The Paris climate change conference was a triumph of diplomacy, delivering an agreed text among 195 states with a definite programme of action flowing from it.
But critics validly ask if the action promised is enough to limit global warming to 1.5° or 2°, whether the methods agreed are sufficiently rigorous, and how quickly alternative non-fossil energy resources can and should be mobilised. Most important of all they ask how compatible the continued goals of global growth and consumption are with ecological limits and future sustainability.
Barack Obama put the planetary and timing issues well when he said in his speech to the Paris conference that it needed to reach "not simply an agreement to roll back the pollution we put into our skies, but an agreement that helps us lift people from poverty without condemning the next generation to a planet that's beyond its capacity to repair".
He expressed satisfaction with the outcome in a White House broadcast: "This agreement represents the best chance we have to save the one planet that we've got."
These questions are asked in a policy span ranging from the centre-right to the radical left, hinging on their differing views of capitalism. When deep climate-change sceptics such as Nigel Lawson say "green is the new red", they accurately identify an emerging political cleavage that will surely grow over the next generation.
Diplomacy is important as an enabling political framework for global action, all the more welcome in the light of other crises equally in need of action at that level. Climate change is linked to development policies, inequalities, technological change and economic priorities.
France's diplomatic effort transcended its history as a colonial power, reaching a new global audience through its ability to listen, compromise and then act. The European Union's complementary role was much more effective than in 2009 at Copenhagen, where it was marginalised in a last- minute brokered deal between the US, China, India and other emergent states.
On this occasion there is a qualitatively better buy-in by all of them, in a much more balanced geopolitical and multilateral setting that also helps restore the credibility of the United Nations.
The ratchet mechanism allowing reviews of the goals and targets every five years is a valuable innovation. Their linkage to a rolling peer review of national programmes will bring climate change priorities more into domestic politics, where they can get most effective scrutiny.
But the text is short on compulsory targets and sanctions on fossil fuel outputs and industries. There is no carbon tax. It leaves aviation and shipping untouched. The lethal methane gas outputs of fracking and beef and dairy agriculture are underplayed.
That leaves expert critics of the agreement such as Kevin Anderson of the Tyndall Centre in the UK despairing that the time to take action is so tight and the methods agreed so inadequate.
He warns that existing trends will result in global warming by 3.5° to 4° by the end of the century. That is an average, including the seas, so the rise in land temperatures would be even higher.
In consequence, he says: “If we saw those sorts of changes, we’d see dramatic reductions in the staple food crops. So that’s a really big issue, if we have big 40 per cent or so reductions in rice, maize, wheat, sorghum, those sorts of crops. Huge changes in sea level rise by the end of the century, but also locking in very large sea level rise changes going forward beyond that. And we’d see [an] increase in droughts and in flooding, increase in severity of typhoons in the southern hemisphere.”
The greatest achievement of the Paris conference is arguably to bring such stark warnings into the political domain, so they become much more the substance of evidence-linked debate and contestation.
Radical critics of the agreement such as Naomi Klein and the coalition of civil- society activists who gathered in Paris say this opens up real opportunities for protests and social movement action against governments and fossil-fuel industries. Marxist critics such as the ecologist John Bellamy Foster say it calls into question capitalism as a global economic system prioritising growth, consumption, short-term profitability and waste completely.
Martin Wolf put it aptly in the Financial Times: "The question is whether humanity has the will or even the time to finish a journey that it has started so late." The planet will look after itself. It is our species – and many others too – that we must be worried about.