18 months (and counting)

Do you remember the good old days when we had "12 years to save the planet"?

Now it seems, there's a growing consensus that the next 18 months will be critical in dealing with the global heating crisis, among other environmental challenges.

Last year, the Intergovernmental Panel on Climate Change (IPCC) reported that to keep the rise in global temperatures below 1.5C this century, emissions of carbon dioxide would have to be cut by 45% by 2030.

But today, observers recognise that the decisive, political steps to enable the cuts in carbon to take place will have to happen before the end of next year.

The idea that 2020 is a firm deadline was eloquently addressed by one of the world's top climate scientists, speaking back in 2017.

"The climate math is brutally clear: While the world can't be healed within the next few years, it may be fatally wounded by negligence until 2020," said Hans Joachim Schellnhuber, founder and now director emeritus of the Potsdam Climate Institute.

The sense that the end of next year is the last chance saloon for climate change is becoming clearer all the time.

"I am firmly of the view that the next 18 months will decide our ability to keep climate change to survivable levels and to restore nature to the equilibrium we need for our survival," said Prince Charles, speaking at a reception for Commonwealth foreign ministers recently.

One of the understated headlines in last year's IPCC report was that global emissions of carbon dioxide must peak by 2020 to keep the planet below 1.5C.

Current plans are nowhere near strong enough to keep temperatures below the so-called safe limit. Right now, we are heading towards 3C of heating by 2100 not 1.5.

As countries usually scope out their plans over five and 10 year timeframes, if the 45% carbon cut target by 2030 is to be met then the plans really need to be on the table by the end of 2020.

What are the steps?

The first major hurdle will be the special climate summit called by UN Secretary General Antonio Guterres, which will be held in New York on 23 September.

Mr Guterres has been clear that he only wants countries to come to the UN if they can make significant offers to improve their national carbon cutting plans.

This will be followed by COP25 in Santiago, Chile, where the most important achievement will likely be keeping the process moving forward.

But the really big moment will most likely be in the UK at COP26, which takes place at the end of 2020.

The UK government believes it can use the opportunity of COP26, in a post-Brexit world, to show that Britain can build the political will for progress, in the same way the French used their diplomatic muscle to make the Paris deal happen.

"If we succeed in our bid (to host COP26) then we will ensure we build on the Paris agreement and reflect the scientific evidence accumulating now that we need to go further and faster," said Environment Secretary Michael Gove, in what may have been his last major speech in the job.

"And we need at COP26 to ensure other countries are serious about their obligations and that means leading by example. Together we must take all the steps necessary to restrict global warming to at least 1.5C."