Comments 1 to 29:

1. Doug Hutcheson at 16:00 PM on 12 January, 2012
   The question seems to be when, not if, we will see dynamic changes to the large ice sheets (Greenland and Antarctica). Given that so many indicators are already at or exceeding IPCC estimates, I feel that planning for a pessimistic sea-level outcome this century would be prudent. Can't see much prudence in the political agendae being pursued around the world at present. As we sow, so shall we reap.
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2. Daniel Bailey at 16:38 PM on 12 January, 2012
   Note: A comment questioning SLR predictions was redirected to this How much will sea levels rise in the 21st Century?, more appropriate, thread. Please respond there if such is your interest.
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3. Bern at 16:43 PM on 12 January, 2012
   Doug H: prudence would be recognising that, however much wealthier the future world may be, relocating, say, the cities of New York, London, Amsterdam, and many others to higher ground will cost a lot more than switching away from fossil fuels now. However, that also ignores the "let somebody else pay the bill" mentality that seems to pervade those whose main goal in life is to add another zero to their net worth. While ice melt & sea level rise is by no means the worst impact predicted from climate change, I think it's probably the one that would get the most response. It'd be hard to deny the ice sheets are melting when famous coastal landmarks start spending part of their day underwater. Of course, by then it will be far too late to do anything about it.
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4. Bernard J. at 18:01 PM on 12 January, 2012
   The thing that I find frustrating about almost all discussion on the topic of sea level rise is that it's all referred to in the context of increase by 2100 - as if it all suddenly just stops then. Consider that the rise was 20 cm in the 20th century, and likely to be around 1m in the 21st. What of the period between 2100 and 2200? And beyond? What of the eventual plateau once our emissions are finally controlled? I want to see and hear from the people who believe that we have no responsibility to the future, their justification for inaction. It's bizarre how so many denialists think that the faceless 'future generations' will fix 'it', either through an extraordinary but apparently inevitable cornucopian accumulation of wealth (how's that supposed to work, exactly?), or by miraculous techology, or both. Consider that America has been populated by colonialists for about 400 years, and Australia for about half that time. Each country is still intimately tied to its respective Western founders, and by the standards of most other cultures of the world we are mere babies. Effectively, each of the colonisations was little more than 'yesterday' in the scheme of things. And yet it seems that the decendants of those colonial 'fathers' and 'mothers' regard the time spanning backward to be far more important than the same periods projecting into the future. Hnnn. I suspect that generations 200 and 400 years hence will not have the same respect for us that we, today, apparently exhibit for our own ancestors. Indeed, I suspect that we will be perceived by our descendants with the same contempt that many native Americans and indigenous Australians have for the European settlers who invaded their respective lands those centuries ago. It's long past time that the world faced the fact of warming, and of concommitant sea level rise, and gave the future as much right to a decent world as we demand for ourselves today.
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5. Rob Painting at 18:35 PM on 12 January, 2012
   Bernard J - I agrees wid ya! The Pliocene is where we're heading (so far) in terms of sea level rise. That's around 25 metres higher than present. There was a presentation at the last AGU where one of the scientists confirmed as much. I think it was part of James Hansen's lecture. Sure it'll take about a thousand years to get there, but so?
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6. Tony O at 19:58 PM on 12 January, 2012
   Coming out of the last ice age we got as fast as 4m per century. We have changed the forcing more than an order of magnitude faster than anything in the paleo record and yet we are expecting rises slower than that which has previously happened. Ice sheets are incredibly complex, expect surprises. I realy do have to agree with Bernard J'c comment it is not going to stop in 2100. While we may not be able to stop it, we will be able to make it worse.
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7. tmac57 at 03:04 AM on 13 January, 2012
   One source that I checked said that the net national savings rate in the U.S. is -2.5% . If the U.S. populace is unwilling to make sacrifices in the short term to provide for their personal future,what are the odds that they will make any sacrifices to provide for the welfare of future generations? There seems to be a mass denial going on about more things than just the climate.
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8. Stephen Baines at 04:23 AM on 13 January, 2012
   BernardJ, RobP and Tony O...I agree wholeheatedly. The fact that the debate has been framed arbitrarily by the 2100 endpoint has warping effect in my opinion. The kinds of changes to city-centers that will be occurring over the next several centuries is unheard of in history. Think about it, do people really think central NYC, Miami, Sydney or London could manage the consequences >4 meter of sealevel rise without substantial downside even over 2-3 centuries? That is a lot of infrastructure and people. Then there is all the heritage, natural and cultural, that is under threat as well. And this is a multi centrury pattern we are committing to now. This is one aspect where the IPCC and virtually every reasonable scientifically body is probably acting too conservatively, simply because they are trying their damnedest to appear level-headed. They should be depicting the full range of possibilities on this front so people can really assess what the risks are.
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9. Stephen Baines at 04:23 AM on 13 January, 2012
   tmac57...I'm pretty sure the personal savings rate in the US is nearer positive 2-4%. It's been higher over the last few years in response to lost equity in the housing market and fears about the economic future spawned by the financial crisis. My guess is the rate varies substantially with economic status. In a way that pattern proves your underlying point that people on the whole respond to very obvious and more recent stimuli. I just wouldn't be as extremely cynical about it.
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10. Philippe Chantreau at 06:07 AM on 13 January, 2012
    Problem is, even 2100 seems remote and not so much of a concern for many. Humans are ill equipped to plan and commit for that kind of time frame. Not so long ago, a typical life expectancy was 40 to 50 years in what is now the developped world. In a lot of the rest of the world it's not that much higher. Billions of humans live with constant reminders that they may very well not be around in 1 year from now.
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11. PhilMorris at 06:42 AM on 13 January, 2012
    Rob@5. A thousnd years to get to a 25 m rise? If we've learnt anything over the last few years, it is that the rate of global warming and the effects have been far greater than the IPCC predictions. The Greenland and Antartic ice sheets don't have to melt to cause sea level rises - they just have to slide off the underlying ground into the ocean. Not long ago the predictions were for the Artic to be ice free in summer around 2050. Now we're looking to 2015, and totally ice free in the early 2020's. We've already reached the tipping point. Even if all fossil fuel buring were to stop tomorrow, human activity would still be releasing substantial quantities of GHG through agriculture and land use. And we know that fossil fuel burning will continue unabated for the forseeable future.
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12. william at 06:50 AM on 13 January, 2012
    Let's assume for the sake of the argument that climate change is not happening and if it is we are not causing it. It would still be incredibly worthwhile to stop burning fossil fuels. 1) they are very valuable feed stocks for industry and as such are more valuable than as fuel 2) We will need them in the future to stop a slide into another ice age which really would wipe our our civilization. If we used them to keep Atmospheric Carbon dioxide to about 300ppm, they would last a very long time. 3) We are corrupting foreign governments and bringing misery to the people of oil rich societies. This misery comes back to bite us in many ways. 4) The fossil fuel money comes back to buy up main street, wall street, air ports and sea ports all resulting in us becoming tenants in our own countries. 5) Burning fossil fuels releases a whole raft of nasty carcinogenic pollutants etc. etc. etc.
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13. Mal Adapted at 08:18 AM on 13 January, 2012
    Doug H.:

    I feel that planning for a pessimistic sea-level outcome this century would be prudent.

    So do I, but the denial industry has made that problematic. In coastal Virginia, some "skeptical" residents don't want their local government to do any planning:

    When planners redesignated property as a future flood zone, activists said officials were acting on a hoax. They argued in meetings and online that local planners are unwitting agents of Agenda 21, a U.N. environmental action plan adopted in 1992 that the activists see as a global conspiracy to grab land and redistribute wealth in the United States.

    What a world 8^(!
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14. dr2chase at 09:13 AM on 13 January, 2012
    Regarding change required in coastal cities, I think there might be more than one way to look at it. Consider Florida. in 1912, what was in Florida? Not much. Says Wikipedia, "In 1900 its population was only 528,542". Humans are well-known for their loss/gain asymmetry, so we may see the flow of millions of people out of (coastal) Florida in the space of a century as something catastrophic, but in terms of new construction and infrastructure required somewhere, it's no different from the century we just had. One difference is that all the wealth that people perceive they may own in Florida real estate will evaporate, and it will evaporate well ahead of the rise in sea level (once it becomes widely believed that the sea level is rising and will continue to rise). But it was pretty well worthless (to "civilized" people) 100 years ago (swamps, alligators, mosquitos, snakes, malaria, yellow fever), so really, no change there, either. So if you take that view, and it's not that hard a view to take, climate change in the US will just be a matter of moving people around. And taking that point of view, I do wonder, how will people behave if we start to see centimeters-per-year in sea level rise? Where will they move?
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15. Doug Hutcheson at 10:19 AM on 13 January, 2012
    Mal @ 13: Just proves the old saying that failing to plan is planning to fail. If I were one of those residents living in a future flood zone (declared or not), I would quietly and quickly put my home on the market, hoping to attract a buyer from the deniersphere. My brother in law recently purchased a property in a canal estate, not ten feet above the high tide mark. I had to bite my tongue when he told me how cheaply he had bought it. Sigh.
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16. William Haas at 10:27 AM on 13 January, 2012
    If human caused CO2 is really the cause of all of this then I think that there is little that is going to be done that will actually reduce CO2 levels and with it sea levels. If CO2 levels are not the cause than what will be will be. Sea levels have been changing for billions of years and I doubt that we are ever going to be able to change that. Very low level property close to the sea has always had a certain risk associated with it.
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17. scaddenp at 10:57 AM on 13 January, 2012
    So William, you dont think removal of FF subsidies, "Hansen tax" etc can change FF use? The primary obstacle to action at the moment is misinformed denial. Climate (and sea level) has changed in the past but mostly slowly and before we had settled agriculture, but AGW forcing are causing climate change at rates normally associated with large mass-extinction events. The good news is that we can solve this problem, unlike say an asteroid strike. Perhaps you might like to take the challenge here. If you are entertaining the idea that its not bad, then please see Its not bad
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18. Riduna at 11:08 AM on 13 January, 2012
    Rob @ 5 "it'll take about a thousand years to get there ....." 500 years according to Hansen. He talks of a 5 metre SLR by 2100, My estimate based on decadel doubling of land-based ice loss is 4 metres. But 4 metres or 5 metres - who's quibbling?
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19. skywatcher at 11:09 AM on 13 January, 2012

    Sea levels have been changing for billions of years

    Yes, they have, and always in response to some kind of forcing. Ditto climate change. They never change without a forcing of some sort. We are providing a very large forcing by altering the planet's radiative energy balance with all our FF-derived CO2. Uniquely in geological history, we are aware of this issue. We are a step ahead of orbital forcing or plate tectonic forcing that has altered sea levels in the past. We are, unlike the continets and the Earth's orbit, able to see what we are doing, see that it is altering sea levels (among many other things), and do something about it, say... by substantially reducing our CO2 emissions.
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20. Riduna at 11:20 AM on 13 January, 2012
    Philippe Chantreau @ 10 A further problem is that SLR is as non linear as melting of ice sheets. Present rate of increase, a mere 3.2mm/annum worries no one and, based on that rate, few people believe that within 50 years we are likely to be looking at SLR in the order of 50cm/annum. And when that point is reached it will be far too late to "adapt" to the coming threat to major coastal cities. Move cities and their 3-4 billion inhabitants to higher ground. No problemo! Really?
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21. scaddenp at 12:08 PM on 13 January, 2012
    Also William, you came here saying that you wanted to find the truth. Good for you, so do I. However, dont let that turn into a search for reasons for doing nothing. First you find out what the science actually says, then you do a risk assessment to determine action.
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22. skywatcher at 12:56 PM on 13 January, 2012
    #20 Agnostic - am not sure if 50cm/annum is reasonable - even in Meltwater Pulse 1A it was most likely up to ~50mm/yr, maybe a bit higher, which is quite enough to be going on with...
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23. skept.fr at 22:53 PM on 13 January, 2012
    #17 scaddenp : The primary obstacle to action at the moment is misinformed denial Do you really think that? I suppose you speak of US "action", because the 193 other nation-states of our world do not really decide their economy and energy policy from Lindzen, Spencer, Michaels and other outsiders' views...
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24. skept.fr at 22:56 PM on 13 January, 2012
    #20 Agnostic : "few people believe that within 50 years we are likely to be looking at SLR in the order of 50cm/annum" In fact, I'm among the people who do not believe that. What is the source for this "likely" SLR?
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25. Steve Case at 03:09 AM on 14 January, 2012
    50 cm/annum doesn't sound like it's that much, but it's well over a millimeter per day and over 150 times the current rate.
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26. scaddenp at 06:25 AM on 14 January, 2012
    Skept.fr - this is offtopic for here. I have responded here
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27. dr2chase at 06:29 AM on 14 January, 2012
    #20 Agnostic - as others have noted, I think you may have made a metric typo. 50mm/yr is 5m/century, which is the same as Hansen's geologic-record-says-it-could-be-faster worries, and plenty fast. It doesn't take much to cause problems -- a meter's rise starts to mess with access to barrier islands in Florida (where lots of people live in expensive waterfront homes). Drainage in all sorts of low-lying areas near the coast also gets worse -- whatever the ten-year flood is now, imagine it 3 feet higher.
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28. JoeTheScientist at 14:00 PM on 16 January, 2012
    Bernard J - It's impossible to project meaningfully into the 22nd century. So much of the GW and SLR projections depend on 1. Population growth 2. Economic growth, and with it- energy growth 3. Shift to more GHG-intense fuels - peak oil, leading to more coal use and greater emission intensity Nobody can really predict where these drivers will go, and so the IPCC forecasts a range of possible scenarios. We have to know where these go in the 21st century before we can speak meaningfully of the 22nd. Right now there's an enormous amount of research in alternative energies. Today solar and other technologies cost much more than fossil alternatives, but in 15-30 years green technologies may wind up being cheaper, making them no-brainers to adopt. Just think of what happened with personal computers in 40 years! Unlike the 70s, when energy research was driven by fake scarcity created by OPEC, this time the scarcity is for real. This time the research won't just fade away.
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29. adelady at 18:14 PM on 16 January, 2012
    JoeTS "Today solar and other technologies cost much more than fossil alternatives..." Depends where you are what the costs are. Germany managed to instal - in December - almost twice as much as the USA did for the whole of 2011. And they did it at half the cost. http://thinkprogress.org/romm/2012/01/10/401882/germany-installed-2-gw-of-solar-pv-in-the-month-of-december/ But even in the US, it's expected that both solar and wind will match or be cheaper than conventional power generation around 2015. Certainly by 2020.
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