Hillside Woods is getting about the same amount of rain—or slightly more—as it used to, but rain is delivered in more intense dumps with drier periods in-between, a pattern more like a subtropical system than a traditional New England weather pattern. Dry spells can reduce soil nutrient cycling, and pummeling rains on dry soil contribute to erosion (a process unfortunately assisted by the presence of invasive earthworms). In addition, temperature and moisture level changes alter the kinds of fungi and bacteria that can thrive, and forest residents are intricately dependent on these relationships. These kinds of changes can make Hillside's trees and shrubs more susceptible to insects and disease.

Extremes of temperature are tough on everyone, from plants to animals to people. Energy spent weathering heat waves and cold snaps stresses the residents of Hillside Woods. It is now generally warmer—and, critically, warmer at night—in summer, which changes dew patterns: for water to condense out of the air and form dew, it needs to cool off at night. Instead of the August hazes of the 1970s, we get sunny skies that pull moisture up into tropical-looking puffy clouds, followed by intense and often scattered thunderstorms. All of these shifts put pressure on plants and animals that are evolved to live in different conditions.

Precipitation delivers nitrogen and phosphorus, among other pollutants, from smokestacks and tailpipes. Lawn fertilizers, pet waste and certain soaps and detergents can also contain nitrogen or phosphorus. The presence of these chemicals helps algae to grow—often faster than ecosystems can handle—harming water quality, food resources and habitats, and decreasing dissolved oxygen in Sugar Pond. In sufficient volume, algal blooms cause aquatic life to die. Excess nitric and sulphuric acids can also leach aluminum from soils, a phenomenon known as acid rain. Do your part: Leash and clean up after your dog, do not apply fertilizer on your property, use soaps low in phosphates and make your next car an electric one.

Plants consume CO2 and transform it into plant cells. Increased CO2 accelerates growth, which can cause some plants to outpace others. For example, swift-growing plants like vines will accelerate their growth rates more steeply than more slowly growing plants such as trees, disrupting the growth balance between them. Poison ivy is one vine that's been in the news for benefiting from increased atmospheric CO2. Researchers are investigating other impacts of increased CO2 in the atmosphere, with some surprising conclusions, such as upsets in balance of minerals up-taken from soils and acceleration of tree growth leading to shorter tree lives.

To date, Hillside Woods has been mercifully spared from fire. But intense dry spells can create tinderbox conditions, which, combined with teens' misuse of fire in the woods, could spell disaster.

In a warming climate, southern insects that would normally perish during a northern winter manage to survive and expand their numbers. The southern pine beetle is one insect that is moving north and will eventually devastate area pine trees. Climate change also disrupts migration timing, such as when flowering plants bloom before their migratory pollinating insects or birds are able to arrive to pollinate them or eat their berries. Read more about the southern pine beetle.