What is carbon capture and can it stop global warming?
If we are to avoid the worst impacts of global warming, we urgently need to reach reduce carbon emissions. But what about removing the carbon that’s already in the atmosphere?
In this article we explain why carbon dioxide, alongside other greenhouse gases, is causing global warming. We also look into what carbon capture technologies could be scaled up in the future to remove historic carbon from our air.
Why does carbon dioxide make our planet get hotter?
Carbon dioxide is a greenhouse gas that absorbs and traps heat close to Earth. We need some in our atmosphere to keep temperatures above freezing, but too much causes our planet to heat up dangerously.
Carbon levels have fluctuated for hundreds of thousands of years – with low levels causing ice ages and higher levels leading to warmer periods. From around 4,000BC to the 1850s, carbon levels remained stable, creating an environment where plants and animals could thrive.
However, over the past 60 years, carbon dioxide has increased 100 times faster than it would have done naturally – to levels never seen before on our planet.
Watch the video below to discover how climate scientists study carbon levels.
How can we remove carbon from our atmosphere?
1. Reach net zero carbon emissions as soon as possible
The first and most important thing to do is to transition away from fossil fuels. Burning fossil fuels releases carbon that’s been locked underground for thousands of years. The faster we can replace it with low carbon energy for power, heat and transport, the better.
Other impactful ways to reduce carbon emissions include adapting our diets to include less meat and dairy and dramatically reducing plastic production worldwide.
2. Restore and protect carbon sinks
The Earth has several carbon sinks – including forests, soil and oceans. These carbon sinks absorb more carbon than they make and play a very important role in fighting climate change. However, they are under threat.
An area of forest the size of a football pitch is destroyed or damaged by humans every second. Heatwaves and drought are leading to more and more wildfires. Soil is being over-farmed and carbon is being unlocked from permafrost as it melts.
Phytoplankton in our oceans are eating microplastics, impacting their ability to absorb carbon and affecting the whole food chain.
We need to work together to rapidly restore and enhance these natural carbon sinks, by putting a stop to deforestation, extending the photosynthesis season of agricultural land and preventing plastic reaching our oceans, to name a few.
3. Use carbon capture and storage (CCS) technologies
Carbon capture involves trapping carbon as it is emitted by industrial processes, transporting it and then storing it deep underground. As of the end of 2022, there were nearly 200 carbon capture and storage facilities around the world, and many more in development.
It is possible that carbon capture and storage technologies could help to reduce emissions from industries that are particularly difficult to decarbonise, such as steel, cement and energy production.
However, a lot of the funding for CCS currently comes from oil, gas and coal industries. In order to meet net zero we need to be leaving these depleting fossil fuels in the ground where they belong.
One CCS technology that has gained attention is bio-energy carbon capture and storage. This captures and permanently stores carbon emitted during bioenergy generation. However, some key challenges remain – not least the sustainability of the bioenergy. It is important that the fuel source for this technology does not displace or damage vital natural ecosystems and infrastructure.
4. Use direct air capture (DAC) technology
The International Committee on Climate Change (IPCC) has made it clear that in order to limit global warming, we will need to remove historic carbon from the air. Not an easy task at all.
Direct air capture technology involves using enormous fans to pull in air from the atmosphere. The carbon dioxide in air then binds to a chemical and is removed from the atmosphere for good.
Although there are a few direct air capture plants around the world, the technology is still in its infancy and would need to be dramatically scaled up to make a significant difference. Carbon makes up only 0.4% of the air, so removing it in this way is very energy intensive, inefficient and expensive (up to $540 or £380 per ton).
DAC plants in operation
The most successful air capture plants to date – Orca and Mammoth, are in Iceland. Between them, they have the potential to remove up to 40,000 tons of carbon a year – which is about the same as the annual emissions from 28,000 combustion engine cars.
They are funded by businesses that buy carbon-capture credits to evidence their sustainability commitments and reduce their own emissions.
So, will carbon capture help stop global warming?
Carbon capture technologies are developing fast and will likely play an important role in our future fight against climate change. However, until they are dramatically scaled up, they simply can’t remove carbon from our atmosphere in the quantities needed.
Our best chance of limiting global warming is to cut carbon emissions and work alongside nature, rather than against it.
