IPCC report: Time for global leaders to respond

A look at the science of the Intergovernmental Panel on Climate Change (IPCC), and the broader impact.

By Tricia Curmi

Dr Emily Shuckburgh is Director of Cambridge Zero​​​​​​​ at the University of Cambridge and Reader in Environmental Data Science at the Department of Computer Science and Technology.


As the report of the first working group of the sixth assessment of the Intergovernmental Panel on Climate Change (IPCC) is published: what is the broader context into which the updated scientific evidence base will land?

Climate change has accelerated despite scientific warnings

The composition of today’s atmosphere really is unprecedented throughout all of human history, pre-history and beyond. The pace of human influence on the atmosphere is deeply alarming. In 1910, atmospheric carbon dioxide levels were 300 parts per million (ppm), 80 years later in 1990 they had risen substantially to surpass 350 ppm.

In 1992, concerned by the potential impacts of this change, nations agreed to reduce greenhouse gas emissions to avoid dangerous climate change. The United Nations Framework Convention on Climate Change (UNFCCC) was born. Yet less than 25 years later, in 2015 carbon dioxide emissions had reached 400 ppm. Today in 2021, they have already passed 415 ppm, and are edging towards 420 ppm.

Current global temperature at 1.2°C above pre-industrial levels

And the changing atmospheric composition means that in 2020, global temperatures exceeded 1.2°C above pre-industrial values.

Back in 1995, the second assessment report of the IPCC noted a discernible human influence on global climate. Each report since has been bolder in this statement.


Global atmospheric CO2 concentrations from 1700 to 2021. Credit: Met Office.

The Paris Agreement: commitment to 1.5C

In response, in 2015 nations came together in Paris to agree to keep global temperatures well below 2°C of warming, with an ambition to keep them below 1.5°C.

National emission reduction pledges are not currently on-track to achieve this goal. Estimates indicate that, if pledges are enacted, temperatures may rise by more than 2.5°C.

Additionally, current policies (as opposed to pledges) are likely to lead to more like 3°C of warming this century. If the worst impacts of climate change are to be avoided, quite simply, nations need to do more.

Evidence of extreme weather events

Around the world we are now seeing the devastating effect that climate change can have on lives and livelihoods as floods and wildfires ravage communities and heatwaves result in hundreds of thousands of deaths annually.

There are now hundreds of examples of extreme weather events that have occurred in recent years for which the risk of occurrence has increased as a consequence of the climate change we have already experienced.

Climate change was once tomorrow’s problem, now it is very much today’s. And every fraction of a degree of additional warming will make that problem substantially worse – for human, for society, and for the natural world.

Findings from the 2018 IPCC special report

As highlighted in 2018 in the IPCC special report, there are real concerns that if we do not keep temperatures below 1.5°C we may pass the point of no return for treasured ecosystems such as coral reefs, or for the vast ice sheets covering Greenland and West Antarctica that hold many metres of potential sea level rise.

What needs to happen to keep 1.5° alive?

As we approach COP26, the 26th meeting of the signatories to the UNFCCC, it is clear that immediate action is needed by governments to dramatically step-up the global response. The next ten years are critical.

To have a reasonable chance of limiting temperature rise to 1.5°C:

  • global emissions need to be halved this decade
  • emissions need to hit net zero by around the middle of the century.

This is not impossible, but it will require strong and determined leadership. And emissions reductions must be accompanied by a greater emphasis on adaptation, especially if the most vulnerable are to be supported in withstanding the impacts of climate change that they will inevitably face in the coming years and decades.

Evidence of economic benefits of green recovery

Fortunately, at a time in which the coronavirus pandemic has put so much pressure on global economies, there is ample evidence that green recovery measures can deliver strong economic multipliers.

Indeed, it is estimated that each percentage point of GDP spent on investment can be expected to increase GDP ultimately by around 2 to 3 percent. Investment in a green recovery could support an estimated 1.7m new jobs in the UK alone by 2035 and would deliver assets and infrastructure that are fundamentally more resilient.

Climate change poses a huge global challenge, but also an immense opportunity. Already, the last decade has seen an 80% reduction in key renewable costs such as solar PV and battery storage, with strong evidence of spill-overs into other parts of the economy.

With 940 million people still having no access to electricity globally and three billion having no clean fuel for cooking, the potential for a clean energy transition is vast. Across all sectors of the global economy there are innumerable opportunities to unleash creative solutions.

With determination and focus, an exciting future could await, fuelled not by fossil carbon but by technological innovation, support for nature and the services it provides, and by each and every global citizen leading more sustainable lives.

The IPCC reports lay out in stark terms the scale and the urgency of the climate challenge. Global leaders must respond at COP26 with vigour to embrace the opportunities. This may be the last chance to secure a multigenerational legacy we can be proud of.


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