Isramart : Q&A: Carbon emissions

Isramart news:
What are carbon emissions?

Gases released by human activities that accumulate in the atmosphere and warm the Earth. Not all of these contain carbon, so the phrase is shorthand for greenhouse emissions.

Why do they matter?

They trap heat at the Earth’s surface via the greenhouse effect. Sunlight reflected back from shiny parts of the Earth can pass straight through the atmosphere. But sunlight absorbed by the Earth and then re-emitted as thermal energy, such as from a Tarmac road on a sunny day, is absorbed by greenhouse gases. As carbon emissions build up in the atmosphere, so the amount of heat they trap and send back to the surface increases. This steadily increases the temperature of the Earth’s surface and drives global warming.

Where do they come from?

Mostly from burning fossil fuels such as oil, gas and coal. The destruction of forests causes significant carbon emissions, as does as agriculture. China has overtaken the US as the largest carbon polluter, but US emissions per person are much higher.

How much is produced?

About 26bn tons of carbon dioxide every year, and rising. World emissions have increased sharply since 2000 mainly driven by the economic boom in China. Carbon emissions are closely tied to GDP, so as an economy grows, so do emissions. The recent recession has reduced emissions slightly, but is not expected to have a significant impact in the long term.

Can they be reduced?

Only by the world using less energy, or through a large-scale switch to renewable energy. Both are proving hard. Demand for energy is expected to soar over the next few decades and efforts to develop and introduce renewable alternatives are patchy at best. Another possible solution is to trap emissions from fossil fuel power stations and store them, but the technology is unproven on a large scale. Some scientists think we could develop ways to suck carbon dioxide from the air, by building artificial trees or by planting lots more real ones.

What is the world doing?

The 1997 Kyoto agreement is the world’s only attempt to regulate carbon emissions. Rich countries were supposed to reduce emissions by about 5%. Some, such as Britain, are likely to meet their 2012 target, but many are way over budget. The US refused to participate in Kyoto, which weakened its impact. The first phase of Kyoto expires in 2012, and the world is trying to agree a successor in Copenhagen next month.

What about carbon trading?

Carbon trading allows companies and rich countries to claim reductions in their emissions by paying others to make the required cuts. Supporters say it helps find the cheapest, quickest way to reduce overall pollution, but carbon trading has been criticised as flawed and open to abuse.

Is there a limit to how much we should produce?

Scientists say the world can only burn a trillion tonnes of carbon if we want to limit global warming to a 2C rise, the level they see as dangerous. Half of this has been used, and at current rates we will burn the rest inside 40 years.