Undoubtedly the day's biggest news bar none... President Xi Jinping says China '...aims to have CO2 emissions peak before 2030 and achieve carbon neutrality before 2060'. It's the world's biggest carbon emitter, so it matters - in several ways

(By the way, because translations can lose important nuances I've pasted the wording above straight from Xinhua, which ought to know) http://www.xinhuanet.com/english/2020-09/22/c_139388452.htm

First, China is the world's biggest emitter of carbon dioxide, the main greenhouse gas which causes climate change, and of all greenhouse gases put together

Previously it had pledged to peak emissions 'around' 2030 - now it's 'before'. And it had not previously said anything about a long-term goal of #netzero - ending its net contribution to climate change. Now it has, following Sweden, the UK, France, the EU, New Zealand, many more

Is its pledge compatible with the #ParisAgreement, making the goal of limiting global warming to 1.5ºC more likely to be delivered? Far more learned people than I will do the maths properly but ballpark, the answer is 'it's on the cusp':

@IPCC_CH calculates 50% chance of 1.5ºC for global #netzero CO2 in 2050 if we also get approx halving of emissions by 2030 and sharp reductions in other greenhouse gases. China-2060 is roughly in line with global-2050 - it's the other two bits that are currently much less clear

Obviously many details remain to come out - perhaps remain to be worked out in Beijing - including a roadmap with timelines and interim targets and sectoral plans. 'Aims to' isn't 'will'. But already it's an interesting diplomatic move (the second reason why this matters)

It cocks a snook at Donald Trump's administration, China's biggest rival, and could go some way to alleviating the problems Xi's administration has caused in relationships with Europe through its actions in, eg, Hong Kong

It also could mark the start of a 'shoulder-to-shoulder' march on climate change with the EU, whose leadership can claim a bunch of credit for this, after @vonderleyen and others urged Xi earlier this month to make exactly this announcement - again, isolating Donald Trump

...although a Joe Biden victory in November could change things vis-a-vis the US again, of course. Meanwhile it's interesting as a side-note that the UK govt's decision to leave the EU gave it, the host of next year's #COP26, no discernible place at this particular table

Anyway... the third way in which this matters is, obviously, money. China is the world's biggest... well, everything, really - biggest burner of coal, market for energy, builder of renewables, global investor in both fossil and clean energy... hence, a market mover like no other

Translated into action this pathway would mean China reducing coal, oil and gas use faster, building renewables, electric cars and perhaps nuclear reactors faster, switching international investments from coal to clean faster, going big on negative emissions tech...

...all of which would pretty clearly shift the goalposts for stacks and stacks of companies and investors around the world

The obvious next move is for China to present the pledge formally to other nations via the UN climate convention, by putting it in its enhanced Nationally Determined Contribution (NDC) with many of the missing details filled in. Could it do so this year? Perhaps - seems the EU is

So, lots to come on this one but... seriously, this is big. Mark the day. Even without those missing details, ripples are going out right now, right around the world, and will be felt for a very long time to come