The USA is no stranger to severe winter storms but the monster – known as Nemo – currently hammering the north east coastal states may have been supercharged by climate change according to some climate scientists.
The storm is a result of two weather systems – a disturbance from the Gulf region with lots of moisture and a cold front from the west – colliding. It has already dumped record amounts of snow in many areas and there are fears that if the peak winds coincide with the Saturday morning high-tide cycle, moderate to major coastal flooding could result. The National Weather Service (NWS) is warning that coastal areas whose defences were weakened by Hurricane Sandy may experience more beach erosion and potential flooding, even though the storm surge will be far lower during this event.
Like all storms nowadays, the environment in which Nemo formed has been affected by climate change so, whilst there are many factors implicated in the creation of this storm, human induced climate change is one of them.
NCAR scientist, Kevin Trenberth told Climate Progress:
“Ingredients for a big snow storm include temperatures just below freezing. In the past temperatures at this time of year would have been a lot below freezing but the ability to hold moisture in the atmosphere goes down by 7% per degree C (4% per deg F), and so in the past we would have had a snow storm but not these amounts.
The moisture flow into the storm is also important and that is enhanced by higher than normal sea surface temperatures (SSTs). These are higher by about 1 deg C [almost 2°F] than a normal (pre-1980) due to global warming and so that adds about 10% to the potential for a big snow.”
Sea level rise, caused by warming seas and melting ice caps also adds to the destructiveness of these superstorms. On Nantucket Island, where coastal flooding is anticipated from this storm along with hurricane-force winds, the sea level has risen by about half a foot during the past 50 years.
Scientists have warned for some time that certain types of extreme weather will become more frequent and more intense as natural variability joins with background conditions altered by long-term climate change to supercharge events. The US Global Change Research Group found in 2009 that cold-season storm tracks are shifting northward and the strongest storms are likely to become stronger and more frequent.
The naming of this storm ‘Nemo’ has caused some controversy. In the light of scientific warnings and current observations, perhaps ‘Omen’ would have been a more appropriate name.