The Amazon Rain Forest and Climate Change

• Earth and Its Climate
  • Introduction
  • Our Atmosphere
  • Climate and Weather
  • The Greenhouse Effect
  • Greenhouse Gases
  • The Carbon Cycle
• Evidence of Climate Change
  • Man-made Change
  • Temperatures
  • Oceans
  • Snow and Ice
  • Rain, Drought, Extreme Weather
  • Ecology
• Future Projections
  • A Quick Look
  • Warming
  • Oceans
  • Ocean Ecosystems
  • Terrestrial Ecosystems
  • Health
  • Economics
• Brazil, the Amazon, and Climate Change
  • Brazil’s CO₂ Emissions
  • Tropical Forests and CO₂
  • Deforestation
  • Fires and Weather
  • Other Consequences
  • Carbon Sequestration and REDD
• International Agreements
  • UNFCCC: Convention on Climate Change
  • Kyoto Protocol
  • Emission Reductions

The Carbon Cycle

Carbon dioxide (or CO₂) doesn’t just stay in the air. It also moves into and out of the atmosphere, living organisms, soil, rock, and water. For example, over very long periods of time, the weathering of rocks, which is a chemical reaction between carbon dioxide in the air and stone, can add carbon to rivers that run into the ocean. Eventually, this carbon settles to the bottom of the ocean and forms limestone. It can later be released back into the atmosphere from volcanoes when the rock is melted.

In ancient times when Earth had a much warmer climate, huge swamps buried plant material faster than it could decay, and when the buried remains were subjected to heat and pressure, they became coal. In similar ways, microorganisms buried on lake and sea bottoms throughout Earth’s history produced oil. These processes locked up lots of carbon as oil, gas, and coal. By burning these fuels in the last 150 years, we have suddenly released into the atmosphere carbon that took hundreds of millions of years to store.

Plants are an important part of the carbon cycle. They absorb carbon dioxide in the air to make wood, stems, and leaves. Animals, including humans, take up carbon when they eat the plants, and then release CO₂ back into the atmosphere in breathing. Plants also release CO₂ back into the air when the leaves fall or the plants die. Forest fires release large amounts of CO₂ as the wood burns.

Threats to tropical forests, including drought, disease, fires, or logging and clear cutting, release that carbon dioxide to the atmosphere and decrease our planet’s carbon absorption and storage capacity. Tropical deforestation currently accounts for 15-20% of all human-caused CO₂ emissions, and with millions of hectares of tropical forest destroyed each year, we are quickly losing this resource for combating climate change.