Scientists have long used the concept of a tipping point to measure the state of the planet in light of climate change. A tipping point is a "critical threshold in a system beyond which change becomes self-perpetuating, leading to substantial, widespread, frequently abrupt and often irreversible impacts," said the Potsdam Institute for Climate Impact Research's 2024 Planetary Health Check. However, others believe the use of tipping points is "oversimplifying the diverse dynamics of complex natural and human systems," and "conveying urgency without fostering a meaningful basis for climate action," said a perspective piece in the journal Nature Climate Change. Some tipping points are more likely than others, and many are "shrouded in uncertainty," said ClimateWire. "In other words, scientists don't know how close we are to toppling them." Every small amount of environmental and climate change has an effect, not just those that exceed a tipping point threshold.
Mountain glaciers melting:The world's glaciers are "melting at double the speed they had in the past two decades," the U.N. report said. Many of those glaciers are in the mountains, including the Andes and Himalayas. As a result, "downstream communities become increasingly vulnerable to disasters like floods," said Yale Environment Review. Plus, "when glaciers eventually shrink, water unavailability presents another problem." Many glacier-fed areas are rapidly approaching or have already reached "peak water," the point of maximum meltwater a glacier produces before its freshwater output steadily declines. Meltwater is crucial to sustaining certain regions during dry seasons with low rainfall.
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Ice sheets collapsing: The Greenland ice sheet and the Antarctic ice sheet, the two largest in the world, are on the brink of collapsing. According to NASA, Antarctica is losing ice mass of about 50 billion tons per year, and Greenland is losing about 270 billion tons per year. "Substantial ice loss is likely irreversible on multi-millennial timescales," said the University of Exeter report. In addition, ice sheets collapsing "would result in severe regional impacts, including significant contributions to sea level rise and destabilization of local infrastructure and water supplies," said the Planetary Health Check.
Biosphere tipping points
Accelerating extinctions: The planet is in its sixth mass extinction event. A new study found that more than 3,000 species of terrestrial vertebrates are currently threatened with extinction because of natural disasters, which are worsening due to climate change. In addition, "human activities such as land use change, overexploitation, climate change, pollution and introduction of invasive species," have "put our foot on the extinction accelerator," the University of Exeter report said. The Amazon rainforest and other rainforests are particularly at risk, suffering not only from human influence but also "unprecedented climate-driven disturbances such as increasing dry season length and intensity, more intense and frequent rainfall and temperature extremes," said the report.
Dying coral reefs: Coral reefs are largely in danger due to climate change. Warming oceans are disrupting the delicate aquatic ecosystem causing bleaching, which is when "thermal stress causes corals to expel the symbiotic algae that provides them with food (resulting in a characteristic loss of color)," said the University of Exeter report. According to the IUCN Red List of Threatened Species, 44% of coral reefs globally are at risk of extinction. "Without relevant decisions from those with the power to change this trajectory, we will see the further loss of reefs, and progressive disappearance of coral species at larger and larger scales," said David Obura, the co-chair of the International Union for Conservation of Nature (IUCN) SSC Coral Specialist Group. Coral reefs also hold a quarter of all marine life on Earth and their collapse could drastically alter the ecosystem.
Uninsurable future: The combination of the aforementioned tipping points means more places on Earth are becoming uninhabitable — and uninsurable. "Insurance companies are refusing to cover properties because they're located in severe weather zones or because the housing stock is old," said Fortune. "And banks won't give you a mortgage because of the same risk." There has been a seven-fold increase in the amount of damage from natural disasters since the 1970s. Once home insurance becomes too expensive or unavailable, "people are left without an economic safety net when disasters strike," the Interconnected Disaster Risks report said. This shift is a "flashing red light for an American economy that is built on real property," said The New York Times. "With fewer buyers, real estate values are likely to decline, along with property tax revenues, leaving communities with less money for schools, police and other basic services."
Groundwater depletion: Much of the world's drinking water comes from underground reservoirs called aquifers. The bad news is that these aquifers are rapidly emptying, with 21 of the 37 largest aquifers losing water faster than they can be replenished. The water in the aquifers "has accumulated over thousands of years, and would equally take thousands of years to fully recharge," the U.N. report said, so these crucial reservoirs are "essentially a non-renewable resource." Approximately 2 billion people worldwide rely on groundwater as a primary source of drinking water, but most groundwater is used in agriculture. "We can no longer consider groundwater as a boundless source of easily accessible freshwater," the report added. And its increasing inaccessibility has "worrying implications."
Ocean and atmospheric tipping points
Unbearable heat: November 2024 was the second hottest November on record and scientists are predicting that 2024 will be the hottest year ever measured, according to a study by Copernicus. Along with its toll on humans, heat exacerbates a number of other ecological problems, including melting glaciers, extreme storms and extinctions. As temperatures rise even higher, the heat's impact will get more extreme and harder to reverse.
Changing ocean currents: The extreme heat has also caused a meteoric rise in ocean temperatures which can lead to a shift in ocean currents. The Atlantic Meridional Overturning Circulation (AMOC) is at risk of being disrupted as soon as the 2030s, according to one study, because the "surface waters in the northern North Atlantic may become less dense," said the University of Exeter report. Cold water is denser than warm water and the current works through different water temperatures rising and sinking. The current is crucial to maintain the climates of western and northern Europe.
Ocean deoxygenation: A new study published in the journal Nature Ecology & Evolution found that "lakes and reservoirs have experienced oxygen losses of 5.5% and 18.6% respectively in the past 45 years, and the oceans have dropped by 2%," said Popular Mechanics. While not previously considered a tipping point, scientists argue that it should be. Deoxygenated water can be detrimental to marine populations, leading to mass extinctions. It stems from warming temperatures, along with human factors like fertilizer runoff. "Failure to address aquatic deoxygenation will, ultimately, not only affect ecosystems but also economic activity, and society at a global level," said the lead author of the study, Kevin Rose, in a press release.
Ocean acidification: The ocean is taking more hits than some other places on Earth. The big blue is also experiencing acidification, which is when the ocean becomes more acidic as a result of absorbing too much carbon dioxide. "Ocean acidification is approaching a critical threshold … particularly in high-latitude regions like the Arctic and Southern Ocean," said the Planetary Health Check. "These areas are vital for the marine carbon pump and global nutrient cycles, which support marine productivity, biodiversity and global fisheries." However, a larger problem is that "even these current conditions may already be problematic for a variety of marine organisms, suggesting a need [to] re-evaluate which levels can actually be called safe," Levke Caesar, a co-author of the report, said to The Guardian.
Space debris: The tipping points also extend to space, where floating detritus threatens both current satellites and our ability to put new ones into orbit. Satellites are crucial to our daily lives, assisting in everything from weather reporting and tracking natural disasters to navigating and communicating. "Each piece of debris becomes an obstacle in the orbital 'highway,' making it increasingly difficult for functional satellites to avoid collisions," the U.N. report said. In a positive twist, Japanese scientists have created the world's first wooden satellite, which will "test the idea of using biodegradable materials such as wood to see if they can act as environmentally friendly alternatives to the metals from which all satellites are currently constructed," said The Guardian. Wood can also burn up upon reentry to Earth and prevent debris.
Devika Rao has worked as a staff writer at The Week since 2022, covering science, the environment, climate and business. She previously worked as a policy associate for a nonprofit organization advocating for environmental action from a business perspective.
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