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Top climate researchers have laid out the stark math facing humanity at COP28 climate talks.

The planet is warming so fast that absent major cuts to fossil fuel use, overshooting the 1.5C threshold is becoming almost inevitable, according to a new report released at the summit in Dubai. That could force the world to rely on as-yet-unproven carbon dioxide removal technologies to pull billions of tons of the planet-warming gas out of the atmosphere in a bid to lower global temperatures.

One thing is clear: Only truly radical transformations will prevent Earth from heating 1.5C above pre-industrial temperatures, according to the report, which details 10 major new climate research insights. The world is currently on a dangerous trajectory to surpass the warming limit for at least a few decades. 

“As the crisis becomes stronger, so does the science and that means now we’re able to attribute specific extreme weather events to greenhouse gases,” saidAditi Mukherji, a co-author of the report and a principal researcher at the International Water Management Institute in Sri Lanka. “This wasn’t possible 10 or 15 years ago because the impacts were not so visible and clear.”

Global temperatures were around 1.4C (2.5F) above the pre-industrial average for the first 10 months of 2023. That makes this the hottest year on record, according to the United Nations. Greenhouse gas emissions continued increasing after hitting a historic high in 2022, with extreme weather events made worse by climate change killing thousands and displacing millions.

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Keeping global warming to relatively safe levels will require “a rapid and managed fossil fuel phase-out,” said the report, which was put together by research nonprofits Future Earth, The Earth League and the World Climate Research Programme. That means governments and the private sector need to stop pushing forward new fossil fuel projects, accelerate the early retirement of existing ones and rapidly increase renewable energy deployment. 

Removing CO2 from the atmosphere is not a replacement for “rapid and deep emissions reductions,” the scientists said. Rather, it’s an added guardrail against the worst impacts of climate change. The world currently relies on forests to remove the bulk of carbon emissions put into the atmosphere, thanks to the ability of trees to absorb CO2.

Capacity to remove carbon from the atmosphere needs to soar from about 2 billion metric tons of CO2 to at least 5 billion metric tons by 2050, the scientists said. (Other estimates put that number as high as 10 billion tons.) Only 0.1% of current removal comes from manmade technologies, but that ratio will need to increase. 

Carbon removal technologies ranging from using special rocks to machines are in their infancy and can only remove a few thousand tons of CO2 from the atmosphere annually. They’ll need costs to come down and deployment to speed up.

That’s partly because the role of so-called carbon sinks — the parts of the land and the oceans that absorb more carbon than they emit — might be negatively impacted as the planet warms, diminishing the capacity of natural ecosystems to remove CO2. Scientific research shows that major sinks, such as the oceans and the Amazon, are already capturing less CO2 than they used to and warming could degrade their ability further. 

A number of companies have made investments in carbon removal in an effort to help bring down costs. So, too, have governments. Notably, the Biden administration put more than $1 billion into research hubs to test carbon-removing machines earlier this year. That’s part of a bid to ensure the US can reach its goal of net-zero emissions by mid-century, a target research shows the world will have to reach to keep 1.5C in reach.

“You can’t keep emitting and hope carbon removal will save the day — it won’t,” Mukherji said. “It will be one of the several tools on the kit, but the most important still remains cuts to greenhouse gas emissions.”

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