Fossil fuel emissions are pushing Earth’s climate toward a dangerous new phase of climate “overshoot,” scientists warned Wednesday in a new report from the United Nations Environmental Programme.

The report, Limiting Overshoot, projects that global temperatures will exceed the 1.5-degree Celsius (2.7 degrees Fahrenheit) warming threshold identified in the Paris Agreement within a few years, intensifying deadly climate impacts. It says the best chance of restoring a safe climate is to begin cutting greenhouse gas emissions immediately, halve them by 2035, and figure out ways to remove billions of tons of carbon dioxide from the atmosphere before the end of the century.

The 1.5 degrees of warming identified in the report and the Paris pact refers to the increase in global temperatures since the preindustrial period of 1850 to 1900, before humans altered the atmosphere and climate with billions of tons of fossil fuel emissions and other industrial and agricultural pollution.

Under the 2015 agreement, more than 190 countries pledged to keep the global temperature below that level because they knew warming above that would mean even greater intensification of extreme weather events, ecosystem losses and the potential submersion of small island countries.

Multiple scientific studies, including global assessments from the Intergovernmental Panel on Climate Change, project that warming of more than 1.5 degrees Celsius will cause severe damage to human health, food and water supplies, as well as infrastructure and economies.

Scientists have calculated that at the current pace of emissions, warming could reach a catastrophic 2.7 to 3 degrees Celsius by 2100. If all the measures promised by governments under the Paris Agreement are implemented, warming could be limited to about 1.7 or 1.8 degrees Celsius, which would make it easier to return below the 1.5-degree Celsius threshold.