Carbon neutrality is a state of net-zero carbon dioxide emissions. This can be achieved by balancing emissions of carbon dioxide with its removal (often through carbon offsetting) or by eliminating emissions from society (the transition to the "post-carbon economy"). The term is used in the context of carbon dioxide-releasing processes associated with transportation, energy production, agriculture, and industry. The term ‘carbon neutrality’ did not exist back in 1992 when the UN Convention on Climate Change (UNFCCC) was agreed. Nevertheless the idea of balancing carbon sources and sinks is embedded in Article 2 of the UNFCCC, so you could say that carbon neutrality is part of the DNA of the Convention!

"Achieving carbon neutrality by 2050 requires unprecedented political will and cooperation – but it's not impossible." Climate policy expert Farhana Yamin explains what becoming 'carbon neutral' means and how we can make it happen. Many individuals, companies and countries around the world have made a commitment to being carbon neutral. This means taking action to reduce their greenhouse gas emissions to zero – and then ‘offsetting’ an equivalent amount of any remaining emission.

An attractive aspect of carbon neutrality is that it is easy to understand and allows everybody, from a country right down to a business or an individual, to be part of the solution to climate change. And there is no need to wait for national or international legislation before becoming carbon neutral – although, as a lawyer, I have to say that laws can help by creating incentives and improving transparency. The Elders’ call to world leaders to achieve carbon neutrality by 2050 is very timely. The intensive preparations by governments, civil society and business leaders who negotiated a new global legal agreement on climate for adoption in Paris in 2015 was the widest possible basis of support.

Globally, there are two main ways we can achieve carbon neutrality by 2050. One is based on 100 per cent renewable energy – utilising energy efficiency at scale to reduce energy demand, and simultaneously decentralising and decarbonising power generation and transmission so renewables can make a stable contribution.

The second way is with a high share of renewables but using technologies that result in ‘negative emissions’. This concept has emerged recently to describe the possible use of bio-energy with carbon capture and storage (BECCS) to produce negative carbon dioxide emissions by combining biomass use with geologic carbon capture and storage (CCS). In lay terms, crops absorb carbon dioxide as they grow. When burned in a power station, the resulting carbon dioxide is captured and then buried in wells, mines or geologic formations underground or under the sea. Electricity generation using BECCS then becomes a net absorber of CO2 rather than a net emitter.

In theory, achieving carbon neutrality could be easier if CCS and BECCS could be scaled up cost-effectively. But in real life there are very few projects that show this to be the case. The enormous amount of land and water needed to grow crops to burn could also worsen food and water security, especially for the world’s poor – adding to climate injustice.

The Intergovernmental Panel on Climate Change (IPCC) report clearly shows that we need to limit carbon emissions to around one trillion tonnes (see the The Trillion Tonne Communiqué). Around half of this has been emitted already. At current rates, we will have passed the one trillion cap in around 30 years. This means the transition to a virtually zero-emissions economy has to start now and be substantially in place by mid-century. This timeframe is very ambitious but technically feasible. It would require an unprecedented level of political will and cooperation – but something that is unprecedented is not the same as something that is impossible.