1 November 2012
What Those Who Understand Atmospheric Physics Are Talking About After Sandy
Posted by Dan Satterfield
Asking if Hurricane Sandy was caused by climate change is like asking someone at the South Pole which way is north. This kind of storm could almost certainly form in a world where the CO2 levels have been unchanging and Arctic sea ice levels were stable. That said, anyone who claims Sandy was ( or was not) caused by the changing climate just doesn’t get it.
It may be possible with some attribution and detection studies to say something about how much more likely it was for this storm to have occurred but that is for the future, and it will not be easy. So, what can we say about Sandy that is scientifically accurate??
1. The oceans are over a degree Celsius warmer than they were a century ago, and we saw record warm oceans (2-3 degrees C above normal!) off the East Coast for most of the last several months.
2. The planet itself is also a degree Celsius warmer than it was a century ago, and this means the atmosphere (on the whole) is holding 5-7% more water vapor than it was a century ago.
3. Sea level has risen at least a foot over the past century, but that is just on average. Along the coast of Delaware and Virginia, the sinking shorelines combined with the rising water, mean the water has risen over 18 inches in the past 60 years alone. Ask someone in New Jersey, who had a foot of water in their house, if they wish it were 18 inches lower.
What we CAN say is this:
If a storm exactly like Sandy hit in October of 1912, it would have been less wet and the storm surge would have been a foot lower at least.. We can also say that a storm exactly like Sandy 90 years from now will be much wetter with water levels at least 24 inches higher. (The Mid-Atlantic coast is sinking at the rate of a foot a century, and the sea is rising at the same rate already. That’s two feet if nothing changes! The best science says the sea alone will rise 36 inches over the next century as the planet warms and the oceans expand.)
What meteorologists like myself, and climate researchers are talking about is the huge blocking high over Greenland. October or November hurricanes re-curve into the Atlantic because of a much stronger fall jet stream, but the Greenland block turned Sandy into the coast. The track of Sandy was very RARE. Nearly unheard of actually, especially for this time of year. Dr. Jeff Masters has an excellent post about the Greenland block and how rare it is this time of year. Finish this post then read his.
Could the loss of Arctic sea ice be a factor in that big Greenland high pressure system. Dr. Jennifer Francis has research that says yes. (Andy Revkin at Dot Earth has a good post about this as well here.) Would the high have developed anyhow? Perhaps, but it would seem ridiculous to assume that the amazing loss of Arctic Ice would have little effect on the atmosphere over the Northern Hemisphere. That claim would be an extraordinary supposition that goes against the laws of physics and would require some profound evidence. The shoe is on the other foot now I think.
Rising sea levels and a warming planet are sneaking up on us little by little, but it will not be perceived that way. Instead, it will be realized in sudden and catastrophic events like floods, hurricanes and heat waves and droughts.
As I write this, 6.3 million people across 7 states are still in the dark…
I hate to be a doom and gloomer but we dodged a bullet: The storm ran into a “flat” part of the map. If it had tracked up the Chesapeake, we would have had a surge to write home to mother about. The funnel effect would have put ten feet or better of water in the streets of our Federal capital.
I think the idea that sea level rise can explain the whole story particularly in the Northeast is over played. For example, USGS reports indicate that from Boston to NC, sea level rise is up to 3.8 mm/yr between 1950 – 2009 whereas annual sea level rise is about 1.0 mm/yr during the same time. Sallenger et al. (2012) published a paper titled “Hotspot of accelerated sea-level rise on the Atlantic coast of North America” in Nature, which I think gives great insight in to this problem in the Northeast.
Interesting post and observation. I’ve not researched hurricanes much, but was curious about how many tropical storms recurved eastward out into the Atlantic rather than moving towards the Gulf Coast this year. It may simply be a matter of me following them more closely. Any comments?
Thanks AGU for believable info!
The loss of sea ice has definitely had an effect on the atmosphere. Look at the Barrow AK temperature for October:
Cannot find anything to fault in that discussion. I recently watched the BBC Horizon program on the effects of global dimming and how that has masked global warming. And now, we are starting to reduce the pollutants that were producing the dimming, which implies we can expect more of this type of storm in the future. Abe Licoln said it best:
The dogmas of the quiet past are inadequate to the stormy present. The occasion is piled high with difficulty, and we must rise with the occasion.
This is a total nitpick on an otherwise nice summary, but I think you mean “6.3” not “63”.
I did and thanks- corrected it.