Without significant reductions in emissions, the planet could be on a dangerous “greenhouse trajectory” that would completely solve climate chaos. That’s one of the lessons learned from a new report that found 22 of Earth’s 34 “vital signs” are flashing red, indicating the planet is in crisis.
Earth’s vital signs are markers of the planet’s health, including the concentration of carbon dioxide and methane in the atmosphere, the heat content of the oceans, sea-level fluctuations, and the annual percentage of extremely hot days compared to the 1961-1990 average. Most of these markers will reach record levels in 2024, and 2025 appears likely to follow the same trajectory, according to a report published today (October 29) in the journal BioScience.
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In 2020, Ripple and his colleagues developed the first framework for measuring Earth’s vital signs. Five years later, researchers are warning that the planet has passed a series of tipping points that could push the planet into a self-sustaining greenhouse, a state in which the planet continues to heat significantly even after carbon dioxide emissions have fallen significantly.
The Earth is now 2.2 degrees Celsius (1.2 degrees Celsius) warmer than the average between 1850 and 1900, and unless countries take further climate policy measures (a scenario often referred to as the “cost of inaction”), the planet could reach up to 5.6 degrees Celsius (3.1 degrees Celsius) of warming above pre-industrial levels by 2100. Such a rapid change would mark the turning point of the Holocene, when the Earth entered a period of approx. stability. 11,000 years ago, when the last ice age ended, the scientists wrote in the report.
“Scholars argue that this period of relatively mild climate enabled the development of agriculture, settlement, and the rise of human civilization,” they write. “That stability is now giving way to a period of rapid and dangerous change.”
Rising global temperatures greatly increase the risk of exceeding climate tipping points, such as the collapse of polar ice sheets and the thawing of carbon-rich permafrost. If these systems collapse, both the amount of solar energy Earth can bounce back into space and the amount of carbon it can store will be drastically reduced, locking in further warming and causing further system collapse.
“Crossing one tipping point can lead to a cascade of crossings of other tipping points, destabilizing most of the interactions,” Ripple and colleagues write. “In the worst case scenario, this could send the climate system into a greenhouse Earth orbit, which would lead to a fundamentally different planet with devastating consequences for natural systems and humanity.”
The greenhouse pathway is one of the four most pressing climate risks researchers identified in their report. The remaining three are biodiversity loss. Fresh water will decrease. and a decline in the Atlantic Meridional Overturning Circulation, the ocean current system that brings heat to the Northern Hemisphere.
But of course, this is not the only impact of climate change. “There is [all] “There are a variety of possible impacts of warming, including the collapse of ice sheets, coastal flooding, and increased extreme weather events,” report co-author Michael Mann, Presidential Distinguished Professor and director of Penn’s Center for Science, Sustainability, and Media, told Live Science via email.
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Global warming is proportional to the amount of carbon we emit into the atmosphere. Therefore, to avoid the worst consequences of climate change, “we should focus on rapid decarbonization to stabilize warming below dangerous levels,” Mann said.
“Each year of delays increases risk and cost,” Ripple added. “If we act as if this is a true emergency, we can limit the damage.”
There is still time to act, as impacts have not yet reached uncontrollable levels of warming. And there are reasons to be hopeful. “Some countries have successfully stopped using coal and reduced methane leaks,” Ripple said. (The UK, Ireland, Switzerland, Norway and several other European countries no longer include coal in their electricity mix. The European Union and Nigeria are also making visible progress in reducing methane emissions.)
“Deforestation rates in the Amazon have fallen sharply under new guidance, renewable energy capacity continues to set records, and electric vehicle sales are on the rise,” Ripple added.
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