U.S. National Climate Assessment: 2014

The White House released the third US National Climate Assessment (NCA) report yesterday. It clearly states that climate change is not a distant problem of the future; it is happening now and impacting every region of this country.

Issued every four years to assess how climate is changing in the US, this latest report says: “Summers are longer and hotter, and extended periods of unusual heat last longer than any living American has ever experienced. Winters are generally shorter and warmer. Rain comes in heavier downpours. People are seeing changes in the length and severity of seasonal allergies, the plant varieties that thrive in their gardens, and the kinds of birds they see in any particular month in their neighborhoods.” In terms of agricultural production, “Corn producers in Iowa, oyster growers in Washington state and maple syrup producers in Vermont are all observing climate-related changes that are outside of recent experience.”

“U.S average temperature,” according to the report, “has increased by 1.3°F to 1.9°F since 1895, and most of this increase has occurred since 1970. The most recent decade was the nation’s and the world’s hottest on record, and 2012 was the hottest year on record in the continental United States.” Over the next few decades, temperatures are projected to rise another 2°F to 4°F.  By the end of the century, our average temperature could soar by 10°F if greenhouse gas emissions continue to increase unchecked.

While similar in theme to the recently released IPCC report from the UN, this assessment focuses solely on the United States. Emphasizing the fact that rising temperatures will affect different parts of our vast country in different ways, the NCA breaks the nation down into specific regions. It details the current and future impacts of climate change in each one. Here are some regional highlights:

Northeast: Increased frequency and duration of heat waves; Increased flooding due to sea level rise and extreme rain events

Southeast: Increased frequency and intensity of extreme heat events; Decreased availability of fresh water; Increased threat from sea level rise

Mid-west: Increased frequency of extreme heat events; Increased heavy downpours and flooding; Decreased air quality

Southwest: Increased heat, drought, and wildfires; Increased insect outbreaks

Northwest: Decreased summer water supplies due to earlier snow melt; Increased threat from sea level rise; Increased insect outbreaks and wildfires

Alaska: Warming twice as fast as the rest of the nation; Loss of sea ice, melting glaciers, thawing permafrost; Increased wildfires

Hawai’i: Increased saltwater intrusions from sea level rise; Decreased availability of fresh water

As a nation with over 95,000 miles of coastline, the report also addresses the issues of ocean warming and acidification.

Written by over 300 NOAA scientists and endorsed by dozens of other experts from both the public and private sector (including two oil companies), the NCA concludes that, “Climate Change presents a major challenge for society.” It goes on to say, “There is mounting evidence that harm to the nation will increase substantially in the future unless global emissions of heat trapping greenhouse gases are greatly reduced.” While this comprehensive report does not offer policy, it does emphasize the urgent need for both adaptation and mitigation at all levels of government.

The colors on the map show temperature changes over the past 22 years (1991-2012) compared to the 1901-1960 average for the contiguous U.S., and to the 1951-1980 average for Alaska and Hawai'i.  Image Credit: NCA

Change in annual average temperature, 1991-2012. Credit: NCA