Scientists offer hope. Summer could last six months by the end of the century

Having just come out of a period here in upstate New York where the temperatures never rose above 40 degrees for nearly three solid months, when I saw this headline over at NBC News, I thought they might be announcing something really inspiring. “Summers could last half the year by the end of this century.” Upon digging into the article, however, it quickly became apparent that this wasn’t intended to be any sort of celebratory discovery. Yes, it turned out to be yet another global warming article straight out of the Al Gore playbook. But if you happen to live in the northeast, it still sounds like this could turn out to be a pretty good deal.

Summers in the Northern Hemisphere could last nearly six months by the year 2100 if global warming continues unchecked, according to a recent study that examined how climate change is affecting the pattern and duration of Earth’s seasons.

The study, published last month in the journal Geophysical Research Letters, found that climate change is making summers hotter and longer, while shrinking the three other seasons. Scientists say the irregularities could have a range of serious implications, affecting human health and agriculture to the environment.

“This is the biological clock for every living thing,” said the study’s lead author, Yuping Guan, a physical oceanographer at the State Key Laboratory of Tropical Oceanography at the Chinese Academy of Sciences.

Guan and his colleagues combed through daily climate data from 1952 to 2011 to pinpoint the start and end of each season in the Northern Hemisphere. They found that over the nearly 60-year period, summers were becoming an average of 78 to 95 days longer.

I suppose we’d better take a look at the data they’re using and figure out if there’s anything to this theory. Guan’s team claims to have compiled all of the daily climate data from 1952 to 2011. Using that data, they worked to “pinpoint the start and end of each season in the Northern Hemisphere.” Based on those figures, they concluded that over this 59-year period, “summers were becoming an average of 78 to 95 days longer.”

Wow. That’s certainly a shocking figure. But there’s a major problem with it right off the bat. I’m not sure if that was just a typo in the NBC article or somebody lost their calculator, but that figure would indicate that ten years ago, summer was already up to three months longer than it was in the early fifties. As if that number doesn’t already sound well off the beam, the report becomes more specific and says that the other three seasons, on average, contracted by the following amounts.

  • Winters shortened from 76 to 73 days
  • Springs shortened from 124 days to 115 days
  • Autumns shortened from 87 days to 82 days

Now, I was an English major and our boss promised me there would be no math in this job, but those figures look off even to me. Stick with me here. Winters were three days shorter. Spings were nine days shorter. Autumns were five days shorter. I didn’t really even need to take off my socks and shoes to figure out that those three seasons were, on average, a total of seventeen days shorter. But the summers were “an average of 78 to 95 days longer?” Let’s split the difference and say summers were an average of 87 days longer. I may need to break out the calculator for this one, but that means that the entire year was 80 days longer than it was 59 years earlier. Did they start selling new calendars with three extra months on them and I just never noticed?

UPDATE: I went back and checked and it turns out that NBC News corrected their typo in the last paragraph excerpted above. It now reads, “summers grew from an average of 78 to 95 days long.”

Okay, so now at least the math works out a bit better. So they’re saying that summers gained 17 days while the other three seasons lost 17.

Even if we accept those figures, the next question I had was how they “pinpointed” the start and end of each season. The four seasons we recognize are pretty ambiguous in nature. Right now it’s a comparatively balmy 60 degrees where I am and my calendar tells me that spring officially began this weekend. So winter is over, right? But we’ve had years here where we were hit with snowstorms as late as the second week of May. Does that mean that in those years, winter lasted until May, and spring was only six weeks long?

My point is that Guan’s team may be able to identify the precise temperature at any given weather station on any given day of the year during the period under study. But he’s talking about the average “winter” being five days shorter over a fifty-year period. I assume we just have to take his word for when winter starts and ends? What kind of science is this?

There’s one final point to touch on since so much of Guan’s figures rely on temperature measurements from when Eisenhower was president. The accuracy of thermometers and other measuring devices has changed over time. Perhaps it hasn’t changed all that much, but it’s changed. And when you’re talking about such small numbers of degrees, I remain skeptical if the average temperatures went up by the precise amounts claimed down to one-tenth of a degree.

In any event, I’m not going to complain about an extra week of summer. If we could just work on trimming back winter by a month or so we’d be all set.