What is the IPCC climate change report – and what does it say?

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Photograph: Idrees Mohammed/EPA

What is the IPCC?

The Intergovernmental Panel on Climate Change is made up of the world’s leading climate scientists, charged with publishing regular comprehensive updates of global knowledge on the climate crisis, intended to inform government policymaking. Each “assessment report” takes about five to seven years to complete, involving hundreds of scientists reviewing the work of thousands more experts. The current report – being published in four parts, from August 2021 to October 2022 – is the sixth since the body was set up in 1988.

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What are the four parts?

The three working groups that make up the IPCC each publish their own reports. The first looks at the physical basis of climate science – that is, how the chemistry and physics of the atmosphere are changing and are likely to change in future, and whether human influence is responsible. The second – the group producing the latest report – assesses the effects of climate change, such as extreme weather, droughts, floods and temperature rises, and how humanity can adapt to these.

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The third group looks at ways of cutting emissions, and the fourth report is a synthesis, to be published in October, ahead of the Cop27 UN climate summit, to be held in Egypt in November.

What does the report say?

The warnings make for grim reading.

3.5 billion people are highly vulnerable to climate impacts and half the world’s population suffers severe water shortages at some point each year. One in three people are exposed to deadly heat stress, and this is projected to increase to 50% to 75% by the end of the century.

Half a million more people are at risk of serious flooding every year, and a billion living on coasts will be exposed by 2050. Rising temperatures and rainfall are increasing the spread of diseases in people, such as dengue fever, and in crops, livestock and wildlife.

Even if the world keeps heating below 1.6C by 2100 – and we are already at 1.1C – then 8% of today’s farmland will become climatically unsuitable, just after the global population has peaked above 9 billion. Severe stunting could affect 1 million children in Africa alone. If global heating continues and little adaptation is put in place, 183 million more people are projected to go hungry by 2050.

The ability to produce food relies on the water, soils and pollination provided by a healthy natural world, and the report said protection of wild places and wildlife is fundamental to coping with the climate crisis. But animals and plants are being exposed to climatic conditions not experienced for tens of thousands of years. Half of the studied species have already been forced to move and many face extinction.

Maintaining the resilience of nature at a global scale depends on the conservation of 30% to 50% of Earth’s land, freshwater and oceans, the IPCC report said. Today, less than 15% of land, 21% of freshwater and 8% of oceans are protected areas, and some regions, like the Amazon, have switched from storing carbon to emitting it.

What role do governments play?

IPCC reports run to thousands of pages, incorporating data from years of research. But the key document that emerges at the end of the process is a distillation of all this knowledge known as the summary for policymakers, which contains the key messages. It is pored over line by line by the lead scientific authors but also by representatives from governments, a process open to all states who want to contribute. Critics say this process waters down key messages; defenders say the scientists take a robust line and few significant changes are made.

Will governments try to water down this report?

This second part of the report is likely to be the most politically sensitive, because it deals with the probable real world impact of the climate crisis, including issues such as the potential for food shortages. One of the most contentious issues is over how the world adapts to the climate crisis and the question of “loss and damage” – the impacts of the climate crisis that are too great for countries to adapt to.

This issue has dogged the United Nations Framework Convention on Climate Change (UNFCCC) climate negotiations for more than a decade, and at the Cop26 climate summit in Glasgow last year many countries were disappointed that rich nations failed to agree a programme to issue funding to poor countries for the loss and damage they sustain.

Concerns have already been raised by some campaigners that “loss and damage” has been changed to “losses and damages”, but analysts say this change is minor and does not change the substance of the findings. The substantive issue will be what the report says about adaptation and the global need to adapt to extreme weather that, as the first IPCC working group found in August, is becoming inevitable.