Climate change: Invest in technology that removes CO2 - report

Technology to remove the planet-warming greenhouse gas CO2 from our atmosphere must be urgently ramped up, leading climate experts say in a new report.

Scientists say big cuts in CO2 emissions won't be enough to limit global warming.

And nature alone will not remove enough of it from the air.

CO2 is the most important gas warming the planet, and is emitted when fossil fuels such as gas and oil are burnt.

"To limit warming to 2C or lower, we need to accelerate emissions reductions. But the findings of this report are clear: we also need to increase carbon removal too," says lead author Dr Steve Smith from Oxford University. "Many new methods are emerging with potential."

There's consensus among scientists that the world is warming primarily because emissions of CO2 (estimated at 33 billion tonnes in 2021) far exceed the amount that is being removed (this report suggests two billion tonnes a year).

Until emissions and removals are balanced - so called "net-zero" - global temperatures are predicted to rise.

But getting there won't be easy. The latest UN climate reports say to fully achieve "net zero" there will need to be some CO2 removal, so called "negative emissions", to compensate for sectors that can't easily decarbonise.

Currently almost all of the world's CO2 removal occurs through natural processes. That's primarily plants and trees taking in CO2 from the air, and the soil absorbing and storing it.

But there are limits to how much nature can do. For example, how much more of the world can realistically be given over to forests? Some optimistic scenarios suggest that natural CO2 removal could be doubled by 2050, but that's still only about 4 billion tonnes of CO2 a year.

This new report titled "The State of Carbon Dioxide Removal" says that to restrict and reduce global temperatures in the future there needs to be investment in developing technological solutions now.

The methods it cites are all fairly new, and at different stages of development and deployment. Put together they currently only make up a tiny fraction of the worlds CO2 removal.

One, known as BECCS, involves incorporating CO2 capture into biomass-based electricity-generation, in which organic matter such as crops and wood pellets are burned to produce power. Other options include: huge facilities where the carbon is extracted from the air before being stored in the ground; the use of specially treated charcoal (biochar) that locks in carbon; and "enhanced rock weathering" - loosely based on the carbon removal that occurs with natural erosion.

The use of CO2 removal technologies is not without its critics. Some campaigners doubt that they can be cost effective and fear that they can be an excuse to defer and delay the transition away from fossil fuel use.

This report stresses that removing CO2 should not be seen as a "silver bullet" to tackle climate change but that meeting the UN's climate goals will require technology as well as nature to reduce greenhouse gas levels.

That all assumes that global CO2 emissions from burning fossil fuels will, as pledged at numerous climate summits, fall rapidly. So far yearly emissions have yet to start a downward trend.

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