The red dates for 2010 are observed days with temperatures above 90°F; the red dates in 2050 are projected accounting for climate change. Images: Climate Central.
For most of us in the United States, and particularly on the East Coast, July's temperatures were a bit outside our usual summer comfort zones. As you can see in the graphic above, from Climate Central, in Philadelphia there were 17 days above 90°. The striking thing is that in four decades time, at current rates of greenhouse gas emissions and warming, these sort of conditions will be the new norm.
I'll let the graphics mostly speak for themselves, but this is how the folks at Climate Central derived the data:
To compute by how much average July temperature may change in the future, and compare that change to the July 2010 departure from historical averages, we used climate model simulations of future changes for the lower 48 United States. This data has a level of geographic detail of about 12 kilometers, and we extracted the data that the models simulate at the locations of our cities of interest (corresponding to the grid point closest to the city's latitude/longitude coordinates). This data has been obtained by a procedure that is detailed on the Climate Wizard website.
We took these so-called downscaled (more highly detailed) computer model projections for July average temperatures from 16 global climate models, and used emissions scenario A1B, which assumes that emissions will continue at a rate similar to that of today's emissions.
We looked at the average change predicted by these 16 models by 2050, averaged the July temperatures of the twenty years straddling the future date, and compared them to current average values from the same simulations.
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More on Global Warming Effects:
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