As millions begin to recover from the devastation inflicted on us all, we need to be aware that human activities made Sandy a stronger and wetter storm. Global warming has made the oceans warmer and has caused sea levels to rise – both of which worked to exacerbate the impacts of Sandy. See Figures 1, 2, 3, 4.
The fuel for hurricanes is warm ocean water that releases tons of water vapor. This water vapor then condenses into clouds and rain which releases heat known as “latent heat”. This latent heat drives the power of the winds much like stepping on the gas pedal makes the engine output more power. The warmer ocean, in essence, put a turbocharger on Hurricane Sandy’s engine.
This extra water from the warmer oceans must eventually come down and it does so as flooding rains. Some places in the mid-Atlantic had over 12” of rain and a few higher locations to the west saw nearly 3 feet of snow as colder air wrapped around the backside of the storm. As Governor Cuomo said to President Obama, “We now have a 100 year flood every two years”. Global warming = heavier rains and floods. We saw this last year with Hurricane Irene.
Global warming also causes sea levels to rise for two reasons: 1) as water warms, the molecules move faster and take up more space (known as thermal expansion) and 2) a warmer climate melts ice sheets and glaciers and that water over time makes its way into the ocean. Due to global warming, storms are now riding on much higher sea levels which is causing the storm surge to reach higher levels and farther inland. Residents on Long Island and NY City saw this phenomenon first-hand. NY City saw surges approaching 14 feet – higher than for any storm in the past 400 years! Sea levels have risen over a foot in the past 100 years and are projected to increase another 2-5 feet by the year 2100. Imagine Sandy coming in on an ocean that is 5 feet higher than today? The surge would be nearly 19 feet.
If somebody asks you, “Did global warming cause Hurricane Sandy?” they are asking the wrong question. Sandy certainly may have occurred in the absence of global warming but it would not have been as strong nor as damaging. I tell people, “Think of a hurricane as a fire in a fireplace. Global warming did not start that fire but it is certainly adding a few logs to it.”
Some sobering facts about hurricanes and climate change:
• Of the 11 most intense North Atlantic hurricanes ever recorded, five have occurred in the last eight years (Wilma, Rita, Katrina, Dean and Ivan).
• The record-breaking rainfall dumped by Hurricane Irene in 2011 was the main impact of the storm in which flooding and other damage totaled over $15 billion,
making Irene the 10th billion-dollar disaster in 2011 and the sixth most expensive hurricane in U.S. history.
• With more than $100 billion in damages, Hurricane Katrina remains the costliest
weather-related disaster on record.
• In June 2012, tropical storm Debby produced record-breaking rainfall across Florida, in some locations dropping over 20 inches of rain in 24 hours. When Tropical Storm Debby formed on June 23, it was the first time ever that four storms formed before July since record keeping began in 1851.
• According to data from 2007, the number of category 4 and 5 hurricanes has increased by nearly 75% since 1970.
There is a strong scientific consensus that the most intense Atlantic hurricanes will become more frequent in the coming decades if greenhouse gas pollution continues to grow even at a moderate rate. The increase in damages due to climate change will rise to an average of over $40 billion per year, as stronger hurricanes are exponentially more destructive than weaker storms.
We have choices to make. The sooner we begin to shift away from burning fossil fuels such as coal, oil, and natural gas to using cleaner energies such as solar, wind, wave, and geothermal, we will prevent the oceans from becoming even warmer and sea levels from rising even higher.
We will always have hurricanes but we do not need to make them worse!