The C40 Cities Climate Leadership Group comprises 97 cities worldwide that represents one-twelfth of the world's population and one quarter of the global economy.

The group is focused on tackling climate change and taking urban action that reduces greenhouse gas emissions.

Responding to the summit, its executive director Mark Watts said: “National leaders are recognising the scale of the climate emergency and moving towards the urgent action needed to avoid the catastrophic impacts on the horizon.”

He continued: “The science is clear - global emissions must be cut by 50% in the next decade if we are to avoid climate breakdown.

"And the change is already underway in C40 cities - with LA’s commitment to providing a 97% carbon-free energy mix by 2030, Oslo’s (Norway) carbon targets enshrined into the city’s budget, the world’s largest 16,000 strong electric bus fleet in Shenzhen (China), the world’s most ambitious Ultra Low Emission Zone in London, and with Accra (Ghana), Durban (South Africa), Medellín (Colombia) and other cities which have historically low emissions, but are still delivering tough climate action to support global efforts."

The leaders of Turkey and Chile are among the next to speak.

President Sebastián Piñera of Chile encourages leaders to consider the role oceans play in the climate. He asks for help in protecting them.

He invites other countries to join Chile in establishing a marine protection area around Antarctica to protect wildlife and ecosystems.

Image source, pool

Guy Delauney
BBC News, Belgrade

After years of suffering some of the worst air quality in Europe, campaigners in Serbia have started what they call an “ecological uprising”.

Dozens of groups from across the country came together for an event in the capital, Belgrade, earlier this month. The grassroots organisations are campaigning for cleaner rivers, better air quality and improved waste management. They hope a united front may push the government into action.

“Environmental protection is the single topic that unites the people,” says campaign coordinator Aleksandar Jovanovic.

Serbia’s environment minister accused the protesters of prioritising “quick political gains” over genuine solutions. But within days the government suspended operations at a Chinese-owned copper mining complex accused of breaking regulations.

It could be a coincidence – but perhaps it shows the authorities are listening after all.

Reality Check

When people talk about climate change, they often confuse the two - and there's an important distinction.

The weather is what’s happening right now and what might happen in the near future.

Climate is what’s measured over a longer period of time - it’s usually at least 30 years, but can stretch over centuries or millions of years.

Scientists look at look-term trends to see how the climate is changing.

And the trend is clear: our planet is getting hotter.

Image source, Getty Images

Arguably the most famous climate activist in the world - Greta Thunberg - is spending her Earth Day addressing members of the United States Congress for the first time.

Thunberg, 18, appears as a witness this morning at a virtual hearing held by the Environment Subcommittee in the House of Representatives.

The Swedish teen became famous a few years ago by skipping school on Fridays to protest outside the Swedish parliament and call for stronger action. Her actions have since sparked several student-led strikes and protests in countries around the world.

Thunberg slammed world leaders at the United Nations climate summit in 2019, exclaiming "how dare you" for their perceived lack of urgency on the issue.

Today's hearing will challenge the role of fossil fuel subsidies in preventing action on climate change. Democrats say the subsidies are outdated and need to be eliminated, while Republicans argue they are an important aspect of the US energy market.

Thunberg reportedly intends to tell lawmakers the US is far behind where it needs to be in the climate fight.

Anthony Zurcher
BBC North America reporter

Last week, the US expelled diplomats and imposed new sanctions on Russia, including limits on US financial services to the nation that could have real bite if strengthened.

Earlier this week, Russia encouraged the US to recall its ambassador. Tensions between the two nations since Joe Biden took office in January have been growing.

At the US-organised climate summit on Thursday, however, Russia and the US were, for once, on the same page.

“Our discussion today demonstrates how deeply we all share the concern with regard to global climate change and how much we are all interested in redoubling the international effort to address this issue,” Putin said in his remarks during the first session's virtual meeting.

On Tuesday, I asked White House Press Secretary Jen Psaki whether the Biden administration was pleased Putin decided to attend the summit, and she was initially coy.

“We invited him to attend, as we did 39 other leaders,” she said.

When pressed, however, she acknowledged Putin’s attendance was valuable.

“It just sends a message about the recognition that addressing climate, addressing the climate crisis is something that even when you have disagreements about other areas, we can agree on that,” she said.

Image source, pool

The Mexican president opens by boasting about his nation's reforestation efforts.

"We have planted 700 million plants," says President Andrés Manuel López Obrador. He includes that over 450,000 agricultural workers in Mexico are already receiving compensation in order to plant fruit trees on their lands.

He encourages the US government to help continue this programme in countries across Latin America.

He also proposes a climate related visa for migrants wanting to enter the US.

"Migrants are exceptional people. We have to organise them in a very humane way and a practical manner with a love of nature," he says.

The US is currently experiencing higher than normal levels of migrants at the southern US border and Biden has been under scrutiny for his handling of the situation.

Image source, Pool

King Salman bin Abdulaziz Al Saud of Saudi Arabia is the next world leader to speak.

The monarch says "the Saudi vision for 2030" incorporates efforts to cut carbon emissions by 50% by 2030 and other green initiatives implemented by his son, Crown Prince Mohammed bin Salman.

King Salman says climate action needs to account for the difference in development needs among countries.

Image source, Pool

Jair Bolsonaro, President of Brazil, says his country is "at the forefront" of the fight and contributes to less than 3% of global climate emissions annually despite having a large population.

He talks up "a green revolution" in the Brazilian countryside, built on sustainable agricultural practices, saying: "We produce more using less resources, which makes Brazilian agriculture one of the most sustainable practices on the planet."

Bolsonaro has drawn lots of heat as president for his environmental policies, particularly in the Amazon rainforest, and for his pushback on the country's climate targets.

But the Brazilian leader insists environmental bodies have been strengthened and defends "the right to development" in Brazil and other countries.

Image source, Pool

Bhutan is not only carbon-neutral, it is carbon-negative, says Prime Minister Lotay Tshering of his small kingdom nation.

This is because of its significant hydropower operations, according to the leader.

"We remain highly vulnerable to the impacts of climate change," he notes.

Suggesting constitutional requirements for ecological protection, Tshering adds: "I cannot understand this irony of contributing a lot to environment preservation yet having to suffer so much."

Chris Mason
Political Correspondent

The Prime Minister's contribution to today's virtual climate jamboree included familiar lines from him: the UK being the "Saudi Arabia of wind" power and him being a man keen on having one's cake and eating it: "cake, have, eat" as he put it.

Boris Johnson said "I'm not saying any of this is going to be easy" but also said tackling climate change should "not be some expensive, politically correct green act of bunny hugging. This is about jobs and growth".

He didn't dwell on what many said would be the colossal costs and changes society would have to take on to get to net zero emissions.

There is a bigger picture here too: the Prime Minister casting himself as a globally central figure in all this, ahead of the COP26 climate summit in Glasgow in November.

Mr Johnson welcomed the return of the United States "to the front rank of the fight against climate change," with President Biden replacing Donald Trump.

Mr Biden will be an enthusiastic participant in Glasgow later this year, whereas it would have been far from certain a re-elected President Trump would have even turned up.

Climate change, the ultimate international issue, has turned diplomacy green: for the Prime Minister, it is central to his vision for "Global Britain."

Reality Check

In his opening remarks at the climate summit, President Biden said, “America represents less than 15% of the world's emissions”.

Looking at carbon emissions, that’s about right – the US produces just under 15% of the world total. (Although historically, it has emitted more than any other country to date: twice more than China.)

Generally the larger economies with big populations contribute the most.

China currently produces by far the most carbon emissions overall, following its rapid economic growth over the past couple of decades.

The US is the next largest emitter, and total carbon emissions have been steadily declining in recent years.

An alternative measure is emissions per person.

The US produces considerably more carbon emissions per person than China.

The countries which produce the most carbon per head are oil-producing nations in the Middle East, such as Qatar.

Poorer countries such as DR Congo and Somalia produce only a fraction of the world’s total emissions.

Image source, pool

President Alberto Fernandez of Argentina is next.

"We have to be aware of the suicidal path we are walking," he says.

He shares Argentina's plans to combat climate change.

"We have to work together, we have to have social justice, financial justice, and environmental justice."

Image source, pool

President Ursula von der Leyen of the European Commission follows Argentina.

"This will be the make or break decade," she says.

"The Paris Agreement is humanity's life insurance. We are getting dangerously close to 1.5 degrees of global warming."

Image source, Pool

President David Kabua of the Republic of the Marshall Islands tells summit attendees that curbing climate change is crucial to "the safety and security" of his low-lying atoll nation.

The largest economies must signal their "unequivocal" commitments now in the climate fight, he says.

"Too often vulnerable countries hear the excuse that steep emissions cut are too costly," says Kabua.

"Leading from the frontlines, we were the first to strengthen our NDC (national climate plan) in 2018."

Kabua calls for "50% of climate financing to go toward adaptation" measures.

Prime Minister Mario Draghi of Italy also opens by thanking Biden.

"Now we are confident that together we will win this challenge," he says.

"As we fight the pandemic, we cannot lose sight of the other crisis," Draghi urges.

He encourages incorporating green policies into financial plans as countries build back from the pandemic.

Image source, Pool

President Joko Widodo of Indonesia says his country is on the right track in the climate fight.

He says the country has now reached its lowest level of deforestation.

He also says it is "rehabilitating 620,000 hectares of mangroves" as a carbon sink.

Widodo says that "opportunities in biofuels, lithium ion batteries and electric vehicles" should be capitalised on.

Image source, Pool

President Matamela Cyril Ramaphosa of South Africa is now up.

"We are all so delighted to have the United States back working with all of us to tackle the global challenge of climate change."

Developing economies are particularly vulnerable, especially in Africa, he insists.

His speech focuses on the importance of combatting climate change to help underdeveloped nations that suffer from drought, floods, and famine.

Reality Check

Image source, Getty Images

China is the largest overall producer of coal, but at the summit its President Xi Jinping said his country has plans to limit consumption of the fossil fuel and “strictly control” coal fired power projects.

Chinese coal production increased by 4% in 2019, according to the latest statistics available on the Our World in Data website.

After declining during the pandemic year, the use of coal - a key driver of global warming - is predicted to increase in 2021 according to the International Energy Agency.

Among the top countries, coal production rose in Indonesia and by a small amount in Australia.

Australia is a major exporter of fossil fuels and was responsible for the largest amount of coal produced per capita.d

In the same year, overall production fell in the United States and India.

Image source, Pool

Emmanuel Macron is back. He begins his speech from the start again and it looks like we finally have a translator.

"Let's move more quickly on innovation and disruptive technologies," says Macron, who has positioned himself as a key player in the global climate fight.

The French leader also calls for greater cooperation with the financial sector.

He calls on allies to push forward with a mandate for social justice in work done to curb climate change.

It is up to the world's largest countries to develop the framework for carbon neutrality, he notes.

Image source, pool

President Moon Jae-in of the Republic of Korea begins by thanking President Biden for re-joining the Paris Climate Agreement.

He then announces two pledges made by the Republic of Korea today.

The first is to "raise our reduction target" in greenhouse gas emissions and continue to work to have net-zero emissions by 2050.

"Second, Korea will end all public financing at home or overseas of coal fired power plants."

Image source, Pool

Russian President Vladimir Putin is now speaking.

"It is no secret that the conditions that facilitated global warming go way back. But what kind of comprehensive solutions can we see today?

"It's not enough to tackle the issue of new emissions, it is also important to take up the task of absorbing the CO2 that is already in the atmosphere," he says.

Russia is already doing this work by maintaining strong ecosystems, Putin says.

They are now going back to Macron.

Roger Harrabin
BBC environment analyst

Boris Johnson was in ebullient form on his virtual conference address. He assured global leaders that tackling climate change was "not bunny-hugging".

He continued: "Cake; have; eat, is my message to you".

He also mentioned the vitally important Glasgow Financial Alliance for Net Zero, an umbrella body bringing together banks and the insurance sector.

They’ll be tasked with shifting trillions of pounds away from investments in fossil fuels. Instead, it will encourage investment towards renewables. Some will consider this one of the most important announcements of the day.