Commenting on the latest report by the UN Intergovernmental Panel on Climate Change (IPCC), UN Secretary-General António Guterres has declared it as nothing less than a ‘code red for humanity. The alarm bells are deafening, and the evidence is irrefutable’.
The report, prepared by 234 scientists from 66 countries, highlights that human influence has warmed the climate at a rate unprecedented in at least the last 2000 years.
Unless rapid and deep reductions in CO2 and other greenhouse gas emissions occur in the coming decades, IPCC scientists warn that achieving the goals of the 2015 Paris Agreement ‘will be beyond reach’. Global warming of 2°C will be exceeded during the 21st century. The assessment is based on improved data on historical warming, as well as progress in scientific understanding of the response of the climate system to human-caused emissions.
‘It has been clear for decades that the Earth’s climate is changing, and the role of human influence on the climate system is undisputed,’ said IPCC Working Group I Co-Chair, Valérie Masson-Delmotte. ‘Yet the new report also reflects major advances in the science of attribution – understanding the role of climate change in intensifying specific weather and climate events.’
The experts reveal that human activities affect all major climate system components, with some responding over decades and others over centuries.
The report makes clear that while natural drivers will modulate human-caused changes, especially at regional levels and in the near term, they will have little effect on long-term global warming.
The IPCC experts project that in the coming decades climate changes will increase in all regions. For 1.5°C of global warming, there will be increasing heat waves, longer warm seasons and shorter cold seasons. At 2°C of global warming, heat extremes are more likely to reach critical tolerance thresholds for agriculture and health.
But it won’t be just about temperature. For example, the report says climate change is intensifying the natural production of water – the water cycle. This brings more intense rainfall and associated flooding, as well as more intense drought in many regions. It is also affecting rainfall patterns. In high latitudes, precipitation is likely to increase, while it is projected to decrease over large parts of the subtropics. Changes to monsoon rain patterns are expected, which will vary by region, the report warns.
Moreover, coastal areas are predicted to see continued sea level rise throughout the 21st century, contributing to more frequent and severe coastal flooding in low-lying areas and coastal erosion. Extreme sea level events that previously occurred once in 100 years could happen every year by the end of this century.
The report also indicates that further warming will amplify permafrost thawing, and the loss of seasonal snow cover, melting of glaciers and ice sheets, and loss of summer Arctic Sea ice. Changes to the oceans, including warming, more frequent marine heatwaves, acidification and reduced oxygen levels, affect both ocean ecosystems and the people who rely on them, and they will continue throughout at least the rest of this century.
For cities, some aspects of climate change may be magnified, including heat, flooding from heavy precipitation events and sea level rise in coastal areas, the experts warn.
Furthermore, IPCC scientists caution that low-likelihood outcomes, such as ice sheet collapse or abrupt ocean circulation changes, cannot be ruled out.
‘Stabilising the climate will require strong, rapid, and sustained reductions in greenhouse gas emissions, and reaching net zero CO2 emissions. Limiting other greenhouse gases and air pollutants, especially methane, could have benefits both for health and the climate,’ says IPCC Working Group I Co-Chair Panmao Zhai.
Publication of the report comes as world leaders will gather in Glasgow for the 26th UN Climate Change Conference of the Parties (COP26). For nearly three decades, the UN has been bringing together almost every country on earth for the COP global climate summits. In that time climate change has gone from being a fringe issue to a global priority. Most experts believe COP26 has a unique urgency.
In the run up to COP26, as conference President, the UK with its partners in Italy has been working with almost every nation to reach agreement on how to tackle climate change. More than 190 world leaders are expected to arrive in Scotland. Joining them will be tens of thousands of negotiators, government representatives, businesses and citizens for 12 days of talks beginning on 31 October 2021.
The commitments laid out at the last meeting in Paris (COP25) in 2015 did not come close to limiting global warming to 1.5°C, and most observers agree the window for achieving this is closing. Countries must go much further than they did even at that summit to keep the hope of holding temperature rises to 1.5°C alive. COP26 therefore needs to be decisive, if the predictions in the IPCC report are to be avoided.