In an inspiring speech to students at the London School of Economics (LSE), John Kerry, United States special presidential envoy for climate, spelt out the urgency of tackling climate change—“the stakes could not be higher”—but also said “I head to Glasgow [to COP26] an optimist.” Hard-boiled, old cynic that I am, I must confess that his speech reduced me to tears—more tears of inspiration than despair. Like a master politician he spoke with stories, statistics, great quotes, and compassion.

Kerry was at the first Earth Summit in 1970 and has been an activist on climate change ever since. He was also at the meeting in Rio de Janeiro that gave birth to COPs and at the Paris COP that led to the Paris agreement. As he explained, the Paris agreement did not achieve the commitments the world needs to keep the global increase in temperature below 1.5C above—but it did “pull us back from the brink,” set a mechanism for reviewing progress, and sent a signal to businesses of the direction in which the world intended to travel. “For the first time in modern history, more investment went into renewable energy than went into fossil fuels.”

“Let’s be clear,” said Kerry, “the time for debating the causes of climate change is long over and the time for action is also long overdue…the stakes could not be higher.” The meeting was chaired by Lord Stern, the economist, who has led global thinking on the economics of climate change, and Kerry praised him for pointing out that “economists have grossly undervalued the lives of young people, your lives, your livelihoods, your ability to count on the barest of bare minimums and the right to live on a habitable planet.”

“The journey from Rio to Kyoto to Paris, and now Glasgow has taught me many things, folks, but above all that has taught me that success in the climate fight is defined not by words alone but by actions that they inspire. Glasgow has already produced more climate ambition than the world has ever seen, and in that regard, Glasgow has already achieved success…[but] we must do more to avoid the worst consequences of the climate crisis.” 

In public life, explained Kerry, you must make choices every day, and some are hard because costs and benefits are closely balanced. But addressing climate change “is not a hard choice…[it] is the only choice. In every way the cost of inaction is far greater than the cost of action.”

“Now we must significantly accelerate our efforts. That is a judgment, not of me or of President Biden, or of anybody in politics. It’s the judgment of the best science and mathematics. That’s what this is about. Not ideology, not politics, it’s about mathematics and physics. And according to the most recent report from the scientists at the United Nations Intergovernmental Panel on Climate Change … devastating consequences await us if global temperature rises above 1.5 degrees…And we are now already just at about 1.2.”

“We no longer,” Kerry continued, “need scientists to tell us what will happen because we’re seeing it happen now already. And we see it for ourselves here in the UK. In July, the Met Office issued its first ever extreme heat warning, as a deadly heat wave took over.” Germany had unprecedented floods that killed almost 200 people and swept away homes and bridges. A supercharged storm drowned people in their basements in the dead of night in New York City, months after more than 150 people froze to death in Texas. The rainforest of the Amazon is burning and being destroyed at the rate of 10 000 acres a day. Ten million people a year already die from air pollution around the world, another five million die because of the heat. “Without dramatic action, my friends, some of these things may make life unlivable.”

Kerry spelt out the difference between a temperature increase of 1.5C and 2C. “At 1.5 degrees, crops from corn, rice, and wheat are in peril. At 2.0 degrees many of those crops wither and die, especially in Africa and Southeast Asia, threatening starvation for tens of millions of people….Glaciers from the Alps to the Himalayas are melting, posing devastating consequences for the billions of people that rely on the waters of the great rivers that they feed from….Tens of millions of people are migrating due to climate change, which could destabilise entire regions…and economies could potentially collapse.”

“Let me be clear,” said Kerry, “No one, no one is exaggerating when they call this an existential threat….that is what makes this the decade of decision. And now we must make it, the decade of action. To prevent catastrophe, the scientists tell us, we must cut our global greenhouse gas emissions by at least 45% by 2030 in order to get to net zero by 2050. We head to Glasgow in that context, and I head to Glasgow an optimist.”

Can we, asked Kerry, close that gap that currently exists to stop us keeping temperature increase below 1.5C? He thinks we can.

“We’re seeing growing ambition from governments around the world,” commitments and investment from the private sector, and revolutionary technological developments. “Between Paris and Glasgow—despite a president who denied the science… we have seen real progress in the United States [and] …we’ve committed to reducing our emissions this decade by 50-52%….When I began in this role nine months ago…very few [countries]… were on track to reach the 1.5 degrees goal. Now nations representing nearly 65% of global GDP [more than half of the top 20 economies in the world] will arrive in Glasgow committed to the 1.5 degree limit…with real plans.”

Kerry warned, however, that damage is already here and the world has to adapt to climate change as well as mitigate it… “every dollar spent in adaptation can save up to $10 down the road.”

“There is,” continued Kerry, “another profound reason for optimism….more and more businesses around the world are joining this fight….a revolution is taking place in boardrooms…Corporate leadership in many places is now requiring investment in the environment, shareholders are demanding that their companies be part of the solution. And those investments are paying off.”

“Last year wind and solar accounted for 90% of new electricity capacity in the world….renewable energy is the cheapest energy available, and the costs are beginning to fall.” But investment needs to be in trillions not billions. The UN finance report says that we need to increase investment in the transition to renewable energy from 2.6 trillion to 4.7 trillion every year. “No government on earth can fill this gap alone….It can only happen with the full participation of the private sector.” A group of banking alliances will head to Glasgow and announce that they represent $85 trillion that they are prepared to invest heavily in the energy sector. 

This is, said Kerry. “a huge economic opportunity…[the] biggest transformation since the industrial revolution.”

But “we still face a gap….Everything I have said to this moment, underscores why I believe we can overcome that gap, but it’s going to take all of us. The world must work together to close this gap, but particular responsibility lies with the top 20 economies of the world, [which]… are responsible for 80% of all the emissions.”

Countries’ plans will in Glasgow “be held up to scrutiny, the scrutiny of the world….Coming out of Glasgow, we will be ready to experience the greatest springboard of all, the combined power of individuals around the world demanding accountability.”

“There’s a temptation on this issue, folks, to talk too much about GDP and emissions targets and not enough about human beings…We’re not just talking about statistics here. We’re talking about families, about people. We’re talking about parents and children and neighbours and friends.”

We should all be angry with the lack of progress, “but I also believe this momentum we are seeing is real and meaningful and will grow. I know that you and your voices and your actions are already making a difference, but also know that you can do more next week in Glasgow. We have the chance to win a victory for the next century for life on this planet. And then we’ll have to get up every single day and do it again…until the work of this decisive decade is decidedly done.”

You can watch the speech at https://www.lse.ac.uk/granthaminstitute/events/john-kerry/.

Richard Smith was the editor of The BMJ until 2004.

Competing interests: none declared.