Effects of climate change on biomes

Climate change is already changing the world's biomes, which are large areas with similar plants, animals, and weather patterns. These changes happen because the temperature and weather are shifting over long periods, leading to more extreme storms and hotter days. As the climate changes, animals and plants must move to new places to survive, which can cause problems for the way they normally live and work together.

For example, many species are moving to higher mountains or farther north to find cooler temperatures. However, not all species move at the same speed or in the same direction, which can break the balance between them. Some places, like drylands and deserts, are also growing larger because of climate change, especially in areas such as southwest North America, northern Africa, southern Africa, and Australia.

Mountains, which cover a quarter of the Earth, are also at risk. Boreal forests, also called taiga, are warming faster than most places, making them drier and less healthy. Perhaps the most vulnerable of all are coral reefs, which are home to many sea creatures. Even a small rise in ocean temperature can harm most coral reefs, making it hard for them to survive.

Terminology and classification

On Earth, biomes are big parts of the biosphere. They are defined by the plants, animals, and weather in a certain area. A biome includes many different ecosystems and ecoregions. According to the World Wildlife Fund, there are many ecoregions, about a dozen biome types, and just a few biogeographic regions for land, ocean, and freshwater areas.

General impacts

The 2007 IPCC Fourth Assessment Report found that human-caused warming has changed many living systems over the past few decades. The Sixth Assessment Report showed that many animals and plants are moving toward cooler areas or to higher elevations, and that spring events like bird nesting are happening earlier.

Climate change can also change how animals and plants work together. When some species move faster than others, it can break these important connections. This makes it harder to plan for nature’s future, so we need to be ready for changes. If Earth gets much warmer, some ocean, forest, and polar areas may see big changes sooner. By the year 2050, many places could lose some of their natural balance if temperatures rise too high.

Terrestrial biomes

Deserts and drylands

See also: Desertification § Climate change

Climate change is making dry areas like deserts grow larger. Scientists think that by the end of this century, drylands could cover more of the Earth’s land. This change is especially noticeable in places like southwest North America, northern Africa, southern Africa, and Australia.

Grasslands

Tundra

Many animals that live in cold places, like the Arctic and Antarctic, such as polar bears, are at risk. Climate change is also making it harder for animals like snowshoe hares to hide in the snow because there is less snow.

Mountains

Mountains cover a big part of the Earth and are home to many people and animals. Climate change can harm these places in many ways. It can cause more forest fires, change when snow melts, and affect plants and animals that live high up. Warmer temperatures might let lower-elevation plants and animals move higher up the mountains, but they may run out of space to move.

Boreal forests

Main article: Taiga

Boreal forests, also called taiga, are warming up faster than the rest of the world. This makes them drier and causes many problems. Trees are having a harder time growing, and some are moving north to cooler areas. Very cold days are becoming less common, which helps harmful insects survive. In North America, forests have been burning more often and covering larger areas since 1970.

Scientists think that if the climate keeps changing, some boreal forests might turn into grasslands, while other cold areas might become forests. This could happen if temperatures rise a lot, but it would take many years.

Temperate forests

In the western U.S., warmer and longer summers since 1986 have led to many more big forest fires. Even though some of this is due to policies about fighting fires, the warming climate is also making fires more common.

A study from 2018 found that trees are growing faster because there is more carbon dioxide in the air, but the wood they produce is lighter.

Expansion of beetles that can harm trees

Before, very cold weather would stop pine beetles from causing too much damage. But since 1998, warmer winters in British Columbia have let these beetles destroy huge areas of forest. Warmer temperatures help the beetles live longer and attack more trees, especially in places that didn’t used to be warm enough for them.

Tropical forests

Main article: Effects of climate change on the tropics

The Amazon rainforest, the largest tropical rainforest in the world, helps make its own rain. But if too many trees are lost, the forest could turn into a dry savanna. Deforestation has been a big problem, but climate change also makes wildfires more likely and changes the rain patterns. If the world gets too warm, the Amazon might change into a savanna over many years.

Forest fires in Indonesia have also become more common since 1997. These fires often start to clear land for farming and can burn large areas of peat, releasing a lot of carbon dioxide into the air.

One big worry is that animals that live in tropical forests might lose their homes because of the increasing heat.

Freshwater biomes

Lakes

When lakes get too warm, fish can grow smaller and struggle to find enough food. This makes them more likely to be eaten by other fish. A study in 2023 looked at fish in lakes in Minnesota. It found that if lake temperatures rise by 4 °C in July, some cold-water fish like cisco could disappear from many lakes. Other fish, like yellow perch, would become less common, while warm-water fish like bluegill might become more common.

Rivers

Many plants and animals need cold water to survive, especially those that live in areas fed by glaciers. Warmer temperatures can reduce the flow of cold water, making it hard for some fish, like salmon and cutthroat trout, to live and reproduce. Heatwaves can also strongly affect rivers, especially when there are fewer predators to help balance the ecosystem. Fish that need cold water may see their numbers drop significantly.

Salmon and other fish often rely on higher water levels in rivers to spawn. With less snow falling due to climate change, rivers may have less water, making it harder for salmon to reproduce. Rising sea levels can also bring salt water into rivers, changing fresh water habitats into salty ones. This can harm fish like sockeye salmon, which need fresh water to spawn in the spring.

Marine biomes

Polar waters

In the Arctic, the waters of Hudson Bay stay ice-free for three weeks longer than they did thirty years ago. This change affects polar bears, which like to hunt on sea ice. Birds such as gyrfalcons and snowy owls, which hunt animals that depend on cold weather, may also be impacted by these changes.