Progress was always going to come down to world’s two largest economies

Tackling climate change always boiled down to what the world's two largest economies and biggest emitters of greenhouse gases – the US and China – were prepared to do about it; they needed to work out a quid pro quo if there was to be any chance of a global agreement.

Intensive talks over the past year or more led to yesterday’s historic announcement in Beijing that the US would cut its emissions by up to 28 per cent by 2025, while China said its emissions would peak in 2030 or even earlier, with more energy efficiency and use of renewables.

This game-changing move came just after the UN climate change secretariat released draft negotiating texts for the forthcoming UN climate conference in Lima, Peru, to prepare the ground for a universal agreement at a climate summit in Paris before the end of 2015.

UN climate chief Christiana Figueres said a "positive momentum" from the US-China understanding "opens the door for all major economies – and in particular all other industrialised nations – to bring forward their contributions to the Paris agreement in a timely fashion".

As she noted, the real importance of the announcement was that it sent “a clear signal to the private sector and the financial markets on where global policy is now heading”, and thus had the potential to “unleash and accelerate” innovation to achieve a “low-carbon, resilient world”.

With the EU already pledging a cut of “at least 40 per cent” in its emissions and yesterday’s announcement in Beijing, the world’s three largest economies “are now firmly set on a path towards a low-carbon economy and there’s no looking back”, according to Greenpeace.

It is, of course, much easier for a totalitarian regime such as China to make the required changes than for a democratic society such as the US, where President Barack Obama’s room for manoeuvre is circumscribed by the incoming Republican-controlled US Congress.

The scale of the challenge to limit global warming below two degrees has been underlined by the International Energy Agency's latest World Energy Outlook, which predicts that primary energy demand worldwide would be 37 per cent higher in 2040, with coal and oil still in the mix.

It forecasts that demand for these fossil fuels would only reach a plateau by 2040, with renewables accounting for nearly half of the global increase in electricity generation between now and then and even overtaking coal as the leading source of power station fuel.

According to the agency, the “entire carbon budget allowed under a two degree climate trajectory is consumed by 2040”, based on current trends, highlighting the need for a “comprehensive and ambitious agreement” at the UN’s 21st climate conference in Paris next year.