Climate change is widespread, rapid and intensifying and some of these trends are now irreversible during our present time frame, according to the Intergovernmental Panel on Climate Change report.
Human-induced climate change is affecting weather and climate extremes in every region across the globe. Scientists are observing changes across the whole of Earth’s climate system – in the atmosphere, oceans, ice floes and on land. Many of these changes are unprecedented and some shifts are in motion now. Other shifts such as continued sea-level rise are already “irreversible” for centuries to millennia, warns the report.
IPCC experts say there is still time to limit climate change. A strong and sustained reduction in the emission of carbon dioxide and other greenhouse gases could quickly make air quality better and in 20 to 30 years, global temperatures could stabilise.
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Responding to the IPCC Work Group I Report, UN secretary-general António Guterres said it was “a code red for humanity. The alarm bells a deafening and the evidence is irrefutable”.
Guterres noted the internationally-agreed threshold of 1.5 degrees above pre-industrial levels of global heating was “perilously close. We are at imminent risk of hitting 1.5 degrees in the near term. The only way to prevent exceeding this threshold is by urgently stepping up our efforts and pursuing the most ambitious path.”
“We must act decisively now, to keep 1.5 alive,” said Guterres.
Human activity has warmed the world’s climate at an unprecedented rate
Reacting to the report, the UN chief said the solutions are clear: “Inclusive and green economies, prosperity, cleaner air and better health are possible for all, if we respond to this crisis with solidarity and courage.”
Guterres added that ahead of the COP26 climate conference in Glasgow in November, all nations – especially G20 economies – need to join the net zero emissions coalition and reinforce their promises to slow down and reverse global heating “with credible, concrete and enhanced Nationally Determined Contributions” that detail exact steps that must be taken.
Prepared by 234 scientists from 66 countries the report highlights that human influence has warmed the world’s climate at a rate unprecedented in the last 2,000 years.
In 2019 alone the atmospheric CO2 concentrations were higher than at any time in the last two million years. Concentrations of methane and nitrous oxide were higher than at any time in the last 800,000 years.
Global surface temperature has increased faster since 1970 than in another 50-year period over the last 2,000 years. Meanwhile, the global mean sea level has risen faster since 1900 than over any preceding century in the last 3,000 years.
The report shows that emissions of greenhouse gases from human activity are responsible for approximately 1.1˚C between 1850-1900. Averaged over the next two decades, global temperature is expected to reach or exceed 1.5˚C of heating.
Improved data collection shows achieving Paris Agreement is impossible on the world’s current path
The IPCC scientists warn global warming of 2˚C will be exceeded during this century. Unless rapid and deep reduction of CO2 and other greenhouse gas emissions occur in the next few decades, achieving the goals of the 2015 Paris Agreement will be impossible. This 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.
IPCC Working Group I co-chair Valérie Masson-Delmotte said it has been clear for decades that the Earth’s climate is changing. “The role of human influence on the climate system is undisputed. 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 IPCC experts reveal that human activities affect all major climate system components, with some responding over decades, others over centuries. Scientists point to evidence of observed changes in extremes such as heatwaves, heavy precipitation, droughts and tropical cyclones. Their attribution to human influence has strengthened.
They add that many changes in the climate system become larger in direct relation to increase global warming. This includes an increase in the frequency and intensity of heat extremes, marine heatwaves and heavy precipitation; agricultural and ecological droughts in some regions; the proportion of intense tropical cyclones; and a reduction in Arctic sea ice, show cover and permafrost.
The report clearly states 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.
Everything is changing right now
The IPCC experts project climate changes in all regions over the coming decades. If the temperature change stays at 1.5˚C of global warming there will be increasing heat waves, longer warm seasons and shorter cold seasons.
At 2˚C global warming, heat extremes are more likely to reach critical tolerance thresholds for agriculture and health. But, it won’t just be about the temperature. Climate change is intensifying the globe’s water cycle. This means more intense rainfall and associate flooding as well as more intense drought in many regions.
This means in high latitudes precipitation will increase, but decrease over large parts of the subtropics. Changes to the monsoon rain pattern will vary by region, the report warns.
Coastal regions will be affected by the continued rising of the sea level throughout the 21st century. This will contribute to more frequent and severe coastal flooding in low-lying areas and coastal erosion. Moreover, sea-level events that used to occur once in a century could happen every year by the end of this century.
The report indicated that further warming will amplify the thawing of permafrost and the loss of seasonal snow cover. Glaciers and ice sheets will melt, as will summer Arctic sea ice. Changes to the ocean (warming, more frequent marine heatwaves, ocean acidification and reduced oxygen levels) will affect ocean ecosystems and the people who rely on them.
Effect of climate change on cities will be even more profound
The IPCC experts warned that some aspects of climate change may be magnified for cities. This includes heat, flooding from heavy precipitation events and the sea-level rise in coastal cities. They caution that low-likelihood outcomes, such as ice sheet collapse or abrupt ocean circulation changes, cannot be ruled out.
IPCC Working Group I co-chair Panmao Zhai: “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 for both health and the climate.”
The report explains that from a physical science perspective, limiting human-induced global warming to a specific level requires limiting cumulative carbon dioxide emissions, reaching at least net-zero CO2 emissions, along with strong reductions in other greenhouse gas emissions.
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Inger Andersen, executive director of the UN Environment Programme (UNEP) suggests multiple, recent climate disasters including devastating flooding in central China and western Europe have focused public attention as never before.
“As citizens and business and governments, we are well aware of the drama. The drama exists, we have seen it and we heard about it in every news bulletin. And, that’s why we need to understand, that the expression of what the science says is exhibited before our very eyes, and of course what this excellent report does is, it projects those scenarios outwards and tells us, if we do not take action what could be the potential outcomes. Or, if we do take action, what will be a very good outcome,” she said.
WMO chief Peteri Taalas pointed out the need to move from climate mitigation to paying attention to climate adaptation. “Since the negative trend in climate will continue for decades and in some cases for thousands of years.”
“One powerful way to adapt is to invest in early warnings, climate and water services. Only half of the 193 members of the WMO have such services in place, which means more human and economic losses. We have also severe gaps in weather and hydrological observing networks in Africa, some parts of Latin America and in Pacific and Caribbean island states, which has a major negative impact on the accuracy of weather forecasts in those areas, but also worldwide.
“The message of the IPCC report is crystal clear. We have to raise the ambition level of mitigation,” said Taalas.
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Change is required on all fronts
Responding to the release of the report, Kate Williams, CEO of 1% for the Planet said the report sheds stark light on the challenges and urgency of the climate crisis and its impact on our lives, communities and planet.
“As citizens of a global community, we have no choice but to channel this news to positive action. From the daily decisions to issues and actions that we support and engage in on the largest scale, each of us must join this call to confront the devastating reality of climate change.
“Collective action is at the core of our model and we’re committed to driving positive change, together, so that our planet and future generations can thrive. Taking immediate action is not a choice. It is our only chance to confront the devastating realities of climate change and avoid irreversible damage,” said Williams.
You can inspect the IPCC Working Group I: Sixth Assessment Report online.