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.
Scientists say it will likely be bad news – but with “nuggets of optimism”.
And environmental experts have said it will be a “massive wake-up call” to governments to cut emissions.
The last time the IPCC looked at the science of global warming was in 2013 – and scientists believe they have learnt a lot since then.
In recent years, the world has seen record-breaking temperatures, raging wildfires and devastating flooding.
Some papers studied by the panel show that some of the changes humans are inadvertently making to the climate will not be reversed for hundreds or maybe thousands of years.
The IPCC’s findings – which will be revealed at a press conference at 09:00 BST – will also be used during a major summit hosted by the UK in November.
The summit, COP26, which is run by the UN, is seen as a critical moment if climate change is going to be brought under control. Leaders from 196 countries will meet to try and agree action.
Alok Sharma, the UK minister who is leading the summit, said at the weekend that the world was almost running out of time to avoid catastrophe – and the effects of climate change were already happening. (Courtesy BBC)