As efforts to cut planet-warming emissions fall short, large-scale projects to suck carbon dioxide out of the atmosphere will be needed by the 2030s to hold the line against climate change, scientists have said.



Many new technologies that aim to capture and store carbon emissions, thereby delivering “negative emissions”, are costly, controversial and in the early phase of testing.

But “if you’re really concerned about coral reefs, biodiversity [and] food production in very poor regions, we’re going to have to deploy negative emission technology at scale,” said Bill Hare of Climate Analytics, a science and policy institute.

“I don’t think we can have confidence that anything else can do this,” the Berlin-based chief executive told a London climate change conference.

World leaders agreed in 2015 an aim of holding global warming to 1.5C above pre-industrial times. Scientists believe this is key to protecting small island nations from sea level rises, shoring up food production and preventing extreme weather.

Carbon-sucking technologies may even be needed to hold the planet to a less ambitious two degrees of warming, said scientists at Chatham House, a British thinktank.

The world has already seen an average of about one degree of warming, they said.

“It’s something you don’t want to talk about very much but it’s an unaccountable truth: we will need geoengineering by the mid-2030s to have a chance at the [1.5C] goal,” Hare said, referring to efforts to cool the planet through engineering.

These ideas include planting carbon-absorbing forests across large areas, then harvesting the wood for energy and pumping the emissions produced underground – a process likely to feature in an Intergovernmental Panel on Climate Change report next year.

Machines might also be developed to capture carbon dioxide directly from the air and pump it underground or otherwise neutralise it.

But efforts to store captured carbon underground are “showing no progress … and even backwards steps in some cases”, said Corinne Le Quéré, director of the Tyndall Centre for Climate Change Research at the University of East Anglia.

Underground carbon storage has been promoted as part of a push by the United States and other countries to develop “clean coal” technology.

Similarly, planting more forests – a technology known as Beccs, or bioenergy with carbon capture and storage – raises questions about food security and land rights, scientists said.

Le Quéré said Beccs is “probably essential to take us to zero emissions” although “it’s really difficult to imagine we can use land at the levels required in the models”.

She called for experts to focus on proven approaches, such as improving energy efficiency, promoting cleaner transport, eating less meat and scaling up renewable energies.

Many experts fear that launching costly “negative emissions” technologies could reduce the pressure to act swiftly to cut emissions now.