Day One of the White House's Earth Day climate summit has now ended.

Over six sessions, we heard from leaders, officials and activists from more than 40 countries, including top officials in the Biden administration.

Day Two takes place tomorrow, with two final sessions.

Thanks for following our reporting and analysis. Live coverage was brought to you by Marianna Brady, Holly Honderich and Sam Cabral, and edited by Paul Rincon, Helen Briggs and Mark Kinver.

The BBC's Outside Source programme asked three young climate activists about their thoughts on the Leaders Summit. Here's what they said.

Daisy Jeffrey in Australia - part of “Friday’s for Future” campaign

“I would hope to see significantly more pressure put on Australia by this US presidential administration than the last.

“I hope that this summit will see the Australian government bow to political pressure, because at the moment instead of looking to invest in renewables and a renewable future this government is investing in gas and saying that gas is the way forward and that is simply an inaccurate and quite backwards way of thinking.

“We’re tackling climate change abysmally.”

Melissa Kowara in Indonesia - a member of Extinction Rebellion Indonesia

“First of all they have to declare that we have an emergency to begin with, because the level of awareness and the climate literacy is still so slow and this declaration will work as a mandate to all the ministries, all the private entity and the civil society to actually act together.

“What I really want to see is that countries around the world start really looking into tackling the climate crisis issue directly at its roots.”

Thandile Chinyavanhu in South Africa – part of Greenpeace Africa

“It’s very important that our government takes action and deviates away from our fossil fuel addiction.

“I don’t believe South Africa’s ambitions are ambitious enough.”

Critics of climate change proposals often question whether climate advocates are willing to make eco-friendly changes to their personal lives.

Will you stop eating meat? Will you stop riding on airplanes? Will you take shorter baths?

With an Earth Day climate summit hosted by the White House in full swing, those critics turned their eyes to national climate advisor Gina McCarthy and transportation secretary Pete Buttigieg, for their choice of transportation to attend an event touting electric vehicles.

Buttigieg has made a show of riding to his meetings on a bicycle, but was also recently pictured taking that bike off the back of an SUV parked a few blocks away.

There has been plenty of reaction coming in to the announcements at the Leaders Summit. Here's a selection of the comments from environmental campaign groups.

Steve Trent, executive director of the Environmental Justice Foundation, said:“We need more ambitious commitments from the big emitters and more binding plans on climate finance, fossil fuel phase outs, and nature restoration which match the urgency of the crisis we face.”

Melita Steele, programme director of Greenpeace Africa, commented:“African leaders must do more than just be at the table of biodiversity and climate summits.

"We need them to be serious about tackling emissions at home and unequivocal about protecting their country’s natural biodiversity in order to tackle a climate crisis which has the continent seeing worse and worse extreme weather impacts every year.”

Catherine Abreu, executive director of Climate Action Network Canada, said:

“[Canada’s] new target is not aligned with a 1.5C compatible future - that would require a 60% emissions reduction goal.

“We hope to see Canada continue to ramp up ambition, both in future years and as NDC consultations occur in coming months on the road to [the COP26 climate meeting in] Glasgow.“

Abby Maxman, chief executive of Oxfam America, described President Biden’s announcement as a “step in the right direction” but added that more action was needed.

“The richest 1% of the world’s population are responsible for more than twice as much carbon pollution as the 3.1 billion people who make up the poorest half of humanity," she said.

“As the world’s richest country and largest historical emitter of greenhouse gases, the US owes it to the world's most vulnerable to increase its emissions reductions target in order to prevent additional climate change impacts."

Image source, Pool

In a separate breakout session, Interior Secretary Deb Haaland is leading officials from around the world in a discussion of nature-based solutions to reduce emissions and strengthen climate resilience.

Nature-based efforts have been proposed around the world to combat climate change, by reducing deforestation and the loss of wetlands, restoring marine and terrestrial ecosystems, and promoting sustainable agricultural practices.

Haaland, the first Native American cabinet secretary in US history, has made restorative justice a key aspect of her climate change goals.

She is moderating a panel that includes environmental ministers from Canada, Costa Rica, Gabon, Indonesia, Peru and the Seychelles, as well as two indigenous activists.

Image source, Pool

The Biden administration has indicated that climate change will be a key plank of its foreign policy.

His director of national intelligence, Avril Haines, and ambassador to the UN Linda Thomas-Greenfield both argue it requires a diplomatic, economic and militaristic effort, what administration officials refer to as "a whole-of-government effort".

They note the Pentagon has already designated climate change as a national security threat and as a threat multiplier.

In the US, the past year has seen wildfires in California, hurricanes in Louisiana and blackouts in Texas, says Thomas-Greenfield, while the world has seen monsoons, droughts and other disasters.

"It doesn't matter where you live. Climate change is a challenge for every person, in every country," she says.

Only "a multilateral toolkit" can ensure that countries and people do not fight over scare resources as the world gets warmer, she says.

Thomas-Greenfield says real global cooperation can instead bring "shared economic opportunity".

Image source, Pool

Defence Secretary Lloyd Austin is now leading a session on how the climate crisis poses a threat to energy, economic and national security.

"Few things deserve to be called existential, but the climate crisis is existential," he says, detailing problems caused by coastal erosion, natural disasters and other impacts of global warming.

He notes that the US intelligence community under President Biden is undertaking comprehensive climate assessments, which it had not done before.

He points out the UK's intelligence assessments of climate security have "raised the bar" on how to do these evaluations.

Austin is joined by director of national intelligence, Avril Haines, US ambassador to the United Nations, Linda Thomas-Greenfield, NATO secretary general Jens Stoltenberg and defence officials from six different countries.

Nick Beake
Europe Correspondent

Image source, Getty Images

Pope Francis has just added his voice.

In a video recorded in the Vatican, he warned that the climate crisis will take on an even greater significance in the post-pandemic world. Leaders must do more to protect the gift of nature, he stressed.

In another message, to mark Earth Day – an annual event calling for greater protection of the environment – Francis said Covid-19 had proved the global community could work together to tackle a catastrophic threat.

But the head of the Catholic Church said if leaders were not courageous and truthful in their efforts to combat climate change, the result would be self-destruction.

When then-President Trump visited Rome in 2017, Francis brought up in conversation the race to save the planet.

But just a week later Trump announced America was to withdraw from the Paris climate agreement.

However, the new incumbent in the White House, a proud Catholic, appears much more on the Pope’s wavelength.

Image source, Leadership Summit on Climate

Michael Regan, administrator of the US Environmental Protection Agency (EPA) is steering an all-female panel of American mayors, global and Indigenous leaders focused on ground-up solutions in their communities.

The women gathered today are a "testament to how women around the world are raising the mantle of climate leadership, developing sustainable solutions", Regan says.

Introducing Hindou Oumarou Ibrahim of the Indigenous Women and Peoples Association of Chad, Regan notes that the world's Indigenous people make up only about 5% of the global population but effectively protect about 80% of global biodiversity.

"How we can lead in harmony with nature?" Ibrahim says. "Without Indigenous peoples there is no way."

She says developed countries must now follow the leadership of Indigenous communities in taking climate action.

For us, she says, "protection of nature it is not a policy, it is our way of life".

Asha Karim survived a narrow escape from the 2020 California wildfires. She gave us her thoughts on Biden's new climate pledge.

What are your thoughts on Biden's climate pledge?

While of course I wish we'd done more earlier, I think it's never too late to act. Any reduction in harm to the planet is worthwhile. We got here by largely ignoring the problem, so to decide that it's now too late to do anything, that ignorance somehow freed us from responsibility strikes me as selfish and silly. Climate change is a series of positive feedback loops that will keep building upon one another, even more rapidly if we don't change course.

Will politics get in the way?

It is politicised, in that there is lot of vested financial interest in maintaining the status quo. That financial power is very present in American politics, and we see it reflected in subsidies and lax regulation in many of the industries that heavily contribute to our emissions.

Can the US reclaim climate leadership?

I hope we can lead the way to a much higher standard than we see globally today. I think that committing to the level of action we see elsewhere is a step in the right direction, but far from enough. Being that it is a politicised problem, it may take a while to make change.

Will Americans be on board with his plan? What do you hope the US government will do first?

I think the American people are onboard with the plan. Climate change has become difficult to ignore. More intense storms, fire seasons, shifts in weather patterns impacting local wildlife - there is some effect of climate change that has touched every person's life in some way. I think most Americans would like to see the US take this problem seriously.

As for what we should do first, cutting subsidies for meat and dairy production and reducing our dependence on coal would be impactful places to start.

Today's climate summit has a lot of important people making a lot of big promises to combat climate change - carbon caps, finance adaptation, and international cooperation.

But let's go back to square one - what even is climate change?

The Earth's average temperature is about 15C but has been much higher and lower in the past. There are natural fluctuations in the climate but scientists say temperatures are now rising faster than at many other times.

This is linked to the greenhouse effect, which describes how the Earth's atmosphere traps some of the Sun's energy.

Read more about the basics of climate change.

Kim Cobb is a climate scientist. She works at the Georgia Institute of Technology. She gave us her thoughts on Biden's new climate pledge.

What are your thoughts on Biden's climate pledge?

This is exactly what we need to get back on track. It is absolutely reflecting a high level of ambition. It's roughly in line with science based targets to keep warming to a minimum this century.

We really have an army of amazing folks working on this in DC right now. The winds are at our back in this particular moment. With every American talking about jobs, talking about public health benefits in our low carbon future, this is language that resonates.

And I think that there's a way to craft this policy to make sure that there's equity for all and economic benefits for all along the way. I'm just inspired to try to do what I can to go as far as we can, as best as we can.

Will politics get in the way?

Obviously, getting anything through Congress right now is not a slam dunk, to put it mildly. And I think the devil is going to be in the details as to exactly how this policy is crafted to appeal across the aisle.

I have confidence that this administration is bringing people who have worked on policies successfully before.

So I think everything we're hearing right now is really aligned towards success. But the next months are going to be absolutely crucial.

What do you hope the US government will do first?

How are we going to make sure that communities that are deeply invested in fossil fuel infrastructure are not left out of the economic winds in our low carbon future?

These kinds of issues are going to be important in terms of building that coalition. At the same time, you have to address the long standing voices who have brought this kind of target forward, such as the youth voices and the people who have focused on environmental justice.

Around the world, there are teams of people who are working to track down and destroy hidden sources of greenhouse gases - stopping them from harming the planet. Some of the gases, which are used in refrigeration, have many times the global warming potential of carbon dioxide.

The BBC's Tom Heap meets some of the people part working to stop these gases causing damage to the planet.

Read about the best climate solution you haven't heard of.

Victoria Coles is an Associate Professor at the University of Maryland Center for Environmental Science. She gave us her thoughts on Biden's new climate pledge.

What are your thoughts on Biden's climate pledge?

It is never too little too late! As the administration’s proposed infrastructure plan notes, we already need to spend billions on mitigating climate impacts to build resilience for roads, airports, ports and other infrastructure. That doesn't include the billions from climate and weather-related losses since 1980. Those costs of prior inaction should be front and center when we think about the expense of reducing emissions.

Can the US reclaim climate leadership?

I am a scientist, not a policy expert. However, I think that legislative rather than executive action is required to stabilise US climate policy from changes in administration. I hope that the American Jobs Plan retains its aggressive investment in climate related action and that, at a minimum, some form of climate legislation can make it through congress. In my view, this, coupled with action rather than discussion, will be needed to convince global leaders that America is serious about climate change.

Will Americans be on board with his plan?

The Yale climate opinion maps, external demonstrate clearly that the majority of Americans support climate policies such as carbon taxes and tax rebates for electric vehicles. The only question in their survey that was not over 50% pro-climate was "the percentage of adults who think global warming will harm them personally".

Americans worry about climate, they view it as harmful to plants, animals, developing countries and other Americans. But until they view it as an existential threat to their own families, they may not vote for candidates that recognise the climate crisis as a threat to global and national interests.

Reality Check

At the climate summit, leaders sought to outbid each other with their pledges on cutting carbon emissions over the next decade.

The numbers can be confusing, so let’s try to make sense of them.

The US pledged to cut carbon emissions by around 50% (from 2005 levels) by 2030.

The UK announced a "world-leading" target to cut emissions by 78% (from 1990 levels) by 2035, having previously committed to 68% by 2030.

Other countries such as Canada have also increased their commitments.

Different countries use different years as the starting point for comparison, usually from when their emissions peaked – partly to show their pledges in the best light.

For example, the US compares their 2030 target to 2005 levels, and the UK uses 1990 levels - about the time when emissions peaked in their respective countries.

However, by either comparison point, the UK’s 2030 target is the most ambitious.

New Zealand Prime Minister Jacinda Ardern joined other world leaders in today's summit as part of a special session of climate finance.

Ardern urged other countries to follow New Zealand's lead in pricing carbon, ending subsidies for fossil fuels and finance environmental adaption.

And for Ardern - calling in some 14,000 km from the summit's host - the appearance meant a rather inconvenient call time. On Instagram, the prime minister noted she had a 02:00am local call time for the international meeting.

French President Emmanuel Macron urges world to 'move more quickly' in tackling climate change.

Image source, Getty Images

John Kerry, US President Joe Biden's Special Presidential Envoy for Climate, has led a roundtable of global financial leaders - all making their own commitments to tackle the climate crisis.

David Malpass, President of the World Bank Group, promised record spending "in the way that gets the most done".

"The core of the plan is to spend more," he said - focused on flattening carbon emissions from the world's biggest emitters.

Malpass also acknowledged what he called the "severity and the inequality of the current environment" - noting that poverty, inequality and climate change are linked and require a comprehensive, inclusive solution.

Chief executive of Citigroup, Jane Fraser, followed shortly after, repeating the corporation's March commitment to be net zero in carbon emissions by 2050.

"Net zero is easy to say, but very hard to do," Fraser said.

Kerry thanked her for the support but said that reaching net zero - a formidable challenge - will still not be enough.

"Even if we get to net zero, we still have to get carbon dioxide out of the atmosphere," he said. "This is a bigger challenge than a lot of people have grabbed on to yet."

Image source, House

Greta Thunberg is now speaking about the emotional toll of the climate fight on young people.

She is pressed on the issue by California Democrat Katie Porter, who says her nine-year-old child told her: "The Earth is burning and we're all going to die."

Thunberg says it's "understandable" that younger generations might be saddened or angry by global warming and political inaction.

"It would be strange if we didn't feel that way because then we wouldn't have any empathy."

"But there is still much hope and, if we choose to take action and act together, there's unlimited things that we can do."

She adds that her experience taught her that "the best medication against anger and anxiety is to take action yourself".

The hearing on fossil fuel subsidies now comes to an end.

Image source, House

Greta Thunberg tells the US House Environment Subcommittee that, in her conversations, she found a lot of readiness for climate action.

"People are actually more open for change than we realise," she says.

To those who depend on the fossil fuel industry for jobs and livelihoods, she says: "Who can blame them?"

People working within the industry "cannot be left behind," she adds.

Pointing out that climate issues are not the fault of those people, Thunberg notes that climate advocates would prefer to work with the industry than against or without it.

"Climate justice is social justice. We can't achieve climate justice without social justice," she says.