Above, Mike Mann discusses his new piece in Scientific American, which outlines critical thresholds in climate warming in the not-too-far-off future.
Most scientists concur that two degrees C of warming above the temperature during preindustrial time would harm all sectors of civilization—food, water, health, land, national security, energy and economic prosperity. ECS is a guide to when that will happen if we continue emitting CO2 at our business-as-usual pace.
I recently calculated hypothetical future temperatures by plugging different ECS values into a so-called energy balance model, which scientists use to investigate possible climate scenarios. The computer model determines how the average surface temperature responds to changing natural factors, such as volcanoes and the sun, and human factors—greenhouse gases, aerosol pollutants, and so on. (Although climate models have critics, they reflect our best ability to describe how the climate system works, based on physics, chemistry and biology. And they have a proved track record: for example, the actual warming in recent years was accurately predicted by the models decades ago.)
I then instructed the model to project forward under the assumption of business-as-usual greenhouse gas emissions. I ran the model again and again, for ECS values ranging from the IPCC’s lower bound (1.5 degrees C) to its upper bound (4.5 degrees C). The curves for an ECS of 2.5 degrees and three degrees C fit the instrument readings most closely. The curves for a substantially lower (1.5 degrees C) and higher (4.5 degrees C) ECS did not fit the recent instrumental record at all, reinforcing the notion that they are not realistic.
To my wonder, I found that for an ECS of three degrees C, our planet would cross the dangerous warming threshold of two degrees C in 2036, only 22 years from now. When I considered the lower ECS value of 2.5 degrees C, the world would cross the threshold in 2046, just 10 years later [see graph on pages 78 and 79].
So even if we accept a lower ECS value, it hardly signals the end of global warming or even a pause. Instead it simply buys us a little bit of time—potentially valuable time—to prevent our planet from crossing the threshold.
Cautious Optimism
These findings have implications for what we all must do to prevent disaster. An ECS of three degrees C means that if we are to limit global warming to below two degrees C forever, we need to keep CO2 concentrations far below twice preindustrial levels, closer to 450 ppm. Ironically, if the world burns significantly less coal, that would lessen CO2 emissions but also reduce aerosols in the atmosphere that block the sun (such as sulfate particulates), so we would have to limit CO2 to below roughly 405 ppm.We are well on our way to surpassing these limits. In 2013 atmospheric CO2 briefly reached 400 ppm for the first time in recorded history—and perhaps for the first time in millions of years, according to geologic evidence. To avoid breaching the 405-ppm threshold, fossil-fuel burning would essentially have to cease immediately. To avoid the 450-ppm threshold, global carbon emissions could rise only for a few more years and then would have to ramp down by several percent a year. That is a tall task. If the ECS is indeed 2.5 degrees C, it will make that goal a bit easier.
Why would he feel the need to concoct a story about a scientific consensus around the totally-artificial 2C value? The Met office’s scientist in charge of climate impacts is on record saying “most climate scientists do not subscribe to the 2 degrees ‘dangerous climate change’ meme”. /He then explained how this 2C obsession can be very dangerous in terms of policy as it is increasingly clear that emissions will keep rising for a long time.
Even Dear Kev doesn’t mention it often or not at all.
Even the UCS has tried to push the discourse away from the 2C meme, mentioning how “serious risk of substantial climate damage” still exists “at warming less than 2C”.
So you think we should change the “meme” as you call it – to something less – perhaps +1.5C? I am sure Michael Mann wouldn’t object to that.
I think Mann is way behind on the discourse, doesn’t listen to anybody, is creating noise and not much else. I also think danger and global warming do not follow the decimal system, so that 1.49 isn’t so much better or worse than 1.51.
The UCS quote is from Feb 27, 2014.
Yet again you only suggest that 2C is wrong, but never bother to come with anything that is supposedly a better target for emission cuts or any action to handle the problem. An adhom attack on Mann doesn’t help much as he is basically repeating that if 2C is a goal (which btw the worlds state leaders have agreed upon), we have to stop thinking that “climate change happens in year 2100” – but consider that we might reach 2C already in 22 years! I believe scientists are getting better at being more precise about the urgency of the problem, and Mann is certainly no exception to voice this.
As far as I know, 2C is as good as any target based on the scientific knowledge we have around possible feedback mechanisms that get out of control when we pass that and go into 3C territory. If climate change ramps entropy faster than we can invent technology to “fix it” – we have clearly lost completely.
As Mann say, its the “unknown unknowns” that keep him up at night, and many of those lie above 2C.
I think Michael Mann brings a good piece of information to the table by informing that even if climate sensitivity is towards the low end of +2.5C from a doubling of CO2, that only buys us another decade to seriously reduce emissions.
No doubt we need to reduce emissions right now if we consider peaking at 450ppm as a safe limit. And no doubt the committed warming will already manifest itself in the coming decades due to the lag in the system with the great heat uptake in the oceans that needs to be vented.
So why didn’t Obama’s “shovel-ready employment programs” include programs to upgrade home insulation, improve the R-value of windows, add daylighting where feasible, and other things that would put e.g. building tradespeople back to work?
A friend took advantage of the ARRA’s $5B modest income home weatherization program. $250M was allocated to improve low income home energy efficiency. HUD got $4B to upgrade public housing.
Right – so it is somehow Mann’s fault that he addressed the meme created by others and used by everyone around the world. The standard of discussion for the past ten years.
And that makes him behind in the discourse?
Then you just dropped a few bombs about making noise and being useless just for artistic effect. So, you criticize Mann for using a universal meme that everyone uses because it may be too conservative – which is the exact opposite of your own position, which is that 2C is too alarmist.
In other words – you have proven in 100 words or less that you have no fucking principles at all, are a complete hypocrite, and are way more biased than Mann could ever be on his worst day.
And you wonder why everybody here ridicules you, don’t you Maurizio? Pathetic.
And there comes the bile again. Listen, stupid, if you cannot bother to find out what the UCS has to say, or what National Geographic news has to say, or what Richard Betts has to say, read this fresh article from the Tyndall Centre.
http://Www.tandfonline.com/doi/pdf/10.1080/14693062/2013/835705
It’s dated 27 sep 2013.
You might even discover the trivial truism that 2C is a policy target and not scientific.
The whole idea of a target might be wrong and dangerous (the authors ask if the target is deemed already passed, will the institutions that have worked about it be dismantled?).
Ps to John: thanks for the suggestion but it’s not for me to indicate what to replace the 2C meme with.
In his infinite capacity for obfuscation and confusion, Omno states that “2C is a policy target and not scientific”.
Where did that number come from, O-Log, if not from “science” looking at data and making some projections? And should we have people basing policy decisions on non-science and non-fact? Plucking things out of thin air or their anal orifices as you do?
PS I know irony is an alien concept to Omno, but seeing him call someone “stupid” is truly so.
But why do you even bother to say that the 2C target is not realistic when you don’t provide any information about what we should aim for instead? You are the one that often complains that science has become to politicized – well the 2C is basically the only thing that has come out of science with a clear political target. And of course you view this as some kind of threat? (and now implying that the threat is that its perhaps too high a target) – If scientists are not allowed to hint on politics, then its our job to provide the solutions.
So far you have not provided any solutions, just telling us that “this is wrong”, “that is stupid”, “Mann is an idiot”… don’t you ever get bored?
I for one think its important that the international community at least agree on something with regards to emission cut goals. And you know, some countries are doing a pretty good job at it too.
Having bagged Gingerbaker as yet another slow-witted reader of my AGW-impossible page, I can restate the obvious for the millionth time..the issue is not if 2C is too high or too low, the issue is that the 2C target has been made up as a guidance to policymakers who have proceeded to misinterpret and misuse it absolutely.
Every repetition of the 2C meme will only worsen the situation.
What to replace it with? It’s a challenge for scientists who are experts in policymaking too. It’s not a matter for a comment to a blog post. But we can rest assured that Mann is way, way behind on this. Not sure who else you’d like to hear from…is there any organization more warmist than UCS??
And the original point: why does Mann feel the urge to introduce a flawed, useless, policy-endangering meme in his article, something he himself rebukes at the end? If his argument is powerful, and his evidence incontrovertible, and the danger so great, why add pointless noise? Imagine on the Titanic if the abandon-ship call had been accompanied by a weather report for the following week, or statistics on the number of unmarried girls onboard…useless, pointless, distracting, potentially counterproductive. Nobody was such a fool.
ps same problem for the 40-y lag…it’s “plucked out of thin air’. In general any round figure is scientifically immaterial. So don’t use them as if they were science.
I disagree. Mann uses the 2C target by translating it into a year when we will pass that to make the point that IF that is a target then we will blow past it in 22 years time UNLESS there is action taken today.
If anything, that is as good a policy that could be done based on the established 2C target as a lowest common denominator between countries. What is your suggestion then? Throw this away and discuss for a decade what our next target is? I know the whole Mann and 2C bashing is basically another attempt at dragging out any decision, at least if you don’t have a good alternative you better shut up as you are basically just adding noise to the discussion.
Just if something isn’t attainable doesn’t mean we should throw it away. Kids can draw cute pictures of stick figure people standing on a planet holding hands, writing that there should be peace on earth. Even though its unlikely to ever happen, doesn’t mean striving toward that goal should be tossed away. I view the same with regards to climate change – we know that we are already committed to serious warming from the lag in the heat uptake in the oceans and decades of venting, but instead of giving up we need to wake up and take action now. We also know that our dependence of fossil fuel is unsustainable so there are more reasons besides AGW to strive for a low carbon society.
Peter Gabriel, signal to noise:
“man i’m losing sound and sight
of all those who can tell me wrong from right
when all things beautiful and bright
sink in the night
yet there’s still something in my heart
that can find a way
to make a start
to turn up the signal
wipe out the noise”
Its about time to wipe out the noise folks.
Unsure what you “know”, John. I cannot possibly have any power in “dragging out” decisions. The Tyndall Centre, the Met Office and the UCS seem unlikely candidates for that, or National Geographic.
Mann is noise. Omnipresent, litigious, unable to debate, conspiracy theorist, partisan activist for how many years now? See what’s he achieved.
I think Mann has achieved quite a lot by irritating the bejesus out of the climate deniers – even to the point where they try to sue him because of his research. He exemplifies how insane the right wing has become in USA in trying to silence people who are telling inconvenient truths. I am happy he is going strong and fighting back towards the noise with information from real science. I am also very happy he is very vocal about the bullying he is subject too (and even write a book about it) to show what scientists are up against these days from the denier cacophony choir. I wish there are more scientists like him coming out so we can end this stupid nonsense where politicians are supposedly deciding what science is accepted or not based on their convenience level.
Why don’t we aim for 350 ppm? If you want a low-risk target, that’ll do it.
(Hitting the target is another matter.)
Forgot to include the title: “Going beyond two degrees? The risks and opportunities of alternative options” by Andrew Jordan et al. Climate Policy, 13:6, 751-769.
While I think Omnologos’s way of stating what he thinks is unnecessarily contentious, I get his point, which is that 2C may in fact be too generous a target. We are already seeing larger and larger effects from climate change, so going as far as the 2C limit might actually be far worse than we anticipate.
I also think setting a number value like that gives politicians a false sense that they have time to deal with the issue later. They don’t. We don’t. Not if we love our children, or the natural world as we’ve always known it.
Politics is about the next election. For politicians to care more about the future, more voters have to care, and those who do care have to care more. If politicians give it a thought, they can’t think that procrastination will limit atmospheric CO2 to 450 ppm given the current trends. The arithmetic is simple.
Which reveals an extreme gaping hole in our form of governance. When votes determine whether or not our government will protect us from massive danger or not, it’s not a good thing, especially when getting the votes requires a level of expertise that’s pretty much impossible for the majority of the population to attain.
It’s an interesting challenge. Who’d have thought that sound science would become less respected than political identity? However, changing the population’s opinion about science is more achievable than changing the form of government. Acid rain and ozone depletion were addressed by Republican administrations. (That was back when Republicans were logical.)
Perhaps, the deniers have already won their self indulgent game. How do people who have made the effort to develop significant expertise, or are at least rational enough to not demonize those who have, counter silly tedious arguments for delay? I wish we were shooting a layup rather than a half court buzzer beater, but we still have to shoot.
At the end of the SA article, Mann writes this:
It is impossible to tell if Maurizio is a raging psychopath in his private life, but he does a great job of imitating one on the internet.
The story so far…Mann starts his piece with a completely useless piece of information that is also outdated and not scientific. Months earlier, everybody agreed the 2C meme was only provided to policymakers as a reference point, but has dangerously evolved in a meaningless and confusing ‘target’.
The discussion on how to move forward has been going on for a while and even the UCS is openly against using the meme.
Holding two mutually-exclusive thoughts in his head, Mann tells his readers the useless piece of information isn’t actually useful. The end.
More and more projection.
The cognitive dissonance residing in your brain is starting to prompt hallucinations, Maurizio.
The 2C meme and its apparent flaws in informing policy makers is not the same thing as the real risks of actual temperature rise of 2C above pre-industrial levels.
….” I get his point, which is that 2C may in fact be too generous a target. ”
I don’t see that as the point of his comment, because it is not his position. His position is that AGW is not catastrophic, and we are all alarmists. His position is that 2C is arbitrary because there is no proof that a 2C rise poses a significant threat. He has said this multiple times.
The point of his post was, as ever, to take any opportunity to denigrate Michael Mann. Mann mentions 2C, so he will find a source which criticizes 2C. The lurid hypocrisy that the criticism he trumpets against 2C is the exact opposite of his own position on 2C is what he is currently trying to downplay.
Hell, tomorrow he’ll probably criticize Mann for using 2C because it is too alarmist as a target. Remember, this is the same sophist whose web page has the prominent essay:
“Why AGW is logically impossible” (http://omnologos.com/why-agw-is-logically-impossible/)
So don’t throw some links about 2C at us, Maurizio. We all know what 2C is and we all see what you did here. Once again, you are attempting to smear one of world’s preeminent climate scientist for no good fucking reason. You deserve all the bile being aimed in your direction.
Whatever his intentions were, I chose to interpret them that way. How do I say this… I think the bickering between sides is way more harmful than helpful, and serves as a wedge that drives people further apart. He’s one of those people that seems to use barbs at every turn, negative conversation, but maybe there’s a way to turn that around to a positive discussion. One side might start it but the other side doesn’t have to follow along. You see where I’m coming from?
Private enterprise is beginning to take climate change seriously http://climatestate.com/2014/03/26/private-enterprise-is-beginning-to-take-climate-change-seriously/
Past panel reports have been ignored because global warming’s effects seemed too distant in time and location, says Pennsylvania State University scientist Michael Mann.
This report finds “It’s not far-off in the future and it’s not exotic creatures it’s us and now,” says Mann, who didn’t work on this latest report.
http://www.nzherald.co.nz/world/news/article.cfm?c_id=2&objectid=11225449
Exactly! This is the immediate “take home” from Mann’s angle on this. Climate change isn’t something that happens in 2100 which is the year so often used in the projections from e.g. IPCC and a lot of the science.
By labeling a year only 22 years into the future with 2C and knowing that 2C is the target that many of the worlds politicians aim for as a dangerous threshold, he basically urges the society to get the notion that this will affect even our current mid-life generation (in other words, those with kids). It strengthens our responsibility to act on the information we have now as the clock is certainly ticking.
Note that Mann also say that serious consequences from climate change might come sooner, or it might be later. The uncertainty on that it could come earlier tells us that as a risk management issue, we better get our act together now.