Temperature Records of the Week

A certain global warming denialist website, co2science, regularly posts a “temperature record of the week.” I showed how they use clever cherry-picking to make their case look good in another post. But hey, two can play at that game; I too can post a “Temperature Record of the Week.” In fact, I’ll post two.

Lest anyone think I’m only choosing stations that make my case look good, I’ll let the co2science website pick one of the two! First, this is from this week’s co2science website:

To bolster our claim that “There Has Been Little Net Global Warming Over the Past 70 Years,” each week we highlight the temperature record of one of the 1221 U.S. Historical Climatology Network (USHCN) stations from 1930-2000.

This issue’s temperature record of the week is from Cheraw, SC. During the period of most significant greenhouse gas buildup over the past century, i.e., 1930 and onward, Cheraw’s mean annual temperature has cooled by 1.50 degrees Fahrenheit. Not much global warming here!

Wow! The natives of Cheraw had better learn how to make igloos!

Or should they? As I mentioned before, they start in 1930 and end in 2000 because that’s their best chance to get the trend they want. What if we looked at all the data available? I got data from GHCN, the global historical climate network. It turns out they’ve been recording temperature in Cheraw, SC since 1887, and the GHCN data go through the end of 2004; here’s a graph of annual average temperature anomaly, together with a smoothed version generated using a wavelet transform:

Hmmm… It seems Cheraw, SC actually isn’t cooling. In fact, during the period covered by the available data, Cheraw’s mean annual temperature has warmed by 0.47 degrees Celsius (0.85 degrees Fahrenheit). Not much global cooling here!

By the way — the opening line for their “Temperature Record of the Week” page used to say, “To bolster our claim that There Has Been No Net Global Warming Over the Past 70 Years.” Now it says “To bolster our claim that There Has Been Little Net Global Warming Over the Past 70 Years.” It’s such a “little” change.

Now it’s my turn. This week’s “Temperature Record of the Week” is from Yosemite National Park in California:

During the period covered by the available data, Yosemite’s mean annual temperature has warmed by 2.47 degrees Celsius (4.44 degrees Fahrenheit). Not much global cooling here!

In fact, during the time covered by the available data Yosemite’s temperature has risen at a rate of 0.0254 deg.C/yr. More to the point is the trend during the modern global warming era, from 1975 to the present. For Yosemite, the trend is a warming at a rate of 0.023 deg.C/yr. That’s even faster than the global average (0.018 deg.C/yr).

But Yosemite isn’t setting high temperature records yet. That’s because daytime high temperature in Yosemite shows no trend (a trend-line fit gives a warming rate of 0.0015 deg.C/yr, but the fit is not statistically significant — so we can’t even say with confidence that the trend is different from zero). But nighttime low temperatures are getting warmer rapidly; at Yosemite, the overnight low has warmed at a rate of 0.043 deg.C/yr (that’s 7.7 deg.F per century).

That’s exactly as predicted by “global warming theory.” Greenhouse gases inhibit infrared radiation from escaping earth’s surface and cooling the earth. Hence they inhibit nighttime cooling, raising nighttime temperatures more than daytime temperatures, overall. This also means that the diurnal temperature range (DTR) is getting smaller; there’s less difference between the daily high and the overnight low.

Yosemite is on the edge of the desert southwest, which is the part of the continental U.S. that has warmed most rapidly over the last century. Predictions are that as the earth warms, a very wide swath from the grain belt in the midwest to the desert southwest will dry up — essentially, the grain belt of the U.S. (the breadbasket of the world) may just turn into a desert.

That won’t be good for the U.S. economy; it may in fact be disastrous. It won’t be good for the world food supply; it just might be disastrous.