The Earth is experiencing warming of the atmosphere and its surface due to increased emission of heat-trapping gases emitted by human activities. This warming has been caused by the burning of fossil fuels like coal, oil and natural gas which produce a lot of carbon dioxide and other harmful toxins in the process. Deforestation is another major contributing factor to global warming. Plants absorb and release carbon dioxide as they grow, which maintains environmental balance, but as we continue to cut down trees for commercial and domestic purposes, the balance is disrupted.
The increase in atmospheric greenhouse gases absorbs and radiates some of the energy absorbed by the Earth from the Sun, causing temperatures to rise. Based on the physics of how these gases work, just a doubling of CO2 concentrations would cause a temperature increase of about 1°C over pre-industrial temperatures, but the effect is more complex and there are feedback effects that amplify or diminish the initial warming.
Scientists now agree that the climate changes we have already observed cannot be explained by natural processes, and will worsen unless measures are taken to reduce emissions. These climate change impacts include the loss of ice and snow from glaciers and polar ice sheets, ocean acidification, and changes in the water cycle, such as more frequent heavy rains and floods.
Warming is also affecting biodiversity, with the loss of habitats forcing animals to relocate or even become extinct. The International Panel on Climate Change’s (IPCC) fifth assessment report states that warming of 2.7 to 8.1 degrees Celsius puts many plants and animal species in danger of extinction, and this is a likely scenario under even the lowest-emissions scenarios.