AD Main Menu

Why Alaska's heat wave is a bad example of global warming

Ben Anderson
Some are taking this unusually-cloudless satellite photo of Alaska taken during the state's recent heat wave as an example of global warming -- but doing so is a risky way to argue for climate change. NASA photo

Alaska has experienced odd weather this spring, late cold and snow then record early-summer heat, and the oddity is giving new fuel to the debate over global warming. Last month, former half-term Alaska Gov. Sarah Palin posted a photo to her Facebook page, noting a late-season snowfall in Southcentral Alaska and using it as an excuse to offer a denial of climate change.

"We'll move our graduation b-b-q indoors and watch the mini-blizzard from 'round the fireplace. (Global warming my gluteus maximus.)," Palin's post said.

The snowfall certainly was one for the record books -- it pushed Alaska's largest city of Anchorage into its longest-ever snow season, spanning nine months from September to May. It came on the heels of the winter of 2011-2012, when Anchorage experienced the most-ever snowfall in a single season. Those are a couple of fun factoids, but it's dangerous to use a single example of cold weather as a round dismissal of global warming.

But it goes both ways, too. Palin has been quiet since Alaska tripped into a recent, lengthy heat wave that saw daily high temperature records shattered in various communities around the state and sparked up wildfire season. But several science writers have already fallen victim to using Alaska's hot weather as a "manifestation of extreme warming," taking Palin's basic premise of "it's cold outside, therefore global warming doesn't exist" to the other end of the spectrum.

Many have latched onto an unusually cloudless photograph of Alaska taken by NASA earlier this week as the catalyst for concerns.

In a blog post for Discover Magazine, Tom Yulsman resorts to a bit of hyperbole to highlight the current fire season and stretch of warm weather in Alaska. Yulsman notes that the state's run of record-breaking temps were "showing no signs of abating," but neglected to mention the fact that the weather was indeed cooling off in portions of the state already on Wednesday, the same day the blog post ran. He also erroneously lumps the climate of Fairbanks in with areas in the further northern portions of the state -- saying that maximum temperatures in the Interior Alaska city typically only hit the high 60s to low 70s. Fairbanks and surrounding cities regularly hit 80 degrees and higher during hot days in the summer months.

To Yulsman's credit, he does take the long view on much of the globe's warming, going back to the middle of the 20th century when making points about the Earth heating up and the amplified effects of warming in the Arctic. These are well-established numbers that take into account overall temperature observations and a long-term warming pattern.

In particular, Yulsman cites numbers that Alaska's temperatures were higher in the years 2000-2009 when compared to average temperatures between 1951 and 1980. But that number, while correct, is also a bit misleading. That's because though the first decade of the new millennium was warmer overall when compared to those specific years beginning mid-20th century, Alaska was simultaneously cooling off from an all time high in those gap years between 1980 and 2000. From 2000-2010, Alaska actually cooled off by an average of 2.4 degrees, with 19 of 20 official weather stations reporting declines in that decade. In 2012, the state overall was 2.9 degrees cooler than normal.

Though the town of Barrow, at the far northern tip of Alaska, has recently experienced some warmer-than-normal temperatures -- caused perhaps in part by greater heat absorption by open water now appearing where Arctic sea ice would normally be -- much of Alaska has actually been locked in a cooling pattern that is expected to continue for some time. But Barrow's location as the farthest north U.S. community, and one actually above the Arctic Circle, fits with the long-term pattern of overall warming in the Arctic.

Phil Plait over at Slate also cites the NASA photograph as a sign of things to come, and compares the high pressure system that settled over Alaska to a pattern that's developed in Greenland, and hints again at the increased heat absorption caused by more extensive open water in the Arctic. Becky Oskin at NBC News takes a more nuanced approach, citing a National Oceanic and Atmospheric Administration scientist who said that Alaska's weird weather is likely an anomaly rather than a direct result of climate change.

As for the wildfires, well, it is shaping up to be a potentially sizeable wildfire season in the state. But even that is no reliable indicator of overall warming. Alaska, like almost anywhere else -- and perhaps even more pronouncedly -- experiences highs and lows when it comes to forest fires. Alaska's biggest fire season took place in 2004, when more than 6.5 million acres burned as the result of 701 fires. But if you want to find the next-worst wildfire season, you'd have to go all the way back to 1956, when fire claimed 5 million acres in the Last Frontier.

There have been other big fire years scattered over the decades, including the 1970s and 1990s, making it difficult to pin down the effects of warming on wildfires, especially since the spread of fire can be so dependent on wind and other weather factors, and single fires can grow to be vast, while dozens of small fires can do little damage.

Yulsman later updated his post with comment from Alaska Department of Natural Resources spokeswoman Elizabeth Bluemink, who suggested that any predictions for 2013's fire season are likely premature.

It may be equally premature to equate Alaska's current warm spell with "extreme warming," just as it's dangerous to cite 2012's cold summer, or Anchorage's particularly chilly July that year, as an example of "extreme cooling." Moderation, it would seem, is the key to accurately representing data and making an informed decision on climate change.

Contact Ben Anderson at ben(at)alaskadispatch.com