The following changes in climatic conditions have been observed in the Northeast:
- Since 1970, the average air temperature has increased by 2°F; the rise in temperature during the winter was 4°F.
- Days with temperatures over 90°F have become more frequent.
- An increasing trend in precipitation has been observed throughout much of the year and, most notably, over the last 50 years, the number of days with very heavy precipitation has increased.
- Winter precipitation has come more typically as rain rather than as snow, leading to reduced snowpack.
- Winter ice is disappearing earlier from lakes and rivers, and river flows are peaking earlier in the spring as the snow melts.
- Average sea surface temperatures have been increasing in the North Atlantic.
- In the mid-Atlantic region from New York to North Carolina, rates of relative sea level rise ranged between 2.4 and 4.4 mm/year (~.094 and .173 in) or about .3 m (~11.8 in) over the twentieth century; low-lying topography and a high storm frequency make this area particularly vulnerable.
The following climate-related changes are projected for the Northeast:
- Air temperature will rise an additional 2.5 to 4°F in winter and 1.5 to 3.5°F in summer over the next several decades.
- Under a higher emissions scenario, by late this century:
- The summer heat would occur three weeks earlier and end three weeks later and the average number of days above 100°F for certain cities would increase,
- Short-term droughts are projected to occur as frequently as once each summer in the Catskill and Adirondack Mountains and across the New England states, and
- Winters will be shorter with fewer cold days, more precipitation, and a reduced snow season.
- Severe flooding due to sea level rise and heavy downpours is likely to occur more frequently.
- The densely populated coasts of the Northeast face substantial increases in the extent and frequency of storm surge, coastal flooding, erosion, property damage, and loss of protective wetlands.
- As the average temperatures of the ocean continue to increase, the center of lobster fisheries is projected to continue its northward shift and the cod fishery on Georges Bank is likely to be diminished.
See National Climate Assessment: Northeast Region
Find more resources on the Northeast Regional Resources List.