The real debates on climate science are not whether its happening, or whether its human caused, but rather along the lines of “how soon, how hard, how hot?” – or in the case of sea level, “how high?”
Perfect example. This week retired Chief Atmospheric scientist from NASA, James Hansen, the “Father of Global Warming’, together with an impressive list of co-authors, issued an as yet unreviewed paper with an urgent warning about the effects that may result from the 2 degree “safe” level of warming that international negotiators will be looking at in Paris this fall.
The new study, which includes nearly 300 references and is 66 pages long, argues that the 2°C target—hard-won as it might be politically—isn’t good enough, and is in fact “highly dangerous.” At that temperature, the study says, enough ice-sheet melting causes a positive feedback loop that leads to more melting and rising seas. Instead, Hansen and his co-authors say, a far better target would be to return to an atmosphere with 350 parts per million CO2. That number currently stands at about 400 parts per million.
The researchers make their case in part by describing paleoclimate data from the Eemian, an interglacial (warm) period that lasted from about 130,000 to 115,000 years ago. During that time, temperatures were less than 1°C warmer than they are today, but sea level stood about 5 to 9 meters higher due to large-scale ice sheet melt. The end of the period experienced powerful storms as well, according to sedimentary evidence the researchers cite.
–Hansen told reporters that his goal was to bypass the lengthy peer-review process for fear that the paper wouldn’t be available to its intended audience in time—international negotiators at the Paris talks. Peer review, he said, would instead be a real-time process, occurring in full view of the public. “That’s the merit of a discussion-type journal,” he said.
Other scientists agree that having this discussion is critical. “Too often in debates about climate change risk, the starting point is a presumption that only global warming in excess of 2°C represents a threat to humanity,” says climate scientist Michael Mann of Pennsylvania State University, College Park. “This new article makes a plausible case that even 2°C warming is extremely dangerous, too dangerous to allow.”
But when it comes to the paper’s findings, Mann says, “I am a bit skeptical about some of the specifics.” For one thing, he says, it contains a scenario in which the fresh meltwater from ice sheets increases exponentially over time, “which may not be realistic.” It also uses a low-resolution ocean model that doesn’t include key currents that transfer heat to higher latitudes, such as the Gulf Stream.
Climate scientist Kevin Trenberth of the National Center for Atmospheric Research in Boulder, CO, agrees that the paper is “provocative and intriguing,” but that “it has many conjectures and huge extrapolations.” Trenberth cites issues from the low-resolution ocean model to the lack of important ocean-climate patterns such as the El Niño-Southern Oscillation. He also calls the freshwater injection experiments “not … at all realistic.”
Hansen has written in the past about “scientific reticence” in the face of potential catastrophic risks of climate change. The current paper is sparking a useful debate about just how deep a hole we are in. Optimism is a useful tool in attacking any tough problem, but rose colored glasses can blind us to how high the stakes really are.
Maybe they will invent a breakthrough anti-aging drug soon enough, and we can be around in 2100 to collect on our bets on SLR.
And I’ll take 7:2 against that the bets will be collected in legal currency. More likely we will all be trading barter with bullets, chocolate, toilet paper, and Bic lighters. And maple syrup, of course.
There’s a tendency to hope for the best, but Hansen has a history of being first, being labeled extreme, and being right. Plus, the paper is Hansen et al, and those are some pretty good scientists. So even if they’re just “mostly right” we’re in for a heap of trouble with 2 deg. It’s going to take something like a Pearl Harbor event to wake up the mass of the public, and I’m interested in what the crock community might suggest that event might be. Any ideas?
There are a lot of candidates, but certainly, the next time a major hurricane hits Miami/South Florida, that’s going to be a big WTF for a lot of folks.
There are five problems with the climate equivalent to Pearl Harbor scenario:
1) So far, climate change hasn’t gone exponential – it’s still more of a gradual change. We don’t react well to such problems. Instead, we tend to think that we have more time, it’s not bad enough to make real changes, or more study is needed. This ties in with:
2) Shifting baselines. Each generation adapts to its own environment, and tends to only notice the changes to their specific environment. Longer term changes, although they would be dramatic and very shocking if they were witnessed by the same person over 100+ year stretches of time, are often unnoticed and ignored. (Changes in fisheries over time are a good example. We think we’re doing well when we can get a population from a 95% to a 90% lower population than before 1900.) It’s the same with climate change. Most people don’t notice direct changes.
3) Catastrophic weather is localized. Sure, there’s a history-making derecho in DC, but the rest of the world is fairly normal at the same time, so it doesn’t impact them.
4) Our record for acknowledging the urgency of climate change with previous catastrophes doesn’t lend any sort of optimism. Look at the issues in the last decade – wildfires in Russia, the US, Australia, and now, Glacier National Forest. Record flood events in Pakistan and Asia. Hurricane Sandy off NYC. Record heatwaves in the U.S. Midwest and Europe, record droughts in California, and on and on. Our tendency is to move on. Ohh! Look! The Kardashians!
5) No one catastrophic event can be isolated with absolute certainty that it’s climate change. The preponderance of events clumped together is major indicator, but as a people as yet, we’re failing miserably to recognize it. I think there is some chance at some future point that most (not all by a long shot) people will start to see the importance of changing our patterns, but as for one big event that suddenly changes everyone’s minds – I wouldn’t hold your breath.
Forest Fires in the American West would open some eyes. Trees hundreds of years old drying up and burning. If the West is so drought-ridden, people will ask, what are the trees doing there in the first place? Also, I think people are going to see that what is hitting California is no fluke. After some short-term relief, it’ll settle back in and people will ask: if there’s not enough water to farm here, what are all the farms doing here?
Wes, Hansen originally ”predicted” in the 90’s that: will be global warming by 5C-6C by 2060, then they changed to 2100. From 5C-6C down to 2C is more, than from 2C down to zero! Him talking as if the global temperature can be adjusted as on Fujitsu air-conditioner, is an insult to human intelligence!
how come he is not insulting your intelligence?!
citation, please, on your version of Hansen’s prediction. Bottom line, Hansen said it would get warmer, and it’s gotten warmer.
http://thinkprogress.org/climate/2012/05/08/479652/lessons-from-past-predictions-hansen-1981/
http://www.realclimate.org/index.php/archives/2012/04/evaluating-a-1981-temperature-projection/
https://tamino.wordpress.com/2014/03/21/hansens-1988-predictions/
http://www.realclimate.org/index.php/archives/2007/05/hansens-1988-projections/
Peter and ubrew make good points, and jimbills hits the nail on the head with all his remarks, particularly with “…but as for one big event that suddenly changes everyone’s minds – I wouldn’t hold your breath”.
We are the slowly boiling frog, and IMO, all the various impacts of AGW—-floods, wildfires, drought, ocean acidification, species extinction, extreme weather, sea level rise, ice sheet collapse, atmospheric and ocean temperature rise, permafrost melting, and so on—-are just not occurring often enough and in enough places on the globe to get mankind’s attention.
When AGW caused disasters strike, they tend to be localized, the survivors tend to blame things on bad luck, and are all too willing to gamble that it will happen to someone else next time. IMO, we need recurring waves of disaster repeatedly striking areas before people will believe.
My candidate for the big attention getter is sea level rise. since it will impact so many cities around the world, and Miami-South Florida will be a “poster child” when it goes under. In the U.S., CA drying up and blowing away (or burning, and/or washing away in torrential rains), with all the impacts that will have on the rest of the country would also get people’s attention, but only when our fruit, nut, and veggie supply dries up.
I think the ecological collapse of a major western world city so that is no longer functional long term will be the turning point.
There are some possible candidates already mentioned: California’s fire/water crisis, Florida’s rising salty damp issue.
The other is the 30 cm mark of sea level rise. At this point it’s quite clear that it’s not just a few inches rise till 2100 but multi metres.
The other is the collapse of the Middle East as a viable place to live. There are signs of that for the last few years which ISIS has taken advantage of.
So I see denial as continuing until it’s just not able to be taken as tenable in any way.
A major permanent collapse is needed that can’t be explained away like the Pearl Harbour metaphor used above.