"Global warming causes major damage to the global economy and the natural world and engenders risks of catastrophic and irreversible outcomes," the global lender said in a semi-annual report released ahead of the IMF and World Bank fall meetings of finance leaders and policymakers next week.

The stark warning was issued as protests continue to demand immediate action to cut carbon emissions and avert an ecological disaster. On Monday, thousands of climate-change protesters took to the streets in cities around the world, launching two weeks of peaceful civil disobedience.

U.N. climate scientists warned last month that if greenhouse gas emissions are not slashed the world must face a reality of cities vanishing under rising seas, rivers running dry and marine life collapsing.

In its Fiscal Monitor report on Thursday, the IMF noted the long-term goal of the 2015 Paris Agreement was to limit temperature rises to 2 degrees Celsius (3.6 degrees Fahrenheit), but that current global commitments to reduce emissions were consistent with the warming of 3 degrees Celsius.

The Fund also noted that many countries are set to miss their own targets and that the United States has said it will pull out from the Paris climate deal in 2020.

"Implementation of existing commitments is, therefore, the first-step priority, but mechanisms to boost action at a global level are urgently needed," the report said.

Carbon taxes, which would raise the cost of fossil fuels, would be the most comprehensive means of tackling global warming, according to the report, as it would make people and businesses reduce emissions, convert energy or switch to greener power sources.

Implementing a carbon tax of $75 per ton would have the greatest impact in reducing emissions, with the price of coal rising more than 200 percent above baseline levels in 2030.

The cost of electricity and gasoline would also rise considerably and by varying degrees in countries. Gasoline prices would rise 5% to 15% in most countries, the IMF said, "well within the bounds of price fluctuations experienced during the past few decades."

A global price floor would be the most efficient way of doing this, but another option would be for advanced economies to have a higher floor price or for them to provide financial and technical support to emerging market countries in exchange for their commitment to more ambitious targets, the report said.

The Fund estimates that the $75-per-ton carbon tax would prevent 725,000 premature air pollution deaths overall in the Group of 20 industrialized nations by 2030, a lot of them in China.

REUTERS