After yesterday’s tongue-in-cheek mention of Obama’s healing the planet (and sea level rise with it) here’s the real lowdown on the current knowledge. It seems that all the science that Hansen uses to base his 5-6 meter sea level rise has now been overturned by more recent scientific findings. Basically, there is no longer any valid scientific backing for Hansen’s extreme sea level rise projections. – Anthony
Guest essay by Patrick J. Michaels and Paul C. “Chip” Knappenberger
Retired NASA scientist and peripatetic global warming crusader James Hansen has a—let’s put it delicately—unique view of sea-level rise resulting from mankind’s use of fossil fuels. Specifically, he believes global average sea level will rise some 15 to 20 feet by 2095. The central estimate from the most recent report from U.N.’s Intergovernmental Panel on Climate Change (IPCC) is about 15 inches.
Hansen’s an outlier, and proud of it, thinking himself more courageous than other scientists who, he says, are “reticent” to tell the public how bad things really are.
We think that Hansen doth protest too much. His scientific arguments for a large and rapid sea level rise this century simply don’t hold water.
He laid out a summary of his logic on sea level rise in a book chapter (co-authored with Makiko Sato) published last year titled “Paleoclimate Implications for Human-Made Climate Change.”
Below, we have reproduced the relevant text on sea-level rise from that chapter along with our comments highlighting recent findings from the scientific literature which refute each and every one of Hansen’s claims.
From Hansen and Sato (2012):
Sea Level Change Estimates for the 21st Century
IPCC (2007) projected sea level rise by the end of this century of about 29 cm (midrange 20-43 cm, full range 18-59 cm). These projections did not include contributions from ice sheet dynamics, on the grounds that ice sheet physics is not understood well enough.
This is true. Twenty-nine centimeters is the same as 11.4 inches—about 1 foot. And although the IPCC did not specifically include ice sheet dynamics in their models, they did estimate that dynamics may add another 4 inches to their midrange forecast.
Rahmstorf (2007) made an important contribution to the sea level discussion by pointing out that even a linear relation between global temperature and the rate of sea level rise, calibrated with 20th century data, implies a 21st sea level rise of about a meter, given expected global warming for BAU greenhouse gas emissions. Vermeer and Rahmstorf (2009) extended Rahmstorf’s semi-empirical approach by adding a rapid response term, projecting sea level rise by 2100 of 0.75-1.9 m for the full range of IPCC climate scenarios. Grinsted et al. (2010) fit a 4- parameter linear response equation to temperature and sea level data for the past 2000 years, projecting a sea level rise of 0.9-1.3 m by 2100 for a middle IPCC scenario (A1B). These projections are typically a factor of 3-4 larger than the IPCC (2007) estimates, and thus they altered perceptions about the potential magnitude of human-caused sea level change.
True, these projections are 3-4 times larger than the IPCC estimates. They are also founded on weak arguments. As we discussed in a Current Wisdom post back in December, new research by Jonathan Gregory and colleagues concluded that the methodology (a “semi-empirical” approach) used in each of the specific papers cited by Hansen was inadequate to base robust sea level rise projections. According to Gregory, et al., “[The lack of a relationship between global climate change and the rate of global mean sea level rise, GMSLR] also calls into question the basis of the semi-empirical methods for projecting GMSLR, which depend on calibrating a relationship between global climate change or radiative forcing and the rate of GMSLR from observational data (Rahmstorf, 2007; Vermeer and Rahmstorf, 2009; Jevrejeva et al., 2010).” Note that the methodology employed by Jevrejeva et al., (2010) is the same as that used in Grinsted et al (2010) as cited by Hansen. So, to the extent that the studies cited by Hansen “altered perceptions about the potential magnitude of human-caused sea level change” they led to misperceptions.
Alley (2010) reviewed projections of sea level rise by 2100, showing several clustered around 1 m and one outlier at 5 m, all of these approximated as linear in his graph. The 5 m estimate is what Hansen (2007) suggested was possible under IPCC’s BAU climate forcing. Such a graph is comforting – not only does the 5-meter sea level rise disagree with all other projections, but its half-meter sea level rise this decade is clearly preposterous.
Hansen admits that his 5 meter (16 feet) sea level rise projection by 2100 is a large outlier. We don’t disagree!
However, the fundamental issue is linearity versus non-linearity. Hansen (2005, 2007) argues that amplifying feedbacks make ice sheet disintegration necessarily highly non-linear, and that IPCC’s BAU forcing is so huge that it is difficult to see how ice shelves would survive. As warming increases, the number of ice streams contributing to mass loss will increase, contributing to a nonlinear response that should be approximated better by an exponential than by a linear fit. Hansen (2007) suggested that a 10-year doubling time was plausible, and pointed out that such a doubling time, from a 1 mm per year ice sheet contribution to sea level in the decade 2005-2015, would lead to a cumulative 5 m sea level rise by 2095 [Hansen and Sato Figure 7].
Fig. 7. Five-meter sea level change in 21st century under assumption of linear change and exponential change (Hansen, 2007), the latter with a 10-year doubling time.
The good old “exponential” rise—the alarmist’s dream. Even though you can’t tell I am correct now, just wait! Never mind that most of us will be long dead by then, or that every other observational or theoretical paper disagrees with the magnitude of Hansen’s non-linear rise—as Hansen freely admits:
Nonlinear ice sheet disintegration can be slowed by negative feedbacks. Pfeffer et al. (2008) argue that kinematic constraints make sea level rise of more than 2 m this century physically untenable, and they contend that such a magnitude could occur only if all variables quickly accelerate to extremely high limits. They conclude that more plausible but still accelerated conditions could lead to sea level rise of 80 cm by 2100.
But of course, everyone else is wrong:
The kinematic constraint may have relevance to the Greenland ice sheet, although the assumptions of Pfeffer at al. (2008) are questionable even for Greenland. They assume that ice streams this century will disgorge ice no faster than the fastest rate observed in recent decades. That assumption is dubious, given the huge climate change that will occur under BAU scenarios, which have a positive (warming) climate forcing that is increasing at a rate dwarfing any known natural forcing. BAU scenarios lead to CO2 levels higher than any since 32 My ago, when Antarctica glaciated. By mid-century most of Greenland would be experiencing summer melting in a longer melt season. Also some Greenland ice stream outlets are in valleys with bedrock below sea level. As the terminus of an ice stream retreats inland, glacier sidewalls can collapse, creating a wider pathway for disgorging ice.
In fact, a large body of recent literature into the dynamics of the Greenland ice sheet supports to idea that kinematic constraints act to keep ice loss from Greenland in check, even in a warming climate—contrary to Hansen’s assertions. We have detailed these in past issues of Current Wisdom. For example, we discussed the work of Moon et al. (2012) who concluded: “Finally, our observations have implications for recent work on sea level rise. Earlier research used a kinematic approach to estimate upper bounds of 0.8 to 2.0 m for 21st-century sea level rise. In Greenland, this work assumed ice-sheet-wide doubling of glacier speeds (low-end scenario) or an order of magnitude increase in speeds (high-end scenario) from 2000 to 2010. Our wide sampling of actual 2000 to 2010 changes shows that glacier acceleration across the ice sheet remains far below these estimates, suggesting that sea level rise associated with Greenland glacier dynamics remains well below the low-end scenario (9.3 cm by 2100) at present. Continued acceleration, however, may cause sea level rise to approach the low-end limit by this century’s end.” In other words, kinematic increases in ice loss from Greenland may add 4 inches of sea level rise by 2100—nowhere close to leading to Hansen’s multi-meter rise.
Hansen continues:
The main flaw with the kinematic constraint concept is the geology of Antarctica, where large portions of the ice sheet are buttressed by ice shelves that are unlikely to survive BAU climate scenarios. West Antarctica’s Pine Island Glacier (PIG) illustrates nonlinear processes already coming into play. The floating ice shelf at PIG’s terminus has been thinning in the past two decades as the ocean around Antarctica warms (Shepherd et al., 2004; Jenkins et al., 2010). Thus the grounding line of the glacier has moved inland by 30 km into deeper water, allowing potentially unstable ice sheet retreat. PIG’s rate of mass loss has accelerated almost continuously for the past decade (Wingham et al., 2009) and may account for about half of the mass loss of the West Antarctic ice sheet, which is of the order of 100 km3 per year (Sasgen et al., 2010).
While West Antarctica may be losing ice mass, East Antarctica appears to be gaining, as higher sea surface temperatures lead to more moisture in the atmosphere which leads to greater snowfall there. Since the temperatures are far below freezing throughout the year, the increased snowfall accumulates over time, adding ice mass across vast areas of East Antarctica. This effect has long been anticipated, and observations over the past few years are now starting to verify this forecast. (e.g., Boening et al., 2012; Lenaerts, et al., 2013). The latest estimates of the net ice loss from the whole of Antarctica find either minimal loss (a sea level rise equivalent of 0.71 inches/century) with no acceleration (King et al., 2012) or that the continent is actually gaining ice mass (Zwally et al., 2012). Either finding is completely at odds with Hansen’s accelerating ice loss scenario.
PIG and neighboring glaciers in the Amundsen Sea sector of West Antarctica, which are also accelerating, contain enough ice to contribute 1-2 m to sea level. Most of the West Antarctic ice sheet, with at least 5 m of sea level, and about a third of the East Antarctic ice sheet, with another 15-20 m of sea level, are grounded below sea level. This more vulnerable ice may have been the source of the 25 ± 10 m sea level rise of the Pliocene (Dowsett et al., 1990, 1994). If human-made global warming reaches Pliocene levels this century, as expected under BAU scenarios, these greater volumes of ice will surely begin to contribute to sea level change. Indeed, satellite gravity and radar interferometry data reveal that the Totten Glacier of East Antarctica, which fronts a large ice mass grounded below sea level, is already beginning to lose mass (Rignot et al., 2008).
Oops. Wrong again. Breaking scientific research just published online from the journal Science (Rowley et al., 2013) conclude that the apparent 25 ± 10 meter sea level rise during the Pliocene was probably due to vertical land motions during the intervening 3 million years rather than an actual sea level rise from more water in the oceans from melting ice (Hansen’s mechanism). Rowley and colleagues developed a model of the dynamics of the earth’s mantle and glacial rebound that can explain why ancient (Pliocene) seashore deposits are located about 25 meters above the current sea level across the southeastern United States. Previously, as in the research relied upon by Hansen, these elevated shoreline deposits has been used as primary evidence arguing for much higher sea levels during the warmer Pliocene era. Again, contrary to Hansen’s assertions, Rowley et al. state that “[i]nferences of Pliocene global sea-level heights or stability of Antarctic ice sheets therefore cannot be deciphered in the absence of an appropriate mantle dynamic reference frame.” Hansen has made no such considerations.
Hansen concludes:
The eventual sea level rise due to expected global warming under BAU GHG scenarios is several tens of meters, as discussed at the beginning of this section. From the present discussion it seems that there is sufficient readily available ice to cause multi-meter sea level rise this century, if dynamic discharge of ice increases exponentially. Thus current observations of ice sheet mass loss are of special interest.
Unfortunately for Hansen and fortunately for the rest of us, virtually all the science comprising his “present discussion” has been undermined by more recent findings. The foundation of his “multi-meter sea level rise this century” which was never robust to begin with, has now collapsed completely.
We do agree, however, with his final sentence that “current observations of ice sheet mass loss are of special interest.” This is a topic that we very often discuss in our Current Wisdoms and will most certainly do so in the future. The gist of the recent observations is that the rate of sea level rise is quite modest (about a foot per century) and any speed-up is also expected to be quite modest—a combination which proves Hansen’s projections are alarmist.
And we are not reticent about it.
References:
Boening, C. et al., 2012. Snowfall-drive mass change on the East Antarctic ice sheet. Geophysical Research Letters, 39, DOI:10.1029/2012GL053316.
Hansen, J.E., and M. Sato, 2012. Paleoclimate implications for human-made climate change. In Climate Change: Inferences from Paleoclimate and Regional Aspects. A. Berger, F. Mesinger, and D. Šijački, Eds. Springer, 21-48, doi:10.1007/978-3-7091-0973-1_2.
Lenaerts, J.T.M., et al., 2013. Recent snowfall anomalies in Dronning Maud Land, east Antarctica, in a historical and future climate perspective. Geophysical Research Letters, doi:10.1002/grl.50559.
King, M., et al., 2012. Lower satellite-gravimetry estimates of Antarctic sea-level contribution. Nature, doi:10.1038/nature
Moon, T., I. Joughin, B. Smith, and I. Howat, 2012. 21st-century evolution of Greenland outlet glacier velocities. Science, 336, 576-578, doi:10.1126/science.1219985
Rowley, D.B., et al., 2013. Dynamic topography change of the Eastern United States since 3 million years ago. Sciencexpress, doi:10.1126/science.1229180
Zwally, H.J., et al., 2012. Mass gains of the Antarctic ice sheet exceed losses. Presentation to the SCAR ISMAA Workshop, July 14, 2012, Portland Oregon.
Hansen is basically spiking his retirement at the expense of legit science and reasoned public policy debate.
Hansen expects sea level to rise in the next 82 years more than it did during the height of warmth during the Eemian, the previous interglacial. This is patent nonsense, yet bought hook, line & sinker by the media & low-information voting public.
The Eemian, as you know, was much warmer than our current interglacial (fading fast), without benefit of a Neanderthal industrial revolution. Scandinavia was an island, for instance, & hippos swam in the Thames at the site of London. Yet neither the West Antarctic nor Greenland Ice Sheets disappeared (otherwise no cores from that interval), to say nothing of the massive East Antarctic sheet.
Darn, and I was hoping for beach front property in Richmond. All of these sea level rise predictions seem to be of the not-seen-yet-but-just-wait type.
Does Gavin parrot this same nonsense at ReallyWrongClimate?
I wonder if Hansen will follow Gore’s lead & retire to a beachfront? Maybe in FL instead of CA:
“Miami and its suburbs are located on a broad plain between the Florida Everglades to the west and Biscayne Bay to the east, which also extends from Florida Bay north to Lake Okeechobee. The elevation of the area never rises above 40 ft (12 m) and averages at around 6 ft (1.8 m) above mean sea level in most neighborhoods, especially near the coast. The highest undulations are found along the coastal Miami Rock Ridge, whose substrate underlies most of the eastern Miami metropolitan region. The main portion of the city lies on the shores of Biscayne Bay which contains several hundred natural and artificially created barrier islands, the largest of which contains Miami Beach and South Beach.”
He might like to live on the Rock Ridge Island to be.
I note Hansen’s fondness for the word “disgorge” when describing to ice loss:
disgorge (verb):
To discharge by the throat and mouth : vomit
Vomit – well, that’s what I think of whenever I read anything written by Hansen…
Why is anyone still listening to this mollusk?
What precisely are the catastrophes predicted (or projected) by CAGW-believing alarmists?
Few actually buy Hansen’s boiling oceans on the Venus Express, so what do they foresee that justifies the end of industrial civilization?
Sea level rise? We’ve dealt with the same rate of increase as now (or more) for over a century.
Drought in the Great Plains breadbasket? Crop yields will increase in Canada & the Ukraine. In most places, in fact, thanks to more abundant plant food in the air.
Higher air conditioning costs? Build more nuke plants, plus save on winter heating.
“Extreme weather”? No sign of it. Indeed the opposite, as elementary meteorology would predict.
I’m sure to be missing some alleged catastrophe the arrival of which keeps getting postponed, rather like the Second Coming.
None of the alarmists’ doomsday scenarios is likely, in any case, so why worry? Unless their real goal is more government control.
Like Pat Michaels, RC pretty much pushes the Pfeffer at al. (2008) argument.
It’s good to always remember that he was the custodian of the GISS temperature record. Someone as liberal with the science as this example shows certainly needs to have their temperature record adjustments audited with utmost scrutiny.
It would be interesting to see if Gavin begins to dissociate himself from Jimbo’s extremism. He could really increase his street cred if he does.
Worked out a couple of years ago 400,000 cubic kilometres of ice must melt to raise sea level by 1 metre. Ice needs 334 kilojoules per kilogram to melt at 0C, will need more if colder. Problem is how to get that energy to the ice, especially over the limited time scale, just 100 years. And 5 metres of sea level rise? Sun would have to go nova.
@ JCH says:
May 29, 2013 at 10:42 am:
The science of ice sheets is totally settled. It is settled that no one knows.
But assuming the least melting has more scientific basis than the worst, ie WAIS collapse, as per Hansen.
There never was any justification for it. I keep drumming this fact in my comments but people just don’t get it. What got me into climate science in the first place was Al Gore showing a map of Florida under water from a twenty foot sea rise. This was obvious nonsense and pretty soon I had proof of it. But neither Science nor Nature would publish it so I went one step further and published it in my book. Here is the lowdown on sea level. Chao, Yu, and Li (11 April Science 2008) corrected all published figures on sea level rise for water held in storage since 1900. When these corrected figures were plotted sea level curve for the last 80 years became linear and had a slope of 2.46 millimeters per year. This is all you need to know about sea level. If you have done data evaluation you should know that anything that has been linear this long is not about to change anytime soon. Hence all this babble about the recent rate change is just nonsense and can be thrown out. You can predict from their sea level curve that sea level rise in a century will be 24.6 centimeters or a little under ten inches and you will probably be right within ten percent or better. Any other nonsense about meters or feet of sea rise is just stupidity by people sitting in a computer cave somewhere in an ivory tower and practicing wishful thinking.
Appreciate the comments on ice sheet dynamics. Complications such as underlying geology, more snow with more evaporation, etc make simplistic assumptions sure to be wrong.
The Arctic Ocean had sea ice in the high CO2 environment of the Eocene. Greenland’s ice caps coalesced into an ice sheet in the balmy Miocene.
There is so much to find out, but thanks to a homeostatic planet, plenty of time in which to learn.
Hydrocephalic indeed.
Onerous mitigations contained in California’s pair of “global warming solutions” acts were based on these catastrophic predictions of sea level rise. Will Gov. Brown now back off on these ridiculous measures? Probably not. They were patterned after Agenda 21 (redistribution, diminishing private ownership of property, social justice, equity).
Damn, there goes the business plan of selling houses with flexible fittings built on concrete pontoons instead of slabs, buy a house now and after the flooding you’ll still have a house barge. And the franchises have been selling so well in Jersey. Of course those mooks have been tossing in a “hurricane protection” angle, best to distance myself before the investigations start. Hansen’s associates should be able to sympathize.
Including or excluding Archimedes’ principle …?
On the occasion of Hansen’s retirement, Gavin had this interesting comment-
“…the stuff that Jim wrote 20 years ago has set the tone for the whole field [and the] predictions he made have generally worked out very favorably (for him, not really the planet).”
Gavin Schmidt on Hansen retiring, 04/02/2013
Hansen’s prediction of 5 m rise by 2100 is on the extreme low end of his many sea level prognostications. But this classic Hansenism takes the cake-
“”I’ve come to conclude that if we burn all reserves of oil, gas, and coal, there is a substantial chance we will initiate the runaway greenhouse. If we also burn the tar sands and tar shale, I believe the Venus syndrome is a DEAD CERTAINTY.”
Hansen, Storms of My Grandchildren
Hansen’s Venus syndrome requires evaporation of the world’s oceans, which is equivalent to a sea level rise to the tropopause, or about 17,000 meters at the equator.
Now that is some sea level rise, don’tcha know!
Technically, of course, Hansen is not “falsified” by opposing theories or by more credible scientists.
He will, however, be ultimately falsified by the data as it accumulates.
But, by the time such data accumulates, he will also have killed many millions by his false and extreme religion of CAGW that DOES kill innocents every day by denying them food, clothing, shelter, heat and cooling, transportation, sewage disposal and treatment, clean water, and a healthy, growing economy
I do hope that Hansen lives long enough for him to see his predictions torn to shreds and laid at his feet by a grateful nation.
Another day, another funny. Glad Pat and “Chip” haven’t lost their senses of humor.
REPLY: another day, another snide comment from “sceptical” who actually isn’t sceptical at all – Anthony
Chad Wozniak says:
May 29, 2013 at 10:27 am
Why is anyone still listening to this mollusk?
Because the media, given the choice between “noting to see here, move along” and “it’s worse than we thought!” will always go for the latter, since the headlines are more interesting and draw readers. So, Hansen has immensely more entertainment value – what? You thought the news was a source of information??
From John Tillman on May 29, 2013 at 11:10 am:
Except the current default setting is ice age, heavy planetary glaciation. We’re in an interglacial, a temporary respite. On a geological scale, this brief extreme period is as “homeostatic” as an eruption of Old Faithful. We’ve had the initial surge, the flow has been tapering off (long term temps show cooling).
Right now we’re waiting to see if there’ll be spurting, or if the collapse will simply be quick and deadly.
“Plenty of time” is a perspective issue. We will not be frying. But it’s quite possible we’ll be plunged back into the ice before we figure out how the climate of an interglacial really works.
I don’t think Gavin is too worried about his Pat-cred. You don’t see Dawkins struggling to meet the Gish standard, ya know?
“Either finding is completely at odds with Hansen’s accelerating ice loss scenario.”
Did he say acceleration would encompass the entire continent by the year 2012? No? Oh, then it isn’t really at odds with his statement then, is it?
Does every one realize that Dr. Hansen’s doubling every ten years, exponential, 5 meter sea level rise possibility would result in a one millimeter per DAY of sea level rise by December 31, 2100?
That’s 100 times what today’s, if you can believe it, rate is. That means all the worlds rivers, calving glaciers and ocean warm up would have t be proceeding at 100 times today’s rate.
Do these guys ever run the numbers?
Don’t forget that Hansen is an astronomer and his idea of CO2’s potential to warm came from his extrapolation of what was going on on Venus. With the hubris that can go with someone in his work (and the lower standards that necessarily go with trying to make measurements in the Universe) , he trod into earth science as if there was no body of knowledge about paleoclimate and even historic climate. He learned his climatology by having things that he’d never heard of before, like the 20th century hot year of 1936, the LIA, the MWP, etc thrust in his face. Hey, why accept this stuff- let’s get rid of it (his hubris was worse than we thought). Most of his work has been toward cooling off such inconvenient things as the 1936 record, which in 1998 he did by tilting the instrumental graph anticlockwise a few degrees to make 1998 hotter.
His prediction over 20 years ago that the highway along Hudson R. near his office would be underwater by now:
http://wattsupwiththat.com/2010/11/28/freaking-out-about-nyc-sea-level-rise-is-easy-to-do-when-you-dont-pay-attention-to-history/
“He said that [in 20 years]: “The West Side Highway [which runs along the Hudson River] will be under water. Problem is, here it is 20 years later, and people still drive that highway today without the use of Jet-Skis.”
This didn’t cause him to recant – he just changed the curve from linear to exponential and hung onto the same forecast for 2100. Hey, what’s an order of magnitude one way or the other anyway in predictions such as SLR by 2100?
– – – – – – –
Kaboom,
A grassroots effort to have NASA’s GISS independently audited for specific periods is needed. I recommend that a good period to audit NASA’s GISS would be the period that corresponded to the periods of preparation of the IPCC’s TAR, AR4 and AR5. We could see if GISS’s activities / products influenced and/or supported the manipulations of the assessment processes by the IPCC.
Let loose the independent skeptical auditors!
John
Hey come on, he ‘s only off by a few meters in sea level rise. Only one or two, maybe three orders of magnitude wrong.
What about the oceans boiling due to the back radiation from additional anthropogenic CO2 ?? He’s off by a silly number of orders of magnitude – a hundred maybe, plus or minus ?? Could it be the most wrong a “scientist” has ever been in the history of science ??
Is that Powerpoint slide still on the internet? I think my computer might have chosen to disgorge it Frank (smiley face).
25 years ago Hansen said the West Side Highway nearby his office would be underwater in 40 years. That implied a fairly linear increase, or at least an exponential increase whose initial rise wouldn’t be hidden until far in the future. If the Hudson hasn’t risen by more than an inch in the next five years, his prediction will look very unlikely.
Gary Pearse – at 1:15 pm
Don’t forget that Hansen is an astronomer and his idea of CO2′s potential to warm came from his extrapolation of what was going on on Venus.
And that’s because Venus has an atmosphere that’s 95% CO2 and it’s hot enough there to melt lead?
Mars has an atmosphere that’s 95% CO2 and it’s cold enough there to snow dry ice.
stacase says:
May 29, 2013 at 2:52 pm
Well observed. Venus suffers under the mass of its atmosphere, not the composition thereof.
As always, the best long-range forecast is a very long-range forecast, so that nobody alive today will be alive to verify it.
While his grandchildren snicker in the background.
I believe by 2095 the absolute concentration of CO2 may actually be lower than it is right now. I base this on the trends in efficiency and population. Efficiency keeps getting better and population is clearly starting to level off, having started to do so two generations ago in the most advanced countries and now beginning in even the least developed places. These two trends will radically reduce both output and ongoing concentration. The biosphere will rapidly take up the CO2 that is currently in technical slight excess. Meanwhile as a knock from the improved efficiency there is less waste heat and hence less anthropogenic heat flux at and near the surface. Whatever impact 20th and early 21st Century warming has had on sea level may actually reverse or least that component will be removed, leaving the overarching long tail of the Great Melt.
given expected global warming for BAU greenhouse gas emissions
Perhaps we should wait for the expected warming to materialize before being concerned about sea level rise. Both Hadcrut3 and Hadsst2 show no rise in temperature for over 16 years since March 1997. See:
http://www.woodfortrees.org/plot/hadcrut3gl/from:1997.1/plot/hadcrut3gl/from:1997.1/trend/plot/hadsst2gl/from:1997.1/plot/hadsst2gl/from:1997.1/trend
Heh. “IF”!
All these weasel words Hansen et al. use such as “if”, “seems”, “implies”, “potentially”, “may”.. and yet somehow he’s damn certain the planet’s doomed. One thing you might want to consider, Jimmy:
“Doubt is not a pleasant condition, but certainty is absurd.” – Voltaire
John Whitman says:
With this government? The very one that told the Justice Dept to conduct an investigation into the activities of the Justice Department?
Laughter is about the only thing that keeps me from slitting my wrists.
“stacase says:
May 29, 2013 at 2:52 pm”
Excluding distance from the Sun, the mass of the atmospheres are very different to that of Earth, thus pressures are very different. Venus is about 92 times that of Earth whereas Mars is about less than 10 millibars.
I’ve come to the conclusion ( as a lefty believer in climate change, but hopefully not a catastrophist) over the years that regardless of which side of the debate you adhere to, predictions are always a disaster and invariably return to bite you on the bum. Maybe terms like ‘potentially’ could be used or ‘this is possible in a given set of circumstance’ would be better. Although I believe that humans are influencing the climate to an unknown degree, I do believe skeptics have a much better case when they use observational data to support their arguments than those on the believer side who exagerate potential impacts to gain support. Exageration may have a passing influence, but in the long run it does more damage to the believer cause than any peer reviewed paper can ever do, and sadly this article highlights a classic example of the problem.
I like growing my own crops, but the experience of climate change in my gardens are that I can no longer grow the crops such as corn and french beans that require a warmer summer in the same way as I did ten years ago, hence I have invested in a large polytunnel. This is climate change for us in Wales, a cooling and reduction of sunlight. So when someone tells me to to grow drought resistant veg it can be really annoying, and to see James Hansen’s predictions really undermines local faith in models and predictions. I’m still an adherent of climate change, but we do need to talk about cooling and it’s effects on UK agriculture.
Has Hansen actual made ANY claims that have stood the test of time and enquiry ?
Venus also rotates very slowly (backwards in fact). A day on Venus is 116 Earth days long (the Sun is up for 116 days).
On Earth, while the Sun is up, the average temperature rises 0.8C per hour. If you run the numbers on how fast energy is accumulating to produce those temperature increase rates, and apply that to how long the Sun is up on Venus (including its higher Albedo), you easily get into the 400C range. Now throw in very strong winds and higher atmospheric pressure to spread the heat around to the dark side more-or-less consistently, one gets the average temperature on Venus.
Let’s say the Sun was up on Earth for 116 24 hour periods. How hot would it get. Would the ground be thoroughly baked. Would lakes evaporate away. Would the ocean evaporate on the sunny side. The answer is, we would not be here and the Earth would be a completely different place with 400C temperatures.