would not be warming since the second half of the 20th century; it would be cooling.

Of course, July is the warmest month of the year in the Northern Hemisphere. This July, however, appears to be on track to be the warmest month globally on record. This year will probably not be the hottest year on record, based on current trends, but it will be near the top.

Here is a tweet from Gavin Schmidt, director of the NASA Goddard Institute for Space Studies:

The NASA visualization below “brings it all home” on a global scale. This communication is vital, because not all regions of the globe are warming equally. The lower 48 states, for example, are warming considerably but not as much as many parts of the Eurasian landmass. Western New York is warming less than many parts of the U.S. But no part of the globe is warming as fast as the arctic, which is precisely what was predicted by climate models decades ago.

I often feature information from climate.nasa.gov because it is such an excellent source of information regularly updated by world-class climate scientists. However, if anyone believes this is “just” NASA’s thinking, the data is really quite uniform with separate samplings and analyses by five different organizations in very close agreement with one another.

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