United States’ climate envoy John Kerry issued a stark warning on Tuesday, claiming that the suffering brought about by the Covid-19 pandemic would be “magnified many times over in a world that does not grapple with, and ultimately halt, the climate crisis.”

In a speech delivered in London, Kerry — who on Thursday is due to attend a G20 ministerial meeting in Italy focused on the environment, climate and energy — sought to emphasize the magnitude of the challenge facing the planet, according to CNBC.

“The climate crisis, my friends, is the test of our times,” he said. “And while some may still believe it is unfolding in slow motion, no, this test is now as acute and as existential as any previous one.”

Former Secretary of State Kerry also stressed the need for geopolitical cooperation, acknowledging that “no country and no continent alone can solve the climate crisis.”

Turning to China, Kerry noted that “a foundational building block” of its growth had stemmed from “a staggering amount of fossil fuel use” and called on it to step up when it came to cutting emissions.

In a remotely delivered address to the United Nations General Assembly last September, Chinese President Xi Jinping said his country was targeting peak carbon dioxide emissions by 2030 and carbon neutrality by the year 2060. For his part, Kerry claimed China needed to do more.

“As a large country, an economic leader and now the largest driver of climate change, China absolutely can help lead the world to success by peaking and starting to reduce emissions early during this critical decade of 2020 to 2030,” he went on to add.

“The truth is there’s no alternative, because without sufficient reduction by China, together with the rest of us, the goal of 1.5 degrees is essentially impossible.”