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What exactly are carbon sinks?

If we are to mitigate anthropogenic climate change, we must limit our CO₂ emissions. So what’s the good news about negative emissions? Come this way to take a deep dive.

^{This is what it’s all about: A carbon sink takes up CO₂ and reduces its concentration in the atmosphere. This process is also referred to as ‘negative emissions’.}

Climate change has long since been a well-known issue. Anthropogenic greenhouse gas emissions (i.e. emissions caused by human beings) have caused a rise in global temperatures. For this reason, Germany has set itself ambitious targets: it plans to reduce its emissions by 65% by 2030 and by 88% by 2040, all compared to the levels of 1990. By 2045, the country is to achieve net greenhouse gas neutrality, with the remaining emissions set off by carbon sinks.

^{Mitigation measures alone are not sufficient}

Forecasts by the Intergovernmental Panel on Climate Change show that mitigating greenhouse gas emissions alone will not be enough to limit the global rise in temperatures to less than 1.5° Celsius – a limit referred to in the Paris Agreement as preventing irreversible damage from climate change. Based on the current emissions levels, the global carbon budget could be used up by 2030. Apart from climate change mitigation measures, it will be necessary to remove more CO₂ from the atmosphere than is released into it. The EU and Germany are striving to achieve net negative emissions after 2050.

^{Key points paper for a ‘Long-term strategy for negative emissions’ published}

The process of capturing CO₂ emissions from the atmosphere is also called ‘negative emissions’ and is something entirely positive! In February 2024, the Federal Government published a key points paper (in German only) sketching out its Long-term strategy for negative emissions (in German only).

A stakeholder process is currently being used to develop a fully-fledged strategy on the basis of that paper. An online consultation focusing on assessment methods and technologies for achieving negative emissions is due to begin soon. More information on the online consultation can be found on the website for the Long-term strategy on negative emissions’ (in German only).

There are different ways of removing CO₂ from the atmosphere and storing it. A key role is played by natural carbon sinks such as forests and wetlands that use natural processes to bind CO₂ and thus reduce its concentration in the atmosphere. The more suitable areas there are available, the larger their contribution to climate action. Another possibility is an accelerated weathering of rock. This involves using ground-up rock to accelerate a natural chemical process in which minerals bind CO₂.

^{The more ways there are to store CO₂, the better}

There are promising approaches to geological CO₂ storage. Direct Air Carbon Capture and Storage (DACCS) entails the capture of CO₂ from the air and its subsequent geological storage. It is also possible to permanently store plant-based CO₂ after using it for energy generation. This is done through a process called Bio Energy with Carbon Capture and Storage (BECCS). Both procedures have been included in the Carbon Management Strategy.

Negative emissions can help mitigate climate change, but they cannot solve the problem on their own and tend to be costly. Without a rapid and sustainable reduction of greenhouse gas emissions, the climate targets continue to be out of reach.