Snowstorms and Sea Ice

Cross-posted from NextGen Journal

“That’s some global warming”, Fox News proudly announced. “Rare winter storm dumps several inches of snow across South.” It’s cold outside, and/or it’s snowing, so therefore global warming can’t be happening. Impeccable logic, or rampant misconception?

It happened last winter, and again so far this season: unusual snow and extreme cold thrashed the United States, Europe, and Russia. Climate change deniers, with a response as predictable as Newton’s Laws, trumpeted the conditions as undeniable proof that the world simply could not be warming. Even average people, understandably confused by conflicting media reports, started to wonder if global warming was really such a watertight theory.

But sit and think about it for a minute. If it’s cold right now in the place where you live, that doesn’t mean it’s cold everywhere else. It’s simply not possible to look at your little corner of the world and extrapolate those conditions to the entire planet. There’s a reason it’s called global warming, and not “everywhere-all-the-time warming”. Climate change increases the amount of thermal energy on our planet, but that doesn’t mean the extra energy will be distributed equally.

That said, an interesting weather condition has been prominent over the past month, telling a fascinating story that begins in the Arctic. At the recent American Geophysical Union conference in San Fransisco, the largest annual gathering of geoscientists in the world, NOAA scientist Jim Overland described the situation.

Usually in winter, the air masses above the Arctic have low pressure, and the entire area is surrounded by a circular vortex of wind currents, keeping the frigid polar air contained. Everything is what you’d expect: a cold Arctic and mild continents. These conditions are known as the positive phase of the North Atlantic Oscillation (NAO), an index of fluctuating wind and temperature patterns that impacts weather on both sides of the Atlantic.

The negative phase is different, and quite rare: high pressure over the Arctic forces the cold air to spill out over North America and Eurasia, allowing warm air to rush in to the polar region. Meteorologist Jeff Masters has a great analogy for a negative NAO: it’s “kind of like leaving the refrigerator door ajar–the refrigerator warms up, but all of the cold air spills out into the house.” The Arctic becomes unusually warm, and the temperate regions of the surrounding continents become unusually cold. Nobody visually depicts this pattern better than freelance journalist Peter Sinclair:

So what’s been causing this rare shift to the negative NAO the past two winters? In fact, global warming itself could easily be the culprit. Strong warming over the Arctic is melting the sea ice, not just in the summer, but year-round. Open water in the Arctic Ocean during the winter allows heat to flow from the ocean to the atmosphere, creating the high pressure needed for a negative NAO to materialize. Paradoxically, the cold, snowy weather many of us are experiencing could be the result of a warming planet.

An emerging debate among scientists questions which force will win out over winters in Europe and North America: the cooling influence of more negative NAO conditions, or the warming influence of climate change itself? A recent study in the Journal of Geophysical Research predicts a threefold increase in the likelihood of cold winters over “large areas including Europe” as global warming develops. On the other hand, scientists at GISS, the climate change team at NASA, counter that extreme lows in sea ice over the past decade have not always led to cold winters in Europe, as 7 out the past 10 winters there have been warmer than average.

Amid this new frontier in climate science, one thing is virtually certain: global warming has not stopped, despite what Fox News tells you. In fact, despite localized record cold, 2010 is expected to be either the warmest year on record or tied for first with 2005 (final analysis is not yet complete). What you see in your backyard isn’t always a representative sample.

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The Associated Press Gets it Right

It’s been quite the summer. Moscow has experienced several months of weather more akin to Texas, and is literally burning up. Floods in China have killed more than a thousand and left countless others displaced. Pakistan has experienced similar floods due to a massive monsoon season, and now they have to deal with cholera, too. The Arctic sea ice extent is not much larger than 2007, and, so far, it’s been the warmest year on record globally.

We can’t tie a single extreme event to climate change. We can tie long-term trends, like 30 years of declining Arctic sea ice, to a warming world, but we don’t yet have the technology to attribute a single anomalous season to a particular cause. In 2007, for example, factors other than high temperatures contributed to the lowest Arctic sea ice extent on record.

However, these events are exactly what we expect from anthropogenic climate change. We shouldn’t look at them as evidence for global warming, but as examples of what is to come. This is an important warning that most newspapers have been shying away from. After nearly a year of terrible climate change journalism across the board, they didn’t even mention the connection between extreme events and climate change, or the fact that this summer is a very real glimpse into our future.

I gave up on my local newspaper months ago, and I don’t regret that decision. On the handful of mornings that I’ve flipped through the paper instead of reading the Globe and Mail on the Internet (journalism of much higher quality, and it saves money and paper), I’ve seen far too many op-eds and letters to the editor saying very strange things about climate science.

However, a headline yesterday caught my eye. A fantastic article by Charles J. Hanley, a Pulitzer Prize winning journalist, was distributed by the Associated Press and, consequently, picked up by dozens of newspapers across the continent – including my local paper.

I became more and more pleasantly surprised as I began to read through the article:

Floods, fires, melting ice and feverish heat: From smoke-choked Moscow to water-soaked Iowa and the High Arctic, the planet seems to be having a midsummer breakdown. It’s not just a portent of things to come, scientists say, but a sign of troubling climate change already under way.
The weather-related cataclysms of July and August fit patterns predicted by climate scientists, the Geneva-based World Meteorological Organization says – although those scientists always shy from tying individual disasters directly to global warming.

Read the whole article here.

Hanley does a fantastic job of distinguishing between weather and climate, and stressing that we can’t yet attribute extreme events to specific causes while acknowledging that this summer’s wild weather fits with IPCC predictions and will become a lot more common in the future. He interviews our good friend Gavin Schmidt, and explains how rising greenhouse gases are “loading the climate dice” – changing the relative odds of different extremes, rather than eliminating all cold days entirely.

I stood there and clapped. I was so proud of the Associated Press, and of my local paper, that I clapped for them. I feel like there is a smidgen of hope for climate change journalism and public understanding of this issue again. Or perhaps it just comes in waves, and we’re riding our way to the top again.