It concludes that impacts thought to be decades away are already with us and even impacts we expected are more severe.
The IPCC is made up of the world’s top scientists who look at all aspects of climate change and this report is specifically about the current and future effects. It is a synthesis of all recent relevant scientific research and references 34,000 individual studies.
In its near-4,000 pages, it says that human activity has already warmed the world by 1.1 degrees Celsius which brings extremes of heat, heavy rains, droughts, wildfires, more dangerous storms and rising seas.
Nature is being hit harder than expected with half of all species on Earth shifting where they live already. The ice sheets are melting faster, the coral reefs dying earlier, and 45 per cent of the world’s human population is now highly vulnerable to climate impacts.
The report looks at regional differences and there is no surprise that it is the poorer regions of the planet that are most affected, even though they have done the least to create climate change. Africa will be particularly hard hit, with parts of the continent becoming uninhabitable and staple food crops set to see massive declines in production.
The scientists repeat an earlier conclusion that the difference between stabilising global temperatures at an average 1.5C increase and doing so at 2C is massive in terms of the impact on people and nature, and going beyond 2C should be unthinkable. We already know that life on some island nations will be impossible at over 1.5C.
Here in the north-west corner of Europe, we are among the least affected countries so far but the report nonetheless identifies some key risks for us. For people, one is the increasing risk of death and illness caused by heat stress as periods of exceptional hot weather become more common.
For wildlife, increasing land and water temperatures will make species shift about, driving some to extinction, and the areas already vulnerable to wildfires will expand.
The risk of flooding from rivers and the sea will increase, driven by rising sea levels, stronger storms and heavier rainfall. In particular, coastal flood damage is expected to increase tenfold by the end of the century.
There is a chance that rising temperatures might increase agricultural productivity in Scotland but this will be a drop in the ocean compared to the reduced production, driven by rising temperature and increasing water scarcity, in southern Europe and the rest of the globe.
As impacts increase and it becomes impossible to eke out a living in large areas of the world, the number of climate refugees will increase, with the IPCC quoting studies which say around 100 to 150 million people could need a new place to live by 2050.
Its latest report is an impressive but grim read. It is a very major wake-up call that nobody is doing enough on climate and the opportunity to head off the worst impacts is rapidly slipping away.
Dr Richard Dixon is director of Friends of the Earth Scotland