Heat records tumbled across the country this spring and summer as heat waves and warmer-than-normal temperatures blistered much of the U.S. As scientist Deke Arndt and meteorologist Dan Satterfield explain in this edition of Extreme Weather 101, these heat spikes are likely to become more commonplace as greenhouse gases heat the planet.
Climate scientists have long known that human-generated greenhouse emissions are only part of the story with global warming. A rising planetary temperature sets in motion all sorts of secondary effects that can boost the temperature even higher — effects like melting Arctic sea ice, rising levels of heat-trapping water vapor in the atmosphere, and more. When researches try to figure out how high the thermometer will go over the next century or two, it’s important to figure in these so-called feedbacks into their calculations. But they don’t fully understand how feedbacks will play out.
A recent study in Nature Geoscience is helping reduce some of that uncertainty. By 2100, say Andrew MacDougall and his co-authors, the melting of Arctic permafrost will release enough carbon dioxide to boost global temperatures by up to an extra half a degree Fahrenheit, and by 2300, the extra heating could add up to as much as 3°F.
So that’s not good, obviously, especially since the permafrost feedback is just one of many that will add to global warming. But two really intriguing things about that become clear when you look more closely. The first is that the half-degree by 2100 is likely to happen whether or not we slow our emissions from fossil-fuel burning or not.
If that sounds crazy, the second seems even crazier: when you go beyond 2100, the extra warming from permafrost is less if our greenhouse emissions are higher.
Both of these facts sound as absurd to me...
Sometimes a new scientific result is so clearly important that the bottom line needs no explaining — a report showing how ocean acidification threatens food security around the world, for example, or one that ties melting ice in the Arctic to the threat of colder, snowier winters for the U.S.
But it’s tougher to see why anyone should care about the fact that sea level could rise by 3 and a half feet or higher . . . by the year 3000. Nevertheless, that’s what a study published on Tuesday in Environmental Research Letters says — and it is, believe it or not, an important result.
Here’s why: climate scientists have known for a long time that once you pump heat-trapping carbon dioxide into atmosphere by burning coal and oil, it stays there for a thousand years or more. Even if we reduced emissions to zero as of today, Earth would continue warming, and it would stay warm for many centuries to come.
This obviously isn’t going to happen, which makes the paper purely theoretical. Even so, it’s still a useful exercise to ask what the result would be, since it tells us how much climate disruption we’ve already committed to so far. Any greenhouse-gas emissions we create tomorrow, or next week, or over the next 10 years will be on top of that.
Some climate change is already visible in the form of higher seas, rising temperatures and an increase in droughts, heat waves and torrential rainstorms; more is already guaranteed by the emissions we’ve already created...
The villagers of Vunidogoloa on Vanua Levu, Fiji’s second largest island, know firsthand how sea level rise can affect their daily life. According to this article from Alternet, throughout 2012, the Fijians have been in the process of relocating their seaside village — which has been affected by rising seas, erosion, and flooding — to higher, drier ground.
Small coastal communities such as this one are on the front lines of climate change, despite the fact that they have contributed very little global warming gases to the atmosphere in the first place. A similar process is underway in the village of Kivalina, Alaska. Villagers of Kivalina have sued Exxon Mobil for damage incurred by sea level rise, but on Sept. 21, a federal appeals court ruled that the village didn't have legal standing to sue the company, and must instead seek remedies through the legislative process.
The summer meltback of Arctic sea ice still hadn't reached it's full extent when the National Oceanic and Atmospheric Administration (NOAA) released this video on Monday (best guess was that it would happen within a few days), but what it shows is dramatic enough as it is: you can watch the ice shrink inexorably from January 1 through September 14, 2012, at which point it covers nearly 40 percent less area than its historical average.
The melting this year has been so rapid and extensive that the previous record minimum, set in 2007, had already been shattered by August 26, with at least three weeks left in the melt season. For the month of August overall, which was the fourth warmest on record globally, ice cover averaged just 1.82 million square miles, the lowest for any August since modern observations. During August, the Arctic lost an average of 35,400 square miles of ice per day, NOAA reported, which was the fastest rate ever observed for the month. That is the equivalent of losing an area of ice equal to the state of Maine every day for 31 days.