Climate change is already affecting New York, and these changes will have profound effects on its ecosystems, plants and animals. Spring arrives a full week earlier than it did several decades ago, causing plants to bloom earlier and pollinating bees and migrating birds and insects to arrive sooner.
Species that are adapted for warm temperatures or warmer waters are extending their range, as habitat for species favoring cooler temperatures or waters shrinks. In Long Island Sound, fishermen are now catching scup, black sea bass, summer flounder and northern kingfish, warmer water species that were uncommon years ago when the catch was mainly winter flounder, cod, bluefish and striped bass.
Dorothy Peteet, an adjunct senior research scientist at Lamont-Doherty Earth Observatory specializing in paleo-climate, said that at Mohonk near New Paltz, 90 miles north of New York City, temperatures have risen 3.2˚F in the last century. Scientists are seeing changes in plant phenology (the study of cyclic and seasonal natural phenomena) occurring one week earlier than in the past. She notices more birch than oak trees at Mohonk and Black Rock Forest in the Hudson Highlands than she does near the city. “I expect to see an increase in oak pollen and a decline in birch as more warm weather species increase,” she said. “But you can’t say that one species is increasing over another from the pollen record yet.”
While trees are on a longer scale life span so that clear changes are not yet evident, the effects of climate change can be seen in the habitats and distribution of some species, and some interactions between species and food webs. And although global temperatures have only warmed on average about 1.8˚F since preindustrial times, researchers around the world have found that climate change has already prompted myriad changes in species. These include modifications in body size, coloring, wing and bill structure in birds, altered tolerances to hotter temperatures, and variations in sex ratios for species whose sex is determined by temperature.
For many species, temperature is the trigger for key ecological events. And because species differ in the speed with which they can adapt, long-established symbiotic and synchronized relationships between food sources and migrating species, and interactions between plants and pollinators or predators and prey could eventually be mismatched.
In the last several decades, many North American plants and animals have moved approximately 36 feet to higher elevations or 10.5 miles to higher latitudes every 10 years. New environments are often less hospitable for the species entering them as there might be less space or more competition for food. Some species may be moving as far they can go if they are on top of a mountain or hemmed in by some obstruction. A recent study found that almost 50 percent of species that move to a cooler environment end up going extinct.
Ultimately, some species will be disadvantaged by the changes while others will benefit. The vulnerability of plants and animals to climate change and their ability to adapt to it depends on where they are in their habitable range; how well they tolerate stress; how specialized their habitats, food or interactions with other species need to be; their susceptibility to new diseases or pests; their ability to move from their range; their genetic diversity and how large their population is.
Between 1895 and 2011, temperatures in the Northeast rose almost 2˚F and precipitation increased approximately five inches. Already, New York is experiencing more summer days over 90˚F, while winter days below 32˚F have decreased.
By the 2080s, average temperatures in the New York metropolitan region could go up 8.8˚F, precipitation could increase 13 percent, and heat waves in New York City could triple. Sea levels around the city, which have risen a little over one foot since 1900, could rise 39 inches by the 2080s and possibly 6 feet by 2100.
A 2011 New York Natural Heritage Program report studied species that were at risk due to climate change. Of the 119 species examined, 59 percent were found to be vulnerable to climate change, with 17 species designated as extremely vulnerable and nine species as highly vulnerable.
Some of the species most at risk include the Eastern Tiger Salamander; Spruce Grouse; Shortnose, Lake and Atlantic Sturgeon and Bog Turtle.
New York City Audubon reports that more than 100 of the 350 bird species that depend on New York City are of concern. Saltmarsh sparrows are in danger of decline since wetlands are especially vulnerable to climate change. Recovering species such as egrets and peregrine falcons could become vulnerable again; and the red knot, a shorebird, might soon disappear altogether.
As some tree species in the Northeast move north or to higher elevations, New York is expected to lose its spruce-fir forests in the Catskills and Adirondack Mountains by 2100. (What effect might this have on the quality of New York City’s water supply that depends on the natural filtration processes of the ecosystem in that region?) Besides the spruce and fir trees, sugar maple, beech and birch forests as well as elm, ash and cottonwood forests are moving north, while hardwoods like oak and hickory, as well as invasive plants, are moving in.
A 2012 study found that the urban heat island effect, which is exacerbated by climate change, was instrumental in enabling red oak seedlings to grow faster in New York City’s Central Park, where temperatures were on average 4˚F warmer than the Hudson Valley or Catskill Mountains. In spring 2007 and 2008, scientists planted red oak seedlings in Central Park, suburban Hudson Valley and in the foothills of the Catskill Mountains. By late summer, the city red oaks had produced eight times as much biomass as the more rural ones. Kevin Griffin, an earth and environmental science professor at Columbia University and co-author of the study, said that warm summer nights in the city helped the trees perform more of the chemical reactions that promote photosynthesis.
The warmer winters and longer growing seasons are helping pests, pathogens and invasive plants proliferate (many weed species thrive with higher concentrations of CO2 in the atmosphere).
“Some southern species are much more common here than they were 50 years ago,” said Matthew Palmer, a senior lecturer in Columbia University’s Ecology, Evolution and Environmental Biology department. “Two invasive species that were generally a big problem in the southeast U.S.—Mile-a-minute Vine and kudzu—are expanding rapidly in the New York area.”
“The woolly adelgid [an aphid-like insect from Asia] which destroys hemlock trees, also continues to expand its range northward and westward, partly because the milder winters allow them to survive, and also because of the dynamics of invasive species.” said Palmer.
“Warmer temperatures accelerate insect biology. Warmer seasons cause insects to grow faster, produce larger individuals which produce more eggs and more babies, and should give them a longer feeding season.”
While they see signs of change, both Peteet and Palmer emphasized that it’s difficult to tease out the climate drivers from the natural and human-induced drivers of change. “The problem is that we live in a place dominated more by human impact than climate change. We have altered the environment so much that it is hard to see the natural climate change signal,” said Peteet. “But we know what to expect based on paleo records of higher temperatures.”
Fish in Long Island Sound are responding to the impacts of climate change as well as to ocean acidification and human activities such as pollution and shoreline development. The waters of Long Island Sound were 3˚F warmer in 2014 than in 1976. A 2015 study by NOAA found that two-thirds of 82 northeastern marine species have moved north in response to warmer temperatures and increased storms, precipitation and fresh water flowing from rivers in the north (likely due to more precipitation).
The EPA reports that red hake and black sea bass have moved north by about 119 miles. Connecticut’s lobster harvest peaked in the late 1990s at over 3.7 million pounds a year; by 2014, it was only 127,000 pounds; lobsters have migrated about 200 miles up toward the Gulf of Maine. The local species most vulnerable to climate change are the Atlantic salmon and bay scallop. Oysters and clams are also vulnerable because ocean acidification can hinder development of their shells. As Long Island Sound changes from a New England habitat to one more like the coasts of New Jersey, Delaware and Maryland, scientists and fishermen are trying to grapple with the changes; no one knows how fast fish will be able to evolve or adapt.
Climate change could set off cascades of ecological changes, resulting in new interactions between species with unpredictable consequences. Hotter temperatures and heat waves will dry the soil, affecting microbes and fungi that break down organic matter and help keep soil fertile. Plant productivity and thus the availability of food could also be affected by temperature changes and drought.
Warmer temperatures will result in the proliferation of more mosquitoes and ticks, (and the diseases they spread), more insect generations per year and more pathogens surviving the winters. An increase in pests will affect the health of trees, which could compromise the biodiversity of forests.
Flooding from more heavy precipitation will damage plants, disturb aquatic habitats and lead to more runoff, which could result in pollution or eutrophication. Reduced snowfall will endanger small animals that need snow for shelter and alter microbial activity in the soil. Less snowfall will also enable more deer to survive in winter since vegetation will be exposed; their eating habits damage plants, which could harm the forest understory that provides habitat for smaller creatures. Less snowpack will alter stream flows, which could affect fish reproduction and limit water availability for wildlife.
Sea level rise will disrupt coastal ecosystems and result in the seawater inundation of wetlands. Warmer waters will encourage algal blooms and eutrophication, which could create low-oxygen areas where wildlife cannot survive.
When ecosystems are affected, human society will be as well. In New York, climate change will affect crop yields, fishery productivity, the maple syrup and timber industries, and winter recreation. Wet springs could delay planting and harvesting, while heat stress decreases crop yields.
Some may perceive warmer weather as an advantage, such as gardeners who can now plant Southern ornamental species that in the past would not survive here.
A longer growing season may also enable farmers to produce warmer temperature crops such as peaches and watermelon, but higher temperatures will hurt the dairy industry as well as some of today’s valuable crops like apples, cabbage and potatoes. New pathogens and more pests could impact the health of crops, livestock and humans. And the many changes could affect the viability of ecosystems and the services they provide such as pollination, pest control and carbon sequestration.
“Climate and ecosystems are so complex,” said Palmer. “Creating such a big driver of change [CO2] in the system means that there will be ecosystem consequences. Whenever there’s a strong force on a system, there will be unpredictable effects, and the risk of big negative effects is much more likely—it’s fair to say these risks outweigh the benefits.”
A 2014 report, Responding to Climate Change in New York State, recommended strategies to protect ecosystems, wildlife and plants. To improve the resilience of ecosystems, stresses such as insect infestations, invasive species and nitrogen pollution or acid rain should be minimized. Instead of trying to maintain the mix of species in an ecosystem today, ecosystem functioning and biodiversity need to be the priorities since biodiversity makes habitats more resilient to disturbances. And connectivity between habitats must be established and protected so that species can migrate and shift their ranges.