It was the NASA scientist James Hansen who introduced the wider world to the threat of climate change. His testimony before a US Senate committee in 1988 shook Washington and became a driving force of the global movement to address the threat.

That same year, the United Nations formed the Intergovernmental Panel on Climate Change (IPCC). It was to provide the world with detailed assessments of the science of climate change, to chart the risks and lay out possible responses. Its assessments of global warming were to become the largest scientific peer review process in history. Based on the IPCC’s advice, the world negotiated the United Nations Framework Convention on Climate Change (UNFCCC), which was launched in Rio in 1992.

Today, the UNFCCC has 195 national signatories, whose representatives normally gather annually at what is now known as the COP, or Conference of the Parties. COP1 was held in Berlin in 1995. This year COP26 will be held in Glasgow from October 31 to November 12, the event delayed for a year due to the pandemic. The meetings are usually attended by around 10,000 diplomats and negotiators, scientists, activists and people from civil society groups. The particularly significant COPs such as those held in 1997, 2009, 2015 and this year – those at which key commitments are to be renegotiated – generally attract world leaders as well. Prime Minister Scott Morrison has announced he will be going to Glasgow.

This year’s meeting will resemble something like a UN General Assembly crossed with the Davos meeting of the World Economic Forum. The COP has not yet said which leaders have confirmed their attendance, but organisers expect more than 100 will be there, along with members of the British royal family, corporate heavyweights and celebrities.

To many observers, COP26 is the most crucial yet because it will test whether the framework for co-operative emissions reductions agreed to in Paris can, in fact, curb climate change. According to the IPCC, the world has warmed more than 1 degree over pre-industrial levels. Under the Paris Agreement, the parties to the COP undertook to hold warming to under 2 degrees. The same assessment says that to limit warming to 2 degrees we must achieve net zero emissions by 2050, and around 50 per cent by 2030.

Thirty years on from Hansen’s famous testimony in Washington, The New Yorker magazine asked him if he had a message for the next generation. His response was blunt. “The simple thing is, I’m sorry we’re leaving such a f---ing mess.”

So, how did we get here? And what needs to be achieved at Glasgow?

How did we get here?

The first major climate treaty was thrashed out at the second Earth Summit in Rio de Janeiro in 1992 – the meeting at which the Conference of the Parties was also created. The central aim of the UNFCCC was to stabilise greenhouse gas concentrations “at a level that would prevent dangerous anthropogenic (human-induced) interference with the climate system”.

While this aim has not been realised so far, the COPs were the forums to try to make it happen.

The first agreement made under the auspices of the UNFCCC was the 1997 Kyoto Protocol, in which 36 developed nations agreed to reduce greenhouse gases during a set period (2008 to 2012) by 5 per cent compared to 1990 levels. Acknowledging that developed nations had already benefited from the process of industrialisation, it allowed for poorer nations to continue to build their carbon-intensive economies. As a result, while signatories to Kyoto managed to reduce their emissions in keeping with the agreement, global greenhouse gas emissions continued to rise, jumping by 32 per cent between 1990 and 2010, according to a 2019 IPCC report.

A new approach was needed.

Have other COPs succeeded?

By the most crucial measure – the rate at which the world is warming – the process has not yet worked, but it has seen the world agree on the scale of the problem and a course of action.

Some meetings, such as the gathering in Copenhagen in 2009, have been standout failures. There, divisions between developed and developing nations became even more entrenched, with the former declining to set concrete reduction levels by 2020 and the latter insisting on their right to carbon-intensive growth.

In the dying hours of two weeks of negotiations, the US delegation couldn’t even find key players from the major developing nations bloc, let alone negotiate with them. At the last moment US president Barack Obama, still as much a global superstar as politician after his election victory the year before, flew in, hoping to force a useful outcome.

In her memoir, then secretary of state Hillary Clinton recounts discovering that China was hosting a secret meeting attended by leaders of high-emitting emerging economies including India, Brazil and South Africa.

She and Obama decided to crash it.

She recounts racing down long corridors with Obama, their staff in tow, before ducking into the meeting room as White House press secretary Robert Gibbs tangled himself up with Chinese security guards at the door. Those inside were stunned. Despite her breezy description of diplomatic derring-do, all that came of the Copenhagen COP was a political statement affirming the need to keep warming to 2 degrees, with no attendant commitments as to how that might be done.

After Copenhagen, crucial years were lost as emissions continued to rise. COP meetings rolled on and something like a consensus formed that the replacement for the expiring Kyoto Protocol would be negotiated in Paris in 2015.

What was agreed in Paris (and what’s the ‘ratchet effect’)?

Two principles were made central to the talks in Paris, both designed to help overcome the critical gulf between richer and poorer nations: all nations would commit to voluntary emissions cuts, but wealthier countries would help pay for the developing world to meet their targets and adapt to a warmer world. Developed nations agreed to make their emissions peak as soon as possible, and then decline to net zero by 2050.

To achieve the goal, all nations would set “ambitious” reductions targets that would be updated and increased over time. This is often described as the agreement’s ratchet effect.

The president of this year’s COP, British cabinet minister Alok Sharma, has noted that the Paris summit put the world on track for a rise of global temperatures of just under 4 degrees. Commitments made since, should they be met, have put us on course to 2.4 degrees.

This level of warming would be catastrophic, and to critics it is evidence of a failure of the process. But the decline is the point.

Loose language in the Paris agreement has also prompted criticism.

The financial commitment of the developed nations was absolutely crucial to any agreement being secured at all. But the language of the Paris accord was deliberately muddy. Under the agreement, rich nations would create a Green Climate Fund to “mobilise” $100 billion for mitigation and adaptation projects by poorer ones. But what did “mobilise” mean? And which countries would be donors and which recipients? In order to secure agreement, negotiators were not clear on these points.

“Mobilise,” one of Australia’s former top climate diplomats Howard Bamsey has said, “is one of those UN verbs, so you have to parse it very carefully.”

Even the goalposts set by the IPCC shifted in Paris. Tony deBrum, a former president of the Marshall Islands (halfway between Australia and Hawaii), believed that while a 2-degree goal might be tolerable in some parts of the world, it would lead to the complete destruction of many small island nations. He quietly set about forming a bloc of nations that eventually became known as the High Ambition Coalition, which appeared as if out of nowhere moments before the talks’ final session.

Demonstrating the power of smart negotiators from small nations equipped with little more than moral authority and a sense of urgency, deBrum secured 90 votes and reshaped the Paris accord. The agreement’s intent would now be to limit global warming to “well below 2, preferably to 1.5 degrees Celsius, compared to pre-industrial levels”.

So, what’s on the table at Glasgow?

When the world met in Paris in 2015, nations accepted the IPCC’s advice that it must massively reduce emissions to keep it on a path to holding warming to beneath 2 degrees, and as close to 1.5 degrees as possible. In Glasgow, they must reset their reductions targets to make that goal possible.

As Sharma puts it, Paris promised, Glasgow must deliver.

For around two years, Sharma has travelled the world pressing the need for nations to bring to the Glasgow conference emission reductions commitments in line with that target. For vulnerable countries, Sharma said in his last major speech before the conference, “‘1.5 to stay alive’ is not a hollow slogan. It is a matter of survival.”

Sharma and British Prime Minister Boris Johnson have been unequivocal about their terms for success. They say COP26 must result in nations committing to new emissions reductions targets that close the gap between our current warming trajectory and the 1.5-degree goal raised in Paris. To get to that point, the science suggests, most nations must not only commit to net zero emissions by 2050, but agree to 2030 reductions targets that collectively add up to 45 per cent.

This would be a significant feat.

It would mean securing increased ambitions from more than 70 countries accounting for 41 per cent of global emissions. They include China, Russia, India, Indonesia, Brazil, Mexico and Australia, which has so far neither committed to net zero nor raised its 2030 target beyond the 26 to 28 per cent reduction it committed to in Paris.

There is also debate about the mushy language of the agreement. Some nations interpret the prime Paris goal to be 1.5 degrees warming, others 2 degrees.

Former French prime minister Laurent Fabius, who was president of the Paris talks, recently told Politico the 1.5-degree goal was aspirational and that the Paris Agreement would survive even if it was not met. (He and Laurence Tubiana, the former diplomat who was France’s lead negotiator in Paris, urged Sharma over a breakfast not to allow the issue to turn his COP26 presidency into a battle, Politico reported.)

The potential failure of the $100 billion Climate Fund could be used as an excuse for any number of reluctant nations to abandon the agreement, experts have warned. Sharma has confessed that the thought of the financial target being missed keeps him up at night.

“We are now within touching distance of the $100 billion … please step forward now in these few days before COP,” he said.

Since President Joe Biden was elected in the US, Sharma has been joined by the US State Department – the world’s largest diplomatic machine – and US climate envoy John Kerry, an infamously relentless negotiator, in cajoling world leaders to commit to greater efforts.

But success is far from assured.

Well, what would success look like?

“The measure of success at Glasgow is we will have the largest, most significant increase in ambition [on cutting emissions] by more countries than everyone ever imagined possible. A much larger group of people are stepping up,” Kerry said in a recent interview with The Guardian.

But there are other markers of success. There is a push for the meeting to deliver an even faster “ratchet” mechanism, with Denmark and Grenada tasked by Sharma to pursue an agreement for reductions targets to be reset annually rather than every five years.

And some key decisions will be made on the sidelines of the meeting, with Johnson making it clear he wants nations to agree to “consign coal to history” by laying out a rapid phaseout of the world’s dirtiest source of energy. That effort is being championed by a push known as the Powering Past Coal alliance.

The cost of failure in Glasgow is unthinkable, says Sharma.

“At 1.5 degrees warming, 700 million people would be at risk of extreme heatwaves,” he said in his recent speech. “At 2 degrees, it would be 2 billion.

“At 1.5 degrees, 70 per cent of the world’s coral reefs die. At 2 degrees, they are all gone.

“If temperatures continue to rise we will step through a series of one-way doors, the end destination of which is climate catastrophe.”