OTTAWA -- Environment Minister Jonathan Wilkinson says there is no path to eliminating greenhouse-gas emissions that doesn't include phasing out coal power, but critics say Canada's leadership is tainted as long as this country keeps exporting thermal coal.

Wilkinson co-hosted a virtual summit Tuesday for the Powering Past Coal Alliance. Canada created the group with the United Kingdom in 2017 to pushing the world to eliminate coal as a source of energy. The alliance says wealthy countries should be off coal by 2030, and the rest of the world by 2050.

Coal is the single biggest source of global greenhouse-gas emissions, accounting for about 38 per cent of total emissions in 2018.

United Nations Secretary-General Antonio Guterres told summit participants that the whole world needs to be off coal by 2040, or the global warming fight will be lost.

"If we take immediate action to end the dirtiest, most polluting, and the more and more costly fossil fuel from our power sectors, then we have a fighting chance to succeed," he said in his speech.

He said in almost every country, building new renewable power sources, like wind and solar, is now cheaper than building a new coal plant.

The alliance has grown from 18 countries and a handful of subnational governments and businesses when it began in 2017, to more than 36 nations, and 120 members in total.

Wilkinson said more governments are realizing that eliminating coal "is the first and perhaps most important step" toward reaching the goals of the Paris agreement to keep limit the global average temperature increase to 1.5 C above pre-industrial levels.

"We cannot achieve those goals or create a livable future for our children and our grandchildren with coal-fired power continuing on," he said.

Canada cut its coal-power habit by more than half in the last two decades, largely because Ontario phased out its coal plants entirely. Coal maxed out its share of electricity in Canada around 2000, when it accounted for about one-fifth of power sources. In 2018, that had fallen to eight per cent, and only Alberta, Saskatchewan, New Brunswick and Nova Scotia still rely on it.

Canada requires all coal power to be gone or equipped with carbon-capture technology by 2030. Alberta is on its way to closing or transitioning it coal plants to natural gas by 2023. The other provinces are in various stages of the transition, with individual agreements with Ottawa on how it will happen.

But as Canada is moving to strike down coal pollution at home, it's still exporting millions of tonnes of coal to produce power overseas, mostly in South Korea, Japan, Chile, Hong Kong, and Vietnam.

Julia Levin, the climate and energy program manager at Environmental Defence, says Canada's leadership in the alliance is in doubt if it curbs coal use at home only to sell it to other countries.

"There is no role for hypocritical leadership," said Levin.

Environmental Defence estimates Canada exports between 17 million and 20 million tonnes of thermal coal to make electricity each year, which would produce between 37 million and 44 million tonnes of greenhouse gases when burned.

Canada's exports also now include millions of tonnes coming up from Wyoming, Utah, and Montana, after ports on the U.S. west coast began barring thermal coal exports from their docks.

Wilkinson ordered a strategic review of thermal coal exports in 2019, and told The Canadian Press in a recent interview the question of phasing out thermal coal exports in line with closing Canada's own coal plants remains "under review."

This report by The Canadian Press was first published March 2, 2021.