United States
           Environmental Protection
Climate  Change

Indicators  in  the

United  States,  2012
   EPA's Climate Change Indicators in the United States, 2012,
   presents compelling evidence that many fundamental
   measures of climate in the United States are changing.
Temperatures are rising, snow and rainfall patterns are shifting,
and more extreme climate events—like heavy rainstorms and
record-high temperatures—are already affecting society and
ecosystems. Similar changes are occurring around the world.
EPA's report presents 26 indicators, which are organized into the
five categories listed at right.
Observed Changes

          A Greenhouse
      ,  .    Gases:
            gas emissions
            are increasing
            as a result
            of people's
activities. Consequently, average
concentrations of these heat-
trapping gases in the atmosphere
are also increasing.

            and Climate:
            Average U.S.
            ind global
            ire increasing.
          :es of weather and
_		,	as precipitation,
drought, and tropical cyclone
activity, are changing.

            Oceans: The
            oceans are
            getting warmer.
            Sea levels are
            rising around the
            world, and the
         coming more acidic.
                                                                       Snow and Ice:
                                                                       The extent of
                                                                       Arctic sea ice
                                                                       is declining.
                                                                       Glaciers in
                                                                       the United
                                                           States and around the world are
                                                           Oenerally shrinking, while snowfall
                                                           and snow cover in the United
                                                           States have decreased overall.

                                                                       Society and
                                                                       pollen season
                                                                       as is the
                                                           growing season for crops.
                                                           Winter habitats of bird species
                                                           have shifted northward as
                                                           temperatures have risen.

                                                   Climate  Change  In
                 Concentrations of
                 Greenhouse Gases
                 Before the industrial era began in
                 the late 1700s, global carbon dioxide
                 concentrations in the atmosphere
                 measured approximately 280 parts
                 per million (ppm). Concentrations
                 have risen steadily since then, reaching
                 391 ppm in 2011—a 40 percent
                 increase. Current global atmospheric
                 concentrations of carbon dioxide are
                 unprecedented compared with the
                 past 650,000 years.
                                   Global Atmospheric Concentrations
                                      of Carbon Dioxide Over lime
                                      -650,000 years ago to present
                               .1 30°
                               ~ 250
                               •S 50
Sea Level
As temperatures rise,
seawater warms up and
expands, and ice melts.
This raises sea level
worldwide. Sea level
rose relative to the land
along much of the U.S.
coastline between I960
and 2011, particularly
along the Mid-Atlantic
and Gulf Coasts. Some
parts of the  Gulf Coast
have registered a relative
sea level rise of more
than 8 inches since I960.
                                                            -700,000   -500,000  -300,000  -100,000 0
                                                                 Year [negative values = BO

                                                              Data source: Compilation of 12 underlying datasets
                                  Relative Sea Level Change
                                 Along U.S. Coasts, 1960-2011

                H  I

              Hawaii and
         -,   Pacific Islands


        Relative sea level change [inches]:
  „  -7.99 -5.99 -3.99 -1.99
s-8  to-6 to-4 to-2 toO
                                                          t   t
                    0.01  2.01  4.01  6.01  >8
                    to2  to4  to6  to8
                                                      Data source: NOAA, 2012

cheater  Highlights
    With warming temperatures
    and changing weather patterns,
    snowfall amounts have
    decreased in many parts of
    the country (as indicated by
    the red circles on the map),
    with 57 percent of weather
    stations showing a decline. The
    Pacific Northwest has seen
    the largest consistent decline
    in snowfall, but some regions
    have experienced modest
    increases, including areas near
    the Great Lakes.
      Change in Total Snowfall in the
     Contiguous 48 States, 1930-2007
        Rate of change (percent per year):
<-1.2   -0.9  -0.6  -0.3  -0.1 -0.1  0.1  0.3   0.6   0.9
    to -1.2 to -0.9 to -0.6 to -0.3 to 0.1 to 0.3 to 0.6  to 0.9 to 1.2
                                        Less snowfall

                                                              More snowfall

                                                         Data source: Kunkel et al., 2009
    High and Low Temperatures
    Since the 1970s, record-setting daily high temperatures
    have become more common than record lows across
    the United States. The most recent decade had twice
    as many record highs as record lows.

           Record Daily High and Low Temperatures
           in the Contiguous 48 States, 1950-2009
                              I Record hig hs • Record lows
                          Ragweed Pollen Season
                          The length of the ragweed pollen season is closely
                          related to the timing of the first fall frost, which is
                          occurring later than it used to in northern areas.
                          Since 1995, the ragweed pollen season has grown
                          longer at eight of the 10 locations studied. The
                          red circles represent a longer pollen season, with
                          larger circles indicating larger changes.
                             Change in Ragweed Pollen Season, 1995-2011
                                                                          |+26 days
           1950s   1960s    1970s   1980s   1990s   2000s
                                                                                  +18 days

                                                                                  .+24 days
                                                                                    —+21 days
                                                                                      -+14 days
                                                                                         >+13 days
                                               • +12 days
                                                                                     i+12 days
                                                                  Change in length
                                                                  of pollen season:
                                                                   • Decrease
                                                                   • Increase
                                                                                   Data source: Ziska et al., 20


Greenhouse Gases
U.S. Greenhouse Gas Emissions
Global Greenhouse Gas
Atmospheric Concentrations
of Greenhouse Gases
Climate Forcing

Weather and Climate
U.S. and Global Temperature
High and Low Temperatures
U.S. and Global Precipitation
Heavy Precipitation
Tropical Cyclone Activity

Ocean Heat
Sea Surface Temperature
Sea Level
Ocean Acidity

Snow and Ice
Arctic Sea Ice
Lake Ice
Snow Cover

Society and Ecosystems
Ragweed Pollen Season
Length of Growing Season
Leaf and Bloom Dates
Bird Wintering Ranges
Heat-Related Deaths
 Access the 2012 Report Online
 For each of the 26
 indicators, the report
 presents graphics depicting
 changes over time, key
 points about what the
 graphics show, background
 on how the  indicator relates
 to climate change, and
 information  about how the
 indicator was developed.
 The website also features
 technical documentation
 that provides additional
 details about each indicator. Visitors to the website can share report
 content through social media outlets like Facebook and Twitter.
 A print version of the report is available by request or for download
 from the website.
    «, U.S. and Global Precipitation
                                                        Indicator Notes
              Figure I. Pndpilitiin In the Contiguous « States. 19QM011      Figure 3. Rate of Precipitation Chtnge In the United Stales,
            United States
            Environmental Protection
           i Agency
Order Print Copies
Print copies of Climate Change
Indicators in the United States,
20/2, are available upon request.
To order a copy, please submit a
written request to:
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December 2012