by Russel Norman
Interesting article from James Hanson et al in the 18 May 2007 edition of the Royal Society journal which suggests that the IPCC seriously underestimated the impact of climate change on rising sea levels (picked up on this article from Monbiot). The IPCC fourth assessment report had a very conservative figure of maximum 59cm sea level rise by 2100 due to climate change. But they reached this figure after excluding the impacts of ice dynamics in Greenland and West Antarctica because they couldn’t agree on how to model them.
Hanson et al suggest that there is a very serious risk of major ice break up by the end of the century with resulting metres of sea level rise. They look at past climate change to argue that the positive feedback loops are overwhelmingly on the side of warming (especially albedo, that is warming melts ice, which exposes water and land, water and land absorb more heat, so get more warming etc). So the warming and cooling are asymmetric – the planet tends to warm faster than it cools. I thought this extract particularly disturbing:
Iceberg discharge from Greenland increased markedly over the past 15 years. Mass loss increased from 4–50 cubic km per yr in 1993–1998 to 57–105 cubic km per yr in 1999–2004, based on radar altimeters, with probable losses at the higher ends of those ranges (Thomas et al. 2006). Recent analyses of satellite gravity field data yield a net annual loss of 101 +-16 cubic km per yr during 2003–2005 (Luthcke et al. 2006)…West Antarctica seems to be moving into a mode of significant mass loss (Thomas et al. 2004). Gravity data yielded mass loss of approximately 150 cubic km per yr in 2002–2005 (Velicogna & Wahr 2006). A warming ocean has eroded ice shelves by more than 5 m per yr.
We find it implausible that BAU [business as usual greenhouse emission] scenarios, with climate forcing and global warming exceeding those of the Pliocene, would permit a West Antarctic ice sheet of present size to survive even for a century.
Just a reminder, the West Antarctic ice sheet is at least 5m sea level rise if it goes and ditto for Greenland.
Published in Environment & Resource Management by Russel Norman on Thu, July 19th, 2007
Tags: environment
More posts by Russel Norman | more about Russel Norman
on the trolls and those who are unable to keep on topic
As alarming as this paper is, one ought to read it with scepticism. There’s a considerable amount of debate about this among climate scientists. Michael Tobis has this to say on the Google Group globalchange:
Elsewhere on the group (which is a great place to visit to see what scientists in the field are saying) there’s scepticism about the time frame involved, and the maturity of the science surrounding ice sheets. No one rejects it outright, though, since they’re real scientists and not denialists.
On the other hand, Hansen has an enviable reputation among the experts, and has often led the debate. Recently, he has consciously modulated his language into a more overtly political mode. This in itself is troubling, as it indicates that resistance to change from the political and media establishment must be firmly ensconced for a scientist of his stature to feel compelled to take the spotlight.
I’m inclined to wait for the scientific debate on ice sheets to solidify. There’s still more than enough evidence to push for policy change, as Naomi Oreskes recently pointed out in new work that builds on her 2004 study.
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Outstanding link to Oreskes work…
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theres two sea based ice sheets holding the entire west antartic from flowing into the sea.
if those go then i think the rage in coast life style blocks that have pushed up the rates for the locals of those areas is gona crash very hard
i better sell up i’m below the current sealevel as with a few other thousands of people in Auckland
the thing everyones waiting for is for the scientists to come out with a definite time for the big bang but how can they when nothing like this has happenend before for them to get some ideas from
how can they give you a working time frame when the data changes almost minute for minute
the best they can do is give you a good guesstimate, it’s not their fault they just report the data taken at that particular time
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Amon,
“i better sell up i’m below the current sealevel as with a few other thousands of people in Auckland”
I hope that you are not selling to an unsuspecting purchaser!
I will know when global warming is serious when we have to include the likelyhood of a property being flooded on property LIM reports.
Putting the information on LIM rerports should see a huge increase in value for those above the high tide flood line while those owners below the mark, like yourself will have a worthless asset.
With a five meter rise in sea levels my property two streets back from the estuary will be prime waterfront real estate. Bring on global warming!
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Whats a poor boy to do?
Hopefully by the time this all really starts to impart the reality of LIM reports and suchlike will be in the past. We won’t be losing just a few coastal properties but living in a maze of small islands and given that lots of infrastructure is always at sea level then they’ll be lots and lots of work to be done. But you all know this.
Where I live is actually on an estuary, but we do have at least five metres over the spring tide level, but one thing I have noticed is that the ground next to water actually moves a whole lot more than dryer places. What this means is that, as know, place close to water – on rock – would still be usable but most places won’t be. Even if it out of the water, and of a fair sized chuck, the nature of water is such that if it’s soil, and not rock, then theres a good chance it’ll go under soon enough.
Realistically, though, if NZ suddenly went all out to zero emissions, and that’d be a farce because so much of what we import wouldn’t be subject until it reached us, we wouldn’t even be a blip on the whole earth radar.
I suppose as individuals, with a conscience created in protestantism, all we do will count for us but it really won’t matter. New zealand could have an impart for better though if we dropped the silly system and became a model for others to follow. Number one on that agenda would be having much longer holidays because, let’s face it, the fact it’s all happening is because we’re all still working as much as we can. Western civilisation needs to go on a good old fashioned holiday.
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OK,
I recently went to a seminar by a guy who was a member of a US senate committee, which is, as far as I could work out, similar to a select committee in New Zealand (someone who understands US politics a bit more might correct me if I’m wrong). Anyhow, he reckoned the most accurate way to predict the outcome of an election was by how people would bet their money, not by things such as opinion polls.
So here is an idea. Rather than debate the science and politics behind Hanson’s prediction of sea level rise, lets envisage a hypothetical betting game. Here are the rules.
1) You can put $100 on one of two options:
a) IPCC are about right, sea level rise will be less than 1m by the end of the century.
b) Hanson is right, it will be more than 1m.
If you are a climate change denier, you’d put your money on (a), even if you disagree with IPCC.
2) All the money which people put down on the game is divided amongst the people who get the correct answer (no tax siphoned off by the government etc).
Now just imagine we could look forward into the future, so you don’t have to wait 100 years to collect your winnings. Instead, you’ll be richer or poorer tomorrow.
So where do you put your money (a) IPCC is right, or (b) Hanson et al are right?
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Okay, 100.00 means alot to me. I don’t get many of them. The people with lots would most probably bet A whereas, I’d most probably vote B.
Trouble is I won’t bet because I’d much prefer using the cash to get setup towards the outcome I believe in. So even if I did bet, because I’d most probably be right, the people who betted A – their money wouldn’t be worth anything anyways so I’d have been betting something useful now on a useless return then.
I do get what you’re saying though – it makes sense that if the economies going well and most are happy with their returns, that the grumbles don’t matter, cause people will stick with what they know.
Modern society is all about confidence. We put our money down and hope tomorrow is no different from today. Given that Coastal house prices aren’t going down and it’s where lot’s of upmarket housing money is going then all the bets will be on A.
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Artyone
I don’t have the tools at hand but by and large we’ll still be two islands and the bulk of NZ will still be above sea-level. Comes of having all the earthquakes and mountains and stuff…
The things that’ll hurt are the things you’ve observed though. A lot of stuff IS built near the shore, near the sea, on the beach…. and erosion of land not protected by good rock or beach or mangrove swamp is really pretty quick.
We have a period of about a half century to be moving things up into the hills. SH1 from Wellington needs transmission gully built, not futzed with, not because of current traffic concerns on the current SH1 but because of the fact that its going to need a bridge or a ferry to make it from Paekakariki south… and the rail line is only a couple of meters above that.
Warming will be associated with more southerly reach to Typhoons and if significant rebound of the land underneath the Ice occurs there may be tectonic effects that change earthquakes and vulcanism… ie, it won’t be necessary to demolish much of Wellington.
Yet as much as we will be diminished we will still have land, we will still have the ability to grow food, we will still (if we are wise enough to build the things) have electricity from wind and tide and hydro and geothermal and solar.. and we will have enough of those things to remain civilized.
I would not be so sanguine about the prospects of the people of NYC or LA or Shanghai or London… or indeed much of the rest of the world.
The trouble predicted is of a certainty, coming within the lifetime of my children’s children if not sooner.
respectfullly
BJ
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I’ve been following the ice/sea level issue on Hot Topic, most recently here. Note that a scientist working on Greenland comments on how conservative the IPCC position is. And a recent workshop on the West Antarctic ice sheet found that it is already likely to be contributing to sea level rise.
Hansen may be out in front of the IPCC position, but he’s reflecting the concerns of many of the people working on the ice sheets.
It might be worth noting that we have evidence of multi-metre sea level rise in a short timescale (Meltwater Pulse 1A, 14,000 years ago, possibly as much as 1m in 20 years!), so Hansen has some basis for his concern.
(Thanks for the Oreskes link, plum).
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bj, NYC or LA or Shanghai or London…aren’t they all coastal shipping ports? Just like most New Zealand towns and cities. I don’t have the tools either but I would suggest that much of New Zealand’s urban land and port/airport facilities will be underwater with a 1 meter rise. Think Tauranga, Napier, Christchurch, Petone.
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Or they might build a bank to keep the water out, think the Hutt River stop banks….I believe these have been successfully trialled in Europe, somewhere called the netherlands.
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(My last comment is obviously in the spam queue – it had three links, so I’ll keep this one down to one…)
If you want to see what happens to NZ under various sea level rises, try http://flood.firetree.net/ and click on the Australia link. The site uses Google Maps, but the smallest rise it allows is 1m. Doesn’t do much to ChCh, except around the estuary, but Kaiapoi looks a bit damp…
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No change in Kaiapoi then….
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Actually the guy who did the software for that site has admitted its shortcomings.
I think you can fill in the areas where there are spread pixels of blue… especially when coastal erosion is taken into account. The coastline will reach a new equilibrium, also dependent on wave energy and sediment budget etc.
Looking at Christchurch with it set to 7m, I would think that with erosion we get Banks Island again.
With climate change and possibly more intense storms> increase in average wave energy.
If as predicted there is a prevalence of drought, then alluvial sediment supply will decrease. The South Brighton tombolo will be interesting to watch. Also, even sans sealevel rise, the long term effect of hydro development on the Waitaki could well be the inundation of their historic buildings.
One metre rise would result in far more marine transgression than most people would expect. Poor Kaiapoi.
Take a look at the Taieri river area between Lake Waihola and Dunedin… 1m+ rise would cause some salinification of this area deemed to be quite removed from the coast (build a dam now – with turbines).
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>Oamaru’s historic buildings.
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If the change is reasonably modest and takes place over a century timescale, many harbours could have barriers installed on them similar to the Thames Barrier in London. While it would be a fairly large task, it’s by no means impossible in terms of engineering, and far cheaper than moving cities around.
Planning for this kind of outcome could become fairly important. Although it is important to remember that we have not seen any sea-level changes yet, and may not- excess water may tend to flow to the equator from the poles due to centripetal force and increasing viscosity. Bit of a bummer for those on the equator though.
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I was talking to someone who lives in Amberly today. He said the residents wanted a by-pass but the plan was skittled because of the yet to be built gated community Pegasus Town. It seems to me that an existing community shouldn’t miss out to a community that has to import it’s residents from (eg Singapore) I hope people note it’s vulnerability to sea-level rises.
jh
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I think you mean Woodend, jh.
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Maybe Woodend and Amberly are in the same boat.?. [and Pegasus Town is in the Water...only the Big Gate showing]
jh
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Insider,
I believe these have been unsuccessfully trialled in the United States, somewhere called New Orleans.
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jh, Pegasus Town and a proposed iwi subdivision straddle the original motorway alignment, circa 1964. Transit is currently negotiating with the community for a new alignment to complete this project which was temporarily suspended in 1970 when stage 1 of the northern motorway (the Kaiapoi bypass and new Waimak bridges) was completed.
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BucolicOldSirHenry, Wine buffs will be alarmed to see that 1m-2m rise will flood most of Riverlands, the historic centre of Marlborough wineries.
You might have underestimated the impact on Christchurch and surrounding areas.
The entire area between Marshland Rd and the coast, from the Avon to the Waimakariri, is at moderate risk with just a 1 metre rise. I presume this is the result of the effect on the water table.
Lake Ellesmere has the potential to cover sections of the Akaroa Highway.
Ironically Transit is probably in the best position to frighten New Zealanders into taking the consequences of rising ocean levels serious. A few years ago Transit had to hastily build a boulder sea wall to stop the ocean from underscouring the highway at Bruce Bay. Transit has been progressively building a sea wall 100 metres away from the highway but a summer storm removed that coastal strip in less than 3 days. At Kaikoura they have had storms rip the tarseal right off the road. Rising sea levels don’t actual have to flood your bach to be a problem. On a steep 1 in 10 slope a 1 metre height increase results in a 10 metre increase in the distance storm surge will travel. The sorts of events that have flooded or damaged coastal highways were rare in the past but could increase exponentially with every extra centimetre of sea level.
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Has anybody seen any research on what effect rising sea levels will have on water tables?
Seems from this map that Blenheim will become a lakeside town with a 2 metres rise in sea level flooding most of Riverlands. As will much of North-east Christchurch east of Marshlands Rd between the Avon and Waimakariri rivers.
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I think one of the biggest effects of rising sea level will have on countries such as New Zealand will be that there will be millions of environmental refugees. Where will these people go, who will feed and house them?
We only need to look to our nearest neighbour to see how they deal with tens and hundreds of refugees. Is that how we are going to treat the millions of people currently living in low lying areas?
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Forget about environmental refugees. What about all the NZ citizens currently living overseas who have an absolute right to come home any time they choose? If things get rough in Aussie or Europe, we would be welcoming a lot of expats home. See what that does for Auckland house prices…
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To your list of refugees you can add people living in places named Marshlands, Riverlands or ending with lagoon, port or mouth, and anywhere with a high water table.
Those sea level maps show that a 1 metre rise can affect river levels up to several hundred metres inland. In most pleces this will be like having a permanent spring tide. This is going to dramatically reduce peak river flow capacities so there will be more frequent floods in places like Greymouth, Blenheim, North/east Christchurch and across the Napier/Hastings Motorway. We are going to have to make the hard decision that London has made and actually return much of our flood plains to the role nature intended them to have instead of trying to build ever higher stopbanks.
A one metre increase in sea levels is effectively a one metre reduction in the height of groynes, sea walls and other coastal defences. This is going to be major problem on some of our most important tourist highways particularly in south Westland and north of Kaikoura where roads (and the railway) can’t be moved away from the ocean.
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Brookhaven
What sort of time frame are we talking here? Sometimes I’m not sure whether the sea will rise next week or next century.
jh
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jh, Predicting when the sea level rise will occur and by how much is a bit like predicting when the next Great Alpine Earthquake earthquake will occur and how big it will be.
Preditions for sea level rise will be less precise than predicting faultline earthquakes because scientists can’t simply look at the past to narrow down the range of options for the future. Your guesstimate of sometime between next week and next century is reasonable given the limited knowledge currently available of the various causal mechanisims and there potentially cmplex and non-linear interactions.
To date the best prediction paleoseimologists have been able to cme up with for the Great Alpine Fault is 50% probability within 30 years, 90% probability within 100 years, 95% probability it will register 7.9 +/-0.25 and involve betwee 300km and 500km of the northern most portion of the Great Alpine fault.
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“Dutch Answer to Flooding: Build Houses that Swim”
http://www.spiegel.de/international/spiegel/0,1518,377050,00.html
and
http://www.ecoboot.nl/artikelen/floating_houses.php
and
http://www.csmonitor.com/2005/1026/p13s02-lihc.html
and
http://www.treehugger.com/files/2007/03/floating_ecohom.php
and
http://www.inhabitat.com/2006/08/29/interview-koen-olthius-of-waterstu dionl/
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Cool
I designed something very similar for my parents place on the beach in Sag Harbor… we didn’t build it (I was not yet an engineer and there was never any money), but aside from using regular pontoons rather than foam filled, it was exactly the same.
After everyone stopped laughing they realized I was serious. Eleven year olds often are more serious than you expect.
respectfully
BJ
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An earthquake like that would be equivalent to the Inangahua or Murchison Earthquakes?
jh
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jh, If I understand the Richter Scale correctly the energy release at the fault line would be 10 times greater than Inangahua and two or three times greater than Murchison or Napier. In each of these quakes less than 100 km of faultline ruptured. The Great Alpine Earthquake will affect five times more land area than the Napier quake.
At one point the Great Alpine Fault is less than 150km from Christchurch and combined with the geology of the Canterbury plains parts of Christchurch and North Canterbury could experience collapse of masonry buildings. If the quake happened today the waterlogged soil would cause quite a bit of liquifaction in Kaiapoi and slope failrures in the Port Hills suburbs.
It is more equivalent to the Great Wellington quake circa 1850 that lifted much of the CBD above sea level.
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“Huge sea level rises are coming – unless we act now” – James Hansen, head of NASA’s Goddard Institute for Space Studies in New York. He gives a frank and disturbing answer to the question “Why might scientists be reticent to express concerns about something so important?”
http://environment.newscientist.com/channel/earth/mg19526141.600-huge- sea-level-rises-are-coming–unless-we-act-now.html
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