World leaders meeting at a United Nations climate conference starting on Sunday have failed to set policies that would keep global warming "well below" 2 degrees Celsius (3.6 degrees Fahrenheit) above pre-industrial levels — in continuing defiance of promises they made at a summit in Paris six years earlier.
"The time has passed for diplomatic niceties," said UN Secretary-General Antonio Guterres in a tweet ahead of a meeting of the G20 group of big economies at the weekend.
"If all governments — especially G20 governments — do not stand up and lead efforts against the climate crisis, we are headed for terrible human suffering."
In recent years, amid increasingly violent weather extremes and mass student protests, climate change has been thrust into the political spotlight. But while the core science has been clear for half a century — burning fossil fuels releases gases that act like a greenhouse around the Earth, trapping heat and warping the climate — politicians have sidelined the problem.
Now, after 2 1/2 decades of yearly negotiations, tens of thousands of people are descending on the Scottish city of Glasgow to thrash out agreements on emissions at the 26th Conference of the Parties, or COP26. It has been hailed as a "best last chance" to stop the planet from warming 1.5 C above pre-industrial temperatures.
"When things start to go wrong, they can go wrong at extraordinary speed," said British Prime Minister Boris Johnson ahead of the weekend G20 summit, drawing a parallel between climate change and the fall of the Roman Empire. "Unless we get this right in tackling climate change, we could see our civilization, our world, also go backwards."
'Empty promises'
UN climate summits are a forum for world leaders to agree on plans to burn fewer fossil fuels. Beyond the technical negotiations, like agreeing rules on how countries should report cuts to pollution or finalize previous agreements, delegates will haggle over two core issues: emissions and money.
The UK government, which is hosting the event, is pushing leaders to promise to cut their carbon pollution sooner and faster. It has put "coal, cars, cash and trees" at the top of the agenda. The cash part of that slogan is particularly tricky. Rich countries failed to deliver on a promise made at a previous climate summit to pay poorer ones $100 billion a year (€86.5 billion) in climate finance by 2020 — an amount that covers neither the costs of adapting to changes nor greening economies.
Delegates from poor and vulnerable countries, some of whom are reportedly unable to attend the summit because of coronavirus restrictions and the cost of travel, are also calling for rich polluters to pay for losses and damages from climate change-fueled weather extremes they have done little to cause. This is not included in the $100 billion-a-year pledge, which is only for cutting emissions and adapting to the effects of climate change.
But scientists, activists and delegates from countries on the front line of climate change are skeptical of the idea that climate summits can fix the problem. They have criticized rich countries for not honoring their pledges. They have also dismissed promises to cut long-term emissions that are not backed up by policies today.
"This is all we hear from our so-called leaders — words that sound great but so far have not led to action," said climate activist Greta Thunberg at a pre-COP event in Italy last month. "Our hopes and ambitions drown in their empty promises."
Increasingly extreme weather
Carbon dioxide has continued to clog up the atmosphere despite decades of international treaties.
The concentration of the planet-warming pollutant has risen to 413 parts per million (ppm). It was just 375ppm when Thunberg was born in 2003. Like most student strikers, she has never known what scientists broadly consider a safe level. The world crossed that threshold —350ppm — in 1988.
While those numbers sound abstract, they translate into deadly weather extremes.
Today, with global temperatures already 1.1 C hotter than before the Industrial Revolution, the climate has grown more chaotic than it was for the rest of human history. The heat wave that scorched Northwest America in this summer was made 150 times more likely and 2 C hotter because of climate change, according to a study from climate scientists at the World Weather Attribution research group. The same group of scientists found a similar but weaker connection for the rains that triggered deadly floods across northern Europe in July.
Still, without efforts to shift policy in recent years, scientists say, the planet could be facing even deadlier levels of warming. Before the Paris Agreement, the world was headed to heat about 4 C. Now policies put it on track for about 3 C. If pledges are met, temperatures by the end of the century could end up between 2 C and 2.5 C.
Such a temperature rise is well above the promised goal during the Paris Agreement of "well below" 2 C and ideally 1.5 C. That would be an effective death sentence for low-lying island nations, as well as vulnerable communities battling weather extremes across the world. That level of warming would be "catastrophic," said Amos Wemanya, an energy analyst at Kenya-based think tank Power Shift Africa. "Rich countries need to be more ambitious than they are right now, if we are to achieve the 1.5 C target."