Reflections on the Latest IPCC reports

Dr Mike Morecroft

Over the last 3 years, a sizeable chunk of my working (and non-working!) life has been given over to the Intergovernmental Panel on Climate Change’s latest Assessment Report.  This comes in three parts, each produced by a separate working group.  The first is all about the physical climate science and was published last summer.  This was followed by ‘Impacts, Adaptation and Vulnerability’, which I worked on, at the end of February, and ‘Mitigation’ (emission reductions and mechanisms to take greenhouse gases out of the atmosphere) in April.

Each of these reports are vast documents, produced by hundreds of expert authors from around the world and thoroughly reviewed by academic and government experts.  Having seen the process from the inside, I know how extraordinarily rigorous it is.  We have a very strong evidence base, not just on the physics of climate change and the seriousness of its impacts, but also on how we can address climate change.  The science of adaptation and mitigation has strengthened significantly since the last round of IPCC reports.

An important aspect of our Working Group 2 report is assessing what impacts climate change is already having on people and nature.  The evidence of these impacts has grown substantially in the last decade, as has the confidence that climate change is indeed the cause.  Examples include increased heat-related human deaths, coral bleaching, tree mortality, and increased areas burned by wildfires.  There is clear evidence that three species have become globally extinct, as a result of climate change and there have been numerous local extinctions (extirpations) of species.  Around half of the human population is already highly vulnerable to climate change and going forward the risks increase with every fraction of a degree of global warming.  Rising sea levels and more extreme storms increase the risks of flooding, whilst droughts and receding glaciers reduce water supplies.

It is a worrying picture, but it is not too late to avoid the worst impacts.  There are actions that we can take to adapt to climate change, to lower risks.  I have a particular interest in how protecting and restoring ecosystems can reduce climatic risks to people and nature.  Healthy ecosystems can buffer the effects of rising sea levels and floodwaters and green spaces and trees in cities can provide cool and shady places to make urban life more liveable.  People can also adapt in a wide range of other ways, including by designing settlements and infrastructure to be more robust to climatic risks, and tackling poverty and inequality helps to build the resilience of communities.

Adaptation is essential but it has its limits and the need for urgent emission reductions is clearer than ever.  The nations of the world agreed at Paris in 2015 to hold global temperature rise to well below 2ºC and pursue efforts to limit it to 1.5ºC.  Working Group 3 found that holding global temperature to 1.5ºC was still possible, but extremely challenging and it will require the removal of greenhouse gases from the atmosphere, as well as halting emissions as quickly as we can.

The IPCC is commissioned by the governments of the world and reports to them.  It identifies problems, sets out options for dealing with them, and provides the evidence for decision making, but it is for those governments to make those decisions and take action.  Governments however cannot act on their own – they will need to work with local communities, civil society, and businesses if adaptation and mitigation are to be effective.  We can all play our part not just by reducing our own carbon footprints and doing what we can to lower vulnerability to climate change but also by building awareness and knowledge in our communities.  One thing stands out across the IPCC reports, we need to see a step-change in action on climate change within the next decade: there is no time to lose.

Dr Mike Morecroft is the President of JRI

Image: New York, USA – 18 March 2021: Intergovernmental Panel on Climate Change ipcc company logo icon on website. Shutterstock Stock Photo ID: 1948086988