We’ve heard about greenhouse gases warming the earth, but climate experts are particularly antsy about carbon dioxide, or CO2. It's time to learn the facts about carbon dioxide, its impact on the planet, and what we should be doing about it.
You might be surprised to learn that carbon dioxide is not the most potent greenhouse gas (GHG); nitrous oxide is 200-300 times stronger when it comes to warming Earth, while methane’s impact on climate is 25 times greater than carbon dioxide.
The temperature of Earth is dependent on striking the right balance between the energy it gets from the sun and the energy that bounces back and gets lost in space. CO2 poses a big threat as it absorbs much of the heat that would otherwise be lost, and re-emits some of that energy back to Earth, causing the planet to heat up.
CO2 stays around for longer than most GHGs – its lifetime is difficult to determine, but the majority of CO2 emissions can take somewhere between 20 and 200 years to dissolve in the ocean. Due to the amount of CO2 in the atmosphere, ocean acidification is reducing the water’s ability to absorb more of the gas, not to mention threatening the marine food chain and our natural ecosystems.
According to the Intergovernmental Panel on Climate Change, CO2 currently accounts for over three-quarters of the greenhouse gases we’re putting into the air. This is largely down to the burning of fossil fuels we use for electricity or in transport fuel – which when reacting with oxygen, produce CO2. Different fossil fuels produce different amounts of CO2, with coal producing the most, then oil, and then gas.
The surge in worldwide manufacturing since the industrial revolution, coupled with consumer demand and the continued loss of our forests (which do such a good job of breathing in carbon dioxide), has seen current CO2 levels heading for 40 billion tonnes – that’s the equivalent of flying from Sydney to London 20 billion times.
Experts say that to prevent global average temperatures rising by more than two degrees by the end of this century – the point at which the world will face the most dangerous climate impacts, such as floods, droughts and hurricane – global emissions must reach below 22 billion tonnes by 2050. That's just over half the level it is today.
Slow down the rate at which coal, oil and gas is burned and those dangerously high levels of CO2 will start to fall.
So, what does all this mean? Well, it’s all about global averages. In the West, each person has a much higher personal carbon footprint than those in the developing world – due to consuming and traveling much less. While Kenya has an annual per capita carbon footprint of 0.3 per cent, in the US it is 17.5 per cent, accounting for some 16 per cent of the world’s total CO2 emissions.
It’s said that we should aim to keep our carbon footprint below two tonnes of CO2 a year. Right now, the global average is 4.6 tonnes per person, so there’s some way to go yet. Serious reductions in the amount of CO2 being pumped into the atmosphere will only be brought about by changes within the world’s big energy markets. Slow down the rate at which coal, oil and gas is burned and those dangerously high levels of CO2 will start to fall.
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Read more from our content series as we explore everything you need to know about climate change (but were too afraid to ask) in the run up to Paris 2015!