The former US president was speaking at the COP26 summit in Glasgow, where he laid out the progress that has been made in the five years since the Paris Agreement took effect at COP21.

The Paris Agreement was agreed in the French capital and committed signatory nations to limit global warming to 1.5 degrees Celsius above pre-industrial levels.

Obama, who was US president when the Paris Accord was agreed in 2015, highlighted the leadership of young people around the globe and urged more robust action from governments, the private sector, philanthropic endeavours and civil society.

He initially joked about being a "private citizen" and that traffic was now "a thing again", in a subtle reference to the current president - and his former colleague - Joe Biden's motorcade that closed off roads across the Central Belt.

“Even though I’m not required to attend summits like this any more, old habits die hard,” he told the climate change summit.

“And when the issue at hand is the health of our planet, and the world our children and our grandchildren will inherit, then you will have a hard time keeping me away.

“That’s why I’m here today.”

He then got into what needs to be done to address the climate crisis, saying that not enough has been done so far.

"By some measures, the [Paris] Agreement has been a success," Obama said. "For the first time, leaders of nearly 200 nations - large and small, developed and developing - made a commitment to work together to confront a threat to the people of all nations."

READ MORE: COP26 LIVE: Barack Obama in Scotland as COP26 enters final week

"That seemed proof that for all the divisions in our world, when a crisis threatens all of us, we can come together to address it."

He said that at the time of the Paris Agreement, it was believed if governments showed they were serious then private businesses would follow. He added that now a fifth of the world's largest companies have set net-zero emissions targets in the six years since.

"Not just because it's the right thing to do for the environment, but in many cases because it makes sense for their bottom line," Obama continued.

He added that he “wasn’t real happy” about former president Donald Trump’s decision to pull the US out of the Paris Agreement.

“Some of our progress stalled when my successor decided to unilaterally pull out of the Paris Agreement in his first year in office,” he said.

“I wasn’t real happy about that.

“And yet, the determination of our state and local governments, along with the regulations and investment that my administration had already put in place, we were able to keep moving forward despite hostility from the White House.”

He also took aim at the Republican party currently in opposition to Biden's Democratic presidency for showing "active hostility" to climate science.

He added that the governments of other delegates at the summit may also experience the same dynamic, but added the US seems to have a "more vigorous opposition" than other places.

He said: “But that has got to stop – saving the planet is not a partisan issue.”

While hailing the progress being made to combat global warming, Obama said that world leaders are “nowhere near” where they need to be on meeting targets, adding: "For starters, despite the progress that Paris represented, most countries have failed to meet the action plans that they set six years ago, and the consequences of not moving fast enough are becoming more apparent all the time.”

He also took a swipe at the Russian and Chinese governments who - along with the US and India - are two of the biggest emitters of harmful gases.

He said: “I have to confess, it was particularly discouraging to see the leaders of two of the world’s largest emitters – China and Russia – decline to even attend the proceedings, and their national plans reflect what appears to be a dangerous lack of urgency and willingness to maintain the status quo on the part of those governments.

“That’s a shame.

“We need advanced economies like the US and Europe leading on this issue, but you know the facts – we need China and India leading on this issue.

“We need Russia leading on this issue, just as we need Indonesia and South Africa and Brazil leading on this issue – we can’t afford to have anyone on the sidelines.”

He went on to say that tackling climate change has to transcend politics, saying that the world can't afford to go backwards or stay sedentary. 

“The world has to step up and it has to step up now," Obama said. 

While sometimes "doubtful that humanity can get its act together", Obama said that despite despondency over the future, "we are going to have to muster the will and the passion and the activism" of people pushing institutions to do more.

This broad-ranging action means that people will require their minds to be changed, Obama said, telling delegates at the conference that activists need to do "a little more listening".

“We can’t just yell at them, or say they’re ignorant.

“We can’t just tweet at them, it’s not enough to inconvenience them by blocking traffic in a protest – we actually have to listen to their objections and understand the reluctance of some ordinary people to see their countries move too fast on climate change.

“We have to understand their realities and work with them so that serious action on climate change doesn’t adversely impact them.”

He added that, while there were companies looking to “make a buck” by polluting and there were people who would never be convinced of man-made climate change, “we’ve got to persuade the guy who has got to drive to his factory job every day, can’t afford a Tesla and might not be able to pay the rent or feed his family if gas prices go up”.

He then urged young people to "stay angry" about climate change and asked them to channel their frustration into action. 

Obama said: “Keep pushing harder and harder for more and more – because that’s what’s required to meet this challenge.

“Gird yourself for a marathon, not a sprint.

“For solving a problem this big and this complex has never happened all at once.”

What has Obama been doing in Glasgow today?

The former US president arrived in Glasgow on Sunday evening and will be at several events throughout the conference today.

Obama spoke earlier in the day about how island nations are the  “canaries in the coalmine” as a theme of talks today is support for poorer countries to cope with climate change.

He said: “In many ways, islands are the canary in the coalmine in this situation.

“They are sending a message now that if we don’t act then it’s going to be too late.”

READ MORE: Barack Obama demands action to save island nations in COP26 rallying call

He added: “All of us have a part to play, all of us have work to do and all of us have sacrifices to make.

“Those of us who live in big, wealthy nations, those of us who helped to precipitate the problem, we have an added burden to make sure that we are working with and helping and assisting those who are less responsible and less able, but are more vulnerable to this oncoming crisis.”

Calling for more action and for countries to stick to the pledges they have made in Glasgow and previously, he said: “It’s important for us to recognise as was true five years ago we have not done enough.”

The Hawaiian native said he is an “island kid” and ended his speech quoting a Hawaiian saying which he said roughly translates as “unite to move forward”.

READ MORE: Scots wind farm providing 100% of renewable energy for climate summit

Obama alluded to his successor as US president, Donald Trump, as he sought to convince people his country was genuine in its efforts to tackle the climate crisis.

He said: “The politics in the United States are not always easy, as you may have noticed, and my successor maybe wasn’t as interested in climate science as I was, it turned out.

“But there are a lot of people in the US government who care about this deeply and work really hard and are invested.”

Obama added that while “sometimes it may feel like the United States” is not following through on commitments or moving as fast as some people would like, it is “not for lack of trying” by delegates at COP26.