A few months ago, forecasters were predicting a "near-normal" hurricane season. Now, the East Coast is dealing with one of the most damaging storms to date.
Hurricane Sandy claimed scores of lives in the Caribbean. It was downgraded to a tropical storm before making landfall near Atlantic City around 8 p.m. Still, it prompted flooding and mass evacuations and halted Wall Street and early voting.
Scientists predict that the annual number of increasingly intense hurricanes will double over the next century – especially affecting North America's Atlantic Coast.
Why? The short answer, they said, is that it's the result of climate change.
Hurricanes are created – in part – and fed by warmer waters. Relatively cooler air condenses vapor rising from water below and the heat released from the condensation gives the hurricane the energy that whips up 75-mile-an-hour (or higher) winds.
Although the earth has been warming for decades, it's not so simple. Hurricane formation is not completely understood and scientists differ on how rising temperatures affect hurricane conditions.
Data from the last 30 years shows an increase. Others point out there isn't enough evidence to be sure it's the cause.
Using prediction models, experts have determined that the frequency of fierce storms will rise, while weaker storms will dissipate.
"Globally, we actually expect the number of storms to decline. And that's because the middle part of the atmosphere, two or three miles above the surface, gets drier in a relative sense as climate warms," Kerry Emanuel, professor of Atmospheric Sciences at Massachusetts Institute of Technology, told AccuWeather.
If the growing trend shown in early data continues, hurricanes will show themselves to be the most tangible impact of climate change.
Initial estimates put the cost of Sandy at $6 billion. Models of future storms show that damage could surge to $20 to $70 billion.
In Sandy's case, the storm's arrival in the U.S. coincided with the full moon. This raised the storm surge even higher – contributing to flooding and damage.
Costs will increase as population continues to grow along the coast. Over the last roughly 20 years, population density has increased 32 percent along the Gulf coast and 17 percent on the Atlantic coast, according to the U.S. Census Bureau.