The above image shows the coastline of Florida as it was at the Last Glacial Maximum (LGM) 20,000 years ago, now, and as it was 3 million years ago. Mark Lynas in his book Six Degrees published in February 2007 told us of a 1996 paper recording the discovery of fossil leaves from a stunted, ground hugging beech which grew just 500k from the South Pole 3 million years ago. The temperature there now is a bracing -39C.
Lynas, who spent eight years compiling his book from peer-referenced papers, and is generally regarded as scientifically accurate, tells us that 3 million years ago the temperature was 2-3C warmer than now and CO2 levels were 360-400ppm, much as now.
This information would have been available to the IPCC, whose cut-off for considering scientific papers was, I understand, May 2006. Yet in 2007 when the Arctic ice coverage took a dive, they effectively buried the issue of sea level change.
Before I go any further, I should point out that the sea level 3 million years ago is estimated to have been 25 metres, plus or minus 10, so the image above has taken the upper extreme. The LGM was about 5C colder than now, so the image illustrates the difference a few degrees here or there can make to your coastline.
What did the IPCC do?
Scientists contributing to IPCC Fourth Assessment Report (AR4) last year, and specifically the Summary for Policy Makers (SPM) of the Working Group 1 Report (WG1) published in February 2007, decided to leave out of consideration the possibility of future increased ice sheet loss over and above what had been observed from 1993-2003 even though there had been an upward trend. This gave a projected sea level range of 18-58 cm for the 21st century, markedly lower than the 88cm upper bound of the IPCC’s Third Assessment Report (TAR).
If you take the most pessimistic scenario, the A1F1, the IPCC’s best estimates for sea level rise for 1990 to 2095 (not 2000 to 2100) were 28cm for thermal expansion, 12cm for glaciers other than ice sheets, and -3cm for ice sheet mass balance (snowfall minus surface melting). Then a further 3cm was added in for ice flow, that is glacier outflow and the calving of icebergs around the edges.
This gave a best estimate of 40cm for the most pessimistic scenario. There is another way of working the numbers, where the numbers were derived from the midpoint of the uncertainty range of each contributing factor. This gave a net 43cm. It was this number, a kind of best estimate of the worst scenario, and reported in an earlier draft of the SPM, that stuck in the media mind. It was seen as vastly better than the previous worst estimate of 88cm. Those figures were never comparable. Indeed the IPCC AR4 figures are different in a number of ways as was explained in more detail by Stefan Rahmstorf at RealClimate.
In simple terms AR4 looked at the ice sheet loss rate over 1993-2003 and assumed no change or acceleration over the next century. They did this not because they thought there would be no change, but because given the state of ice sheet modelling there was no scientific way of calculating the change. This is how they interpreted their responsibility as scientists to policy makers.
In fact there was further comfort given in their commentary by saying that net ice flow rates “could increase or decrease in the future.” Moreover if this contribution “were to grow linearly with global average temperature change” the increase would only be 10-20cm.
There was some consternation about this from sections of the scientific community. When the SPM of the Synthesis Report was issued in November 2007 it contained an expanded statement. In summary it said that forecast average warming if sustained for millennia would lead to the virtual elimination of the Greenland ice sheet giving a sea level rise of about 7m according to current models. But the paleoclimate record suggests that 125,000 years ago when the temperature was 1-2C warmer than now, the sea level rise was 4-6m. It was implied by the IPCC in the SPM, and confirmed if you look in the more detailed report (look in Section 10), that this could happen after 2100 because ice sheets react slowly over several thousands of years.
In Antarctica they said there was little worry about surface melt and increased snowfall would actually grow the ice sheet.
However, net loss of ice mass could occur if dynamical ice discharge dominates the ice sheet mass balance.
The overall message was, “You worry too much. Nothing much is going to happen anytime soon.”
What did Rahmstorf do?
Stefan Rahmstorf of the Potsdam Institute for Climate Impact Research is a clever man who cut his teeth on general relativity theory. While the IPCC report was being finalised he’d been doing some figuring of his own. In January 2007 he published a paper where he mathematically related historical sea level rise with temperature, taking into account paleoclimate data, and projected these ahead for the next 100 years. He came up with a sea level rise of 0.5 to 1.4m (about 1 metre as the median estimate). While stressing uncertainty he said:
A rise of over 1 m by 2100 for strong warming scenarios cannot be ruled out, because all that such a rise would require is that the linear relation of the rate of sea-level rise and temperature, which was found to be valid in the 20th century, remains valid in the 21st century. On the other hand, very low sea-level rise values as reported in the IPCC TAR now appear rather implausible in the light of the observational data.
This was a very careful assessment. In September he published a response to issues raised by some other scientists. He found that “the conclusions are robust with respect to choices of data binning, smoothing and detrending” and the correlation is real, that is causative rather than nonsensical.
In May 2007 Rahmstorf and other scientists including James Hansen published a one page paper comparing trends in CO2 emissions, temperature change and sea level rise from 1073 to 2007. The results are encapsulated in this figure.
The fact that these are synchronized is no big surprise. This correlation has been going on for just about forever. (Original from NASA)
The Rahmstorf paper tells us:
The rate of rise for the past 20 years of the reconstructed sea level is 25% faster than the rate of rise in any 20-year period in the preceding 115 years.
Also Rahmstorf’s graph displayed above shows the the observations (the shading is the IPCC projections) running ahead of the IPCC projections in an accelerating trend.
This was not actually news to the IPCC. The SPM of the IPCC AR4 of the WG1 (large pdf) gave this table showing an increase in the rate of sea level rise in all components:
You will note that on this table the most rapidly increasing element is the Greenland ice sheet. Reading through the more detailed report it’s clear that they knew things were stirring in Greenland and Antarctica. It’s just that their models couldn’t cope.
Taking a broader view Rahmstorf worked out from the paleoclimate record that for every degree of temperature change the sea level changed 20 metres, plus or minus 10. Take, for example, the last case of ice-sheet melting. 20,000 years ago when the temperature was 5-6 degrees colder, the sea was about 120 metres lower. So six into 120 gives 20 metres per degree.
This makes a lot of difference to the amount of dry land on the planet. James Lovelock tells us that additional land equal in area to the continent of Africa was exposed at that time.
Hansen and many others have told us that 125,000 years ago when the temperature was 1-2C higher than now the sea was 4-6 metres higher. Likewise we have been told that around 3 million years ago when the temperature was 2-3 degrees higher than now the sea level was 25 metres higher, plus or minus 10.
Lynas has also told us that warming of 4C above now would see no ice left.
When the Earth was last four degrees warmer, there was no ice at either pole. (p183 based on a paper by Zachos, J. 2001)
Hansen and colleagues have since confirmed this at 5C which last happened 35 million years ago. The implication is sea level rise of about 75m depending on how much thermal expansion amounts to and that depends on how long the warmer climate persists, but about 70m is related to melting ice.
So we have close to 200 metres of sea level change with a span of about 10C of warming. What is there not to worry about?! I think the sea level change is the elephant in the room with global warming.
Although there was at times action on the part of oil producing countries like Saudi Arabia and recalcitrants like the US to tone things down at the Summary for Policy Makers stage for each group report, on sea level change I don’t think there is any need to impute political nobbling. Measuring sea level rise apparently tests the limits of satellite technology. Look for example at this graph.
Two things stand out. First, the red dots are from the Poseidon satellite, the blue from Jason. New is not necessarily better. Secondly, we are looking a total rise of about 4cm.
One wonders whether in concentrating on minding the millimetres the larger view is being missed. Hansen was certainly looking at the larger view. We’ll talk about what he found in the next post.
I wouldn’t worry too much about all this stuff, Brian; after all, Barack Obama has promised to make the oceans recede, at the same time that he provides care for the sick, and good jobs for the jobless. There’s probably some loaves and fishes included in this deal too, I haven’t read the whole policy paper yet. Maybe we can get the extra fishes by making the oceans recede, you’ll have to check his website for the details I suppose.
And I guess the jobless will have good jobs pulling river-barges and turning giant wooden cranks, to make up for all the energy we’ll need to forego to make the oceans recede. Maybe the jobless will have good jobs pedaling Gilligan’s Island-style home-generators to power the non-electric life-support machines for the sick, who will finally be cared for for the first time in history. Like a man said, It takes a nation of Gilligans to hold us back.
But I trust him. After all, he was briefly a community organizer in a crappy part of Chicago. If that doesn’t qualify you to remake a great nation, then what does?
j_p_z: don’t worry, I didn’t read any of the graphs and links either
j_p_z, I haven’t caught up with Obama’s policy yet. I’m not sure it matters, because he is going to find things different when he gets into the oval office.
I believe the US has the majority of it’s naval installations very much in the firing line of sea level rise. When they twig that these facilities are threatened, I see great hope for the effort the US with their enthusiam and technical ingenuity will engender.
A marvellous argument for reincarnation. Instead of just avoiding the consequences of our laziness and selfishness by karking, it we are actually reborn to into the very sh-t we created.
Unless it shuts down the Gulf Stream, instead.
Good to see an historically long-range view of global climate fluctuations! I’ve written before that scientists & historians trying to understand the world’s pre-literate past know that such fluctuations are part of global history – BUT that build-up of particulates, rather than CO2, in the planetary gas layer, is the very disturbing problem.
RE MELTING ARCTIC: Why did Cabot try to get through the North West Passage through Canada’s far northern ice? Probably because, a few hundred years earlier – when Viking settlers were growing those grapes along Canada’s far-NW seacoast – there WAS a NW Passage & soon will be again.
THERE IS A WELL-MODELED & SCIENTIFICALLY SOUND “Change in the Direction of the Gulf Stream” THEORY which accounts for the 900-1000 year full cycle of recurring “Little Ice Ages” & “Little Mesolithic Hot-House Ages” – the c50min doco on it has been shown in Oz at least twice (SBS or ABC – the former, I think). It also helps account for the different sea-routes from Europe to the Americas taken by Vikings & Colombus (& possibly a Roman expedition – the original of the Aztec/Toltec Quetzalcoatl legend).
Theories on the impact on climate of oceanic currents’ switching direction – even if they prove true – are probably independent of the much longer term fluctuations of global climate which bring with them much longer versions of Ice & Hot-house Ages. These are more likely to result from very long-cycle solar activity.
None of which take into account the impact of mega-volcanic eruptions, meteor strikes … or the over-burning of carbon (whether wood or other bio-materials, or fossil fuels).
In climate change, it pays to remember that our species (and many others) flourished during the Hot-house Mesolithic; but that Ice Ages were major extinction events.
We have a great deal of evidence that mini-Ice Ages have been caused by particulate build-up in the planetary gas layers by volcanic eruptions; but no record of what happens when carbon particulates build-up to similar levels; however, it probably presages another Ice Age of indeterminate effect and length, since our planet’s reliance on carbon fuels cannot be shut down quickly enough to avoid the worst aspects of Chaos Theory.
Banning the burning of biomass carbons – plant materials (especially hard woods & pines) and animal excretia (dung) – is the easiest step in most societies. Cutting back on fossil fuels the next.
The best way to evaluate Climate Change theories (some competing, some complementary) is to imagine yourself living in the year Galileo’s theory of the heliocentric solar system was widely published & discussed (Copernicus’s had been kept very quiet). The Vatican is about to erupt in defence of Geo-centric which in the past few decades, it has embraced with a vengeance. And there are still all those Flat-Earthers around!!
Keep an open mind; but for the earth’s sake:
START TALKING CARBON, FUELS,
STOP BURNING LIVING/ RECENTLY LIVING CARBON and
CUT BACK OF BURNING FOSILISED-CARBON FUELS!!!!
and include methane, DeeCee
thanks, Brian.
BTW i reckon relocation of US naval facilities would be much cheaper for the US than taking action to reduce carbon emissions – aircraft carriers, anyone?
DeeCee you’ve raised a lot of scientific issues that I’m not here to engage in any depth about. On volcanoes and particulates, Hansen and his associates are well aware of these factors. My understanding is that they tend to wash out of the system (literally) on a fairly short term basis – years rather than decades.
I’m going to look at some of the really long term factors as Hansen and his colleagues see them in the next post of the series.
That’s right. As an important recent example, the aerosols from the Mount Pinatubo eruption of 1991 caused a shortrun cooling effect which lasted only 2-3 years.
There is also an article in today’s Sydney Morning Herald about the oceans warming faster than expected, which is relevant to this post.
Update: Here’s another link.
“BTW i reckon relocation of US naval facilities would be much cheaper for the US than taking action to reduce carbon emissions – aircraft carriers, anyone?”
Yes – that’s part of the argument that we shouldn’t do anything too expensive to ameliorate climate change until we know what the impacts are going to be. So sea levels rise. So what – we move if need be. Take Melbourne for example (where I live) and ask yourself this –
100 years ago – how many of Melbourne’s current buildings existed?
100 years from now – how many of Melbourne’s existing buildings will still be standing with or without sea level changes?
If sea levels do move considerably over the next 100 years – well, instead of replacing that aging building in Port Melbourne with another one its place, we move it further inland. If sea levels don’t move much – we either replace the aging building where it is or maybe we decide to move it anyway.
I’ve heard Paul Nortons commentbe fore; in Adelaide Pinutubo coincided with an exceptionally wet following winter (’92) and it was the last time the Murray was in really full flow.
Would a few strategic sticks of dynamite around the general vicinty of say, Anak Krakatoa or Merapi, do the trick?
Thankyou Brian. Although a lot of the science goes straight over my head(or should that be, in one ear and out the other) your posts are giving me a much better understanding of the problems we are facing with climate change.
Maybe, Paul W but be careful what you wish for! You might get rain but the sun might disappear for a few years. Not good.
Actually the IPCC report says that “large volcanic eruptions produce interannual to decadal fluctuations in the global mean sea level” (5.5.2.4) Exciting until you realise they are talking about millimetres.
Paul N it’s good to know that scientists are getting on top of these things. More doubtful whether it really matters much. They are spending a lot of energy working out regional variations on sea level rise, which can be due to the direction of currents, salinity, flexing of the earth’s crust, even atmospheric pressure. But the differences seem to be mostly tiny.
But the recent research plugs a reasonably big hole. In the table I reproduced the IPCC said that the observed increase from 1961 to 2003 was 1.8mm per year, whereas the sum of the four main contributors was only 1.1mm.
But none of this helps to tell us when the Greenland ice sheet is going to go critical, which is what we want to know.
Andrew, as you note, moving cities isn’t actually that difficult or expensive and can be encouraged to happen over time simply through natural wastage.
However, it’s a bit harder to move productive agricultural land or potentially important things like, say, forests.
Now, it may be that the projected changes would open up new possibilities for the establishment of both, as previously climatically hostile areas become more temperate. But what if they don’t? How much of the world’s food production capacity would be lost as a rise in sea level causes knock on effects inland, such as increased flooding and soil erosion?
I have to admit I don’t know, but it’s an area that bears examination.
Well Greg M, what do expect me to suggest. there are so few Indonesions in the Simpson or Gibson Deserts.
“I have to admit I don’t know, but it’s an area that bears examination.”
Neither do I IB – and I suspect, nor does anyone really. Which is why my position on climate change can be summarised as –
The climate changes, there may be impacts, we adapt, life goes on.
Of course we should pursue all and every ‘no regrets’ way of mitigating climate change – but I worry the climate change has been co-opted by many anti-capitalist, anti-globalist individuals and groups as tool to propagate their ‘anti-’ agendas.
Debbieanne, I’ve been wanting to get some of this off my chest for a while, but even six months ago when I had the idea people would have been less receptive.
Paul W, much of Indonesia is quite low lying. There might be a lot of them wanting to come here if the waters rise. But then they wouldn’t want to die in the desert, so where will they go?
I’ve got another three posts in the pipeline, Andrew. It doesn’t get any better. Whether you will change your position, I don’t know. I’ll just put the stuff out there and you can do what you like.
Paul, I know that you’ve got to take your volcanoes where you find them and there are none in the Simpson and Gibson deserts, but you might have suggested a less populated place with volcanoes for the climate cooling eruption. New Zealand, for instance.
“There might be a lot of them wanting to come here if the waters rise. But then they wouldn’t want to die in the desert, so where will they go?”
Where is there evidence that many Indonesians might want to come here?
Is their quota in the annual migrant intake always full?
By comparison how many want to go to Malaysia or the Philipines where they share a language and many aspects of daily life?
Is your question really an example of an exaggerated and slightly xenophobic fear ?
Regardless of ethnicity I think most people want to stay in their own countries and work towards improving the situation when things become a challenge.
This whole notion that people of the lesser developed countries of the world are all just longing for an excuse to go elsewhere (always a fear of whitey)is right off topic and deserves a bit more contemplation.
I’m not even bothering to comment further on the lunatics who are talking about blowing up another nations volcanos.
That’s Mr Baka Bashir to you…, you’ve got it all wrong, I’m afraid. If the Indonesians leave Indonesia because the waters are up there will be lots and lots of people in Vietnam, Singapore, Malaysia and the Philippines looking for somewhere to go also, not to mention China, Korea, Japan and Bangladesh. That’s just in our corner of the world.
I suppose. Seen one volcano; seen em all. What about earthquakes instead?
Paul W, earthquakes and tsunamis, along with the subvention of tectonic plates, do release CO2 as I understand it, but contra Ian Plimer, not enough to make any difference in the current context.
But then an earthquake is even harder to organise than a volcanic eruption, I would think. How often does the earth move for you?
Brian, Having just watched Q and A, not a lot.
Paul, I was too busy labouring over my next post, about to go up, but I do find Christopher Pyne a massive turnoff.
Kinda glad I missed it.
Sounds like it musta been a near thing.
Yeah! That’s right, Andrew. What matter that hundreds of millions are at peril, let’s keep our eye on the main game. Dirty stinking ferals wanna take our V8s offavus, melt’em down and turn’em inna nose-rings.
Pearls before swine, Brian.
Am I taking a bait?
That same ridiculous mentality that WBB is talking about was alive and well on all the ABC’s various current affairs programs. The one glimmer came with them inadvertantly giving away the game as to that twat from the opposition back bench calling for the 10 cents a litre petrol cut, as an “embarrassment”.
Watching Steve Fielding on the senate coverage was as nauseating and you do despair at the mentality left in parliament with the dismissal of some good politicians after last election, particularly in the senate.
You want to choke precious middle class twats, don’t you??
I don’t think measuring equipment knows or cares what the political and economic philosophies of the reader might be.
If you can explain how a spectrometer can be “co-opted” by the opinion of somebody standing nearby, then I’ll worry along with you. Perhaps greenies are capable of making thermometers boil-over with their mind-waves, hmmm?
Otherwise, I’m inclined to take more notice of the readout of the scientific instruments than I am of anybody’s opinions on the matter.
DeeCee, how come your comment at 5 gets picked up on my Google reader, whereas the post doesn’t?
Mercurious,
I’m not questioning the science or the measured facts – they speak for themselves. AGW is a real phenomenon. What I’m not sure about is the impact of AGW and how long those impacts will take to be felt. Should we do anything about AGW? Absolutely – but let’s make sure the medicine isn’t worse than the cure.
If you’ve got arthritis in your wrist – maybe it’s better to learn to manage the pain than to cut your arm off.
Bill Heffernan’s grand vision of a populous north may be closer to fruition than he believes – but they may be a bit browner skinned than he would like.
“If you’ve got arthritis in your wrist – maybe it’s better to learn to manage the pain than to cut your arm off.”
A better analogy might be:
If you’ve got a systemic infection never before seen by medicine, and you don’t have a very good idea how long it will run or how harmful it will be, but you’ve been getting sicker and sicker for a while – maybe you should take a course of antibiotics rather than whining about how you’ll have to stay off the grog for a week.
I hope you’re right FDB – and a course of anti-biotics is all it takes. That would be non-invasive and have minimal impact on quality of life. I can keep living my current living standards and take anti-biotics – however I’m not sure that’s what is being advocated here. I keep hearing calls for me to give up the car, take public transport, cut back on energy consumption etc etc…. seems worse than a course of anti-biotics!
“I keep hearing calls for me to give up the car, take public transport, cut back on energy consumption etc etc”
NNNNOOOOOO!!!!!
The humanity!
Drive the car less. You can still keep it, but as it will cost you more and more to run it, you’ll find it increasingly attractive to take public transport. If the political will is there to make people pay.
You may also become more sanguine about a fluctuation of a few degrees temp in your home, whether you care about AGW or your hip pocket. If the political will is there to make people pay.
The problem is that people have been complaining about the possible lifestyle pay cut for so long, and nothing’s been done. What could have been easy and pain-free treatment if adopted 20 years ago is now going to hurt more, because the infection has thrived. All this “baby-with-the-bathwater”, “treatment-worse-than-disease” palaver is in many ways worse than the full-blown denialism, because it gives real succour to inactivists.
It also creates the impression that those who are advocating for urgent action aren’t trying to think about what will work best with a minimum of bad effects. That they don’t think human life, liberty, comfort and pleasure are worthy ideals. This is pretty insulting.
Andrew, on what’s worse the cure or the disease, we do have to get some appreciation of how bad it is and then take concerted action on a planetary basis. I suppose that’s stating the bleeding obvious. Monbiot back in 2006 looked at a carbon budget for the world, took account of what the studies said about failing carbon sinks (Stern mentions them but doesn’t take them seriously), took a bead on 2030, divided the world carbon budget by projected world population, and concluded that Britain needs to cut emissions by 90%. Then he looked at what Britain has to do.
It’s still one of the most logical and consistent workings through of the problem. Because he gives up on nuclear and Britain has limited renewable energy resources he concludes that people will have to largely give up on private cars. He also suggests eliminating supermarkets. You either shop online from the warehouse or walk down to the local.
We are much better placed and have almost unlimited energy from concentrated solar and geothermal, if it works, and it’s looking good. So we could drive plug-in electrical or maybe hydrogen fuel cell cars to our hearts content, provided that we can feed ourselves, make a crust and pay the bills.
I’m at the stage of trying to work out how bad the problem is. It looks bad so I’m putting it out there, and we’ll see how we go.
If it’s real bad we might have to have legislation to restrain our natural exuberance. I hope not and it’s not the object of the exercise.
Yes, I remember not having a car, keeping energy consumption to a minimum and using public transport. It was called “being poor in the UK”. Oddly enough, I still managed to get to places, didn’t freeze to death in winter, didn’t suffer from malnutrition (much) and even managed to quite enjoy myself in a number of ways. After much saving, I managed to obtain a small motorcycle which, together with its successors, acted as my sole means of personal transport for many years, consuming 2.8l/100km or so of fuel on journeys that could not conveniently be undertaken ahoof or by public transport.
In short, my world did not end from having to do these things, and my carbon footprint was but a tiny fraction of what it is now.
Of course, now that I have a comfortable white collar income and an adequate (though somewhat unconventional) standard of living I don’t relish the prospect of returning to my late teens/early 20s. But it wouldn’t kill me if I had to and, realistically, I’d probably be healthier as I’d lose the kilos I’ve gained since obtaining a regular income.
Monbiot says that if he has to take public transport it takes him heaps of times, because of the bad connections etc and he arrives feeling homicidal. He’s arguing for a re-engineered public transport service and a much upgraded, customer-friendly travelling experience.
Spot on about public transport. Our governments have been spending over 90% of their transport budgets on roads and freeways, seemingly oblivious of declining oil supplies. They are only now looking at as petrol prices rise significantly.
You only need to look what Sydney did with public transport during the Olympics – then they went back to gridlock, smog and carbon emissions.
Traffic volumes have actually dropped quite noticeable on freeways over the last two weeks. And the trains are jam packed, with no new lines in sight and new carriages 18 months away.
“He also suggests eliminating supermarkets. You either shop online from the warehouse or walk down to the local.
Great ideas. Set-up local markets like we used to have. And In Britain…I used to luv walking down to the fresh vege & meat markets in Harrogate, UK…used to pick up cds & clothes there too. Can relate to your useful comment Intellectual Bogan. Then we can be real Market Democrats…:)
Monbiot has some worthy views Brian. The changing of the transport system is one of them.