Above: modeled global average temperature with business as usual emissions.
Less terrifying, more horrifying. That, more or less, was the between-the-lines takeaway from Friday’s National Research Council (NRC) briefing on abrupt climate change.
The event was part of an announcement of the NRC’s newly released and finalized report, “Abrupt Impacts of Climate Change: Anticipating Surprises.”
Several of the scientists involved in the report were present, including James White from the University of Colorado at Boulder, Anthony Barnosky from the University of California at Berkeley, and Richard Alley from Penn State University.
In one of the most shocking statements, Barnosky said the world’s oceans are now undergoing a change in pH and temperature that is so rapid and severe, that if we stay on our business-as-usual emissions pathway, then we will see the most significant degradation in the world’s oceans since 250 million years ago when there was the “end-Permian extinction event.” That was possibly the most extreme extinction event in Earth’s entire history. Over 90% of marine species in the fossil record went extinct.
“Just in the next five or six decades we will see some very major problems,” Barnosky said.
Today, the change in temperature of the ocean is primarily being caused by the growing global energy imbalance resulting from the thickening blanket of greenhouse gases in our atmosphere, especially carbon dioxide.
The change in pH of the ocean is primarily being caused by the growing global atmospheric concentration of carbon dioxide, which becomes an acid, carbonic acid, when it dissolves in water. As the methane clathrates increasingly thaw, they will also acidify the water.
On extinction more broadly, Barnosky said that tropical coral reefs and land species in the tropics are first in line for extinction. And coral reefs will disappear in decades on our current emissions path as well. “These are not small effects and again – we’re already starting to see them happen.”
All participants, even Barnosky himself, seemed to be stunned by the details and implications being presented.
Richard Alley made an effort to shore up morale by pointing to some of the massive and abrupt catastrophes we can essentially rule out now. “North Atlantic [ocean circulation] probably will not change abruptly,” he said, and there is “fairly high” confidence in that outlook. However, he added, circulation will change, and probably already is changing – but it just won’t “shut down” like some had worried. At least not this century.
On the topic of amplifying feedbacks, Alley said that “if we warm the world, nature will amplify what we do.” And he added that “often long-term feedbacks are ignored – and so you get optimistic projections of how much carbon we can emit.”
Asked about the feasibility of “going back” after crossing tipping points, Alley said that it depends on the tipping point. In the case of the Arctic sea ice, if we cool the planet back down to temperatures a little below today’s, then we can probably regrow the sea ice he said, adding that on the other hand, if West Antarctica collapses, then the temperature would have to drop much further to start the ice sheet growing again. As for Greenland, the ability “to return” depends on how long the climate remains in a warm state. The longer it’s warm, the harder it will be to “return” he said.
Alley didn’t get into how we might cool the planet back down, although in previous public statements, he has referred to carbon dioxide as being something like a global temperature dial. Also in reference to “returning,” he mentioned hysteresis loops, a trait of some complex systems where returning to the previous state requires following a different path back. Sometimes the return path can be more difficult too.
In other less-terrifying but still-horrifying news, Alley described how – as best he can tell – there do seem to be enough “safety valves” on sea floor methane clathrate deposits to limit its release – but it will still be a chronic problem – rather than the massive “clathrate gun” possibility (where the methane erupts from the oceans so fast that global temperatures spike and essentially a massive ecological upheaval ensues with wildfires, famines, and so on).
Unfortunately, both the clathrates and thawing Arctic permafrost will become significant sources of ongoing greenhouse gases, at least if we stay on our current emissions path. That means to stabilize climate in the future, we’ll need to do more than just stop burning fossil fuels. We’ll also need to mop up the permafrost and clathrate emissions. And, with elevated chronic bubbling of methane from the sea floor, it will also acidify the ocean from the bottom up.
Regarding a possible collapse of the West Antarctic Ice Sheet, Alley said he’s inclined to say it’s not terribly likely this century. And, if it does happen, he’s leaning towards it being a somewhat slow process. But there are still processes involved where there just isn’t enough information yet – and so he won’t fully rule out something more rapid.
Jim White highlighted that a previous NRC report (2004) on abrupt climate change was the first time anyone had even looked at the issue in a systematic way. And he added that “calls to action” from that 2004 report have largely gone unheeded thus far.
Early in his presentation, White alluded to food storage as one possible safeguard against increasingly hostile weather and crop shortfalls, but he didn’t go into much detail. The global food system is quite remarkable in how little reserve is stored at any given time. Even without climate change, it seems like a significant crop shortage could put many countries, even developed ones, into a world of hurt.
In response to a question on tipping points in our built systems, White answered that there has been no comprehensive assessment to see how our infrastructure will hold up to climate change. The first step he said, is to identify “what you have at risk,” but that has generally not been done. For example, he cited how it took Hurricane Sandy hitting New York and New Jersey before there was a serious evaluation of what could be done to safeguard against such an event.
He also cited Florida, which hasn’t had a major storm surge disaster yet – that is, one where the elevated (and rising) sea level makes the surge potentially worse than ever before.
And White also pointed out that low topographical relief makes it easy for storm surge to push far inland along much of the US Southeast coast.
Fundamentally, the feeling from the conference was that some very decent and hardworking people have identified a very bad set of circumstances headed towards mankind, and the general reaction has been a human one: shoot the messenger and/or ignore the problem and hope it goes away.
In the context of this report, that strategy of denial and rejection has sort of worked so far (by a certain logic anyway). After all, a lot of sudden apocalyptic climate change events have been ruled very unlikely with high confidence, at least for another 100 years or so. But the horror of the situation is that very real chronic problems are growing worse. The odds of those chronic problems going away, unfortunately, is about as close to zero as you can get.
The basic truth between the lines of this press event was that we are facing a world that is becoming increasingly hostile to humankind.
We are literally making the planet into a wasteland like this is some post-apocalyptic science fiction story. It is just shocking. And the most horrifying aspect of it all is that we’ve waited to reduce emissions so long that we’re exiting the win-win field of possible climate responses. We’re now headed into a world of lose-lose. That’s the news nobody wants to convey – or hear. But there it is.