World leaders will gather in Glasgow next week for the Cop26 climate summit, where it is hoped they will be able to describe more clearly how they will keep the global temperature increase below 1.5°C above pre-industrial levels.
While many have set out ambitious long-term targets to cut emissions, for some countries, it is unclear how they will meet their goals.
Here is what world leaders have said about the summit:
US — Joe Biden
US President Joe Biden is expected to use the summit to press countries to take steps to keep the 1.5°C temperature rise limit in reach. He is expected to be joined by 13 senior US officials and advisers, including his climate envoy, John Kerry.
One of his first acts upon ascending to the presidency was to rejoin the 2015 Paris Agreement and pledge to reach net zero emissions by 2050. In April, the White House announced a target of a 50 per cent to 52 per cent cut in emissions from 2005 levels by 2030.
But Mr Biden’s signature climate change legislation is currently stuck in Congress.
Mr Kerry said “Glasgow has already summoned more climate ambition than the world has ever seen” but the summit remains the “last, best chance” to beat the climate crisis.
UK — Boris Johnson
“It is a huge undertaking by the whole of the UK,” said Mr Johnson. “Every part of the UK is now working together. What we have got to do is, we have got to lead the world to get everybody to commit to net zero by 2050.”
Cop26 president Alok Sharma has also urged China to be more ambitious.
“I was there in September, I had constructive discussions but China, along with every other country, needs to come forward with ambitious plans to cut emissions by 2030 before Cop26,” he said.
China — Xi Jinping
Arguably the most important leader expected not to attend Cop26 in person is China’s President Xi Jinping. His country is by far the largest emitter in the world and responsible for more than a quarter of all carbon pollution.
In a surprise announcement in September, Mr Xi said China plans to achieve carbon neutrality by 2060.
But the country's new five-year plan does not detail the steps for reaching this goal. Meanwhile, China continues to build new coal-fired power plants, the single largest source of carbon pollution, despite Mr Xi calling for a commitment to green development.
“We must abandon development models that harm or undermine the environment and must say no to shortsighted approaches of going after near-term development gains at the expense of the environment,” he said this year.
On Thursday, China submitted updated nationally determined contributions (NDCs) to fight climate change to the UN.
The submission documents showed that China aims to reach its carbon dioxide emissions peak before 2030 and become carbon neutral before 2060, enshrining earlier pledges made by Mr Xi.
China also formalised a commitment to raise the share of non-fossil fuels in its primary energy consumption to 25 per cent by 2030, higher than a previous pledge of 20 per cent, and increase wind and solar power capacity to more than 1,200 gigawatts.
Some experts had been hoping for more. A Chinese government official said this week the main priority of Glasgow was to establish a $100 billion-a-year fund that richer countries will pay into for the developing world to help mitigate climate risks.
Li Shuo, a policy adviser at Greenpeace China, said Beijing's lack of new pledges “casts a shadow on the global climate effort".
“In light of the domestic economic uncertainties, the country appears hesitant to embrace stronger near-term targets and missed an opportunity to demonstrate ambition,” Mr Li said in emailed comments.
Russia — Vladimir Putin
Russian President Vladimir Putin is another high-profile leader who will not attend in person and plans to address the talks via video link. He has said he wants Russia to be carbon neutral by 2060.
Using 1990 levels as a benchmark, Moscow said it plans to reduce carbon emissions by 30 per cent by 2030, a target deemed “critically insufficient” by Climate Action Tracker.
Mr Putin has said hydrogen, ammonia and natural gas are expected to play a larger role in the energy mix in coming years and that Russia is ready for dialogue on ways to tackle climate change.
Speaking before Cop26, Environment Minister Alexander Kozlov said Russia, the world's fourth-largest emitter, will focus on its forests, nuclear plants and hydroelectric power.
India — Narendra Modi
India is the world's third-largest polluter but has a per capita carbon footprint far lower than the world's other top emitters. Indian Prime Minister Narendra Modi will be attending the event in person.
Environment Minister Bhupender Yadav has said rich countries need to acknowledge their “historic responsibility” for emissions and protect the interests of developing nations and those vulnerable to climate change.
He said that simply announcing net-zero goals was not the solution to the climate crisis.
“It is how much carbon you are going to put in the atmosphere before reaching net zero that is more important.”
Brazil — Jair Bolsonaro
Brazilian President Jair Bolsonaro, who has often voiced climate-sceptic views and faced criticism for the rise in deforestation during his tenure, will not be in attendance.
However, there are signs that Brazil may take on a more climate-friendly approach.
Brazil will step up its Paris Agreement targets at Cop26 as it tries to recover credibility for its environmental policies and its stewardship of the Amazon rainforest, the country's top diplomat for climate talks said.
“I ask everyone for the benefit of the doubt and to look towards the future and not the past,” Paulino de Carvalho Neto, the Brazilian Foreign Ministry's secretary for multilateral political affairs, told Reuters
Brazil will formally lodge with the Paris Agreement secretariat its commitment to bring forward its target for carbon neutrality, or net-zero gas emissions, from 2060 to 2050, he said.
Environment Minister Joaquim Leite, who will head Brazil's delegation, is expected to raise the country's target for reducing emissions by 2030 from 43 per cent to 45 per cent, compared to 2005 levels.
Australia — Scott Morrison
Australian Prime Minister Scott Morrison will attend the Glasgow summit but has already been criticised by some for his apparent inaction on achieving Australia's climate goals.
This week, he said his country will not back a pledge, led by the EU and the US, to cut methane emissions by 30 per cent by 2030.
“What we have said very clearly, though, is we are not signing up to the 2030 methane request,” he said.
The country has a large carbon footprint and is one of the world's biggest exporters of coal and liquefied natural gas.
“If a wealthy country like Australia is not going to take serious action to cut emissions, then other countries will say, 'well, why should we bother to?'” former prime minister Malcolm Turnbull said.
Canada — Justin Trudeau
Canadian Prime Minister Justin Trudeau has already left for Europe where he hopes his country can lead the “global fight against climate change".
Mr Trudeau is currently on track to meet his country's climate pledges, including promises to end the sale of gas-powered cars and create an emissions-free power grid, both by 2035.
“Canadians understand that the economic prosperity of our country is rooted in ensuring a cleaner future for our children and grandchildren,” he said.
“I look forward to working with leaders at the G20 leaders summit and Cop26 so that, together, we can build a cleaner and more prosperous future for all.”
He has been working with the Netherlands to ensure to ensure countries "step up" to climate change pledges.
Germany — Angela Merkel
Outgoing Chancellor Angela Merkel has said the summit “must provide further impetus for concrete measures” to bring global warming down to a “tolerable level”.
She has admitted that the Paris goals are ambitious but insists they are achievable.
While Ms Merkel has billed herself as a climate-focused chancellor, she has been criticised on the domestic front for not taking on the powerful coal and car lobbies.
Turkey — Recep Tayyip Erdogan
President Recep Tayyip Erdogan will not attend Cop26 after dropping out at the last minute. Turkey's parliament ratified the Paris climate agreement last month.
A senior Turkish official told Reuters that there were concerns over "the number of vehicles for security and some other security-related demands were not fully met".
France — Emmanuel Macron
French President Emmanuel Macron this week urged China “to give a decisive signal by raising its level” of its climate ambition and to move firmly onwards with its transition from fuel.
UAE — Sheikh Abdullah bin Zayed
This month, the UAE became the first Gulf country to commit to net zero by 2050.
“The major economic opportunities offered by the path to net zero directly support a vision to develop the Emirates into the most dynamic economy in the world,” the UAE government said.
Saudi Arabia — Crown Prince Mohammed bin Salman
Saudi Arabia recently committed to net zero by 2060 but said oil production would continue.
The country's Crown Prince Mohammed bin Salman unveiled a Middle East Green Initiative on Monday that he said was aimed at securing 39 billion riyals ($10.4 billion) for an investment fund and clean energy project as part of efforts to reduce regional carbon emissions.
South Korea — Moon Jae-in
South Korean President Moon Jae-in will be attending the summit and has repeatedly vowed to step up the government’s official emissions target.
On Monday, the country committed to reducing national carbon emissions by 40 per cent of 2018 levels by 2030 before the Cop26 summit, a “very challenging target” when compared with its initial 26.3 per cent goal.
Last year, Mr Moon said the country would be carbon neutral by 2050 and unveiled a Green New Deal to create jobs and help the economy to recover from the coronavirus-induced slowdown.
South Korea is one of the world’s most fossil-fuel reliant economies, with coal making up more than 41 per cent of the country’s energy mix and the use of renewable power at a little more than 6 per cent.
The country's revised NDC is a more difficult target for South Korea, compared with developed nations that have already been cutting emissions from the 1990s, Mr Moon told a presidential committee meeting on carbon neutrality.
“This is the most ambitious reduction target possible under our circumstances,” he said.
New Zealand — Jacinda Ardern
New Zealand is under pressure to do more to curb carbon emissions, which are increasing, but recent carbon-cutting announcements made little mention of agriculture, which contributes 48 per cent of the country's greenhouse gas emissions.
But Prime Minister Jacinda Ardern said she will not be in attendance.
She has previously described action on climate change as a matter of “life or death” but has been called out by Swedish environmental activist Greta Thunberg, who accused New Zealand of being “one of the world's worst performers” on emission increases.
“People believe Jacinda Ardern and people like that are climate leaders,” Ms Thunberg said last month.
“That just tells you how little people know about the climate crisis. Obviously, the emissions have not fallen. It goes without saying that these people are not doing anything.”
The Netherlands — Mark Rutte
Dutch Prime Minister Mark Rutte is working with Mr Trudeau of Canada on a joint strategy to ensure countries "step up" to pledges made to tackle climate change.
He met Mr Trudeau at The Hague before the weekend's G20 gathering in Rome and Cop26.
UN — Antonio Guterres
UN Secretary General Antonio Guterres has called on rich economies to make good on a long-standing commitment to provide $100bn a year to help the developing world tackle the growing threat posed by climate change.
“Unfortunately, the message to developing countries is essentially this: the cheque is in the mail. On all our climate goals, we have miles to go. And we must pick up the pace,” Mr Guterres said.
He also said revised climate pledges from some G20 nations did not inspire confidence.
“Even if recent pledges were clear and credible, and there are serious questions about some of them, we are still careening towards climate catastrophe,” he said.
The pope will not attend Cop26 after having surgery this year but on Friday, he led the calls for action at the talks.
The world's political leaders, he said, must give future generations “concrete hope” that they are taking the radical steps needed.
“These crises present us with the need to make decisions, radical decisions that are not always easy,” Pope Francis, 84, said.
“Moments of difficulty like these also present opportunities, opportunities that we must not waste.”
The pope had a chance to raise his climate concerns at a meeting with Mr Biden in Rome.