Others argue that the Paris accord’s architecture is sufficiently resilient, and that efforts to keep global temperature increases to “well below 2°C” — as stipulated by the agreement — will endure.

Activities at the sub-national level in the US also seem to support the argument that the agreement will prevail and domestic opponents of Trump’s decision have mobilised remarkably quickly.

Cities and states with progressive climate policies joined forces across the US, committing themselves to honouring the Paris agreement.

For instance, support came via the bipartisan “US Climate Alliance” of states — including heavyweights such as California and New York — and the “We Are Still In” initiative, which involves hundreds of businesses, investors, and institutes of higher education.

Moreover, these sub-national players are linking up with leading nations to create innovative climate diplomacy networks: California and China have held talks to collaborate on emission reduction efforts, while several US states have intensified climate cooperation with Canada.

Though these developments enhance the Paris agreement’s chances of survival, they will not be enough.

Fight for survival

The resilience of the agreement hinges on how other major emitters will react to Trump’s break.

To pursue effective global climate governance, these countries must repeat the steps taken in the run-up to the 2015 Paris climate meeting, where a strategy of “multiple bilateralism” between US-China, China-India and China-EU (among others) served to build trust and resolve crunch issues.

The emerging consensus among key emitters was translated into cooperation in the world’s club governance fora (G7, G20) and fed into the multilateral negotiations, leading to the Paris agreement’s ultimate entry into force.

True to this spirit, six members (plus the EU) were already pressuring the US to remain committed to the Paris agreement at the recent G7 summit in Sicily. Not that it seemed to do much good, as Trump withdrew from the climate pact a few days later.

The next litmus test for effective global climate governance comes in July, when leaders from countries accounting for 80% of global emissions meet for the G20 summit in Hamburg, Germany, on 7-8 July.

With the US thrusting itself into isolation, the German G20 presidency will seek to gather the broadest possible support for the Paris agreement.

But a question remains: is a G20 entente possible?

It might be, if others show the way.

Climate leaders

From the G7, the EU and Canada display the clearest leadership ambitions.

EU heavyweights have signalled their “strongest commitment” to uphold their pledges to combat climate change.

In his reaction to Trump’s Paris exit, Canada’s prime minister, Justin Trudeau, confirmed his country’s “unwavering commitment to fight climate change”.

The Canadian government has also vehemently denied recent reports that Trudeau wished to scrap references to climate from the draft G20 declaration, in order to appease the US government.

But leaders need followers. And whether followers can be mobilised depends on how G20 members define their interests — economically and politically.

Economically, many G20 countries appear to believe the energy transition — accelerated by the Paris Agreement — must continue.

Investing in low-carbon development is no longer seen as a burden on growth prospects. If anything, there is a growing consensus that Trump’s decision will put the US at risk of lagging behind technologically.

Politically, the relationship between G20 countries and the US (particularly the Trump administration) is tricky.

Are countries like Australia, Japan, Turkey and the UK willing to risk relations with the president of a key ally by adopting a confrontational attitude over climate change?

The answer depends heavily on whether the German G20 presidency can dispel their concerns by convincingly demonstrating that the world is changing — because it is.

Changing world

At an EU-China summit the day after Trump’s announcement, a draft joint declaration on climate change characterised the Paris Agreement as “an historic achievement further accelerating the irreversible global low greenhouse gas emission and climate resilient development” and outlined numerous joint actions.

Although it was ultimately withheld due to trade-related differences, this declaration contains the blueprint for a shifting centre of gravity in global climate governance to Eurasia.

If supported by India’s prime minister, Narendra Modi, who has reiterated support for the Paris Agreement, a solid pro-climate coalition including three of the world’s top four emitters would emerge.

Cooperation with Canada, and with the sub-national forces in the US, could then provide additional momentum to convince other G20 members.

As a major guiding forum, the G20 represents a test run for the future of global climate governance during the Trump era.

The direction this governance will take, depends heavily on the strength of emerging partnerships, and their ability to convince others to join them regardless of US policies.

If the will is robust enough, this “multiple bilateralism” could bring about the dawn of a new era, and the successful implementation of the Paris Agreement.

If it fails, however, global climate politics faces a complicated, daunting future.

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This article was first published by EUobserver