Greta Thunberg was not impressed.

Inside a sprawling conference center in Glasgow, Scotland, this week, world leaders virtually tripped over one another to announce new promises aimed at tackling climate change and its disastrous impacts.

Here was President Biden and more than 100 other leaders, representing more than 85 percent of the world’s forests, pledging to halt deforestation over the next decade. Here were scores more nations signing on to the newly formed Global Methane Pledge, which aims to cut emissions 30 percent by the end of the decade.

Here was the prime minister of India vowing huge investments in renewable energy in the massive country — one of a number of nations to commit to new national climate targets. Here were nearly two dozen countries detailing plans to stop spending tax dollars to fund international fossil fuel projects.

Here were titans of the financial world, who together control $130 trillion in assets, touting a pledge to use their monetary might to help the world hit net-zero emissions by the middle of the century.

Outside the venue earlier this week, Thunberg, the Swedish activist, said the gathering was shaping up like so many that had come before it: Too much talk, too little action.

“They have led us nowhere,” Thunberg said on one of multiple occasions this week that she has criticized the United Nations summit known as COP26. “Inside COP, they’re just politicians and people in power pretending to take our future seriously. … Change is not going to come from inside there.”

Her comments echo other critics who note that for all the pronouncements made so far at COP26, leaders of major-emitting nations such as China and Russia chose not to attend. Meanwhile, the climate plans that nations have submitted would leave the world disastrously off-target from the most ambitious goal of the 2015 Paris agreement: limiting Earth’s warming to no more than 1.5 degrees Celsius (2.7 degrees Fahrenheit) above preindustrial levels.

But not everyone is ready to declare the summit a failure at its halfway mark.

“COP26 is probably unfolding in a way that exceeds expectations compared to where we were a couple months ago, in no small part because I do think we’ve seen a few countries — a few important countries — step up,” said Manish Bapna, president of the Natural Resources Defense Council. “And whether your glass is half full or half empty depends a lot on your expectations of what this COP was likely to deliver.”

Bapna and others have noted that while nations were always unlikely to put the world on a 1.5 Celsius path this year alone, the world is moving in the right direction, even if not fast enough. He noted that only a handful of years ago, existing policies put the world on a pathway to 4 degrees Celsius (7.2 degrees Fahrenheit) of warming. Recently, a U.N. analysis found current pledges would steer closer toward 2.7 degrees Celsius (4.9 degrees Fahrenheit).

Vinisha Umashankar, a 15-year-old climate innovator, on Nov. 2 in Glasgow, Scotland called on world leaders to take actions against climate change. (John Farrell/The Washington Post)

As the fanfare of the first days of the much-anticipated climate summit fades, ahead lies a difficult week of less glamorous but more substantive and thorny negotiations. To find an agreement that represents progress, nations will have to work through a range of issues: from the rules governing global carbon markets, to how often countries should update their emissions-cutting plans, to the amount of funding rich nations should set aside to help vulnerable countries deal with the catastrophes caused by climate change.

“If these countries want to be taken seriously on their latest announcements, then they should first halt the new fossil fuel projects they are licensing at home, end fossil fuel subsidies and shift the fossil fuel financing to renewables,” Mohamed Adow, director of the Nairobi-based think tank Power Shift Africa, said in a statement on Thursday. “And they should include these new commitments in revised and updated [national plans], rather than dressing up empty promises as climate leadership.”

Frans Timmermans, vice president of the European Commission and a key negotiator at COP26, told The Washington Post on Thursday that he welcomed such pressure for more concrete outcomes. And especially the nudging from Thunberg and other young activists.

“I’m very grateful to that movement, and I hope they will stay critical. I hope they will push us even further,” Timmermans said. “I can understand the frustration, because from her perspective we’re not moving fast enough. But we’re moving as fast as we can, and we need to convince others to move with us.”

Maxine Joselow in Glasgow, Scotland, contributed to this report.