Climate Change and the Loss of Biodiversity

Moving north

Imagine a plant that can only grow where summers stay cool. As summers get warmer, the cool places shift north. Seeds that land farther north grow; the plants in the south struggle. Over many years, the plant's home "moves". But what if there is a city, a farm or a lake in the way? Or what if the plant is already as far north as land goes?

This is happening to many species right now, and it is one way climate change is reducing biodiversity.

Weather, climate and climate change

• Weather is what it is like outside today: snowy, sunny, −10 °C.
• Climate is the usual pattern over many years: Ontario winters are usually cold and snowy.
• Climate change is a long-term change in those patterns.

Scientists agree that Earth's climate is warming, and that the main cause today is people burning fossil fuels (coal, oil and natural gas) for energy in cars, homes and factories. Burning them adds greenhouse gases, like carbon dioxide, to the air. These gases trap heat, like a blanket around Earth. Cutting down forests adds to the problem, because trees take in carbon dioxide.

Climate change means more than warming. It also brings changes in rain and snow, and more extreme events such as heat waves, droughts, floods and wildfires.

How climate change reduces biodiversity

1. Habitats change faster than species can adapt. Species that need cold, like brook trout in cold streams, lose habitat when water warms.
2. Ranges shift. Many species are moving north or uphill to stay cool. Species that can't move fast enough, or that are blocked by cities, farms or water, may decline. Species already in the far north have nowhere colder to go.
3. Sea ice is shrinking. Polar bears, including those along Hudson Bay in northern Ontario, hunt seals from the sea ice. When the ice melts earlier in spring and forms later in fall, bears have less time to hunt.
4. Timing gets out of step. Many plants now flower earlier in warm springs. If the insects or birds that depend on them still arrive at the old time, they can miss their food.
5. Pests and diseases spread. Warmer winters allow some species to spread north. Blacklegged ticks, which can carry Lyme disease, have been spreading into more areas of Ontario.
6. Extreme events. Droughts dry up wetlands, and larger wildfires and floods can destroy habitats.
7. Oceans change. Warmer ocean water can cause coral bleaching, which can kill coral reefs, home to a great variety of ocean life.

Climate change also adds to other threats like habitat loss and invasive species. A community already weakened by one threat is harder hit by another.

The impact of this loss

When biodiversity declines:

• Ecosystems become less resilient and less able to recover from disturbances.
• Food sources for people and animals can be affected: fish, wild plants, crops that need pollinators.
• Ecosystem services that we rely on, like clean water, flood control and healthy soil, can be weakened.
• Ways of life are affected. For many Inuit communities, travelling and hunting on the sea ice are part of their food, culture and way of life. Inuit hunters and Elders have shared observations of changes in sea ice, weather and wildlife, and scientists increasingly work together with Inuit communities to track these changes. Many First Nations communities have also observed changes in the plants and animals they harvest.