United Nations Secretary-General Antonio Guterres drew praise Wednesday for taking what supporters called a "powerful stand" to address the climate crisis. Guterres will reportedly exclude major economies, including the United States, from talking at the upcoming U.N. Climate Action Summit because of their failure to produce appropriately ambitious climate plans and their ongoing support for coal.

"This really is something. Thanks to Antonio Guterres," tweeted 350.org co-founder Bill McKibben.

Leslie Hook reported at the Financial Times Tuesday on the exclusions, citing a draft schedule of the summit, set take place Monday. Australia, Japan, South Korea, and South Africa will be snubbed over their continued support for coal. Brazil and Saudi Arabia, both of whom have criticized the Paris climate accord, will also be blocked. The Trump White House, which announced its plans to ditch the deal, will also not be afforded a speaking slot, Hook reported.

Justin Guay, director for global climate strategy at the Australia-based Sunrise Project, framed the move by Guterres as potentially unprecedented.

In all the time I have worked on climate change I’ve never seen the UN take a powerful stand like this. @antonioguterres⁩ has drawn a bright red line - no new coal plants and he’s serious. This is the leadership we need to address the crisis https://t.co/WZXxh3jdOw — Justin Guay (@Guay_JG) September 18, 2019

Clean air campaigner Callum Grieve, in a tweet, suggested it was no surprise. "Did they not get the memo?" he wrote.

Indeed, a FAQ for the summit states:

The summit will focus on tangible climate actions. It will not be a summit of national speeches. Rather, the summit will consist of selected commitments of coalitions of countries, companies, and civil society announcing a range of truly ambitious and credible actions and commitments as well as any national announcement in line with the secretary-general's objective for the summit.

It adds:

The summit will serve as a public platform [...] only for leaders—member states, as well as finance, business, civil society, and local leaders from public and private sectors—who are ready to: mobilize and raise political ambition that will result in enhanced and irreversible commitments to action in national climate plans to significantly cut emissions; strengthen climate resilience; and making public and private finance flows consistent with a pathway towards low greenhouse gas emissions and climate-resilient development;

galvanize bottom-up action from cities, regions, civil society, but also private sector;

contribute to the multi-stakeholder coalitions that will develop ambitious solutions in the action areas of the Summit: global transition to renewable energy; sustainable and resilient infrastructures and cities; sustainable agriculture and management of forests and oceans; resilience and adaptation to climate impacts; and alignment of public and private finance with a net zero economy.

Writing for news collaboration Covering Climate Now this week, Mark Hertsgaard also noted that Guterres had laid down the gauntlet to world leaders:

Don't bring a speech—bring a plan, Guterres famously told heads of state and government in the months leading up to this summit, and it appears that only leaders who followed his instructions will be allowed to speak at the plenary session. To gain a slot, a country had to commit to doing one of three things, said U.N. officials: be carbon neutral by 2050; "significantly" increase how much it will cut emissions (or, in U.N. jargon, significantly strengthen its Nationally Determined Contribution); or make a "meaningful" pledge to the Green Climate Fund, a pool of money provided by wealthy countries to help developing countries leave fossil fuels behind and increase their resilience against climate disruption. U.N. officials expect that 60 to 70 countries will have made sufficiently solid commitments by next Monday that their leaders will be invited to outline their country's plans from the dais, with each leader granted a mere three minutes to speak.

Vox climate writer David Roberts also praised Guterres for the strong move against coal.

"In the endlessly formal, scrupulously polite world of diplomacy, this is a big deal: the U.N. general-secretary is publicly shaming countries that fund new coal plants," Roberts tweeted. "This kind of social license—or withdrawal of social license—matters!"