Image source, Reuters

Wildfires are unplanned blazes that burn in natural areas, such as grasslands or forests.

They can start at any time and in any location, but the risk of them increases when it’s extremely hot and dry. Climate change increases the likelihood of this hot, dry weather.

According to the World Health Organization, about 2,400 people died worldwide from suffocation, injuries and burns related to wildfires between 1998 and 2017.

And at the same time, wildfires make climate conditions worse, by releasing large amounts of carbon dioxide and carbon monoxide into the atmosphere.

We've talked to several experts ahead of the report for their views about what to expect and the state of our planet.

Here's Richard Black, from non-profit advisory group the Energy and Climate Intelligence Unit:

Here's Dr Heleen de Coninck, from Eindhoven University of Technology in the Netherlands, who is a co-ordinating lead author for the IPCC Working Group III:

A lead author of the report, Prof Ed Hawkins, told us:

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Again, how much rain is considered an extreme amount depends on how much rain a particular area normally sees.

However, it's either a heavy amount of rain in a very short period of time, or a prolonged period of rain.

Extreme rainfall can lead to flooding - including flash floods, which are caused by a short burst of heavy rain.

And while many factors contribute to flooding, a warming atmosphere caused by climate change makes extreme rainfall more likely, because a warmer atmosphere holds more water vapour that then rains out.

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The exact temperature at which heat is considered "extreme" depends on where you are in the world.

In the US, for example, it is a period of at least two to three days where the temperature is above 32C (90F).

In the UK, the exact heatwave threshold depends on the county you're in, but it's usually between 25C and 28C. Extreme heat is a prolonged period of at least three days of this temperature or higher.

Because of human-induced climate change, heatwaves are becoming more severe and more likely to happen.

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The link between climate change and extreme weather is so complex that there's a whole branch of scientific study dedicated to it - Attribution Science.

Scientists have found strong evidence that human-induced global warming is making events like wildfires and heatwaves more likely and more extreme, mainly because climate change increases the risk of hot, dry weather. For the same reason, droughts are becoming more severe too.

A warming atmosphere caused by climate change makes extreme rainfall more likely as well, which in turn contributes to flooding.

And while the impact of climate change on the frequency of hurricanes, cyclones and typhoons is still unclear, we know that increased sea surface temperatures warm the air above, making more energy available to drive storms, making them likely to be more intense with more extreme rainfall.

The last time the IPCC released one of these reports was eight years ago, in 2013. That was the Fifth Assessment Report.

That report found that, with 95% certainty, humans have been the dominant cause of global warming since the 1950s.

It looked at the combined average land and ocean surface data between 1880 and 2012, and found the temperature had risen by 0.85C.

It also said the period from 1983 to 2012 in the Northern Hemisphere appeared to be the warmest 30-year period of the last 1,400 years.

Analysis: World will continue to get hotterpublished at 07:30 British Summer Time 9 August 2021

07:30 BST 9 August 2021

Roger Harrabin
BBC environment analyst

The intergovernmental panel brings together representatives of world governments who appraise research by scientists. That means all governments buy into the findings.

The last panel was in 2013 and researchers say much has firmed up since then. Previously, for instance, they were reluctant to ascribe extreme events such as heatwaves and torrential rain to being at least partly down to climate change.

Now in the case of the heatdome in the US in June, they're confident to say it would have been almost impossible without climate change.

They say the world will continue to get hotter.

It will also - especially in northern Europe - get wetter, though droughts will increase too as weather patterns shifts.

The panel studied papers showing that sea level would continue to rise for hundreds or possibly thousands of years because of heat already trapped in the ocean deep.

Research does confirm though, that if politicians can stick to holding global temperature increase down to 1.5C, on pre-industrial times, the worst catastrophes can still be avoided.

The report to be published will be the most up-to-date assessment of how global warming will change the world in the coming decades:

• It is likely to detail significant changes to the world's oceans, ice caps and land in the coming decades
• As well as updates on temperature projections, there is also likely to be a strong focus on the question of humanity's role in creating the climate crisis
• It should include warnings of how soon global temperatures could rise 1.5C above pre-industrial levels. Experts say the impacts of climate change are far more severe when the increase is greater than 1.5C
• As the world has experienced a series of devastating fires and floods in recent months that have been linked to climate change, the report will also include a new chapter linking extreme weather events to rising temperatures

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The IPCC regularly releases reports on climate change.

It doesn't actually conduct its own scientific research, but instead looks at different studies that have been published. The idea is that it informs our understanding of climate change, and how it's impacting our world.

This is the sixth such report in a series that started in 1992. The part of the report that's being released today was put together by the IPCC's Working Group I, which has been looking at the physical science behind climate change.

After this, other parts of the report - which will be released next year - are going to look at the different impacts of climate change, and how we can mitigate its effects.

The Intergovernmental Panel on Climate Change - or IPCC - is an international body set up to assess the science around climate change.

It was established in 1988 by the UN Environment Programme (UNEP) and the World Meteorological Organization (WMO) to put together regular reports with the latest information on climate change.

It regularly assesses the scientific basis of our understanding of climate change, as well as the impacts of it and different ways countries can mitigate its effects.

These reports are aimed at governments, who can then use them to come up with climate-related policies - though they don't tell policymakers what actions to take.

They also form the basis of negotiations at the UN's climate conference, the United Nations Framework Convention on Climate Change (UNFCCC).

Image source, Reuters

Good morning if you're joining us in the UK, and welcome to our live coverage of a major UN report on climate change.

The study is by the Intergovernmental Panel on Climate Change, a UN group that looked at more than 14,000 scientific papers.

It will be the most up-to-date assessment of how global warming will change the world in the coming decades.

The section to be published today at 09:00 BST (08:00 GMT) will look at the latest science underpinning climate change.

We'll bring you details of the report, as well as analysis from our team of experts and correspondents.