Extremely high temperature once in 50 years or once every 6 years in the future
The heat wave in Canada, the fire in California, the flood in Germany, and the drought in Brazil are very obvious reminders that mankind is paying an unusually heavy price for extreme weather.
On August 9, local time, the United Nations Intergovernmental Panel on Climate Change (IPCC) released its latest report "Climate Change 2021: Natural Science Foundations" in Geneva.
The report was jointly completed by 234 relevant researchers from 66 countries.
According to the report, due to global warming, extreme high temperatures that occurred only once every 50 years in the past are now expected to occur once every six years, and heavy rains and droughts will also become more frequent.
This is the first time that the IPCC has quantified the possibility of extreme weather and climate events occurring in a warming climate.
alarm
If the global temperature rises by 1.5℃
Extremely high temperature will occur every 6 years
The report shows that climate change has affected all regions of the world and led to many extreme weather and climate events.
As the planet heats up further, heat waves, droughts and heavy rains will only become more frequent and extreme.
John Kerry, the President’s special envoy for climate change, said: “As the Intergovernmental Panel on Climate Change has clearly pointed out, the impact of the climate crisis — from extreme heat to wildfires to heavy rainfall and flooding — will only continue to intensify unless we Choose another path for yourself and future generations."
Scientists emphasize that these effects of climate change have already appeared. For example, the extreme high temperature in the Northwest of the United States in June caused hundreds of deaths, while Brazil is currently experiencing its worst drought in 91 years.
"The heat wave in Canada, the fire in California, the flood in Germany, and the drought in central Brazil are very obvious reminders that humans are paying an unusually heavy price for extreme weather." Paulo Artaxo (Paulo Artaxo) said.
However, the situation in the future will be more severe, and the intensified climate warming means more frequent extreme events.
Compared with all other extreme weather and climate events, the frequency of extreme high temperatures increases as the climate warms.
If it is not controlled, the global warming is expected to reach or even exceed 1.5°C in the next 20 years, then there may be two extreme high temperatures in the previous century, and it will occur approximately once every 6 years in the future; if the global average temperature rises by 4°C , In this scenario, extreme high temperature weather will occur once every one to two years.
Another author of the report, Argentine physical and climate scientist Carolina Vera, pointed out that the possibility of multiple extreme weather happening at the same time is also increasing.
For example, extreme high temperatures, droughts, and high winds are more likely to occur at the same time, and these extreme weather and climate events may contribute to wildfires.
Scientists said that the forecasts of extreme weather and climate events in the report emphasized the importance of controlling climate change to the level stipulated in the Paris Agreement.
The "Paris Agreement" pointed out that all parties will strengthen the global response to the threat of climate change, keep the global average temperature within 2°C from the pre-industrial level, and work hard to control the temperature rise within 1.5°C.
IPCC Chairman Li Huisheng said: "It is undisputed that human activities are causing climate change, making extreme weather more frequent and severe. To limit global warming, we need to forcefully, rapidly and continuously reduce carbon dioxide and other greenhouse gas emissions. ."
evidence
The UN report is clear for the first time
Humans are causing climate change
The IPCC asserted in the strongest terms so far that humans are causing climate change, and wrote in the first line of its report summary: "Human influences have warmed the atmosphere, oceans and land. This is clear." Previously, the IPCC The report of the United States said that climate change is "very likely" caused by industrial activities.
The report pointed out that since the 19th century, humans have obtained energy by burning fossil fuels, causing the global temperature to be 1.1°C higher than the pre-industrial level.
To avoid further global warming, mankind must take drastic actions immediately-including immediately starting to abandon fossil fuels and stopping the emission of carbon dioxide into the atmosphere by around 2050.
This requires concerted efforts of all countries.
The report describes possible future scenarios, saying that if human efforts are effective, the process of global warming is likely to stop, but this depends on the extent of the world's emissions reductions.
But even with the most stringent emission reductions, the global temperature will still be about 1.5°C higher than the pre-industrial level in the next two decades.
According to the “worst scenario” of the IPCC, if countries in the world take almost no measures to reduce emissions, by 2100, the global temperature may be 3℃~6℃ higher than the pre-industrial level. “This will bring catastrophic consequences.”
At the same time, the most optimistic scenario is that if global carbon dioxide emissions drop to zero around 2050, the global warming will slightly fall below 1.5°C in the second half of this century and stabilize at around 1.4°C at the end of this century.
For the world, this will undoubtedly be a huge and expensive undertaking.
It requires a certain degree of political will, which most governments have been unable to do so far.
United Nations Secretary-General Guterres warned: “This report is a red alert to mankind. The alarm bells are deafening and the evidence is irrefutable: the greenhouse gas emissions caused by fossil fuel burning and deforestation are killing our planet and increasing numbers. One billion people are at immediate risk. Global warming is affecting every region on the planet, and many of these changes are becoming irreversible."
"The world is dangerously close to the internationally agreed upper limit that the temperature rise should be controlled within 1.5°C. We face the imminent risk of reaching 1.5°C in the short term. Only by stepping up our efforts and embarking on the most ambitious path can we avoid it. Cross this threshold." Guterres emphasized, "We must act decisively now to save the 1.5 ℃ target."
According to reports, "Climate Change 2021: Natural Science Foundation" is the first research report on climate change released by the IPCC in the past 8 years, and it is also the largest and most important climate change report in history.
The report was completed by 234 scientists from 66 countries in three years and was approved by the governments of 195 countries.
According to the report, this report aims to provide a basis for negotiations for the 26th United Nations Climate Change Conference to be held in Glasgow, England three months later.
Chengdu Commercial Daily-Red Star News reporter Jiang Yijin