Global Warming Increases Strength of Hurricane Sandy

View of Hurricane Sandy. Photo courtesy: NASA Earth Observatory/Public Domain

Once again, we've polluted our way into dire circumstances. This time we've managed to increase Hurricane Sandy's fury with our interfering ways. Global warming is responsible for an increase in the strength of Hurricane Sandy. Brian Merchant
of TreeHugger explains:

Hurricane Sandy is out in full force; I'm currently waiting for the slow-moving frankenstorm to bear down on me as I tap this out (good thing there plenty of memes to keep me distracted). As is to be expected, there's been some good discussion about how much of the storm is attributable to climate change — Lloyd (a fellow writer at TreeHugger) collected some of the best pieces exploring that link yesterday. And I've argued that humans have built a veritable frankenstorm factory by spewing CO2 into the atmosphere; now we have to figure out how to live in it.

But I thought I'd add some commentary from the horse's mouth; that is, some discussion of the climate-hurricane link directly from a climate scientist. Today, Slate published a Climate Desk interview with Dr. Kevin Trenberth, one of the nation's most esteemed climatologists, and here's how he explained the impact global warming was registering on Sandy:

Most of what is going on with Sandy is weather, and there is a large chance element to it, but it is all occurring in an environment where the ocean is a bit warmer, the air above the ocean is warmer and moister, and that is fuel for the storm and especially adds to the risk of heavy rainfalls and flooding.

The predominant thing is hybrid storms are chance events. They are a crap shoot. With hurricanes there is a very strong environmental component to it. Hurricanes are very dependent on the environment. Therefore, changes in the environment modify the hurricanes. There are higher sea temperatures now, more moisture in the atmosphere, and there is a risk that the storm will be more intense and possibly a little larger ...

The thing that the climate is doing is that the sea temperatures are higher. There is more moisture feeding into the storm. That adds to the rainfalls. The rainfalls could be 5 to 10 percent higher as a consequence of climate change. The sea level is running a little bit higher. Sea level is going up a foot a century at the current rate. Over the last 20 years sea level has gone up 2 1/4 inches ... There are a lot of other aspects feeding into Sandy.

Read the rest over at Slate.

The point is clear, and it's one we've heard many times before. Climate change didn't "create" this storm. It's not responsible for this storm. But by spewing a century's worth of greenhouse gas pollution into the atmosphere, we've created an environment more amenable to nasty storms. We've warmed the air and the oceans, and we've spurred the sea levels to rise — sweetening the conditions for catastrophic storms like Sandy.

Stay dry, everyone.

Pollution Thought to be The Cause of Global Dimming

A haze engulfing buildings in Wuhan, China. Air pollution is believed to be the main cause of global dimming. Photo courtesy: STR/AFP/Getty Images

Measurements from the 1960s to the early 1990s, backed up by a wide range of data and a number of independent studies, showed there were substantial declines in the amount of the sun's energy reaching the Earth's surface. This reduction is known as "global dimming".

The observed "dimming" has strong regional differences across the globe. While the southern hemisphere saw modest dimming in the period 1961–90 (which has continued to date), the northern hemisphere saw much more significant declines (reductions of 4–8%). Since then some parts of the world, such as Europe and North America, have seen partial recovery (known as "brightening"), while other regions (most notably China and India) have seen further although regionally mixed declines.

Global dimming is not thought to be due to changes in the sun's luminosity, as these have been too small to explain the magnitude of dimming observed. Instead, air pollution from human activity is thought to be the major contributor. Aerosols which form from pollution can directly reflect and absorb radiation before it reaches the planet's surface and make clouds brighter and longer lasting, meaning they reflect more sunlight.

While we cannot rule out the possibility that natural variations in the Earth's climate (via naturally occurring cloud variations) have contributed to global dimming, the effects are so closely correlated to trends in atmospheric pollution that there is strong evidence to say human activity is a major player. For example, European and North American clean air legislation in the 1990s corresponded to brightening in these regions. By contrast, China and India have seen further dimming, matching pollution increases from rapid industrialisation.

Global dimming is thought to have had a number of substantial impacts. For example, there is evidence to suggest it has masked part of the historical warming caused by greenhouse gases. Indeed, areas that have undergone brightening have seen rapid warming.

Future global dimming changes can be expected to be closely tied to emissions of atmospheric pollution. Another factor which has not played much of a role historically but which may become more significant in the future is the impact of greenhouse gas warming on global dimming. Warming of higher levels of the atmosphere leads to increased atmospheric water vapour, which in turn absorbs some of the sun's energy before it reaches the surface. If future global warming proves to be substantial, widespread dimming by water vapour could be a consequence – though the cooling effect of this would be unlikely to reduce the overall warming trend significantly.