Cold enough for you?
The temperature today isn’t predicted to rise above freezing, and the low tonight is supposed to be a frigid 18 degrees. In other words, the weather gives us a perfect opportunity to talk a little more about the realities of global warming.
For starters, this isn’t really very cold. Atlanta’s record low for today, Jan. 5, was 3 degrees, set back in 1884; the record low for tomorrow, Jan. 6, was minus 1, also set in 1884. That’s cold. Compared to those temperatures, today is practically balmy.
In fact, winter weather here in Atlanta has been getting warmer and warmer. Over the past 15 years, according to Weather Channel data, we’ve set seven record highs for January. We have set no record lows.
I made a similar point in a column last month, noting that 24 out of the 31 daily record highs for December had been set just in the last 25 years, while we set only 3 record lows in that time frame.
In that column, I also warned against the fallacy of trying to draw larger conclusions from temperatures in just one location, such as Atlanta. But as it turns out, scientists at the National Center for Atmospheric Research in Colorado had noticed the same phenomenon but on a national scale:
BOULDER—Spurred by a warming climate, daily record high temperatures occurred twice as often as record lows over the last decade across the continental United States, new research shows. The ratio of record highs to lows is likely to increase dramatically in coming decades if emissions of greenhouse gases continue to climb.
“Climate change is making itself felt in terms of day-to-day weather in the United States,” says Gerald Meehl, the lead author and a senior scientist at the National Center for Atmospheric Research (NCAR). “The ways these records are being broken show how our climate is already shifting.”
The study, by authors at NCAR, Climate Central, The Weather Channel, and the National Oceanic and Atmospheric Administration (NOAA), has been accepted for publication in Geophysical Research Letters. It was funded by the National Science Foundation, NCAR’s sponsor, the Department of Energy, and Climate Central.
If temperatures were not warming, the number of record daily highs and lows being set each year would be approximately even. Instead, for the period from January 1, 2000, to September 30, 2009, the continental United States set 291,237 record highs and 142,420 record lows, as the country experienced unusually mild winter weather and intense summer heat waves….
“If the climate weren’t changing, you would expect the number of temperature records to diminish significantly over time,” says Claudia Tebaldi, a statistician with Climate Central who is one of the paper’s co-authors. “As you measure the high and low daily temperatures each year, it normally becomes more difficult to break a record after a number of years. But as the average temperatures continue to rise this century, we will keep setting more record highs.”
Climate is an average taken over time, just as a baseball batting average is measured over time. In both cases, you’re still going to get day-to-day fluctuations. Ted Williams was a great hitter, the last man to hit .400 over a season, but even he went 0 for 5 pretty often. He just had fewer of those cold hitting spells than poor hitters did.
Likewise, even in a warming climate, you’re going to get the occasional cold spell, which is what we’re seeing today. You still get variations of heat and cold. But if the planet is indeed warming, you would expect to get fewer and fewer record lows over time, and more and more record highs.
That is exactly the pattern we’re seeing.