Urban

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

Shorter-term fluctuations in the variability of ocean dynamics, atmospheric shifts, and ice mass loss from Greenland and Antarctica have been connected to recent accelerations in the sea level rise rate in this region. Sea levels have risen over the past century, and all global climate models agree that sea level will rise over the next century. Worst-case and lowest-probability scenarios project that sea levels in the region could rise upwards of 11 feet (3 m) on average by the end of the century.

Heavy precipitation events have increased substantially in number and severity in the across the Northeast over the last century, and many models agree that this trend will continue over the next century. Extreme precipitation events could lead to more frequent or severe flooding and an increase in soil erosion. Monthly precipitation in the Northeast is projected to be about 1 inch greater for December through April by end of century (2070–2100) under a high emissions scenario.

All global climate models agree that there will be changes in precipitation patterns across the assessment area, but there is large variability among projections of future precipitation. Most climate models project increases in annual precipitation. Seasonally, winter and spring are also generally projected to have increases in precipitation during the next century. Projections of summer and fall precipitation for this region vary, with many models projecting decreased precipitation or only very slight increases.

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.

All global climate models project that temperatures in New England and northern New York will increase over the next century as a result of continued increases in atmospheric greenhouse gas concentrations.

In general, species-rich ecosystems have exhibited greater resilience to extreme environmental conditions and greater potential to recover from disturbance than less diverse ecosystems. This makes less diverse ecosystems inherently more susceptible to future changes and stressors. Conversely, ecosystems that have low species diversity or low functional diversity (where multiple species occupy the same niche) may be less resilient to climate change or its associated stressors.

Model results project that tree species currently at their northern range limits south of the Central Appalachians will become more abundant and more widespread. The range of eastern redcedar currently occupies a small portion of its range within the Central Appalachians. The range of loblolly pine lays largely to the south, although disjunct populations have been planted in some locations within Ohio and Maryland. Models agree that loblolly pine, shortleaf pine, and post oak will fare well in terms of habitat and basal area.

"Across northern latitudes, past periods of warmer temperatures have resulted in species’ distribution changes toward the north and also upward in elevation. The ranges of eastern hemlock and red spruce lay largely to the north of the Central Appalachians, but these species currently persist in microhabitats that remain cool and moist enough to support them. Red spruce is more limited within the Central Appalachians, occurring at high elevations in the Allegheny Mountains section of West Virginia. Hemlock is more widespread, occupying cool and wet sites at lower elevations.

"Many invasive species that currently threaten forests in the Central Appalachians region may benefit directly from projected climate change or benefit from the slow response of native species. Increases in carbon dioxide have been shown to have positive effects on growth for many plant species, including some of the most invasive weeds in the U.S. Experiments with CO2 fertilization on kudzu seedlings have indicated increased growth, increased competition with native species, and range expansion.