A new report indicates that the world could be on the brink of passing a series of vital climate “tipping points,” any one of which could severely damage the environment and threaten global stability. The report, assembled by scientists in the U.K. and Europe, shows that the world is dangerously close to several potentially disastrous changes.
While climate mediation strategies are generally aimed at addressing issues that feature incremental change, such as the level of carbon dioxide in the atmosphere or the average mean temperature, these harmful tipping points are events that don’t transition gradually but could generate abrupt and lasting change. Examples include the collapse of the ice sheet in Greenland or the failure of the North Atlantic current. Addressing these individual threats may require specific actions in addition to the more general effort to reduce greenhouse gases.
The report, which was led by the University of Exeter, identifies more than 25 potential tipping points, some of which are interconnected. Triggering one harmful tipping point could create “a domino effect of accelerating and unmanageable change to our life-support systems,” according to the report’s authors. Right now, five of these points are already at risk of tipping.
The tipping points under study don’t shift smoothly or gradually. This isn’t a matter of a modest increase in heat waves from one summer to the next or a shift in rainfall over years. These are systems that can flip like a switch, generating persistent and disastrous change.
According to the authors of the report, understanding these tipping points means acknowledging that “business as usual” can’t continue. They show that rapid changes are coming that have wide-ranging effects. Crossing even one of the five harmful tipping points that are close at hand could unravel societies around the globe and cause immense damage to the natural world.
Several of the tipping points currently under threat involve the “cryosphere”—Earth’s protective layers of ice and snow. This year has seen record-low levels of sea ice in both the Arctic and Antarctic over much of the year, according to the National Ice and Snow Data Center.
However, the tipping points identified as most crucial involve ice on land, particularly the potential collapse of the Greenland and Antarctic ice sheets. Recent studies have indicated that the West Antarctic and Greenland ice sheets are subject to severe threats. The collapse of either of these ice sheets could generate extensive sea level rise that greatly exceeds the modest changes already flooding the streets of coastal cities.
Other tipping points that rarely come up in discussions of climate change center on changes to the world’s biosphere being driven by increasing temperatures and shifts in rainfall patterns. These include the collapse of coral reefs, the replacement of open grasslands with forest or desert, and the drying of several of the world’s largest lakes.
When it comes to the oceans, the possible collapse of the Gulf Stream/North Atlantic Current is a well-known possibility connected to severe weather changes in both North America and Europe. But there are other currents where the future is uncertain, including those that drive monsoons in the Southern Hemisphere.
Overall, some of these tipping points may already have been triggered by climate change and environmental destruction. This includes the collapse of some Antarctic ice sheets, the die-off of many coral reefs, the conversion of grasslands into deserts, and the failure of ocean currents in the Labrador and Irminger seas. These things may happen even if global warming is held to the 1.5 degrees Celsius limits under the Paris Agreement.
The report also details warning signs that point to the partial collapse of the Greenland Ice Sheet and the collapse of the Atlantic current. Damage to the Amazon Basin suggests that the world’s largest rainforest could swiftly collapse and be replaced with a drier, less dense ecology that traps far less carbon.
Estimating just how much change each of the triggering events may have is difficult. For example, if all the ice in Greenland were to melt, global sea levels would rise nearly 6 meters (20 feet), but it’s harder to assess the effects of a partial collapse. Similarly, if parts of the Amazon rainforest die back, it’s difficult to determine how much that changes the world’s carbon balance without understanding exactly how much of the forest gets lost and what effect that loss has on surrounding systems.
Not everything in the report is negative. There are some “positive tipping points” that can have great benefits for both the environment and society. Some of the positive tipping points are also close at hand. These include sharp reductions in the cost of renewable energy and increased sales of electric vehicles. The report proposes that negative tipping points should be monitored and addressed with special attention beyond addressing global CO2 levels. It also suggests that positive triggers need to be stimulated through government efforts to shape energy markets and foster innovation.
The result of this report is not to stop worrying about greenhouse gases, stop measuring sea ice, or stop taking steps to mitigate rising temperatures. It’s just that keeping an eye on these things alone isn’t enough. It’s not hotter summers or wetter winters that should be at the top of the list of concerns. It’s how rising temperatures may trigger events that fall like a line of dominoes, taking much of the environment and human society down with them. And the scariest thing may be how often the report confesses that we don’t understand all the factors behind many of these potential disasters.
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