We Have Passed the Tipping Point for Extreme Weather
Passing a "tipping point." It isn't over, yet. But it is.
by Gaius Publius
The concept of "tipping point" — a change beyond which there's no turning back — comes up a lot in climate discussions. An obvious tipping point involves polar ice. If the earth keeps warming — both in the atmosphere and in the ocean — at some point a full and permanent melt of Arctic and Antarctic ice is inevitable. Permanent ice first started forming in the Antarctic about 35 million years ago, thanks to global cooling which crossed a tipping point for ice formation. That's not very long ago. During the 200 million years before that, the earth was too warm for permanent ice to form, at least as far as we know.
We're now going the other direction, rewarming the earth, and permanent ice is increasingly disappearing, as you'd expect. At some point, permanent ice will be gone. At some point before that, its loss will be inevitable. Like the passengers in the car above, its end may not have come — yet — but there's no turning back.
There are many tipping points associated with our current change in climate, our overall warming of the planet. For example, I think the American Southwest is beyond a tipping point for available fresh water. I've written several times — for example, here — that California and the Southwest have passed "peak water," that the most water available to the region is what's available now. We can mitigate the severity of decline in supply (i.e., arrest the decline at a less-bad place by arresting its cause), and we can adapt to whatever consequences can't be mitigated.
But we can no longer go back to plentiful fresh water from the Colorado River watershed. That day is gone, and in fact, I suspect most in the region know it, even though it's not yet reflected in real estate prices.
Extreme Weather Has Its Own Tipping Point
We're also noticing this spring a wave of especially extreme weather throughout the country, and indeed the world. This is from Texas, land of freedom (from use of the phrase "climate change"):
Another two bodies found in Texas after extreme weatherAnd from around the world (emphasis mine):
... [A]uthorities in Central Texas have recovered the body of a second woman killed in flash flooding last weekend along the Blanco River.
Hays County officials say a search team recovered the body Saturday afternoon near the river in the Wimberley area.
It was the second body recovered Saturday along the river. Earlier in the day, a search team recovered a woman's body along the river about midway between Wimberley and San Marcos.
The discovery brings to eight the number of people confirmed as killed in the flood and 27 killed in last weekend's storms statewide. Eleven people remain missing.
At least 31 people have died in Texas and Oklahoma since the storms began last weekend. [emphasis mine]
May has been a month of extreme weather around the worldSo drought has an arc — either back and forth or marching toward an extreme — and so does the occurrence of extreme weather. Especially severe storms come and go, or they just keep coming. And just as drought can have a tipping point, beyond which you can't go back, so can the incidence of extreme weather. At some point, crazy weather becomes the "new normal," or worse, the "new normal" just keeps getting worse.
Even for a world getting used to wild weather, May seems stuck on strange.
Torrential downpours in Texas that have whiplashed the region from drought to flooding. A heat wave that has killed more than 1,800 people in India. Record 91-degree readings in Alaska, of all places. A pair of top-of-the-scale typhoons in the Northwest Pacific. And a drought taking hold in the East.
"Mother Nature keeps throwing us crazy stuff," Rutgers University climate scientist Jennifer Francis says. "It's just been one thing after another."
Jerry Meehl, an extreme-weather expert at the National Center for Atmospheric Research, points out that May is usually a pretty extreme month, with lots of tornadoes and downpours. Even so, he says, this has been "kind of unusually intense."
Has Extreme Weather Passed a Tipping Point?
There's no way to tie any one storm to global warming or climate change. In the same way, there's no way to tie any one lung cancer death to smoking. But over a broad population of smokers, when smokers are dropping like autumn leaves, each of them laced with throat and respiratory cancer, each of them puffing like the Marlboro Man as they fall (several of whom have also dropped like leaves), odds are there's a cause that can be named. Odds are it's already known, looking you straight in the face. Odds are not smoking will change the odds.
The art of analyzing those odds and seeing if they're indeed significant is also known, a statistical process called "event distribution" (think "bell-shaped curve" — how many events fall in the middle and how many at the ends) — measured in units called "standard deviations" or "sigmas" away from the center. As carbon emissions have increased over time, our climate has moved out of its normal distribution, toward more extremes.
For example, if before a nuclear facility was built, a certain town had a certain incidence of cancer linked to radiation (called a baseline incidence), then afterward it had an increased incidence which itself increased over time, you'd suspect radiation from the facility was the cause. Why? Because the kinds of cancer you're tracking are already associated with radiation.
We know that change in heat in the atmosphere changes the weather; that's not in dispute. The difference in temperature between warm fronts and cold fronts, for example, is an indicator of the strength of a storm — smaller temperature differences bring weaker storms; greater temperature differences bring stronger, more violent storms. There are many relationships like these in meteorology.
Atmospheric heat is rising; that's a known. Are storm strength and other indicators of more extreme weather also rising? If so, to what degree?
Those are two questions many are asking. But there's a third question few are asking — Are we so far beyond the "normal" that we'll never go back? In other words, have we crossed a tipping point for extreme weather? The authors of the following video have looked at distributions over time of extreme weather from the 1951–1980 baseline onward and have an answer.
Sadly, the answer is "yes." In every decade since 1980:
- The midpoint has moved toward more extreme weather.
- The move toward more extreme weather has not paused from decade to decade.
- And worst of all, the odds of a "6 sigma" (very very extreme) event have greatly increased. Events that would almost literally never have occurred, where the odds were one in over 500 million, are now starting to appear as possibilities under the "new normal" bell-shaped curve.
Note that the underlying scientific work is a paper by James Hansen and his colleagues, a draft follow-on to this published paper, "The New Climate Dice: Public Perception of Climate Change." Hansen, formerly of NASA, is one of the most prominent scientists in this field; in fact, he's America's original prominent climate scientist.
A Final Word
This is "a" tipping point, not "the" tipping point. We have slid into a "new normal" for weather, but please note:
- We're talking only about the weather, not a host of other effects, like extreme sea level rise. I don't think we've passed that tipping point yet.
- We can stop this process whenever we want to — or rather, we can force the "carbon bosses" and their minions in government to stop whenever we want to stop them. They have only the power we collectively allow them to have.