How do we do it?
Cutting carbon emissions would reduce the amounts of greenhouse gases entering the atmosphere. It may also be possible to remove carbon from the atmosphere – by a process known as carbon sequestration.
Carbon could be removed at the point of production – power stations – but no technologies are yet in widespread use. Carbon capture would increase the cost of energy production significantly. And it is not obvious what should be done with the carbon dioxide captured. A favoured option is burying it deep underground.
There is little agreement about how feasible carbon capture is – both economically and technologically. Some experts see it as a vital way of reducing emissions; others think alternative energy sources are more important.
Researchers are also looking at biological solutions, some of which have a very long history. Long before Europeans arrived, Amazonian Indians were using ‘biochar’ – plant material turned into a form of charcoal – to fertilise their land. This approach can lock up carbon for many hundreds of years.
Photosynthesis is the key biological process through which carbon dioxide is removed from the atmosphere. Alongside rainforest preservation, organisms such as marine phytoplankton may offer a route to carbon capture. As iron is often limited in oceans but is a key element in enabling photosynthesis, adding iron to seas could stimulate phytoplankton growth and draw carbon dioxide out of the atmosphere.
The wider impact of interfering with ecosystems via such large-scale ‘geoengineering’ is unclear; however, European researchers have recently suggested that photosynthetic bacteria in the oceans could be another carbon sink.
The genome sequence of Polaribacter (pictured) contains genes for a light-sensitive protein, proteorhodopsin, suggesting that the microbe may be able to use sunlight to fix carbon into complex organic molecules.
Some microbes – the methanotrophs – are able to metabolise methane. In wetlands the balance of methane users and producers dictates whether sites are net absorbers or emitters of methane, so these microbes are of special interest in such areas.
A better understanding of biological cycling could help improve environmental management and may also identify organisms for use in carbon sequestration.Lead image:
Photo courtesy of Jarone Pinhassi. From DeLong EF, Béjà O. The light-driven proton pump proteorhodopsin enhances bacterial survival during tough times. PLoS Biol 2010;8(4) CC BY
- What is carbon capture and storage?
- CO2 emission standards and investment in carbon capture (2014)
- Guardian: What is carbon capture and storage?
- From the ancient Amazonian Indians: ‘biochar’ as a modern weapon against global warming (2010)
- Iron fertilization in the ocean for climate mitigation: legal, economic, and environmental challenges
- Revealing the role of microbial communities in carbon cycling [PDF]