Climate science explains how global warming can make a superstorms like Sandy more destructive in several ways:
1. Warming-driven sea level rise makes storm surges more destructive. In fact, a recent study found "The sea level on a stretch of the US Atlantic coast that features the cities of New York, Norfolk and Boston is rising up to four times faster than the global average."
2. "Owing to higher sea surface temperatures from human activities, the increased water vapor in the atmosphere leads to 5 to 10% more rainfall and increases the risk of flooding."
3. "However, because water vapor and higher ocean temperatures help fuel the storm, it is likely to be more intense and bigger as well." Relatedly, warming also extends the range of warm sea surface temperatures, which can help sustain the strength of a hurricane as it steers on a northerly track into cooler water.
September had the second highest global ocean temperatures on record and the Eastern seaboard was 5F warmer than average.
4. The unusual path of the storm - into the heavily populated east coast rather than out to see - was caused by a very strong blocking high pressure system that recent studies have linked to warming.
The first two - the impact of sea level rise and increased water vapor - are unequivocal. The third is extremely likely. The fourth is more speculative.
Remember, climate scientists and others have for quite some time been warning New York City that climate change was dramatically increasing the odds of a devastating storm surge. Also a brand new study of storm surges since 1923 finds "that Katrina-magnitude events have been twice as frequent in warm years compared with cold years" - so more severe surges are on the way.
And that's the other key reason we must make the connection to climate change: Scientists worst-case scenarios are already happening - so their latest findings deserve attention so that Sandy doesn't become just another Cassandra whose warnings are ignored. Now climate scientists project that we risk up to 10 times as much warming this century as in the last 50 years.
That's one of the many reasons we must act to reduce emissions ASAP, so we don't keep getting 'new normals' that make Sandy and Katrina seem tame.
The answer to the question of whether an event is caused by climate change is that it is the wrong question. All weather events are affected by climate change because the environment in which they occur is warmer and moister than it used to be... "Climate-driven changes are already evident over the last few decades for severe thunderstorms, for heavy precipitation and flash flooding, for hurricane activity, and for heatwave, drought and wild-fire dynamics in parts of North America."