• What is climate change?

    Climate refers to the average weather experienced over a long period, typically 30 years. The Earth’s climate has changed many times in response to natural causes – the term climate change usually refers to changes that have occurred since the early 1900’s and today is synonymous with anthropogenic (man-made) global warming. Within scientific journals, however, global warming refers to surface temperature increases, while climate change includes global warming and everything else that increasing greenhouse gas (GHG) levels will affect.

    Natural and anthropogenic (human) factors both affect global climate. Natural causes include interactions between the ocean and the atmosphere, changes in the Earth’s orbit and volcanic eruptions. Humans influence global climate by releasing greenhouse gases – such as carbon dioxide (CO2) and other polluting gases such as methane into the atmosphere. CO2 is a common greenhouse gas that is emitted in many ways, by the burning of firewood and the fuel used to power our cars, and by cutting down forests. Rainforests are often called the lungs of the planet for their role in absorbing carbon dioxide which helps to stabilize the world’s climate, and plays an important role in mitigating climate change. Research suggests that tropical forests absorb about 18% of the CO2 added to the atmosphere each year from burning fossil fuels (Lewis et al., 2009). When rainforests are chopped down however, and burned, the carbon stored in their wood and leaves is released into the atmosphere, contributing to climate change. Tropical deforestation released 1.5 billion metric tons of carbon to the atmosphere annually throughout the 1990’s, accounting for almost 20% of anthropogenic greenhouse gas emissions (Gullison et al., 2007).

    There has always been carbon dioxide in our atmosphere, but it is the huge rise in emissions due to our massive increase in burning fossil fuels that has been the main cause in climate change and is why we are told to reduce our carbon emissions, or our "carbon footprint". These gases absorb and trap energy that is radiated from the Earth’s surface forming a blanket around the Earth - like the glass of a greenhouse, warming the atmosphere and increasing temperatures globally. As they build up, the planet's temperature rises. Once released the greenhouse gases stay in the atmosphere for many years.

    In 2007, the Intergovernmental Panel on Climate Change (IPCC), the world’s most authoritative body on climate change, concluded that most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations.

    Current climate models suggest that global temperatures could warm from between 1.4 to 5.8°C over the next 100 years. The potential social, environmental and economic costs associated with this are huge. They include: more extreme weather (including prolonged dry spells), flooding, severe storms, extreme heat and extreme cold. These weather patterns have serious consequences for agriculture, human habitation and property damage; and may lead to an increase in desertification; spread of tropical diseases to previously unaffected areas; and food and water shortages.

  • How important is this threat compared to others?

  • Why is it a threat to great apes?

  • Is climate change dangerous for all species in the same way?

Compiled and edited 2011 by Kay H. Farmer
Reviewed by Hjalmar Kuehl, Josephine Head and Neba Funwi-Gabga

  • References