James Hansen isn't satisfied with an audience limited to those that read his peer-reviewed scientific papers and the odd Congressional hearing attendee. In this essay, NASA's top climate scientist takes the substance of a recent paper that discusses the "reticence" of some climatologists to make their fears about dangerous climate change public and gives his argument a more accessible treatment. The New Scientist version is gripping stuff, right from the first paragraph, which also appears in almost identical form in the Environmental Research Letters original.
I find it almost inconceivable that "business as usual" climate change will not result in a rise in sea level measured in metres within a century. Am I the only scientist who thinks so?
His answer is no. (At right are the consequences for Florida, as envisioned by New Scientist, based on data from Jeremy Weiss and Jonathon Overpeck, University of Arizona. Click for full-size view)
The New Scientist version, which was the magazine's cover story last week, does contain some decidedly unscientific language, however:
Of course, I cannot prove that my choice of a 10-year doubling time is accurate but I'd bet $1000 to a doughnut that it provides a far better estimate of the ice sheet's contribution to sea level rise than a linear response. In my opinion, if the world warms by 2oC to 3oC, such massive sea level rise is inevitable, and a substantial fraction of the rise would occur within a century. Business-as-usual global warming would almost surely send the planet beyond a tipping point, guaranteeing a disastrous degree of sea level rise.
Read the whole thing. It really is a sobering review not only of the physics of ice and climate, but also of the scientific process involved in the IPCC "consensus" and why it doesn't reflect the wider climatology community.
Of course, Hansen and his colleagues could be wrong. There could be some unforeseen factor, a new negative feedback mechanism that will counteract the unavoidable radiative forcing that is pushing to the brink of a tipping point beyond which we will have no hope of mitigating global warming. But is the discovery of a mysterious counteragent really what you want to bet on?
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One of the favorite tactic of denialists is to note uncertainty in predictions, and then use the uncertainty as a reason to do nothing since there is the possibility that nothing needs to be done.
The problem with that trick is that the uncertainty isn't in only one direction. It also includes the chance that things will, as Hansen suggests, in fact be worse than predicted.
And over the last 20 years, that is in fact what we have seen with regards to climate prediction: Things have been consistently worse than predicted: More warming. More melting. More extreme weather events.
Scenarios that were presented 10 years ago as 'worse case' now appear to be merely 'middle of the road'.
And if that doesn't frighten you, you just aren't paying attention.
More scaremongering from Hansen.
The relevant line in this article is,
"The lawyer then asked me to identify glaciologists who agreed publicly with my assertion that sea level is likely to rise more than a metre this century if greenhouse gas emissions continue to grow: 'Name one!'
I could not... "
Indeed the IPCC expects a sea level rise of less than a foot over the next century and even that is hotly contested by many scientists involved in sea level study.
Hansen's "tipping point" is unsupported fantasy. Recent studies have shown that the Greenland ice sheet survived the last interglacial period when temperatures were much higher than they are today or even the wildest predictions of the majority of theoretical climate models.
Also there is little evidence that there is any reason to believe that anything but natural variablity is going on in either the arctic or antartcic.
Let's take a look at a charlatan in action.
"As an example, let us say that ice sheet melting adds 1 centimetre to sea level for the decade 2005 to 2015, and that this doubles each decade until the West Antarctic ice sheet is largely depleted. This would yield a rise in sea level of more than 5 metres by 2095."
Now that was a nice piece of slight of hand (Actually his math is off it would be 2105 before the deluge was 5.12 metres). Anyone with any math background will know they have been bamboozled. By that same trick I can show that two flies can reproduce and within months the earth will be ten feet deep in flies.
To use a geometric progression to generate scary sea level scenarios with absolutely no corroborating data isn't exactly the hallmark of a sober scientist. This is why I have little respect for Mr. Hansen or his work.
Lance -
First, my maths gives:
DateRSLCHANGE
200500.01
20150.010.02
20250.030.04
20350.070.08
20450.150.16
20550.310.32
20650.630.64
20751.271.28
20852.552.56
20955.115.12
Which probably means that you started with a sea level rise of 0, which is contrary to observation. The use of an exponential simply illustrates the effect of feedbacks in the system; you are more likely in the end to see an S-shaped curve as ice sheets re-equlibriate to the new conditions.
As a geologist, I am aware that changes of this size have happened in the geological record, see:
http://www.sciencemag.org/cgi/content/abstract/288/5468/1033
16 meters in 300 years, and I would add that it is unlikely that such a change would be linear; peak rates could easily exceed 1m/decade. And I would also point out that the forcing changes involved were smaller than anthropogenic changes.
So postulsting such a rise is not out of line with observation; if anything, postulating a small and steady rise in the face of a 2-4K temperature rise contradicts observation. And I'd like to see your reference about the Greenland ice sheet 'surviving' (Hint: read the paper, not the ill-informed commentry).
You claim to have read the IPCC report, yet you say that it expects a rise of 'less than a foot'. The range was 18-59cm, excluding ice sheet dynamics, which would give an average rise of 38cm, over a foot.
Andrew,
Hansen clearly states "let us say that ice sheet melting adds 1 centimetre to sea level for the decade 2005 to 2015..."
This indicates that the previous level, before 2005 is to be the baseline or zero. Why would you assume a level of 1 cm? Why not 25 cm or 400 cm for that matter? But let's not quibble over what is obviously a fantasy to begin with. Unless you are saying that you believe that sea level is going to rise exponentially in the next century. If so please provide some hard evidence to back this outrageous claim.
As for my interpretation of the Greenland ice study being wrong here is the words of the author.
"If our data is correct, and I believe it is, then this means the southern Greenland ice cap is more stable than previously thought," said Eske Willerslev, research leader and professor of evolutionary biology at the University of Copenhagen. "This may have implications for how the ice sheets respond to global warming. They may withstand rising temperatures."
The study indicates that temperaures were 9 degrees F higher than present during the interglacial period covered by the data and that the ice sheet remained intact. Now there was some criticism from the usual suspects, the Hadley Centre, that past warmings occured more slowly and that we face a rapid warming. Exactly how rapid warming is supposed to melt ice faster than slow warming was not explained, and is indeed illogical.
Here's a thought experiment. Put two blocks of ice in two seperate cold rooms. Slowly increase the temperature to 70 F over a long period of time in room A. Quickly increase the temperature to 70 F in room B. The block of ice in room A will have already begun melting before the temperature has reached 70 F in room A and there for will experience more melting over all.
Certainly the amount of melting once the temperatures are the same will be no different with the exception that the slowly melting block might be sitting in liquid water which will transmit more heat to block A due to the much higher thermal conductivity of liquid water than air.
As for your claim that forcings due to "anthropogenic" changes are much larger than the ones responsible for past ice sheet melting, where is your evidence? So far the increase in CO2, even assuming all of it is anthropogenic, has resulted in "No significant acceleration in the rate of sea level rise during the 20th century" according to the IPCC TAR.
As for 38cm being the average of the IPCC range of predicted sea level rise, why would you assume the "average" of a range? Even so that gives 1.25 ft slightly more than a foot. My point remains intact. The "concensus" is that we face no catastrophic sea level rise in the next century.
Hansen is blowing hot air, as usual.
Lance -
The correct start point for sea level rise would be 3cm/decade, as currently measured. But Hansen explicitly used 1cm/decade for ice sheet melting alone as a starting point.
As far as greenland goes, you said that the Greenland ice sheet survived the last interglacial (when sea level was 6m higher). The literature quoted suggests that only 2m of this rise came from greenland, as oppoosed to 3m as thought. Try actually reading scientific papers instead of quote mining.
Rapid warming will of course lead to faster melting; your 'thought experiment' is strange indeed. The total time for both scenarios must be identical (obviously), so Room B will have more melting by a certain time. Furthermore, no feedbacks are included, making the pattern of melting very unrealistic.
As far as previous forcings go, solar forcings are around an order of magnitude less than anthropogenic and still show up in the record. Orbital milancovitch changes are only a redistribution of radiation with no overall change, and yet they manage to force glacial/interglacial changes.
If you are denying that the increase in CO2 is anthropogenic or that this does not cause forcing, then you've gone into complete denial of fairly basic physics, so I can't help you there.
Your 'point' on sea level appears to be that if the ice sheets remained intact - which is extremely unlikely based on historical evidence - then sea level rises would be fairly minor. Which is fair enough but irrelevant.
Andrew,
Nowhere does Hansen state anything to indicate a previous increasing sea level to be the starting point of his dishonest little example. You have to use 1 cm as a base line to make his number work. I said it was inconsequencial but you choose to beat a dead horse, ignoring my overall point that there is no scientific reason to expect exponential sea level rise in the next century.
Then you misunderstand, or purposely mistate, my straighforward thought experiment.
I never said that both blocks began melting at the "same time". In fact I stated the opposite. I state that the block in room A was heated over a "long time" to reach 70 degrees F and that the block in room B was then heated quickly to 70 degrees F. Hence the block that was heated slowly over a long time would have already begun melting at the point when they both are at 70 degrees F.
These are the conditions analogous to the two situations we were discussing. One in which a long period of temperature increase eventually reaches a high temperature and one where the high temperature is reached quickly. The Hadley Centre was indicating that "rapid warming" was somehow more likey to cause greater melting. The ice doesn't care how long it took to reach a certain temperature. It melts at the same rate at a given temperature.
The past melting you reference came at the end of the last ice age under very different circumstances than the present. If you are indeed a geologist you know quite well that the current conditions are nothing like the ones that brought about that rapid melting. For one thing CO2 levels were much lower at that time so they were clearly not caused by CO2.
As I'm sure you know CO2 lags past warmings rather than leading them, therefor falsifying any theory that CO2 caused the warming. (Please spare me the standard warmer nonsense about "unkown" factors starting the warming then good ol' CO2 coming in to finish the job.)
Is it your contenton that we actually face exponential sea level rise from melting of the Greenlad ice sheet? If so please give evidence to support your claim.
Put up or shut up Andrew.
Lance -
Hansen explicitly states his starting point; you got your math wrong. Just admit it and quit whining about it.
If your thought experiment implies different abounts of time then it is clearly wrong; I don't see what you are trying to prove by it.
If melting rate is proportional to temperature then the ice cube that is heated fastest will melt most over a given time.
The link I gave showed that rapid sea level changes due to melting have happened before, thus disproving your contention that there was no data to support such a rapid rise. The conditions (changing NH summer insolation) causing the melting didn't even include a net planetery forcing; the mechanism (once the melting started) appear to have been around 2/3rds albedo changes and 1/3 CO2 release feedback; the amount of lag, if any, is highly uncertain. In any case, since CO2 warming is not seen as a driver for this transition, lags are pretty irrelevant.
Sea level rise from a point temperature change would be expceted to follow an S-shaped curve which would appear exponential in the first 1/3 or so of the time interval.
Andrew,
Actually I did find a way to interpret Hansen's seal level example to give 5.12 meters but it doesn't involve your spurious 1 cm level being the starting point for sea level before the iteration even begins which you wrongly claim is "explicitly" stated.
If you interpret the words "and this doubles each deacade" to mean that the doubled amount is the "additional rise" not the net rise then you get Hansen's figure of 5 metres.
Decade Rise in seal level
2005-2015 1 cm
2015-2025 2 cm
2025-2035 4 cm
2035-2045 8 cm
2045-2055 16 cm
2055-2065 32 cm
2065-2075 64 cm
2075-2085 128 cm
2085-2095 256 cm
--------- ------
> 512 cm Total of added rises
This is not clear from the wording of his paragraph, and indeed is not consistant with your attempt to cheat in a figure of 2cm for sea level at the end of the decade 2005-2015 as indicated in your above post.
I find your twisting of my ice block example equally dishonest. Either you grossly misunderstood my argument or purposely tried to obfuscate it.
In any event you have failed to put forward any evidence that, as Hansen claims in his essay's title,
"Huge Increases in Sea Level are Coming-Unless We Act Now"
Notice that he doesn't say may face or possibly face, and that he uses the unscientific word "huge" to describe the coming seal level changes. This is why I rightly labeled Hansen an unscientific scaremonger.
He provides no evidence to support his claim and so far, though I have repeatedly asked for it, neither have you.
Using evidence that sea level has risen quickly in the past as evidence for specific rises in the future is like claiming that a huge asteroid is going to hit the planet in one hundred years because there is geological evidence that one did in the past.
As I said before "Put up or shut up."
"As I'm sure you know CO2 lags past warmings rather than leading them, therefor falsifying any theory that CO2 caused the warming. (Please spare me the standard warmer nonsense about "unkown" factors starting the warming then good ol' CO2 coming in to finish the job.)"
Prove this, Lance. This is standard neoconservative nazi-speak I'm getting damn sick of refuting. The standard neoconservative "proof" relies upon ice-core samples that have been contaminated with meltwater. This is the world's #1 human extinction threat; I'm not pulling any punches here with those on the other side. :(
Since when do you have to be a "neoconservative nazi" to be unimpressed by the weak evidence for anthropogenic climate change? You seem to be confused between political theories and scientific ones.
As far as the CO2 lagging warming being a "standard neoconservative" idea, here is the standard line from RealClimate.
"From studying all the available data (not just ice cores), the probable sequence of events at a termination goes something like this. Some (currently unknown) process causes Antarctica and the surrounding ocean to warm. This process also causes CO2 to start rising, about 800 years later. Then CO2 further warms the whole planet, because of its heat-trapping properties. This leads to even further CO2 release. So CO2 during ice ages should be thought of as a "feedback", much like the feedback that results from putting a microphone too near to a loudspeaker. "
Now notice that they acknowledge that past warming events have happened 800 years BEFORE the CO2 begins to rise. This is not controversial among climate scientists, even non-nazi scientists.
They then claim the warming is due to as yet "unkown" factors. Then in a move of breathtaking illogic they claim that the CO2 is responsible for the warming from that point on.
Oh, also they don't mention that at the end of these inter-glacial periods the temperature goes down while the CO2 level remains high for hundreds of years after the cooling.
What do they cite as evidence for this amazing result? Why climate models of course! So you see it is clear that climate models prove that climate models are true.
If that doesn't make you queasy I'm not sure what would. If you don't see a fundamental problem with this sort of argument, I don't know what would be enough to sway your "faith" in AGW theory.
I'll be honest, I've no idea what you just posted.
"They then claim the warming is due to as yet "unkown" factors. Then in a move of breathtaking illogic they claim that the CO2 is responsible for the warming from that point on"
Are you suggesting CO2 does initiate a "Greenhouse Effect" or are you suggesting the opposite? Are you suggesting CO2 levels are miniscule in affecting climate change compared to the unknown 800 yr Southern Ocean cycle hypothesized (plz link, I'll read any relevant papers)?
Oh c'mon Phil, I think my comments were pretty easy to understand.
You claimed that my comments,
"As I'm sure you know CO2 lags past warmings rather than leading them, therefor falsifying any theory that CO2 caused the warming. (Please spare me the standard warmer nonsense about "unkown" factors starting the warming then good ol' CO2 coming in to finish the job.)"
were "standard neoconservative nazi-speak" that you were "geting tired of refuting."
I then quoted from that hallowed source of AGW gospel, RealClimate, that the CO2 lag was real. Also, as I pointed out in the previous post, they claimed that some "unkown" factor had started the warming 800 years before your favorite molecular villian, CO2, had even arrived on the scene. They illogically, and without evidentiary support, then claimed that CO2 was responsible for much, if not all of the warming after it's arrival. And what, prey tell, did they use as evidence that CO2 was the reason for any warming after its tardy arrival? Their very own climate model of course!
Does that clear things up or are you going to start playing the same games as Andrew to avoid facing my points? Because, honest to God I have better things to do than play word games with the AGW faithful.
The object of debate here is whether carbon dioxide absorbs more incoming radiant energy in the form of incoming sunlight (from the Sun, at the *centre* of the Solar System), than it blocks outgoing towards space (away from the *sphere* of Earth)?
This (the Greenhouse Effect, used by among other things, greenhouses) is basic physics that was discovered in the 19th century by John Tyndall. For instance, see this link:
http://www.tyndall.ac.uk/forum/about-john-tyndall/
We know that since the Industrial Revolution, our emmissions of GHGs (especially CO2) have risen...we know oceans have absorbed about half this anthropogenic amount, and that the other half has gone into the atmosphere. The latter has been measured by scientific instruments and sensors of various types; would be happy to link if needed. I don't see how the basic physics of radiant forcing can be seriously attacked: it is a reason the south side of a well-insulated residence warms up on a sunny day. Lance, you're saying heat radiates out a closed window as fast as sunlight radiates in? Glass and CO2 produce the same effect here.
I dont mean to stifle debate, my point is that the debate should be about: caps vs trading; rich vs poor paying; historical emitters vs contemporary carrying the burden; emitters at 1990 or some other known time when warming was a problem vs emitters today, carrying the burden; behaviour changes vs increased mitigation R+D; whether snow albedo effects cancel out coniferous tree carbon sequestration; whether geoengineering distracts from technically easier solutions; whether the coal industry should be treated like big tobacco....
The nazi reference was that debating 150 year old physics is like debating whether or not the Holocaust was right, instead of debating how to ensure it never happens again. Mid-21st century Africans wouldn't think I'd gone too far by invoking the Holocaust, they already had to deal with generic AIDS retrovirals being blocked; don't need more preventable mass deaths.
Phil,
I, and many others, are unconvinced that anthropogenic CO2 is moslty responsible for the modest 0.6-0.8C warming over the last one hundred years. All your subsequent arguments equating this issue to "holocaust" denial and the tobacco companies are moot if we are correct, not to mention reactionary and emotionally driven.
It would appear that you are intrenched in your opinion on this subject and we will make little headway in any discussion of the scientific issues involved.
I have made an efort to keep this post civil and respectful. You are clearly an intelligent person. I just happen to think you are wrong on this issue.
We live in an open democracy and are entitled to differences of opinion.
Nice chatting with you.
I think greed leading to the unneccessary deaths of hundreds of millions or more is every bit as insidious as the direct execution of 12 million; no emotions just math.
To any AGW denialists: what and where are these epicycles that behave exactly like CO2 radiant forcing in our atmosphere, except they undo the effects of this known CO2 Greenhouse Effect and replace it with their own physical process that initiates the exact same process? Solar forcing (variations in the Sun's intensity) was the best bet, but has been proven (scientifically, not logically from inaccurate premises) not to be a powerful enough process. To deny AGW is to deny many fields of science.
I at least understand the honest argument: it's my money, hands off. Then the debate switches to David Stern style resource costing, and an explanation of why 25% of a mid-21st century growing $hundreds-of-trillion$ economic pie, is better than 75% of a shrinking mid-21st century $tens-of-trillion$ economic pie.
Hi Phil,
You are all over the map. Let me see if I can try to honestly recap your points.
I can see that you are convinced that the science of AGW is rock solid and beyond reproach. In your estimation it is simply a matter of indisputable physics that CO2 is reponsible for the largest portion of the 0.6-0.8C warming of the last century. Also, there is equally sound evidence that the warming is going to accelerate to even more dangerous levels over the next century.
You then make the leap that it will lead to the deaths of "hundreds of millions" of people. (This is at least a rosier statement than your previous claim that it was the "#1 human extinction threat.")
You then slide into a hand waving economics argument that I really tried to follow but couldn't. I assume it was making the point that trading the short term economic hardship of abandoning fossil fuels will be offset by the eventual gains from avoiding the dangerous warming you are convinced is coming.
Sorry, but I totally disagree with pretty much everthing you said. I'm not sure why we have come to such divergent opinions on the subject but I suspect we are pretty much wasting each others time from here on out.
I have found your arguments interesting for the shear absolute certainty, both scientific and moral, that they display if nothing else.
My television doesn't utilize a cathode-ray tube. It's illuminated by tiny fireflies. And I don't hold this opinion just because my leaders have close ties to the firefly industry and my media likes low tax rates.