New Studies Link Intense Rain and Snow Events to Climate Change

If you’re like me, you probably know someone who views this winter’s crazy blizzards as evidence that global warming obviously doesn’t exist.  If you do, you might want to show that person the two studies appearing in this week’s Nature magazine that directly link rising greenhouse gas levels with the growing intensity of rain and snow in the northern hemisphere.

As described by the New York Times:

[T]he researchers used elaborate computer programs that simulate the climate to analyze whether the rise in severe rainstorms, heavy snowfalls and similar events could be explained by natural variability in the atmosphere.  They found that it could not, and that the increase made sense only when the computers factored in the effects of greenhouse gases released by human activities like the burning of fossil fuels.

According to the study, over the second half of the 20th century, the likelihood of extreme precipitation on any given day rose by 7%.  In other words, extreme events like heavier-than-usual rain and snow are becoming more common.  And it’s not just a coincidence or fluke – that 7% increase is well outside the bounds of natural variability.  It can only be explained by climate change.

This finding is a big deal.  According to the Washington Post, “this is the first time researchers have been able to point to a demonstrable cause-and-effect by using the rigorous and scientifically accepted method of looking for the ‘fingerprints’ of human-caused climate change.”

Hold on, you might be thinking.  More rain and snow?  Isn’t climate change supposed to cause more droughts and water shortages, like NRDC pointed out in our recent vulnerability report?  Actually, that’s right.  Paradoxically, climate change is predicted to cause both more floods and more droughts.

While that might seem a little counterintuitive at first, the evidence supports it.  Climate change is expected to push our weather patterns toward the extremes.  While some places might end up getting less rain overall, leading to shortages and vulnerable water supplies, each individual precipitation event might be more intense, leading to flooding.

As these climate change impacts become more common, we won’t be able to rely on past weather and climate patterns as a guide for how things will be in the future.  That makes it a lot harder to plan for things like where to build roads and houses, how to manage our water supplies, and when and where to plant crops.

So what should we do about it?  Of course, it’s crucial that we reduce our greenhouse gas emissions so that we can minimize the occurrences of extreme weather events like those described in the Nature studies. 

But some climate change impacts are inevitably going to happen anyway because of emissions we’ve already put into the atmosphere.  We have to be prepared to adapt to those changes when they happen.  When we’re talking about intense rains and floods, “adaptation” means doing things like:

• Improving monitoring, forecasting, and early warning systems for storm events.
• Preserving and restoring wetlands, floodplains, dunes, and other natural barriers to reduce the impacts of storms.
• Reducing stormwater runoff by requiring low impact development measures to capture and retain the water that falls during storms.
• Requiring the Army Corps of Engineers and FEMA to incorporate the effects of climate change in their analyses of future flood risk.
• Discouraging development in areas that are, and will increasingly be, vulnerable to flooding.

The new Nature studies show that it’s more important than ever for states and local communities to start planning for the changes that are already happening.  If we act quickly to enact well-informed, environmentally sound policies, we may be able to avoid the worst of these impacts – and hopefully be ready to cope with the next big rain or snowstorm.

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