Agriculture

All global climate models agree that sea level will rise. Sea levels have increased over the past century, and this trend is expected to continue. At the current rate of increase, sea levels could rise nearly 6 inches by the end of the century across the Northeast, which is a conservative estimate. Additional warming is expected to increase sea levels in the Northeast by 7 to 23 inches by the end of the century.

The lower Chesapeake Bay is especially at risk due to high rates of sinking land (known as subsidence) Climate change and sea level rise are also likely to cause a number of ecological impacts, including declining water quality and clarity, increases in harmful algae and low oxygen (hypoxia) events, decreases in a number of species including eelgrass and seagrass beds, and changing interactions among trophic levels (positions in the food chain) leading to an increase in subtropical fish and shellfish species in the bay.

The intensity, frequency, and duration of North Atlantic hurricanes, as well as the frequency of the strongest (Category 4 and 5) hurricanes, have all increased since the early 1980s. Hurricane-associated storm intensity and rainfall rates are projected to increase as the climate continues to warm.

Peer reviewed multi-decadal studies have documented an advance in springtime phenological events of species in response to climate warming. Evidence suggests that insect emergence from overwintering may become out of sync with pollen sources, and that the beginning of bird and fish migrations are also shifting.

Evidence at both global and local scales indicates that growing seasons have been getting longer, and this trend is projected to become even more pronounced over the next century. Warmer temperatures will result in fewer days with minimum temperatures below 32°F and a shorter freeze-free season by mid-century, increasing by 3-4 weeks in most areas, trending towards an earlier onset of spring.

With warmer temperatures and an increase of rain-on-snow events occurring in winter, the Northeast is expected to experience a reduced snowpack and earlier breakup of winter ice on lakes and rivers. The earlier snowmelt runoff will result in more frequent high-flow events in winter and spring. For parts of the northern Northeast region the probability of high-flow events may increase by as much as 80%.

A variety of models project that winters will become more mild across the Northeast as temperatures increase. Warmer temperatures will cause more winter precipitation to be delivered as rain. Snowfall, snow depth, and snow pack are all expected to be reduced.

There has been a 71% increase in the annual amount of precipitation falling in very heavy events for the Northeast region (defined as the heaviest 1% of all daily events) from 1958 to 2012. These trends are larger than natural variations for this region. The magnitude or even frequency of flooding could also potentially increase in the winter and spring due to increases in total runoff and peak stream flow during those times.

The Northeast is expected to see increased precipitation in winter, a change of 5 to 20%, by end of century for high emission scenarios. Models are in agreement that this change will be significant in comparison to the current average climate (1970 – 1999).

The Northeast region will potentially experience a decrease in the number of very cold days (below 10°F). The northern Northeast region is modeled to experience the greatest decreases with changes of 21 days or more. The smallest decreases are modeled to occur in coastal and southern areas where the number of occurrences in the present-day climate is small. These simulated decreases in cold days are in line with the recent observed changes in the Northeast region.