So far we have looked at the astonishing melting of the ice in the Arctic, at what the IPCC did or didn’t do about sea level rise and at Hansen’s recent thinking on the matter. Now I’d like to give a few snapshots of what the real world implications would be.
The story of temperature and sea level change is encapsulated in that really neat little image at the top of the post which I got from Climate Code Red (February 2008). They got it via Rahmstorf from Archer, 2006.
We can argue about the extremities. The last glacial maximum may have been 5 or 6C colder than now. Hansen puts an ice-free world at 5C warmer. It might turn out to be 6C if, perish the thought, Armageddon comes to be. But anyone can see there’s a problem. When 10-12C gives you close to 200 metres of sea level change each degree means a lot.
A further insight comes from an Emeritus Professor called William Ruddiman. His thesis is that humans have been altering the climate for the last 8000 years through land clearing and methane-producing rice growing. Hansen reckons that the effect he describes is real, but somewhat less than Ruddiman thinks. Yet it’s a fascinating article (pdf). For our purposes the important point is that Ruddiman finds that the threshold for a new ice age to start building is 245ppm of CO2 corresponding to a temperature about 2C less than the present.
So in that neat little graph you can’t just join up the dots of sea level in a more or less straight line. There needs to be a flat section between the temperature values of 13 and 15C. That represents the unusual stability given us as paradise on earth, or at least civilisation as we know it in the last 8000 years or so. A period when CO2 levels didn’t stray very far at all from 280ppm.
So coming out of the last ice age each degree in temperature change corresponded to about 30-40m of sea level change. Going forward we can look forward to from 12 to 18 metres for each degree of warming.
Remember the three graphs from the post about the IPCC that linked temperature, greenhouse gases and sea level, with ice sheets thrown in. (Original from NASA)
Temperature and GHGs are conjoined as it were. If one moves so does the other. When temperature moves so does sea level as a consequence.
I can’t do tables so here’s five statements that link levels of CO2e and temperatures (referenced to pre-industrial) with sea level rise.
180ppm give a temperature of -5C and a sea level of -120m
280ppm give a temperature of 0C and a sea level of 0m
280-300ppm give a temperature of 1.7 to 2.7C and a sea level of 4-6m
380 (360-400)ppm give a temperature of 2.7 to 3.7C and a sea level of 15 to 35m
425 (350-500)ppm give a temperature of 5.7C and a sea level of 75m
The last three rely on the paleoclimate record going back increasingly into the past, so the uncertainty grows with each one. The last one, for example comes from Hansen. It wasn’t long ago that he was saying 500ppm plus or minus 150 for an ice-free world. Either way the lower bound is 350ppm and to be avoided if possible.
The sea levels would take time, but are implied in the nominated levels of CO2.
The implications of sea level rise are very serious.
In Climate Code Red (February 2008) the authors point out that long before Greenland or West Antarctica disintegrate, with 1-2m sea level rise the results would be catastrophic. The authors quote Stern (November 2006):
“currently, more than 200 million people live in coastal floodplains around the world, with two million square kilometres of land and one trillion dollars worth of assets less than one metre elevation above current sea level.”
In Climate Code Red they suggest that you can use a sea-rise level overlay such as http://flood.firetree.net/ with Google Earth to see where the water goes.
Many major cities are low lying and are very much in the front line of sea level change.
Some of these assets include American naval installations and indeed major centres. On cities Climate Code Red points out (assuming 20% loss of Greenland – I make that 1.4 metres):
Many of the world’s major cities (22 of the top 50) are at risk of flooding from coastal surges, including Tokyo, Shanghai, Hong Kong, Mumbai, Kolkata, Karachi, Buenos Aires, St Petersburg, New York, Miami and London. In almost every case, the city relies on costly flood defences for protection. Even if protected, these cities would lie below sea level with a residual risk of flooding like New Orleans today.
And:
The 2006 Conference of the International Association of Hydrogeologists heard that rising sea levels will also lead to the inundation by salt water of the aquifers used by cities such as Shanghai, Manila, Jakarta, Bangkok, Kolkata, Mumbai, Karachi, Lagos, Buenos Aires and Lima. “The water supplies of dozens of major cities around the world are at risk from a previously ignored aspect of global warming. Within the next few decades rising sea levels will pollute underground water reserves with salt…
Florida is very much in the front line. This is what 6 metres would do to Florida.
In truth I put that one in there so that I could spread the next one right across the page.
This image indicates where there would be problems with just one metre rise. (Original from NASA GISS which looks even more spectacular.)
Southeast Asia would be a mess.
One metre rise would displace perhaps 150m people, 25 metres would inundate about a billion. I don’t know how many 75 metres would inundate, but it would be serious. (Slide 46 from Hansen’s Iowa Coal testimony – large pdf)
That’s what Hansen means when he says that with 5C warming we would have a very different world.
PS I meant to point out that in the graph at the top the one metre dot is really what Rahmstorf calculated using linear projections on what has happened to date. But the long term commitment of a BAU 3C warming is found by drawing a vertical line and intersecting the line between the 3mya and the 40mya ago dots.
As we discussed in an earlier post no-one can tell how long it’s going to take before the full effects of a particular temperature on the sea level will take. Therein lies hope that we have time to turn things around, but Hansen keeps telling us that building ice sheets is a relatively dry process and takes a lot longer than the wet process that destroys them.
Update: Thanks Steve D for the link to this interactive flood map.
Update 2: The next in the series on sea level is on Greenland and Antarctica.
For the joy of seeing what will happen in your neck of the woods check out this interactive flood map
Thanks, Steve. That’s fantastic!
I don’t know if fantastic is the word I’d use, but I know what you mean.
Looks like Sydney Airport hasn’t got much of a future…
Thanks for your beatifully compiled presentations, Brian.
Do you think that the prime minister’s office is watching your postings? Do you think that they have the ability to understand the seriousness of all of this? As someone who has personally handed information to MPs and Ministers, I grieve that these creatures appear to be completely insulated from reality. They are all Mugabes in one form or another.
Toast
I think the visuals tell the story, BilB, and I thank tigtog for teaching an old guy a few new tricks. I still have a few to learn, like I don’t know why mine have a purple border and I don’t know how to wrap the text.
Also Robert Merkel and Mercurious persuaded me to split up one big post into smaller digestible ones, which was a lot more work, but very worthwhile.
There’s one to come, on Greenland and Antarctica, which will be another bundle of joy.
adrian, I haven’t had time to check out how London, New York, Tokyo and Shanghai check out, but I suspect therein lies some hope, when the penny drops. Of those, I suspect the greatest awareness is in London, where, I’ve heard, a couple of metres will put parliament in the soup. I wonder how The Netherlands is going to cope, but I suspect they have better plans than most. I believe Singapore have been consulting Dutch expertise.
Add to that Mumbai.
I want to see a comparison between sea levels now & those a millennium ago. Yes, we do know sea levels along England’s SE coast at the time its Channel forts were built. Today, some of those forts are miles inland.
The UK’s main island is, geologically, tilting into the North Sea; but, like the original position of the forts, this can be/ has been accurately identified – and (as far as I’ve been able to ascertain) does not account for the distance between the original & current position of the forts vis-à-vis the sea coast. In other words, sea levels have to rise considerablly to reach those of a millennium ago. Since the full cycle of medium-term climate fluctuations is estimated at c900-1000 years, these relatively simple calculations should allow scientists to compare today’s sea levels with those near the height of the previous cycle’s.
Added to (again, increasing evidence of) Viking crops in areas which are, currently, still not warm enough to sustain them, we can justifiably assume that temperatures & sea-levels are not yet as high as they were at the peak of the last medium-term climatic cycle. As the first indications of the move out of the Little Ice Age occurred c1750, it is reasonable to assume the average climate will continue to warm for some time yet.
The last medium-term climate cycle can be fairly (and, as more documents surface & scientific dating becomes more sophisticated) accurately mapped by historians, dendrochronologists, polenologists etc. Instead of increasingly hysterical beat-ups of climate-change blame-throwing, what people ought to expect from scientists is the best possible comparative assessment between the current cycle and the previous one; because that will be the best guide we have to the effects of human intervention.
DeeCee there was a link in an earlier thread to an interactive map from Durham University that showed the sea level around Britain during the whole Holocene period.
I haven’t spent a lot of time looking at the Holocene, but it has occurred to me that during the Holocene optimum the sea level should have been higher than now. There is a smoothed graph of temperature in the Ruddiman article (pdf) (last page).
This image from this article plots the Holocene against the Eeemian interglacial. It shows the Eeemian at elevated levels for thousands of years, giving time for a fuller expression of the sea level effects, measured at 4-6 metres higher than now.
The Holocene optimum by contrast shows the optimum as a spike about 5000 years ago.
I’m sure all that is contested to some extent and I have no way of sorting it out.
My point is that we are pushing the system very hard at present. There’s been nothing to compare since the asteroid wiped out the dinosaurs 65mya and that’s not particularly comparable either. We have to think beyond the very short term of the next 100 years or so to the mid-term implications over the next millennium, and beyond.
Otherwise we are not qualified as custodians of the paradise bequeathed to us.
BTW I’ve put an addendum at the end of the post.
Steve D, thanks for the map. I now know that if I don’t starve due to losses of arable land, get killed in serious weather anomalies or a more man-made fashion due to large scale chaos caused by serious changes in land and weather, I will have a seaside property when sea levels rise 14 meters as will my childhood home up the road, and the Redcliffe Peninsula where my parents currently live will stop being a peninsula around 6 meters, not that it will bother them too much, there home will be unlivable at 4 meters.
I’m guessing based on my opening statement you know where I’m going with this. While this is very interesting and important work that the climate science community is doing, I have to wonder if “Real World Implications” are really being taken into consideration. If we have a feeling that we are not going to make it, then where are the contingency plans, the relocation of people further inland, the development of heat-resistant and low maintenance crops, disaster prediction and preparation technologies and so forth? Are they being quietly formed in the back rooms of government or do we really have something to worry about?
Also I do have a more general question about climate sciences that I haven’t read about, so I might have just completely missed it. We seem to be completing the picture of the future based on climate changes in the past, which does make sense in a way, because replicated conditions should cause the same result regardless of how we got there. My question is do we understand what caused these events in the past that shifted our climate by so much before, because what I have seen on a lot of models and charts are more sudden spikes or declines that upsets the climate change equilibrium? I have a feeling I just missed their explanations of these things rather then there isn’t one, does anyone know a specific article that addresses these in particular?
Regarding the 75m sea level and the linearity of the relationship. The true form is likely to be non-linear across parts of the graph due to changing climate sensitivity of an icehouse vs greenhouse world. The transient relationship will also be non-linear, as you note Brian.
425-450 ppm CO2 does not necessarily guarantee an ice free world. It will almost certainly wipe out the Greenland Ice Sheet (GIS) and West Antarctica Ice Sheet (WAIS) at some future point (I’d bet sooner rather than later – anywhere between a few decades to a few centuries and we are likely to be committed to this already at 385 pmm). But not necessarily the East Antarctic Ice Sheet (EAIS), or at least not all of it.
The key is that the EAIS partly maintains its own regional climate due to its height and albedo. So an ice-free world at 450ppm (e.g. 34 million years ago) is different to a partially iced world at 450ppm (3 decades away at current pace), because the albedo (reflectivity/brightness of the Earth), southern polar winds and regional precipitation patterns are different.
Its tough to draw any simple palaeo-analogies, but they remain our best guide, especially about long-term response. Current tipping elements (e.g. Ice Sheets) and carbon-cycle feedbacks (e.g. Siberian methane) may be different, or more vulnerable now compared to the mid-Miocene – or indeed less so. As Wally Broecker said, all we can be sure of is that there will be surprises in the greenhouse.
PinkyOz, in the post on Hansen I linked to his Iowa Testimany where he was trying to persuade the Iowa utilities board not to build a coal-fired power sat ion. I’m presume he failed, but you can download the file from here. In it he argues from first principles about why CO2 is a problem and later gives an interesting account especially from page 15 of what was going on in the last 15 million years.
Wong referred recently to work done locally on sea level rise that identified from memory 711,000 people particularly at risk around Australia. I presume this is work done at the climate adaptation centre set up recently at Griffiths University. I didn’t refer to it in the post because we really need to see what they said in detail about their criteria and what the study actually said.
Thanks again for that, Barry.
Folks Barry has a somewhat more behind him than I do groping around here in the half light.
I’d been thinking along similar lines about Antarctica. It struck me that there are differences in the ocean circulation patterns between now and 35mya, with the channel opening up more between Antarctica and S America and Australia. This seems to provide deep mixing in the Southern Ocean and hence the arrested transfer of heat from the tropics to the poles.
Also Gore points out that precipitation on Antarctica is very low, <25mm, which is a desert by any standard. Hence there is no ready mechanism to transport heat inland, and if the precipitation does increase it will be in the form of snow. So Antarctica might take a bit more heat to fry, but there is plenty going on around the periphery and as the sea rises there will be significant slipping, sliding and melting.
I’m late for work, so see y’all tonight.
Brian,
Thanks for that, Always good to fill in some of the blanks.
“Wong referred recently to work done locally on sea level rise that identified from memory 711,000 people particularly at risk around Australia.”
Most of them are likely to be the rich and they probably have a boat in their backyard anyway.
I sometimes think, as I take my terrier bitch for a walk on the beach, that that rockwall at the back of the beach, the road behind that and the houses back of the road might all have to go so a proper dune system can be re-established to protect the Adelaide coastline from rising sealevels, storm surges etc.
A storm a few years back dropped the rockwall about 35cm, harbinger of what is to come?
joe2, my understanding is that there are some poor people in the front line as well.
Jovial Monk, I’ve been checking out some of the cities around Australia and Adelaide doesn’t seem to be worse that anywhere else, which surprised me. The problem is going to be in the first instance storm surges on top of king tides. Places subject to extreme weather events can mostly expect such events more often.
You mentioned the cities dependent
How floodproof are these things? I’ve heard the theory that looking after Melbourne would be simple because you could just roll a couple of loads of cement across the heads at the end of Port Phillip Bay and all would be hunky-dory…
And what about the cost? Are these systems really feasible for all those 22 cities in the firing line – particularly if they’re going to be starting from scratch?
aussieoskar, I don’t know in any detail. Ask the Dutch, might be the place to begin.
I understand that New York has 2400 km of coastline to protect. Then there is the problem of salt penetration into city aquifers.
I don’t think adaptation is realistic. Mitigation is the only way to go.
That’s James Hansen at Huffington Post.
Brian, re: post 16
Yes, both sea level rise, and larger storm surges, will increase the regularity and severity with which saline water encroaches upon low-lying coastal water tables and damages infrastructure. These risks were a particular focus of a recent meeting of climate change scientists in Sydney (Greenhouse 2007, October 2007: abstracts at http://www.greenhouse2007.com). One report, by J Hunter [pg 37 of abstract book], used extensive coastal tidal gauge data to show that for every 10 cm of sea level rise, the risk of a given extreme event tripled.
To put this in context, a rise in average sea level of just 30 cm (at the low end of projections and likely to occur within decades) would cause a ‘once-in-a-century storm’ to reoccur every 3 years. Thus major hazards for coastal infrastructure arise long before complete inundation, as you note.
Omigod, Barry, that’s worse than I thought! And I’ve been accused of being alarmist on that issue.
It’s not going to be pretty sight if New York gets the treatment, but it might be the salvation of the world.
Can the same thing be done around the straights of Gibraltar?
Barry Brook and Brian how far back from Byron Bay, would you move, to take advantage of future real estate opportunities?
Dunno, joe2. As I’ve said once before our son has a magic computer on his bike that tells him how high he is above sea level and how much he’s climbed in a ride. So buy the relevant gadget and get on your bike!
With Steve D’s wondrous map I had a look at Byron Bay. At 14 metres I’m seeing 3 islands where the headlands are.
Where we are in Ashgrove we’re 80m above sea level according to the boy’s bike. But on the map the water inundates the oval the Broncos train on next to their clubhouse with 14m.
That’s only Greenland, plus W Antarctica, plus thermal expansion and maybe a bit of E Antarctica, where a rim around the edge would surely go as well.
Arch, in one of Hansen’s pieces he talks about chucking up a dam wall in Siberia, from memory and I think Canada to hold ice sheet size bodies of water. So maybe you could do the same thing there. It’d probably mean wiping most of the populated bits of Egypt and Israel off the map, but for the greater good…
BTW at the same meeting Barry mentioned at 19 there’s a presentation by Macadam (pdf) where he says (slide 19):
That’s using the dud IPCC projections.
This thread has probably run out of puff, with me having a chat with myself. Before it disappears I wanted to get in another quote from Hansen at Huffington Post:
Hansen sees his duty as a scientist to give us his best estimate of what’s going to happen, given scientists’ current state of knowledge. He knows, as should we, that it is never going to be possible to predict exactly how the disintegration of ice sheets will unfold.
I’m quite familiar with this territory, albeit with less at stake. In a quarter of a century in the public service we were often called upon to make decisions without the luxury of precise information. You do the best you can with the information you have.
In view of what we found in the post and comments above two metres would cause a lot of grief. Furthermore, if we get two metres this century there is likely to be worse to come in the following century. As he says, finding a stable shoreline, and most of our industrial infrastructure is near the shoreline as well as much fertile agricultural land, will not be possible for centuries.
I’m planning to have a closer look at Greenland and Antarctica in my next post, which I’m thinking should be up by Monday morning.
just wondering given the acceleration of movement in glaciers,and greater likeyhood of sea level rise;what other factors could accelerate sea level rise that haven’t been discussed? methane deposits,greater sea temps,and what will slow this process?
philip, I think it’s mainly anything that puts carbon in the air or prevents it’s absorption in carbon sinks. So the destruction of forests, the release of methane from peat bogs, the release of methane clathrates under the sea would be included. It is said that if we get 2-3c warming then soils will give up carbon.
Another one relates to aerosols. Generally if we clean up air pollution more solar radiation will get through. This is quite a significant factor as shown on this NASA GISS graph.
I believe soot from industrial pollution in Greenland and the Arctic is also a factor, reducing the reflectivity of ice.
The main way of slowing the process is to put less carbon into the atmosphere. Other than that we can implement schemes to take carbon out of the atmosphere, by planting trees, certain agricultural practices etc. Flannery reckons that just as we sometimes have to cut off a badly damaged leg or arm off we might have to take drastic action by putting a protective film of sulphates into the atmosphere to shade the earth at the expense of turning the sky white.
Brian, this post had such good information I have transcribed it to this wiki article. Feel free to contribute to it further (and others too) if you wish.
With world C02 levels now at 380ppm how long will it take for sea levels to rise 15m? I think I may move to a mountain . . .
Holy dooley, Peterc, famous at last! Anything that helps spread the word. But didn’t they already have one on that topic?
Greenlivingpedia is not Wikipedia, although content can be and is cross referenced between the two.
The advantage with Greenlivingpedia is that it is not constrained by Wikipedia policies and protocols, and currently there are no industry or government hacks doctoring the content, as is the case with many Wikipedia articles.
Peterc, thanks, it was late and I didn’t notice the difference. You learn a bit every day, as they say.