The biggest climate meeting of the year is taking place this month, with world leaders and scientists from more than 190 countries invited to the Brazilian city of Belem.
COP30, which will run from 10-21 November, is coming at a particularly precarious time for climate action.
The conference itself has also faced controversy over its location in the Brazilian city, which sits on the outskirts of the Amazon rainforest.
Here’s everything you need to know about COP30 – from why it’s proving controversial, to who’s attending and what will be on the agenda.
The annual United Nations conference brings together world leaders, scientists, campaigners, and negotiators from across the globe, who agree on collective next steps for tackling climate change.
COP stands for “conference of the parties”, with parties being countries that have signed up to the original UN climate treaty (UNFCCC) in 1992 to avoid “dangerous interference” with the climate.
As the largest tropical forest in the world, the Amazon soaks up masses of planet-warming greenhouse gases, making it crucial in the fight against climate change.
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Hosting COP there is a strategic move that Brazil hopes will highlight the importance of protecting this ecosystem.
But the rainforest city of Belem is impoverished and rife with inequality, with most of its 2.5 million residents living in slums.
Questions have been raised about its viability for hosting the roughly 50,000 people projected to attend COP30. There is also a serious lack of accommodation.
The city has been racing to prepare for the event since it was designated host two years ago, with government investments of some $1bn (£751m) going into building new hotels, refurbishing old ones and improving roads, parks, and drainage channels.
They had to get creative, turning to “love” motels aimed at couples, ferries that normally ply the rivers, and school classrooms to host visitors.
Price gouging is a problem every year at COP, wherever it is hosted; however, it’s been so hard to find rooms this year that some furious countries even lobbied Brazil to switch cities.
Even the cheapest hotels have averaged hundreds of dollars per night, according to Reuters reports, spelling an issue for poorer nations.
Ana Toni, Brazil’s climate change chief and CEO of COP30, said more than 163 national delegations had confirmed their attendance and 80% had secured accommodations as of 24 October.
The government is also facing criticism for ramping up oil drilling licensing, with Brazil on course to become a top 5 global producer by 2030.
It approved exploratory drilling by state-run oil giant Petrobras near the mouth of the Amazon just a couple of weeks before the conference’s start.
Burning fossil fuels like oil, gas, and coal is the main cause of climate change.
Brazil is holding a summit for leaders on Thursday 6 and Friday 7 November, hosted by President Luiz Inacio Lula da Silva.
Prince William will be attending on behalf of the King, joined by the British Prime Minister Sir Keir Starmer.
The PM’s spokesperson said the move was part of efforts to restore the UK as “a global leader for climate action and green growth”, calling net zero the “economic opportunity of the 21st century” that could “create good jobs for the future”.
US President Donald Trump will be an unsurprising absentee, having at the UN General Assembly last month branded climate change a “con job”, attempted to withdraw from the Paris climate agreement twice and cancelled multibillion dollar clean energy investments.
He’s not sending any “high-level” officials – but may still seek to influence or disrupt the talks.
A recent push to introduce a green tax on shipping fell through after the US team pressured other countries to vote against it.
“Fewer than 60” leaders have registered to attend, according to the Brazilian hosts, compared with more than 80 at COP29 in Baku, and more than 150 in Dubai the year before.
This COP comes months after two-thirds of the 195 nations that signed the Paris climate agreement missed a significant September deadline to publish new climate plans.
The main goal of the agreement is to keep long-term global temperatures from warming 1.5C above pre-industrial times – the plans map out how each country will play its part.
Yet global temperatures did temporarily exceed the dreaded 1.5C mark last year – the hottest year on record.
Emissions soared to record highs, contributing to extreme wildfires in Brazil, and flooding in Valencia, and warnings that the world has blown its chances of limiting warming to 1.5C.
All of this has added to concerns that climate action has fallen off government agendas, with some experts signalling that the US U-turn on climate policy is disrupting other nations’ efforts.
But the new plans are much higher quality than the previous ones, and mean a “clear” fall in global greenhouse gas emissions is on the near horizon for the first time, the UN said.
More plans are expected to be published during COP30, bringing some hope to the summit.
The fall in emissions is aided by the dramatic and rapid rollout of solar and wind power, which earlier this year provided more electricity than coal did for the first time.
COPs involve a lot of meetings and debates, and often end with new agreements and pacts between the countries.
A raft of things will be on the table this year, including cash for vulnerable nations after last year’s pledge fell far short, and a new fund to protect forests.
But it’s not clear whether there will be major takeaways from this year’s summit, which may make it hard for Brazil to claim it as a success.
The host nation says it’s time to switch from negotiating to implementing existing promises, and pulling off an international meeting at a time of strained global relations will be a success in and of itself.
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COP30 will also take stock of progress since the landmark Paris Agreement and the plans countries have produced.
But ways of making societies resilient to more extreme weather, rather than stopping it or slowing it down, is becoming more pressing and will be discussed too.
And no doubt the USA’s potential absence will be top of everyone’s mind, as will China’s remarkable progress on clean energy, which has soared beyond expectations and brought down the costs for others in the meantime.
Some hope this fact will see China take on a more proactive role in the talks.
Every year people ask what difference COP will make, given the thousands of flights that come along with it, but this year those questions have grown louder as most measures of climate change show things are getting worse.
Defenders of the COP process point to the fact that warming was on course for 4-5C before the Paris Agreement, now it’s around 2.5-3C – still far too high, but better than it was.
About 80% of global GBP is now covered by a net zero target, and funding for vulnerable and poor nations to go green wouldn’t exist without the COP process.
Progress has been both faster than expected and far slower than scientists say is needed to fend off more dangerous and extreme weather like Hurricane Melissa in the Caribbean.
