How much will Earth Warm?

Unquestionably human activity has changed the amount of greenhouse gases in the atmosphere. Since the beginning of the Industrial Revolution, concentrations of carbon dioxide have risen by nearly 40 per cent, whilst those of methane have doubled. In 2005, burning fossil emitted about 27 billion tonnes of carbon dioxide.

Forests have been cut down in vast numbers. Trees absorb carbon dioxide so, with fewer trees, more carbon dioxide is able to build up in the atmosphere. Of course, when trees are burnt they also release the carbon dioxide they store. The IPCC estimates that deforestation produces 5.9 billion tonnes of carbon dioxide per annum, which equates to just under 20 per cent of total global carbon dioxide emissions. The land use changes that replace the forests can also be a source of emissions e.g. methane release from agriculture.

We must also consider that the world’s population is growing and by 2050 is anticipated to reach 9 billion people. This will lead to an increased demand for food, livestock and energy. In turn this will lead to further increases in emissions.

Consequently, global temperatures are expected to rise even faster over the next century and the IPCC estimate that by 2100 we are going to see a rise between 1.1oC (best case scenario if we cut our greenhouse gas emissions sharply) and 6.4oC (worst case scenario if greenhouse gas emissions continue to rise unabated).

The next question to ask is how will global warming impact upon the planet.