WASHINGTON — Leaders of the G-7 club of wealthy nations took major symbolic strides toward solidifying global climate action at their U.K. summit, but stopped short of detailing how to confront two of the most pressing challenges: phasing out coal and financing the developing world’s energy transition.

With palpable relief after four years of former President Donald Trump, G-7 leaders heaped praise on President Joe Biden and sought to marry their own climate efforts to his domestic political agenda, coalescing under the umbrella of “build back better.” They also rallied behind a pledge to conserve 30 percent of lands and oceans by 2030, a goal Biden had already set for the United States.

“You know, we had a president last who basically said, ‘It’s not a problem, global warming,'” Biden said in a news conference capping his trip to the summit in Cornwall, England. “It is the existential problem facing humanity, and it’s been treated that way.”

But climate analysts, eyeing the G-7’s commitment to limit global warming to 1.5 degrees Celsius, emerged from the summit vexed over the failure to commit to specific steps broadly acknowledged as essential to meeting that goal. Continued burning of coal to generate power, for example, is widely accepted to be counterproductive to averting climate change’s worst effects.

“These are the seven countries that have to lead from the front,” said Rachel Kyte, the World Bank’s former special envoy for climate and dean of Tufts University’s Fletcher School. Borrowing a phrase from the ongoing European soccer championship, she added: “It was an open goal, and they missed.”

The U.S. and its G-7 allies did re-up their pledge, first made in 2009, to collectively contribute $100 billion per year by 2020 to help poorer nations reduce emissions and fortify themselves against the growing effects of climate change. That $100 billion goal was never met. But the nations recommitted to that figure anyway, while extending the timeline for reaching it to 2025.

Yet, the joint communiqué that codifies the agreements reached at the summit included no new specific commitments for how countries would reach that figure. The U.S. is billions behind in actually writing checks for pledges it has made in the past.

“They restated a goal that’s been there for a decade, but they didn’t provide clarity about how that was going to be achieved,” said David Waskow, international climate director for the nonprofit World Resources Institute.

Some more hopeful signs did emerge in the hours after the summit ended, with Canada announcing it would double its annual pledge to $4.4 billion in U.S. dollars by 2025, and Germany saying it would triple it during that period, to more than $7 billion.

“That’s really good to see,” said Rachel Cleetus of the Union of Concerned Scientists. The United States, by contrast, “did not put any clear ambition on the table” with respect to global financing, she added.

The G-7 nations did put to paper a pledge to halve their emissions by 2030 and zero them out from their economies by 2050. That marked progress since the most recent G-7 summits, but did not move the ball from what countries including the U.S. have already committed. The United Kingdom and the European Union, in fact, have already pledged to cut much more on an even faster timeline.

And while the leaders vowed to “accelerate the transition away from new sales of diesel and petrol cars” to promote electric vehicles, they did not set a deadline to phase out gas-guzzling vehicles, as some countries before the summit had hoped.

On coal-fired power plants, the G-7 nations did set a deadline of next year to stop financing “unabated international thermal coal power generation.” That’s significant, considering that the world’s largest emitter, China, continues to fund new coal plants overseas.

Yet, the careful phrasing from the G-7 leaders leaves wiggle room to keep financing coal plants that use carbon capture technology to sequester and store carbon dioxide emitted from burning coal.

Perhaps the most glaring omission from the G-7 climate agreement, environmental advocates said, was the lack of any deadline for when nations will stop burning coal at home.

When the environmental ministers for the nations met virtually in May to lay the groundwork for this month’s summit, they jointly committed to achieving an “overwhelmingly decarbonized power system in the 2030s,” technical-speak for saying heavily polluting coal plants would be phased out by the end of the next decade.

But when Biden and other leaders emerged from the meeting, that language was absent from their communiqué, which instead pledged merely to “further accelerate the transition away from unabated coal capacity” without specifying a date.

Jason Bordoff, a White House National Security Council official in the Obama administration, said criticism of the Biden administration over that point was misplaced, given that Biden has already set a goal for U.S. electricity to be carbon-neutral by 2035. That goal broadly assumes phasing out coal anyway, along with cleaner-burning sources like natural gas.

“All the growth in coal use is in emerging markets and developing economies, so the G-7 agreement not to finance new coal projects is very significant, along with the pledge of assistance to help nations move away from fossil fuels,” said Bordoff, founding director of Columbia University’s Center on Global Energy Policy.

Still, the G-7 summit in Cornwall may have been the last, best chance for the world’s wealthiest democracies to increase their leverage over China and other major emitters by uniting behind specific, joint goals well ahead of November. That is when leaders will gather in Scotland for a much-anticipated U.N. climate conference.

All of the remaining venues for high-level global diplomacy before that conference — including September’s U.N. General Assembly in New York and October’s G-20 summit in Rome — will include China.