Human-induced climate change is already affecting many weather and climate extremes in every region around the world. Scientists also monitor changes throughout the Earth’s climate system; In the atmosphere, oceans, floating ice and on land.
Many of these changes are unprecedented, some transformations are now underway, while some – such as the continuous rise in sea level – are already “irreversible” for centuries to millennia, BeforeAnd The report warns.
But there is still time to curb climate change, IPCC Experts say. Strong and sustained reductions in emissions of carbon dioxide and other greenhouse gases could rapidly improve air quality, and global temperatures could stabilize in 20 to 30 years.
The red symbol of humanity
United nations Secretary-General António Guterres He said the working group’s report was nothing less than “a red symbol for humanity. The alarm bells are deafening, and the evidence is irrefutable.”
He noted that the internationally agreed minimum of 1.5 degrees above pre-industrial levels of global warming was “dangerously close. We are in imminent danger of reaching 1.5 degrees in the near term. The only way to prevent this threshold from being exceeded, is to urgently intensify. Our efforts and continue the most ambitious path.
“We must act decisively now, to keep 1.5 alive.”
In a detailed response to the report, the UN Secretary-General said the solutions were clear. “Inclusive and green economies, prosperity, clean air and better health are possible for all if we respond to this crisis with solidarity and courage,” he said.
He added that ahead of the crucial COP26 climate conference in Glasgow in November, all countries – especially the advanced G-20 economies – needed to join in net-zero carbon emissions, and reinforce their promises to slow and reverse global warming, with “concrete credibility,” and enhanced NDCs ( NDCs)” that outline the detailed steps.
The report, compiled by 234 scientists from 66 countries, highlights that human influence has warmed the climate at an unprecedented rate in at least the last 2,000 years.
In 2019, atmospheric carbon dioxide concentrations were higher than ever before In at least 2 million yearsand methane and nitrous oxide concentrations were higher than at any time in the past 800,000 years.
The Earth’s surface temperature has increased faster since 1970 than in any other period of at least 50 years past 2000 years. For example, temperatures during the last decade (2011-2020) exceeded temperatures in the most recent warm period by several centuries, About 6500 years ago, the report indicates.
Meanwhile, global mean sea level has risen faster since 1900, than in any previous century In the last 3000 years at least.
The document shows that greenhouse gas emissions from human activities are responsible for about 1.1°C of warming between 1850-1900, and finds that, on average over the next 20 years, global temperature is expected to reach or exceed 1.5°C.
Unsplash / Roxanne Desgagnés
time is running out
Intergovernmental Panel on Climate Change scientists warn that global warming of 2 degrees Celsius will be exceeded during the 21st century. Unless there are rapid and deep cuts in emissions of carbon dioxide and other greenhouse gases in the coming decades, to achieve the 2015 targets. Paris Agreement “It would be unattainable.”
The assessment builds on improved data on historical warming, as well as advances in scientific understanding of the climate system’s response to human-caused emissions.
“It has been clear for decades that the Earth’s climate is changing, and the role of human influence in the climate system is indisputable,” said Valerie Mason Delmott, co-chair of IPCC Working Group I. “However, the new report also reflects key developments in attribution science – understanding the role of climate change in intensifying specific weather and climate phenomena.”
Experts reveal that human activities affect all major components of the climate system, with some responding over decades and others over centuries.
Scientists also point out that evidence for observed changes in extreme phenomena such as heat waves, heavy rains, droughts, and tropical cyclones, and their attribution to human influence, has been strengthened.
They add that many changes in the climate system are becoming larger in their direct relationship to increased global warming.
This includes increases in the frequency and intensity of temperature extremes, marine heat waves, and heavy precipitation; agricultural and environmental drought in some areas; the proportion of severe tropical cyclones; As well as declining Arctic sea ice, snow cover and permafrost.
The report states that while natural drivers will modulate human-caused changes, particularly at regional and near-term levels, they will have little effect on global warming in the long-term.
Unsplash / Maxim Tolchinsky
A century of change everywhere
Experts from the Intergovernmental Panel on Climate Change (IPCC) expect climate change to increase in the coming decades in all regions. For global warming of 1.5°C, there will be an increase in heat waves, longer warm seasons and shorter cold seasons.
At temperatures of 2°C of global warming, extreme temperatures are likely to reach critical tolerance thresholds for agriculture and health.
But it’s not just about the temperature. For example, climate change intensifies the natural production of water – the water cycle. This leads to torrential rains and associated flooding, as well as exacerbating drought in many areas.
It also affects precipitation patterns. At higher latitudes, precipitation is likely to increase, while it is expected to decrease in large parts of the subtropics. The report warns that changes in monsoon rain patterns are expected, which will vary by region.
Moreover, coastal areas will experience continuous sea level rise throughout the 21st century, contributing to frequent and severe coastal flooding in low-lying areas and coastal erosion.
Previous extreme sea level events An event every 100 years could happen every year by the end of this century.
The report also notes that further warming will amplify thawing of permafrost, loss of seasonal snow cover, melting of glaciers and ice sheets, and loss of Arctic sea ice in summer.
Changes in the oceans, including warming, more frequent marine heat waves, ocean acidification, and decreased oxygen levels, are affecting both ocean ecosystems and the people who depend on them, and will continue for at least the rest of this century.
swelled in cities
Experts warn that for cities, some aspects of climate change may be amplified, including heat and flooding from heavy rainfall events and sea level rise in coastal cities.
Moreover, IPCC scientists warn that low-probability outcomes, such as ice sheet collapse or abrupt changes in ocean circulation, cannot be ruled out.
mitigating climate change
“Climate stabilization will require robust, rapid and sustainable reductions in greenhouse gas emissions, and net zero carbon dioxide emissions. Reducing greenhouse gases and other air pollutants, especially methane, can have health and climate benefits,”
The report states that from a physical sciences perspective, limiting human-caused global warming to a certain level requires reducing cumulative CO2 emissions, and reaching at least net CO2 emissions, along with strong reductions in other greenhouse gas emissions.
The IPCC scientists assert that “strong, rapid and sustainable reductions in methane emissions will also limit the warming effect from reduced aerosol pollution.”
UNICEF / Sukhin
The Intergovernmental Panel on Climate Change (IPCC) is the United Nations body for assessing the sciences related to climate change. It was created by the United Nations Environment Program (United Nations Environment Programand the World Meteorological Organizationsocial support law) in 1988 to provide political leaders with periodic scientific assessments of climate change and its impacts and risks, as well as put forward strategies for adaptation and mitigation.
That same year, the United Nations General Assembly endorsed the action taken by the World Meteorological Organization and the United Nations Environment Program in jointly establishing the Intergovernmental Panel on Climate Change. It has 195 member states.
Thousands of people from all over the world contribute to the work of the Intergovernmental Panel on Climate Change. For assessment reports, IPCC scientists volunteer their time to evaluate thousands of scientific papers published each year to provide a comprehensive summary of what is known about the drivers of climate change, its future impacts and risks, and how adaptation and mitigation can reduce risks.