As global surface temperature rises, tipping points loom ahead
In their 2021 paper, a group of scientists evaluated what they referred to as climate change “tipping points.” These tipping points, which include a variety of climate-related systems, indicate that large — and potentially irreversible — changes have occurred within a system once a certain threshold has been exceeded. The changes can take place over several years or potentially millennia depending on the response times of the systems.
The study quantified these with respect to the rise in global mean surface temperature. There are three clusters of this temperature: a rise between one and three degrees Celsius, three and five degrees Celsius, and above five degrees Celsius. The earth is already approaching the first cluster, which will have the largest impact on Greenland and West Antarctic ice sheets.
In fact, since the study was published, scientists have determined that sea-level rise from the melting of the Greenland ice cap is inevitable; there is no amount of climate change prevention that will be able to slow down or stop this.
While computers have been used in the past to estimate how much the ice caps have melted, a team of scientists used satellite imaging of ice caps from 2000 to 2019 to determine the melting rate.
The study states that, at best, there will be a 27 centimeter rise in sea-level regardless of future action. This is from approximately 3.3 percent of the Greenland ice cap’s volume. However, a model using 2012 data points toward a much larger overall rise if the rate continues — a total sea rise of 78 ± 13 centimeters.
While the trend has not followed the 2012 melting rate, that doesn’t mean it’s not impossible. If no action is taken, the world will potentially see a 78 centimeter sea-level rise. The world is currently sitting at a 1.1 degree Celsius rise, so just into the first cluster of tipping points. The Paris Agreement aims to make sure the rise in global surface temperature is less than two degrees Celsius — ideally, no more than 1.5 degrees Celsius.
According to a study published in Science, it is possible for many of the tipping points to occur at the temperature increase range targeted by the Paris Agreement. This includes coral reefs dying off, forest diebacks in the south and forest expansions in the north, sea ice collapse and sea current die-off, and abrupt boreal permafrost thaw.
Ice caps aren’t the only visible effects of climate change — there are many signs of destabilization in the Amazon rainforest. The resilience of the Amazon rainforest to climate and land-use change is necessary for the rainforest’s survival. However, since the early 2000s, it has steadily been losing resilience, especially in regions with less rainfall and areas close to human activity. This currently includes three-quarters of the entire rainforest. As the Amazon rainforest is home to a large amount of biodiversity and carbon storage, there are heavy implications for climate change on a global basis.
Triggering many of these climate tipping points is non-negligible — even with stringent climate mitigation measures. As the Paris Agreement (a best-case scenario) aims to limit global warming to at most two degrees Celcius, that still puts the world above many climate change limits. While it seems 1.5 degree Celcius is still feasible, countries need to focus on their efforts to limit greenhouse gas emissions and other climate-change causing actions.