Last month, an alliance of large US tech companies—including Google, Meta, Shopify, and the payment company Stripe—announced plans to purchase US$925m in carbon removal over the next eight years. The carbon removal purchases, by a Stripe-owned company called Frontier, will be from 14 different start-ups. They include CarbonBuilt, which is trying to sequester carbon by capturing it in concrete; and Project Vesta, which wants to line beaches with a carbon-capturing mineral called olivine.

If those start-ups don’t deliver the promised tons of carbon removal, Frontier said it has no recourse to be refunded. But it is aiming that its payments will help push the industry’s development, helping discover which methods will allow carbon removal to make the dramatic scale up that will be needed. 

Across the pond, the EU outlined plans in November last year to use technology to remove 5Mtpa of carbon dioxide from the atmosphere by 2030, as part of its goal to reach carbon neutrality by 2050.

The latest report from the UN’s Intergovernmental Panel on Climate Change (IPCC) said that carbon removal is now “unavoidable”, if the world is to reach its global temperature targets. The Paris Agreement outlines a long-term goal of limiting global warming to well below 2C above pre-industrial levels.

In 2021, worldwide energy-related carbon dioxide emissions rose 6% to top 36.3Bt, according to the IEA, setting a new record as the global economy sprang back from the depths of the pandemic. For context, limiting global warming to 1.5C, the Paris Agreement’s most ambitious target, would require global greenhouse gas emissions to fall by nearly half over the next decade. And the world would need to achieve net-zero emissions by the early 2050s.

Even in a scenario where the world aggressively reduces its carbon emissions, some carbon removal will be “essential” to reaching net-zero carbon. This is because while it is technically possible to eliminate most emissions from human activities, such as by switching to low- or zero-carbon forms of electricity and fuel, difficult-to-decarbonise sector sectors will likely have some residual emissions left over—and this is how carbon removal comes in.

Even the IPCC’s most conservative estimates say that humanity will need to capture more than 1Bt of carbon dioxide a year to keep global temperatures from rising more than 1.5C above pre-industrial level, an already unlikely scenario. The median estimate presents an even more challenging 6Bt a year.

But just how strongly carbon removal can—or should—be used is a matter up for debate. There is still some scientific uncertainty about exactly how much carbon can be pulled out of the atmosphere using various approaches. Nature-based approaches, such as planting trees or restoring forests, are the most widely deployed today. But the carbon can return into the atmosphere when the plants die or burn up in fires.

Direct air capture can permanently remove and store carbon, but the machines are currently limited in scale and expensive, and the technology consumes large amounts of energy and water, according to the IPCC report.

Achieving large amounts of carbon removal will require significant research and development to determine the most effective strategies, reduce environmental impacts, and rapidly develop major projects. This will require government policies to mandate and incentivise carbon removal to tackle the biggest hurdle—cost.

Carbon removal will not solve climate change by itself. The key method for fighting climate change remains the same solution that scientists have presented for decades: cutting greenhouse gases as quickly as possible across all sectors—including transportation, energy, and heavy industry.

The discussions around carbon removal comes as temperatures are soaring across South Asia, as heat waves intensify faster than any other type of extreme weather. Parts of northern and central India have recorded their highest average temperatures for April.

Indeed, the capital, Delhi, topped 46C last week. Meanwhile, in neighbouring Pakistan, temperatures are 5-8C above average, according to the Meteorological Department. What India is witnessing now comes as average temperatures there have risen by about 1C, since the beginning of the industrial age, according to Berkeley Earth. 

The numbers of heat-related deaths are poorly estimated in low- and middle-income countries but are likely to be significant and unlikely to be decreasing, given recent trends of urbanisation and limited deployment of heatwave action plans, according to a paper published on Monday by a group of leading climatologists.