Boris Johnson has long envisioned “Global Britain,” a free-trading, swashbuckling world power unleashed by Brexit. And he’s been working hard this week in New York and Washington to get the world’s attention.

Johnson and his diplomats have just six weeks to help secure ambitious, concrete commitments to reduce greenhouse gas emissions — or manage failure — as the host of the upcoming global summit on climate change in November, billed as a final “moment of truth.”

Johnson co-chaired a closed-door roundtable discussion at the United Nations on Monday with U.N. Secretary General António Guterres, in which he urged the assembled world leaders to increase their financial commitments and emissions targets.

The prime minister then traveled to the White House on Amtrak, a low-emissions option that no doubt appealed to the American president, who has a train station named after him in Delaware.

President Biden gave Johnson a boost by announcing that he wants Congress to double the annual U.S. contribution to vulnerable nations dealing with climate change — from $2.4 billion to $11.4 billion.

Johnson had struck a downbeat tone over the weekend, saying there was a “6 in 10” chance of meeting one of Britain’s key COP26 climate conference targets: getting developed nations to agree to a $100 billion-a-year climate fund to help poorer countries cut carbon emissions and mitigate the effects of climate change.

A stinging assessment of action plans submitted so far by 191 countries by the United Nations last week found that global emissions were set to rise by 16 percent by 2030, putting the planet on track to warm by a “catastrophic” 4.9 degrees Fahrenheit by the end of the century. Leaders of small island nations and the least developed countries pressed Johnson in New York to get the wealthiest countries to do more.

“It is inexplicable to us that the world is not acting, and it suggests that we in small islands are to remain dispensable and invisible,” Barbados Prime Minister Mia Mottley told Johnson, according to a participant in the meeting.

She stated that the Group of 20 countries, including the United Kingdom, are responsible for 80% of global greenhouse gas emissions, while the remaining 20% is emitted by the remaining 170 countries combined. That means that concerted efforts from a few key countries could put the world on a much better footing.

According to Robert Falkner, research director of the London School of Economics’ Grantham Research Institute on Climate Change and the Environment, this is Johnson’s moment — “his opportunity to inject high-level energy into the talks.”

He claimed Johnson was meeting stiff opposition from countries such as China, which is now one of the world’s top emitters and is finding it difficult to wean itself off coal.

According to Christopher Meyer, Britain’s former ambassador to the United States, Johnson has arrived in America unsure whether the groundwork for a successful Cop26 has been laid. Johnson is best known for his role in the Brexit campaign, which led to the United Kingdom’s exit from the European Union. He appeals to his domestic core audience of right-wing Tories and Telegraph readers, for whom he used to write a column.

According to a recent Climate Action Tracker report, Britain is one of only a few countries where the overall climate commitment is “nearly sufficient” to meet the Paris agreement’s 1.5C temperature limit. However, it was noted that there is a “significant gap” between Britain’s targets and levels of action. To meet its lofty objectives, British citizens will need to make significant changes in how they heat their homes, how many electric cars they purchase, and how they farm and protect peatlands. Britain has yet to make any announcements on these fronts.

Meanwhile, calls are growing from smaller nations that have contributed little to climate change but are grappling with its most disastrous consequences, as evidenced by the impassioned pleas heard in Johnson’s closed-door U.N. meeting on Monday.

Finally, these leaders said, the fate of small, vulnerable nations is tied to the scale and speed with which the world’s biggest emitters make decisions — the same emitters who, so far, have failed to collectively put the world on track to meet the Paris goals and to adequately provide the funding they promised to help poorer countries deal with climate change.