There will be shock troops. They'll come from all over Europe, including Milan, where Greta Thunberg and the activists from Fridays for Future hosted their own Youth4Climate conference last month, and Stockholm, where Thunberg has been dancing to Rick Astley's Never Gonna Give You Up onstage.
Rickrolling aside, they're angry.
Thousands more will come from Extinction Rebellion (XR), the group dedicated to non-violent disobedience and disruption. "We don't do hate," says XR supporter and Guardian columnist George Monbiot. "We do anger. We do love."
The shock troops will also include the British royal family. Queen Elizabeth, late-blooming activist: "Extraordinary, isn't it," she said the other day. "I've been hearing all about COP. It's really irritating when they talk, but they don't do."
Prince William and Kate, sponsors of the biggest green prize in the world, the Earthshot Prize, will be there.
"We need some of the world's greatest brains and minds fixed on trying to repair this planet, not trying to find the next place to go and live," said William last week. Earthshot, not moonshot, geddit?
Prince Charles and Camilla are going too: "This is a last-chance saloon," he says. "Literally. Because if we don't really take the decisions that are vital now it's going to be impossible to catch up."
Also at Glasgow: well-organised shock troops from a host of small countries, including our Pacific neighbours.
Working with Barack Obama, they won a remarkable victory at the Paris COP conference in 2015. The target was going to be a limit on warming of 2C above pre-industrial levels. But as Ralph Regenvanu from Vanuatu says, "It was the personal presence of Pacific leaders that really made a change and brought us to the 1.5 degree figure that we have now in the agreement."
Half a degree doesn't sound like much, but on low-lying atolls and coastal regions everywhere it could be the difference between survival or being drowned.
Six years after Paris, though, the world has not risen to the challenge: we're still on track to overshoot. And unfortunately, because of Covid, about a third of the Pacific nations delegates may not get to Glasgow at all.
The starting line
Glasgow will also host 25,000 other people, 125 world leaders and two dreams. One is to stop global warming. The other is to stop global warming while preserving as much as possible of our existing way of living on this planet. Those two dreams are often but not always in conflict.
President Joe Biden will be there, attempting to justify America's claim to world leadership. Scott Morrison, the Australian PM, has also agreed to go. He won't have much: his Government remains committed to a low 26-28 per cent emissions reduction goal for 2030 and cannot agree on getting to net zero by 2050.
Net zero by 2050 is the bare minimum committed to in Paris. Halving emissions by 2030 is the much more important goal right now. For developed countries, it should be more.
Vladimir Putin of Russia has declined the invitation to attend. Narendra Modi of India is still to reveal his plans, likewise Mohammed bin Salman of Saudi Arabia and Jair Bolsonaro of Brazil.
No one wants to be the conference villain, perhaps, but their countries are all big emitters and their absence from the conference will leave a big hole.
The biggest hole of all, if he doesn't show, will be created by China's President Xi Jinping.
Xi hasn't travelled overseas since before the Covid crisis struck and observers doubt the Glasgow conference will tempt him to break that habit.
Still, people are hoping. "Without China at the table, there is no pathway to 1.5," said a developing country negotiator recently.
China will be at the table anyway. Its special climate envoy Xie Zhenhua is a veteran of climate talks and he'll be there, and Vice-Premier Han Zheng may turn up too. Xie has been meeting frequently with Biden's own special climate envoy, John Kerry.
There are some reasons for optimism. Two years ago, just 30 per cent of the global economy had net zero commitments: now it's 70 per cent. The science these days is more clearly expressed and far more widely understood.
Even when countries have dithered, hundreds of cities have adopted strong emissions-reductions programmes. Many corporates are not waiting for governments either (although others are doing little more than greenwashing their profiles).
Things are different: new technologies, new economic opportunities and swings in popular opinion have done that. And more weather: this year's rampaging floods in Europe and the heat dome over northwest America have changed the entire conversation. Urgency has arrived.
Britain, the host, really, really wants Glasgow to be a success. Boris Johnson has every intention of seizing the moment and he'll need something of substance to do it with.
Conference president Alok Sharma, a tireless diplomat, was in Milan to witness the anger of Thunberg and others. "What we were hearing shamed this set of world leaders," he said afterwards.
"There is no doubt that young people around the world are going to hold this set of world leaders to account if, at COP26, we are not able to credibly say that we have kept 1.5C within reach."
Keeping the goal within reach: that's the benchmark by which this conference should be judged.
The thing is, because of the way cumulative greenhouse gases work in the atmosphere, if it's not done by 2030 it may be too late to do it at all.
John Kerry says, "There is not a wall that comes down after Glasgow. It is the starting line for the rest of the decade."
All eyes on Rome
We'll get a hint of how well Glasgow will go before it even starts. Next weekend, directly ahead of COP, the G20 meets in Rome. That's the 19 largest economies in the world plus the European Union, collectively accounting for 80 per cent of all greenhouse gas emissions.
There's a busy agenda, with Afghanistan, Covid, supply chains and the emerging energy crisis, but climate is on it. The G20 is where at least some of the leaders will scrub themselves up for an impressive arrival in Scotland. Biden's going to meet the Pope.
Ahead of G20, the diplomats are busy. This weekend the European Commission Vice-President, Frans Timmermans, visits India and Indonesia to talk climate. Kerry has been meeting Russia, Saudi Arabia and Mexico as well as China.
He said last week he was now convinced world leaders were "sharpening their pencils" to write new commitments.
As for Britain, while Johnson wants to be a global leader on climate action, he's having a little trouble getting his ducks in a row.
Britain's goals are to reduce emissions by 78 per cent by 2035, well in excess of most other countries, and reach net zero by 2050. Business Secretary Kashi Kwarteng's new Net Zero Strategy includes a massive expansion of offshore wind generation, which would also put it among world leaders.
But his colleague Rishi Sunak, the Chancellor of the Exchequer, is refusing to fund the plan. He's opposed to any new spending on climate action.
Kwarteng expected Johnson to back him, but the PM took himself off for a holiday on the Costa del Sol in Spain instead. That prompted former British Labour leader Ed Miliband to suggest Johnson should "get off the sun lounger and start being a statesman".
In fact, even Kwarteng is an inconsistent greenie. He wants electricity generation decarbonised by 2035, but he also wants to license new oil and gas in the North Sea.
Britain goes into the conference with a supply-chain crisis and empty supermarket shelves, petrol shortages and soaring energy bills, a bitter dispute with France over Aukus submarines, rising Covid deaths and a climate-strategy war inside the Cabinet. British energy policies are so dysfunctional, 16 energy supply companies have gone bust this year.
Johnson may want Glasgow to be his Churchillian finest hour, climate-wise, but he'll be sorely tested.
Mum and Dad: the US and China
Think of them as Mum and Dad: many of the COP veterans do, apparently.
John Kerry and Xie Zhenhua, the special climate envoys of the US and China, have been eyeballing each other across the table for years now. They're said to get on well and were both key players at the Paris talks. They've been talking a lot.
Their bosses have also been talking. Joe Biden and Xi Jinping had a long phone call recently, after which, in relation to the climate, Biden declared, "There was a very clear commitment to work with the US to achieve our goals. We are very hopeful."
China is now the world's largest emitter, with the US second, although the US is still the largest cumulative emitter. If nothing changes, China will assume that dubious mantle by the middle of the century.
But that's not the reason they're Mum and Dad: they're also proxies for the developed and developing world. They have, shall we say, soft power over many. And no, it's not obvious which one is Mum.
Even if Xi shows up in Glasgow, the hard work will be down to Kerry and Xie. What these two men achieve could determine the success or failure of the whole conference.
Unfortunately, both of them are compromised by a climate policy crisis at home.
China's net zero target date is 2060, which is too late, and it says its carbon emissions will not peak until 2030. They're still building coal-fired power plants.
And right now they're suffering an energy crisis so severe it's caused rolling blackouts and thrown climate planning into disarray.
Energy companies have been ordered to secure supplies for the coming winter "at all costs" and Premier Li Keqiang has made it clear this will affect climate pledges.
Meanwhile, Shanxi province, China's biggest coal region, has closed 27 mines because of flooding.
Kevin Rudd, a China expert and former Australian Prime Minister, cautiously defended China's climate commitments this week. "They really do get the science," he said. "They understand that climate change is an existential threat to the planet and to themselves. It threatens their own rise to great power status."
Rudd believes that inside the Chinese Government there is "a very intense debate between the energy-security bureaucracy and the climate-change bureaucracy. The energy crisis is making that debate even more acute."
On a brighter note, China has stopped funding new coal-fired plants in other parts of the world. This means a new focus on renewables for many Belt and Road projects and has been widely welcomed.
Biden's moment turns to blah blah blah
As for America, Joe Biden's plans were dealt a bitter blow this week: he couldn't get his US$3.5 trillion budget with its key climate-related spending through the Senate.
Biden's 2030 goals include transitioning to 80 per cent renewables with a 50 per cent cut in all emissions. But all 50 Republican senators say no and Democrat Joe Manchin from the coal and gas state of West Virginia has joined them.
The main casualty is the budget's Clean Energy Performance Plan, which would have sped up the transition to renewables, with fines for power companies that don't meet clean energy benchmarks and grants for those that do.
You may think that's the essential formula to help depressed states with dying industries build a new economic foundation. A model for Glasgow, perhaps.
But no. Manchin says he favours "carbon capture" instead, although the technology has proved far less successful than expected.
White House spokeswoman Jen Psaki has put on a brave face. "No one policy, in our view, makes or breaks our chances," she said on Tuesday, and the administration has "multiple pathways" to meet Biden's goals.
The Democrat progressives are furious and say they will not support a budget that's too weak on climate. Congress has given itself until October 31, the day COP26 begins, to get the deal done.
After the Trump years, Biden will be met with goodwill in Glasgow but also with blunt expectations. "The US is still woefully short of what it owes and this needs to be increased urgently," says Mohamed Adow, director of the advocacy group Power Shift Africa.
Greta Thunberg warned in Milan about leaders spouting blah blah blah. Biden wants to be much better than that, but it's not yet clear how he can.
The return of fossil fuels
Here's something else to mess it all up. Someone has been betting the price of oil will soon rise to US$200 a barrel: it's about US$85 now. This wasn't going to be a big issue in Glasgow, but suddenly the world has an energy crisis.
The International Energy Agency (IEA) blames Covid, post-lockdown. "An acute shortage of natural gas, LNG and coal supplies stemming from the gathering global economic recovery", it says, has led to "precipitous" price rises and "a massive switch to oil products".
That's bad because while gas is bad, oil and coal are much worse.
Wholesale power prices in Europe have risen more than 200 per cent this year and some EU countries now want to rethink the union's net zero goals. The IEA warns that this could "derail the whole COP process".
Russia, which supplies 41 per cent of EU gas, is in the spotlight. Its state monopoly supplier Gazprom is accused of "deliberate market manipulation": raising prices to speed up EU regulatory approval of its new Nord Stream 2 pipeline.
Vladimir Putin denies it: "This is just politically motivated chatter, which has no basis whatsoever," he told an energy conference in Moscow last week.
The Fossil Fuel Treaty organisation estimates that between now and 2030, the world is on track to burn 57 per cent more oil and 71 per cent more gas than is consistent with the 1.5C target.
Kadri Simson, the European commissioner for energy, says the current crisis is good evidence that needs to stop.
"We are not facing an energy price surge because of our climate policy or because renewables are expensive," she says. "We are facing it because fossil fuel prices are spiking. We do not yet have green affordable energy for everyone. We need to speed up the green transition, not slow it down."
This will be an abiding theme at Glasgow. Has Covid given us the chance to "build back better", as Johnson likes to say, or has it made everything just too hard?
COP26 president Alok Sharma wants Glasgow to "consign coal to history". But India has begun importing coal to cover its own shortages and says the world will be burning coal for decades. And exporters like Australia and Indonesia have no serious plans to close down their lucrative industries.
Just overnight, Australia, Indonesia and Japan were outed by Greenpeace and the Guardian for trying to pressure the UN climate report writers to soften the message about carbon.
Australia even argues that because its coal is "cleaner", it's part of the solution. But coal is coal. It's a carbon-emissions fossil fuel.
Hot air in the backrooms
Why are 25,000 people heading for Glasgow? Because there are 25,000 conversations to be had. More or less. Here are the hottest backroom topics they'll be wrangling over.
Methane In the northern autumn of 2019, European Space Agency satellites recorded something unexpected. Huge invisible plumes of methane were leaking from a Siberian gas pipeline.
Since then, the same thing has been discovered with pipes and storage tanks for oil and gas all around the world.
Methane is suddenly important, although not because of the belching of cows – biogenic methane – that so exercises climate debaters in this country.
The gas is 80 times more potent than carbon dioxide, in the short term, and those leaks mean it has been contributing to global warming far more than everyone thought. In Texas, methane leaks are so common they entirely negate the gains made by switching from coal to gas in the first place.
There's good news in this. The leakage isn't useful, so there are no vested interests trying to keep it happening. The problem is fixable. And because methane lasts in the atmosphere for only about 20 years, unlike long-life carbon dioxide, stopping the leaks should lower the amount of greenhouse gas quite quickly.
More than 20 countries have already pledged to cut methane and at Glasgow, the engineers will be trying to agree how to do it.
Hopes are high: stand by for a "big breakthrough".
But there's a downside too. This methane focus turns attention away from biogenic methane, at a time when the world really needs to confront the problems of agricultural emissions.
It also distracts from the central problem of carbon emissions. Fixing leaks allows the fossil fuel industry to look progressive while buying it more time to keep on keeping on.
Carbon trading It seemed like a good idea at the time: the Kyoto Protocol on climate in 1997 decided that the market could drive emissions reductions, by allowing countries that found it hard to reduce their own could buy credits from others.
In Paris they enshrined the principle under Article 6 of the Accord: "cross border trading" would continue and the individual "parties" would decide how to do it.
The diplomatic phrase is "constructive ambiguity": everyone can say how it works for them.
It's worked very well for countries like Russia, Ukraine, Brazil and Saudi Arabia, which have been able to "constructively" avoid genuine emissions reductions.
At Glasgow, they'll be trying to revise Article 6 so it passes the sniff test, with a standard set of rules, no double counting and environmental integrity.
Hopes are mixed.
The commitments Everyone signed up to the same goals at Paris, but each country was allowed to decide how to get there with its own "nationally determined contribution" (NDC).
NDCs have allowed a lot of backsliding: according to the UN, current commitments will produce a 16 per cent rise in carbon emissions by 2030, not the 50 per cent cut required, and agreed on, to keep warming within the 1.5C limit.
But that's diplomacy: agreement to have NDCs is what got the Paris Accord signed. Every step leads to the next one.
Countries also agreed to update their NDCs for COP26, and fully 83 plus the EU, so far, have even done it. New Zealand is not yet among them.
Expect a flurry of further announcements this coming week and in the opening days at Glasgow.
The conference will try to add more transparency and some "common timeframes" to the process.
The money Beyond all of that, delegates will confront the biggest question of all: Where's the money?
Developed countries are supposed to provide US$100 billion a year to help developing countries transition to modern green economies. But even in the best year so far, 2019, only $80 billion was provided.
Oxfam estimates that in the years 2020-2025 the global shortfall on that US$100 billion a year will amount to US$75 billion.
Helen Clark's successor at the UN Development Programme, Brazilian environmentalist Achim Steiner, is appalled.
"Isn't it ridiculous," he says, "that in the midst of a trillion-dollar emergency response economy that we're seeing right now, we are haggling over a $20 billion price tag? Time is running out, and we can't find a way in which we can finance this? It's just not acceptable."
In addition to development aid, delegates from the Pacific and elsewhere will advocate for "loss and damage" compensation.
The tipping points
Are we close to the tipping point? Is Prince Charles right to call Glasgow "a last-chance saloon"?
Or are we poised between two tipping points, each facing in a different direction?
The first is the point at which climate change tips into runaway catastrophe. It could have many causes, including shifts in the monsoons of India and West Africa, the collapse of ice sheets in Greenland and Antarctica, the melting of Arctic permafrost and Amazon rainforest dieback.
The weather has been extremely volatile this year, and that's a signal not to be ignored. The floods in Germany, because they were so unexpected, were particularly shocking.
But perhaps this will lead, instead, to the other tipping point. The one where the world recognises the danger and agrees to do enough to stop runaway change.
Change for the better can happen fast. In Norway, it took just five years for the vehicle fleet to transition from 20 per cent EVs to 87 per cent. In New Zealand, we're at that 20 per cent mark now, according to new car sales last month.
EVs will not save the world, but they're an important part of the solution and the vehicle industry is about to flood the world with them.
Adair Turner, chair of the Energy Transitions Commission, a global coalition, says this: "The 1.5-degree threshold is absolutely technologically possible at costs which the global economy could easily absorb."
All we have to do is do it. Inside the next 10 years, because after then it could be too late to pull things back.
They won't get us there in Glasgow. That's too much to ask.
But remember what John Kerry said? Glasgow is the "starting line for the rest of the decade".
Keeping the goal within reach. So that's what the brave Glasgow 25,000 must do: establish a process that's science-based, politically appealing and binding. So that, over the next few years, all countries can adopt new commitments, new economic agreements and new technologies to get the job done. In time.
It's not too much to ask. And those shock troops massing at the Glasgow conference gates, they'll be expecting it too.