This week has seen a series of hard-hitting reports on climate change, timed for the days before the COP26 summit starts in Glasgow.
The conference, which starts on Sunday, is where world leaders are being asked to promise more ambitious cuts in greenhouse gases to prevent greater temperature rises.
Here, we focus on four key numbers to remember from the reports, as we head into two weeks of big speeches and backroom meetings.
That's one Queen Elizabeth, who announced on Tuesday that she would not attend COP26 in person after her doctors advised her to rest. Wasn't her role just ceremonial, you might ask? Yes, but the 95-year-old is also an experienced diplomat and her absence is blow for UK ambitions to bring some of her lustre to the global stage.
But it also gets to something bigger - COP26's guest list could affect its chances of success. If the diplomatic heavyweights don't show up, the agreements risk being less powerful.
Leaders from 120 countries will be there, but Russian President Vladimir Putin, China's Xi Jinping and Jair Bolsonaro from Brazil are not coming, pending last-minute changes of heart. Those three countries are among the biggest polluters and the world needs them to commit to action.
And then there's the impact of Covid-19. Travel restrictions and concerns over access to Covid vaccines for representatives from some poorer nations means some delegates from islands threatened by rising sea levels can't come.
They don't have the clout to make the big decisions, but they are the soul of COPs. They bring the lived experience of climate change to the conference - decisions made here are critical to their lives and their words carry that weight.
The year when the world will finally meet its target to give $100bn to the developing world to help it absorb the impacts of climate change - three years behind the original target of 2020.
Some of that money pays for adaptation - from something as simple as shelters for people to run to in storms, to massive improvements to sea defences or weather forecast systems.
COP26 climate summit - The basics
Climate change is one of the world's most pressing problems. Governments must promise more ambitious cuts in warming gases if we are to prevent greater global temperature rises.
The summit in Glasgow is where change could happen. You need to watch for the promises made by the world's biggest polluters, like the US and China, and whether poorer countries are getting the support they need.
All our lives will change. Decisions made here could impact our jobs, how we heat our homes, what we eat and how we travel.
The delay is a serious blow to trust, and could make it harder to get significant progress at the summit. For years richer countries promised to hand the money over, and have kept missing the target. Will developing countries believe that other promises will be kept?
But the delegations may also decide that the money is so close to being delivered, and that action is so urgent, they are willing to put aside their anger.
The amount by which global average temperature will rise compared with pre-industrial times, if no further cuts in emissions are agreed, according to a UN report released on Tuesday.
That's significantly above the commitments in the 2015 Paris agreement to keep to any rise to 1.5C and "well below 2C".
This figure is not a surprise and it doesn't mean that negotiators will abandon hope of keeping 1.5C alive, but it underlines the urgency behind the summit.
There is a lot to play for. We've seen some significant progress on promises to reach net zero by 2050 - that would be when we stop adding more greenhouse gases to the atmosphere than we can take out of it.
In all likelihood, the conference will see some progress on reining in emissions from various sectors, but will they be fast enough or deep enough to see cuts of 55% by 2030 which is what scientists say needs to happen to keep 1.5C alive?
The finer details of the deals negotiated will make a difference. There will be questions about the common time frames - the schedules that countries agree to keep for their climate promises - and governments being transparent about successes and failures.
413.2 parts per million
That's how much carbon dioxide there is in our atmosphere, according to the latest figures from the World Meteorological Organization.
This is a record high, and it is a problem because CO2 is the most significant of the warming gases pushing up global temperatures.
This is another warning bell ahead of COP26. One of the reasons that CO2 concentrations rose, despite the pandemic, is because trees and oceans have stopped absorbing as much carbon after deforestation and sea temperature increases.
Scientists are worried about runaway climate change as these so-called carbon sinks reduce their gas absorption.
If nature is kind to us, keeping global temperature rises to 1.5C is more achievable. But if planetary changes cause trees, oceans and other areas like wetlands to emit more greenhouse gases, our climate change problem becomes far more of an existential crisis than it is now.
The COP26 global climate summit in Glasgow in November is seen as crucial if climate change is to be brought under control. Almost 200 countries are being asked for their plans to cut emissions, and it could lead to major changes to our everyday lives.