BERLIN (AP) — Economists say countries should ramp up the price of carbon emissions to as much as $100 per metric ton by 2030 to stop catastrophic global warming.

Experts including Nobel Laureate Joseph Stiglitz and former World Bank chief economist Nicholas Stern say carbon dioxide should be taxed at $40-$80 per ton by 2020.

They say prices should rise to $50-$100 by 2030 to give businesses and governments an incentive to lower emissions even when fossil fuels are cheap.

In a report published Monday, they suggest poor countries could aim for a lower tax since their economies are more vulnerable.

The Trump administration has rejected calls to introduce a carbon tax in the United States, saying it would cost jobs.

European Union carbon prices stand at just under $6 per ton.