BERLIN — The United Nations reported Tuesday that fresh pledges by governments to cut greenhouse gas emissions raise hopes but aren’t strict enough to avoid catastrophic global warming.

A report by the U.N. Environment Programme found recent announcements by dozens of countries to aim for “net-zero” emissions by 2050 could limit a global temperature rise to 2.2 degrees Celsius (4 F) by the end of the century.

That’s close to the less stringent target set in the Paris climate accord of capping global warming at 2 degrees Celsius (3.6 F) by the end of the century but far from the agreement’s most ambitious goal of keeping it to 1.5 degrees Celsius C (2.7 F).

The United States, the European Union and dozens of other countries have set net-zero emissions targets. However, the Environment Programme report said the net-zero goals that many governments announced in the run-up to a U.N. climate summit in Glasgow next week remain vague, with much of the heavy-lifting on emissions cuts pushed beyond 2030.

“Climate change is no longer a future problem. It is a now problem,” the program’s executive director, Inger Andersen, said.

“To stand a chance of limiting global warming to 1.5 C, we have eight years to almost halve greenhouse gas emissions,” she said, adding: “The clock is ticking loudly.”

The report is  one of several recent studies to examine the gap between what countries have pledged to do to cut emissions of planet-heating gases and what scientists say is required to meet the Paris goals.

Leaders, diplomats, scientists and environmental campaigners will meet in Glasgow from Oct. 31-Nov. 12 to discuss how countries and businesses can adjust their targets to avert the more extreme climate change scenarios that would result in significant sea-level rise, more frequent wild weather and droughts.