Scientific Method / Science & Exploration

US National Research Council wants abrupt climate change warning system

Tipping points are out there, and we'd like to know when we're approaching one.

Yesterday, the National Research Council (a branch of the US' National Academies of Science) released a report in which it called for the creation of an early warning system that would let us know when we're approaching tipping points in the climate.

While talk of climate tipping points is fairly common, most of it focuses on the climate itself changing to a new state. The new report is quite different, in that it's focused on things that can enter new states even when the climate is only changing gradually. These include individual features of the planet, like ice sheets and things that currently support human infrastructure, like permafrost.

The new report builds on one that the National Academies released in 2002 called Abrupt Climate Change: Inevitable Surprises. That also took the more broad view of climate change, focusing on the fact that the climate itself can shift rapidly, as evidenced by events like the end of the Younger Dryas cold period, where temperatures seem to have shifted dramatically over the course of a few decades.

In looking at the issue more closely, however, it became apparent that it's not only the climate itself that has tipping points. Even as the climate undergoes a period of gradual change, individual aspects of the Earth system can experience sudden shifts. To give one example from the report, a steadily warming climate could destabilize the exit glaciers that drain the West Antarctic Ice Sheet into the ocean. Once destabilized, the glaciers will retreat rapidly, raising sea levels by as much as two meters.

The committee that wrote the new report has now gone through and identified a number of similar potential tipping points, including the sudden release of Arctic methane, sudden increases in extreme weather events, and the shutdown of the Atlantic Ocean's current system. And, as they analyzed these events, they found a mix of good news and bad news.

We'll do the good news first, which primarily comes in the form of potential tipping points we've looked into and found that we're unlikely to reach this century. We've found, for example, that the ice sheets in Greenland are likely to melt slowly, rather than suddenly lurching into the ocean. The Atlantic current system, which ensures there's warm water off the coast of Europe, appears to be stable enough that we don't have to worry about it this coming century.

The bad news is that we seem to have already hit a few tipping points. Coral reefs appear to be dying off globally, and the Arctic sea ice has become thin, unstable, and prone to massive melt offs. Both of these have the potential to cause massive ecological disruptions, including significant extinctions, in the areas affected. (On the good news side, these were the only two items listed as high risk for this century in the report's analysis.)

Overall, the report comes to a conclusion that's pretty difficult to argue with: it would be nice to know when these sorts of tipping points are approaching, rather than scrambling to adjust to them once they've already tipped. This is especially true because a number of them will affect human infrastructure. We've built many roads and pipelines (ironically, many of these were built to handle fossil fuels) on top of permafrost, which we're now realizing isn't going to stay frosted if our carbon emissions continue. We've also built lots of port facilities (again, including many that handle fossil fuels) that would be at risk for sea level rise.

In fact, the stakes are so high that the report recommends setting up a formal early warning system for these sorts of tipping points. This would involve a group that identifies systems where abrupt climate change is a risk and directs research into the factors that control the behavior of these systems, as well as how their behavior changes as it approaches a tipping point. The group would also identify the human infrastructure and ecosystems that would be most vulnerable to sudden changes.

The other thing the committee thinks needs to be done is to look into how the interaction of natural shifts and human activities create distinctive tipping points. So, for example, it's expected that drought will become more frequent in the western US, which will increase reliance on ground water. Except groundwater is also being depleted in many areas of the west; the combination of the two may create a crisis point in a way that neither events could on their own.

It's hard to argue that these things aren't worth looking into (although I'm sure someone will). But finding a group willing to take on the responsibility and find the funding to do so is a different matter entirely. Even with the prestige of the National Academies behind them, good ideas have often come up short in the current political environment.

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