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When you’re in a hole, stop digging. If the world is to have any chance to halt warming below 2 °C, as agreed at the UN’s climate summit in Paris, we cannot develop any more oil wells, coal mines or gas fields.

In fact, we need to go further and start phasing out existing projects, according to the first study of the likely carbon emissions from current fossil fuel extraction.

As more world leaders this week ratify the Paris Agreement at the UN General Assembly in New York, the study finds that “potential carbon emissions from developed reserves – where the wells are already drilled, the pits dug, and the pipelines, processing facilities, railways and export terminals constructed – will take us just beyond the Paris Agreement’s two degrees Celsius warming limit”.

Developed reserves of oil and gas alone, even if coal were phased out immediately, would threaten the agreement’s preferred lower target of 1.5 °C, says the study from , a US think tank that opposes fossil fuels.

The Intergovernmental Panel on Climate Change says capping warming at 2 °C requires total post-2015 emissions to be kept below 843 billion tonnes of CO₂ – or 22 years of emissions at current rates.

But the report’s author, Greg Muttitt, used industry data to calculate that developed reserves of coal, oil and gas will deliver emissions of 941 billion tonnes.

This means countries such as the UK, whose prime minister told the UN assembly this week that her government would ratify the Paris Agreement, should stop all further oil and gas exploration, including fracking.

“There is no room in the atmosphere. No new fossil fuel infrastructure should be built,” says Muttitt. “This means no fracking for gas in the UK or any other new country, and a fairly rapid winding down of existing fracking in the US. All energy development needs to be focused on clean energy from now on.”

Energy analysts say that investment in new fossil fuel resources is already waning in the wake of the Paris Agreement.

Anthony Hobley of the Carbon Tracker Initiative, a think tank set up by former investment analysts, said Muttitt’s hopes of an end to investment in new coal mines could be imminent. Coal burning has been in decline since 2013.  As a result, the industry was stuck with assets worth $200 billion that had “no prospect of paying back their investment cost if the world is serious about the two-degree ceiling”.

Last year, Goldman Sachs said it believed that, led by China, the in 2013.

Read more: Should the UK frack for gas?