EPA's Vessel General Permit and Small Vessel General

another 2.5 to 4°F during the winter season and 1.5 to 3.5°F during the summer season as a result
of carbon emissions that have already occurred (Burakowski et al. 2008, Karl et al. 2009).
Forecasts beyond the middle of this century are sensitive to the level of carbon emissions
produced today. If carbon emissions are not reduced, the length of the winter snow season
would be cut in half across northern New York, Vermont, New Hampshire, and Maine, and
reduced to a week or two in southern parts of the region; the Northeast would have fewer cold
days during the winter and experience more precipitation (Hayhoe et al. 2007, Karl et al. 2009).
Cities in the Northeast that currently experience temperatures greater than 100°F for a few days
each summer would experience an average of 20 days of such temperatures each summer; some
cities in the Northeast -- Hartford, Connecticut, and Philadelphia, Pennsylvania, for example --
would experience an average of 30 days of such temperatures each summer (Karl et al. 2009).
Hot summer conditions would arrive three weeks earlier and last three weeks longer into the fall.
Droughts lasting from one- to three-months are projected to occur as frequently as once each
summer in the Catskill and Adirondack Mountains, and across the New England states. Finally,
sea levels in this region are projected to rise more than the global average, which would increase
coastal flooding and coastal erosion (Kirshen et al. 2008, Karl et al. 2009).
In the Pacific Northwest, annual average temperatures have increased by about 1.5°F over the
past century with some areas experiencing increases of up to 4°F (Karl et al. 2009, Littell et al.
2009, Elsner and Hamlet 2010). Higher temperatures during the cool season (October through
March) have caused more precipitation to fall as rain rather than snow and contribute to earlier
snowmelt. The amount of snowpack remaining on April 1, which is a key indicator of natural
water storage available for the warm season, has declined substantially throughout the Northwest
region. In the Cascade Mountains, for example, the snowpack remaining on April 1 declined by
an average of 25 percent over the past 40 to 70 years; most of this decline is attributed to the
2.5°F increase in temperatures during the winter season over the time interval (Payne et al. 2004,
Christensen et al. 2007).
Over the next century, average temperatures in the Northwest Region are projected to increase
by another 3 to 10°F, with higher emissions scenarios resulting in warming in the upper end of
this range (Christensen et al. 2007, Karl et al. 2009). Increases in winter precipitation and
decreases in summer precipitation are projected by many climate models, though these
projections are less certain than those are for temperature.
There is consensus within the scientific community that warming trends will continue to alter
current weather patterns and patterns of natural phenomena that are influenced by climate,
including the timing and intensity of extreme events such as heat-waves, floods, storms, and wetdry
cycles. Oceanographic models project a weakening of the thermohaline circulation resulting
in a reduction of heat transport into high latitudes of Europe, an increase in the mass of the
Antarctic ice sheet, and a decrease in the Greenland ice sheet, although the magnitude of these
changes remain unknown (Schmittner et al. 2005, Levermann et al. 2007). As ice melts in the
Earth’s polar regions in response to increases in temperature, increases in the distribution and
abundance of cold water are projected to influence oceanic currents, which would further alter
weather patterns. In addition to influencing atmospheric temperatures and weather patterns,
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