Forest [FAR1] | Adaptation Workbook

Timing of critical biological events, such as spring bud burst, emergence from overwintering, and the start of migrations, has shifted in the Northeast.

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.

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Northeast forest productivity may increase due to climate change during this century.

Model projections and other evidence support modest productivity increases for forests across the northeast under climate change, although there is uncertainty about the effects of carbon dioxide (CO2) fertilization. Warmer temperatures are expected to speed nutrient cycling and increase photosynthetic rates for most tree species in the Northeast. Longer growing seasons could also result in greater growth and productivity of trees and other vegetation, but only if sufficient water and nutrients are available.

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Southern or temperate tree species in the Northeast will be favored by climate change.

Impact models agree that many temperate species will experience increasing suitable habitat and biomass across the Northeast, and that longer growing seasons and warmer temperatures will lead to productivity increases for temperate forest types. For the Northeast, models predict a decrease in suitable habitat for spruce-fir forest, moderate decline in suitable habitat for the maple-birch-beech forest, and expansion of suitable habitat for oak-dominated forest by the end of the century.

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Systems that are limited to particular environments will have less opportunity to migrate in response to climate change.

Some species and forest types are confined to particular habitats on the landscape, whether through requirements for hydrologic regimes, soil types, or other reasons. Similar to species occurring in fragmented landscapes, isolated species and systems face additional barriers to migration. Widespread species may also have particular habitat requirements. For example, sugar maple is often limited to soils that are rich in nutrients like calcium, so this species may actually have less available suitable habitat than might be projected solely from temperature and precipitation patterns.

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The growing season in the Northeast is expected to increase by at least 19 days or more by the end of the century, due to fewer days with a minimum temperatures below 32°F

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.

Read more about The growing season in the Northeast is expected to increase by at least 19 days or more by the end of the century, due to fewer days with a minimum temperatures below 32°F

By mid-century, spring stream flow is expected arrive 4 to 9 days earlier, and the probability of high-flow events may increase as much as 80% for some areas of the Northeast.

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%.

Read more about By mid-century, spring stream flow is expected arrive 4 to 9 days earlier, and the probability of high-flow events may increase as much as 80% for some areas of the Northeast.

The winter season will be shorter and milder, with less precipitation falling as snow and reduced snow cover and depth.

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.

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The frequency of heavy downpours is projected to continue to increase across the Northeast.

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.

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Over this century, winter and spring seasons in the Northeast will be wetter, with 5-20% more precipitation occurring during these seasons.

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).

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By mid-century, the northern Northeast region will experience fewer days below 10°F, perhaps as much as 21 fewer days per year.

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.

Read more about By mid-century, the northern Northeast region will experience fewer days below 10°F, perhaps as much as 21 fewer days per year.