This Monday’s report from the United Nations Intergovernmental Panel on Climate Change (IPCC) represents the most complete and conclusive “state of the science” on the climate crisis: why it is happening, how it is affecting all regions of the planet, how much worse things are and what must be done to avoid the worst consequences.
UN Secretary General António Guterres called the report “a code red for humanity.” He noted that “global warming is affecting all regions of the Earth, and many of the changes are becoming irreversible”.
The report is around 3,500 pages long, represents years of research on the subject, was written by more than 200 scientists from more than 60 countries, and cites more than 14,000 individual studies.
Humans are unequivocally warming the planet
This report goes further than any previous IPCC weather report by attributing the blame for global warming directly to greenhouse gas emissions from humans. It is no longer about “natural or man-made” climate change. Society’s dependence on fossil fuels is the reason why the planet has already warmed 1.2 degrees Celsius. All through the emission of greenhouse gases such as carbon dioxide and methane.
Warming is happening even faster than scientists previously thought. The most recent projections tell us that we will reach or exceed 1.5 degrees (a key threshold that scientists say is critical to stay below), within the next decade or two.
The only way to stop warming is to cut greenhouse gas emissions – the longer it takes, the hotter it gets
Just as the report clearly blames carbon pollution for rising temperatures, it is also clear that the only way to slow down and eventually reverse warming is to cut greenhouse gas emissions to zero.
Avoiding 1.5 degrees of heating is almost impossible. However, we can still keep warming around that critical threshold and avoid worsening the shocks that come from moving closer to and exceeding 2 degrees of warming.
Avoiding those impacts will require significant cuts in greenhouse gas emissions immediately. If emissions continue to rise, the world will exceed 2 degrees of warming, possibly before 2050, and will reach 3 degrees before the end of the century.
The impacts of climate change are severe in all regions of the planet and will worsen with every fraction of a degree of warming
Here are some specific impacts and what the report has to say about them.
Heat waves: Extreme heat waves, like the deadly one that occurred in the Pacific Northwest and Canada earlier this summer, are already about five times more likely to occur with our current warming of just over 1 degree Celsius. With a 2 degree warming, this frequency increases to 14 times the probability of occurring. Heat waves are getting hotter. With 2 degrees of warming, the highest temperatures would reach almost 3 degrees Celsius higher than previous heat waves.
Drought: Climate change is increasing the frequency and severity of droughts, like the one currently hitting the western United States. Severe droughts that used to occur on average once a decade now occur 70% more often. If warming continues at 2 degrees, these droughts will occur two to three times more often.
Floods: Climate change is intensifying the water cycle on both sides. While more intense evaporation will lead to more droughts, warmer air can hold more water vapor to produce extreme rainfall (as we’ve seen dramatically in Western Europe and China this summer). On average, the frequency of heavy downpours has already increased by about 30% and they contain about 7% more water.
Hurricanes: They are getting stronger and producing more rain as global temperatures rise. It has already been observed that, globally, a higher percentage of storms are reaching the highest categories (categories 3, 4 and 5) in recent decades. This is expected to continue as temperatures rise.
Rising sea levels: Sea level is rising around the world and the rate is increasing. This is making the high tide flooding and storm surge worse. By 2100, coastal flooding that occurred once in a century will occur at least once a year on more than half of the world’s coasts, according to the report.
Weather “whiplash”: Climate change is not only increasing the severity of extreme weather, it is disrupting natural patterns. That leads to a “weather lash”: wild swings between wet and dry extremes. This has been experienced recently in California, with “atmospheric rivers” causing destructive flooding one year and extreme droughts causing water shortages the next.
Some changes are irreversible, even in the lowest emission scenarios
The warming that has already occurred has caused changes that will persist even if emissions stop and temperatures stabilize.
Ice sheets will continue to melt for hundreds to thousands of years, according to the report. That will cause the sea level to rise well beyond 2100 and stay higher for millennia.
Sea level is expected to rise 2 to 3 meters by 2300, even if warming remains below 2 degrees. But it could reach 5 to 7 meters or more if warming continues unabated.
Atmospheric methane is skyrocketing
This report points to another villain in the climate crisis, methane. It is an invisible gas that contains more than 80 times the power of carbon dioxide to warm the planet in the short term.
The most recent data shows that methane in the atmosphere is skyrocketing and is currently the highest in 800,000 years. In large part due to a combination of natural gas leaks and unsustainable agriculture and livestock.
Considering its enormous warming potential and its shorter life in the atmosphere compared to carbon dioxide, controlling methane could significantly reduce global warming in the coming decades.
The IPCC reports, while long on the science and exhaustive in scope and detail, contain very little to suggest policies to remedy the climate crisis. This report, for example, is purely scientific facts and forecasts for the future.
The main IPCC reports to be released next year will elaborate on the specific impacts and ways to mitigate them. Before that, world leaders will meet at a UN-led climate conference in November. It is billed as the most important climate policy meeting since the Paris Agreement that was signed in 2015.
“As today’s report makes clear, there is no time for delays and no room for excuses,” declared the UN Secretary General on Monday morning. Meanwhile, he implored government leaders to ensure that COP26 is a success to “avoid a climate catastrophe”.