Climate change- what is all the fuss about?

Climate change is constantly in the headlines and will be for the foreseeable future, but what is it and what can we do to stop it?

Climate change hit the headlines again in December with the United Nations Climate Change Conference in Copenhagen, and it will continue to be in the news for years to come as the problem has no definitive answer. But what exactly is climate change and global warming, how are we contributing to it and is it really bad as we’re being told?  Perhaps more importantly – is there anything we can actually do to stop it?

Climate change and global warming are often interchangeable, but the term climate change is now generally used to describe changes caused by human activity. Global warming refers to the trapping of greenhouse gases by the atmosphere leading to an increase in overall temperature of the earth.

Carbon dioxide is seen as the main greenhouse gas produced by human activity, and figures suggest that there are currently 384 parts per million (ppm) in the atmosphere and rising1.  Their accumulation in the atmosphere traps heat, bouncing it back to earth heating the surface and driving global warming.  The carbon dioxide equivalent – the total level of greenhouse gases in the atmosphere including methane and nitrous oxide - is closer to 440ppm.

Burning fossil fuels is the largest anthropogenic source of carbon dioxide, followed by deforestation.  Some of this ‘extra’ CO2 is absorbed by the natural carbon sinks – the oceans, plants, trees – but the rest accumulates in the atmosphere, amplifying the natural greenhouse effect.  The concentration of methane in the atmosphere has risen significantly because of human activity – raising livestock, growing rice and using landfills - while nitrous oxide has risen because of agricultural activities – fertilisers and land usage change.

But what effect does this have on the climate?  The Earth has warmed by 0.74°C in the last 100 years, and by 0.4°C since the 1970s2. Global sea levels have gone up, glaciers and sea ice has melted, floods and droughts are on the increase, and heatwaves are more intense. And the global picture stands to get worse – more flooding, droughts, food and water shortages, disease and loss of tropical forest.    Here in the UK, the Met office predicts summer temperatures to rise by around 4°C, with more flash flooding and more rainfall in the winter3. But it’s hard to know exactly what will happen – scientists use computer power to compile and process all of the various factors needed to model a system as complex as climate - but no one can accurately predict the future.

But it’s not all bad news. Terrestrial ecosystems and the oceans have the capability to absorb carbon dioxide, and several recent studies suggest that their capacity to do so will decrease as carbon dioxide levels increase. However new data shows that the balance between airborne and absorbed carbon dioxide has stayed approximately constant since 1850, despite emissions increasing rapidly4.  Dr Wolfgang Knorr from the University of Bristol found that the variance in the airborne fraction of CO2 since 1850 has been 0.7 ± 1.4% per decade.  The study relies on measurements and statistical data, not on computations with complex climate models.

 “Like all studies of this kind, there are uncertainties in the data,” Dr Knorr said, “so rather than relying on Nature to provide a free service, soaking up our waste, we need to ascertain why the proportion has not changed.”

The British Antarctic Survey has discovered that large blooms of phytoplankton are flourishing in open waters left exposed by the recent and rapid melting of ice shelves and glaciers around the Antarctic Peninsula5.  As the blooms die back, the phytoplankton sinks to the bottom of the sea-bed, storing carbon. It is estimated that this new natural sink is taking an estimated 3.5 million tonnes of carbon (equivalent to 12.8 million tonnes of CO2) from the ocean and atmosphere each year.  Lead author Professor Lloyd Peck said: "Although this is a small amount of carbon compared to global emissions of greenhouse gases in the atmosphere it is nevertheless an important discovery. It shows nature's ability to thrive in the face of adversity.”

So Nature is fighting back – what about us?  Nature is mopping up some of the extra CO2 we’re releasing into the air, but how are we helping? The Kyoto Protocol set binding targets for 37 industrialised countries and the European community for reducing greenhouse gas emissions – about 5% over the five-year period 2008-2012.  Under the Protocol, emissions are monitored and recorded and submitted annually. The December UN conference aimed to achieve an agreement to replace the Kyoto Protocol when it expires in 2012, and talks were given a boost when the US, India and China agreed to attend and set domestic emissions targets.  Although it was accepted that a treaty would not be signed in Copenhagen, it was expected for an agreement to be reached and ratified this year.

The level of greenhouse gases in the atmosphere could be reduced by using renewable energy.  The United Nations Intergovernmental Panel on Climate Change (IPCC) said that we already have most of the technology to enable the reduction of emissions significantly.  The UK currently uses biomass, wind and hydro power to provide renewable energy, but in April the Government will be introducing the Feed-in tariff to boost the use of solar energy. The scheme - already a success in Germany and Spain - offers financial incentives to individuals and businesses adopting solar energy. The biggest factor against the use of photovoltaic cells is the cost, but it’s hoped the move will make renewable energy more affordable, particularly to residential customers who stand to make £1,200 per year from the tariff.

Carbon dioxide in the atmosphere can be reduced by carbon trading, carbon offsetting and carbon capture and storage (CCS). Carbon trading involves countries agreeing on maximum emission levels, and companies purchasing credits to emit a certain amount of CO2. Anyone exceeding their limit can purchase further credits from companies under their limit.  It was hoped that if the cost of purchasing credits was too high that companies might invest in measures to reduce their emissions.  Carbon offsetting sees people paying towards carbon reductions made by someone else, but is unregulated so it’s unclear how much effect it has.

CCS involves extracting CO2 at power stations and pumping it underground. There are three approaches – removing it before combustion, scrubbing it from the exhaust gases or burning the fuel with extra oxygen to produce an almost pure CO2 exhaust able to be sequestered. The Mountaineer Project in West Virginia put CCS technology to use in 2009 using a chilled ammonia process -  ammonium carbonate is used to absorb CO2, resulting in an ammonium bicarbonate slurry, which is converted back to ammonium carbonate in a regenerator and reused to repeat the process. The captured CO2 is sent for storage in deep geologic formations 1.5 miles beneath the plant site.  The project will store around 100,000 metric tonnes of CO2 per year6.

Closer to home, we are all encouraged to think about our own carbon footprint and what contribution we can make towards slowing climate change – recycling, turning things off when we’re not using them and walking or using public transport instead of driving everywhere. I took the Carbon Footprint test on carboncalculator.directgov.uk and discovered my household carbon footprint was 3.83 tonnes per year. I thought this sounded pretty terrible, especially when I make a conscious effort to switch things off when I leave the room, only have the heating on if needed and I only drive when necessary. But when I compared it to the national average of 10.17 tonnes per year, I felt pretty good! 

Climate change and global warming are problems facing not only this generation, but future generations and if predictions are correct, their effects stand to get worse. There are no definitive solutions - burning fewer fossil fuels, using renewable energy sources, and harbouring the gas underground will be beneficial, and Nature is doing her part too - but it’s clear that the amount of anthropogenic carbon dioxide released into the atmosphere needs to be reduced to ensure the future of the planet.