UN scientists are likely to weigh up technology to remove CO2 from the atmosphere, as they gather to finalise a key report.
This idea will be one of many solutions considered over the next two weeks by the Intergovernmental Panel on Climate Change (IPCC).
Also in attendance will be government officials from all over the world, who will need to approve every line in the summary report.
It is due to be published on 4 April.
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This new study will be the third of three important reports from the IPCC issued over the past eight months. The previous two have looked at the causes and impacts of climate change, but this one will focus on mitigation – or what we can do to stop it.
This essentially means that researchers will look at how we can reduce the amount of warming gases that are emitted from human activities.
However, the IPCC co-chair says this mitigation report will look more closely at ways of removing CO2 that’s already in the atmosphere.
“We have a lot more material, this time on carbon dioxide removal. That is, not putting carbon into the atmosphere, but getting it out again,” said Prof Jim Skea, from Imperial College, London.
“The report was scoped out to cover the full spectrum of carbon dioxide removal approaches, which vary absolutely hugely, and the carbon dioxide that is removed can end up in very different stores and in very different places. So it was within the scope of the report to cover the whole lot, basically.”
The kind of carbon removal approaches the report will consider will likely include tree planting and agriculture, as well as the more advanced technological approaches that use large machines to remove the carbon from the air.
They will also look at combined approaches, where land is used to grow crops which can be burned for energy while the carbon is captured and buried.
The use of these types of technology is controversial. Campaigners express doubts that they can be made to work economically and there are also concerns that technology could be seen as an excuse not to make the major changes in energy production that are needed.
Scientists though say that the situation is now so serious that carbon dioxide removal will be needed in addition to massive cuts in emissions and not as a substitute for them.
What ultimately emerges in the short summary for policymakers that will be published in two weeks, will depend on delicate negotiations with government representatives from 195 countries.
Researchers and officials will work through the summary line by line to agree the final text.
There are some concerns that the war in Ukraine might have an impact on the meeting, with representatives from both Russia and Ukraine due to take part.
“We have been running some informal meetings with governments to brief them ahead of the actual approval session,” said Prof Skea.
“I would be optimistic that we would get full participation.”
The new report, part of a regular review of the science dating back to 1990, will also have a new focus on the social aspects of cutting carbon.
“This chapter looks at the social science perspective of demand, and what motivates individual consumers, communities, businesses, to make responsible consumption, reduction, design and investment choices,” said Dr Joyashree Roy, from Jadavpur University and the lead author of this part of the report.
“Responsible production and consumption are also within the scope of this chapter, and we have also been asked to look into what are the drivers of behaviour change.”
There will be much focus on short term actions that governments can take in the remaining years of this decade to keep the rise in global temperatures under 1.5C this century.
This was assessed in 2018 as needing emissions to be cut in half by 2030 – but after the pandemic and with the likely ramping up of fossil fuel use in the wake of the conflict in Ukraine, the scale of emissions cuts may need revising upwards.
Despite this, the report will likely emphasise that there is hope that the worst impacts of climate change can be avoided, if urgent action is taken.