Climate change impacts in the United States
From the darkened living rooms of Lower Manhattan to the wave-battered shores of Lake Michigan, the question is occurring to millions of people at once: Did the enormous scale and damage from Hurricane Sandy have anything to do with climate change? A hurricane barrier in Stamford, Conn. Experts say that the storm, whatever its causes, should be seen as a warning.Hesitantly, climate scientists offered an answer this week that is likely to satisfy no one, themselves included. They simply do not know for sure if the storm was caused or made worse by human-induced global warming.
They do know, however, that the resulting storm surge along the Atlantic coast was almost certainly intensified by decades of sea-level rise linked to human emissions of greenhouse gases. And they emphasized that Hurricane Sandy, whatever its causes, should be seen as a foretaste of trouble to come as the seas rise faster, the risks of climate change accumulate and the political system fails to respond.
“We’re changing the environment — it’s very clear,” said Thomas R. Knutson, a research meteorologist with the government’s Geophysical Fluid Dynamics Laboratory in Princeton, N.J. “We’re changing global temperature, we’re changing atmospheric moisture, we’re changing a lot of things. Humans are running this experiment, and we’re not quite sure how it’s going to turn out.”
Scientists say most of the rise is a direct consequence of human-induced climate change. Ocean water expands when it warms, accounting for some of the rise, and land ice is melting worldwide, dumping extra water into the ocean. Scientists say they believe the rate will accelerate further, so that the total increase by the end of this century could exceed three feet. Full Text: Are Humans to Blame? Science Is Out (http://www.nytimes.com/2012/11/01/science/earth/scientists-unsure-if-climate-change-is-to-blame-for-hurricane-sandy.html?hp)
Will Climate Get Some Respect Now?
Hurricanes form when the ocean is warm, and that warmth is their fuel. The Atlantic waters off the East Coast set a record high temperature this summer. Presumably most of that is natural variation, and some is human-induced climate change.
Computer models suggest that hurricanes won’t necessarily become more frequent, but they may become stronger. As the United States Global Change Research Program, a collaboration of federal agencies, puts it, “The intensity of these storms is likely to increase in this century.”
Climate change adds moisture to the atmosphere, which may mean that storms come with more rain and more flooding.
Sandy was particularly destructive because it was prevented from moving back out to sea by a “blocking pattern” associated with the jet stream. There’s debate about this, but one recent study suggested that melting sea ice in the Arctic may lead to such blocking. Will Climate Get Some Respect Now? (http://www.nytimes.com/2012/11/01/opinion/kristof-will-climate-get-some-respect-now.html?hp&_r=0)
For Years, Warnings That It Could Happen Here
After rising roughly an inch per decade in the last century, coastal waters in New York are expected to climb as fast as six inches per decade, or two feet by midcentury, according to a city-appointed scientific panel. That much more water means the city’s flood risk zones could expand in size.
“Look, the city is extremely vulnerable to damaging storm surges just for its geography, and climate change is increasing that risk,” said Ben Strauss, director of the sea level rise program at the research group Climate Central in Princeton, N.J. “Three of the top 10 highest floods at the Battery since 1900 happened in the last two and a half years. If that’s not a wake-up call to take this seriously, I don’t know what is.”
For nearly a decade, scientists have told city and state officials that New York faces certain peril: rising sea levels, more frequent flooding and extreme weather patterns. The alarm bells grew louder after Tropical Storm Irene last year, when the city shut down its subway system and water rushed into the Rockaways and Lower Manhattan.
On Tuesday, as New Yorkers woke up to submerged neighborhoods and water-soaked electrical equipment, officials took their first tentative steps toward considering major infrastructure changes that could protect the city’s fragile shores and eight million residents from repeated disastrous damage. (http://www.nytimes.com/2012/10/31/nyregion/for-years-warnings-that-storm-damage-could-ravage-new-york.html)
Flooding Threat Grows
Unlike New Orleans, New York City is above sea level. Yet the city is second only to New Orleans in the number of people living less than four feet above high tide — nearly 200,000 New Yorkers, according to the research group Climate Central.
The waters on the city’s doorstep have been rising roughly an inch a decade over the last century as oceans have warmed and expanded. But according to scientists advising the city, that rate is accelerating, because of environmental factors, and levels could rise two feet higher than today’s by midcentury. More frequent flooding is expected to become an uncomfortable reality. (http://www.nytimes.com/2012/09/11/nyregion/new-york-faces-rising-seas-and-slow-city-action.html?pagewanted)
According to the latest statistics from NOAA’s National Climatic Data Center, the average temperature for the contiguous United States during September was 67° Fahrenheit, which is nearly 1.4° Fahrenheit above the twentieth-century average. This marks the sixteenth consecutive month with above average temperatures for the Lower 48.
The map above shows temperature patterns across the United States during September 2012 compared to the recent long-term average (1981-2010). (http://www.climatewatch.noaa.gov/image/2012/warmer-temperatures-continue-in-september-2012)
The Heat is On
September was the 16th straight month with warmer-than-average temperatures for the United States. That means the country as a whole has been warmer than average since two springs ago. And since this year has been so warm, 2012 almost certainly will be one of the hottest years on record. (View Video: http://www.climatewatch.noaa.gov/video/2012/the-heat-is-on)
“The Heat is On” recaps September temperature and precipitation conditions in addition to the wildfires of the past few months. September was the 16th straight month with warmer-than-average-temperatures across the country. This sustained warmth, coupled with dry conditions and drought, helped create abundant dried vegetation, which is fuel for devastating wildfires.
The global Scenarios
The average combined global land and ocean surface temperature for September 2012 tied with 2005 as the warmest September on record, at 0.67°C (1.21°F) above the 20th century average of 15.0°C (59.0°F). Records began in 1880.
The Heat is On view video (http://www.climatewatch.noaa.gov/video/2012/the-heat-is-on)
September 2012 Global Temperature Ties for Warmest September on Record: http://www.ncdc.noaa.gov/
Global Climate Change Impacts in the United States, Thomas R. Karl, Jerry M. Melillo, and Thomas C. Peterson,(eds.). Cambridge University Press, 2009. Report in PDF (http://downloads.globalchange.gov/usimpacts/pdfs/climate-impacts-report.pdf)