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Climate Hustle

Rising Oceans - Too Late to Turn the Tide?

Posted on 24 July 2011 by John Hartz

This article is a re-post of a Universtiy of Arizona news release  by Daniel Stolte, University Communications.

Sea level rise
If sea levels rose to where they were during  Last Interglacial Period, large parts of the Gulf of Mexico region would be under water (red areas), including half of Florida and several Caribbean islands. (Photo illustration by Jeremy Weiss)

Melting ice sheets contributed much more to rising sea levels than thermal expansion of warming ocean waters during the Last Interglacial Period, a UA-led team of researchers has found. The results further suggest that ocean levels continue to rise long after warming of the atmosphere levels off.

Thermal expansion of seawater contributed only slightly to rising sea levels compared to melting ice sheets during the Last Interglacial Period, a University of Arizona-led team of researchers has found.

The study combined paleoclimate records with computer simulations of atmosphere-ocean interactions and the team's co-authored paper is accepted for publication in Geophysical Research Letters 

As the world's climate becomes warmer due to increased greenhouse gases in the atmosphere, sea levels are expected to rise by up to three feet by the end of this century.

But the question remains: How much of that will be due to  ice sheets melting as opposed to the oceans' 332 million cubic miles of water increasing in volume as they warm up?

For the study, UA team members analyzed paleoceanic records of global distribution of sea surface temperatures of the warmest 5,000-year period during the Last Interglacial, a warm period that lasted from 130,000 to 120,000 years ago.

The researchers then compared the data to results of computer-based climate models simulating ocean temperatures during a 200-year snapshot as if taken 125,000 years ago and calculating the contributions from thermal expansion of sea water.

The team found that thermal expansion could have contributed no more than 40 centimeters – less than 1.5 feet – to the rising sea levels during that time, which exceeded today's level up to eight meters or 26 feet.

At the same time, the paleoclimate data revealed average ocean temperatures that were only about 0.7 degrees Celsius, or 1.3 degrees Fahrenheit, above those of today.

"This means that even small amounts of warming may have committed us to more ice sheet melting than we previously thought. The temperature during that time of high sea levels wasn't that much warmer than it is today," said Nicholas McKay, a doctoral student at the UA's department of geosciences and the paper's lead author.  

McKay pointed out that even if ocean levels rose to similar heights as during the Last Interglacial, they would do so at a rate of up to three feet per century.

"Even though the oceans are absorbing a good deal of the total global warming, the atmosphere is warming faster than the oceans," McKay added. "Moreover, ocean warming is lagging behind the warming of the atmosphere. The melting of large polar ice sheets lags even farther behind."

"As a result, even if we stopped greenhouse gas emissions right now, the Earth would keep warming, the oceans would keep warming, the ice sheets would keep shrinking, and sea levels would keep rising for a long time," he explained.

They are absorbing most of that heat, but they lag behind. Especially the large ice sheets are not in equilibrium with global climate," McKay added. "

Jonathan Overpeck, co-director of the UA's Institute of the Environment and a professor with joint appointments in the department of geosciences and atmospheric sciences, said: "This study marks the strongest case yet made that humans – by warming the atmosphere and oceans – are pushing the Earth's climate toward the threshold where we will likely be committed to four to six or even more meters of sea level rise in coming centuries."

Overpeck, who is McKay's doctoral advisor and a co-author of the study, added: "Unless we dramatically curb global warming, we are in for centuries of sea level rise at a rate of up to three feet per century, with the bulk of the water coming from the melting of the great polar ice sheets – both the Greenland and Antarctic Ice Sheets."

According to the authors, the new results imply that 4.1 to 5.8 meters, or 13.5 to 19 feet, of sea level rise during the Last Interglacial period was derived from the Antarctic Ice Sheet, "reemphasizing the concern that both the Antarctic and Greenland Ice Sheets may be more sensitive to warming temperatures than widely thought."

"The central question we asked was, ‘What are the warmest 5,000 years we can find for all these records, and what was the corresponding sea level rise during that time?'" McKay said.

Evidence for elevated sea levels is scattered all around the globe, he added. On Barbados and the Bahamas, for example, notches cut by waves into the rock six or more meters above the present shoreline have been dated to being 125,000 years old.

"Based on previous studies, we know that the sea level during the Last Interglacial was up to 8.5 meters higher than today," McKay explained.

"We already knew that the vast majority came from the melting of the large ice sheets in Greenland and Antarctica, but how much could the expansion of seawater have added to that?"

Given that sea surface temperatures were about 0.7 degrees warmer than today, the team calculated that even if the warmer temperatures reached all the way down to 2,000 meters depth – more than 6,500 feet, which is highly unlikely – expansion would have accounted for no more than 40 centimeters, less than a foot and a half.

"That means almost all of the substantial sea level rise in the Last Interglacial must have come from the large ice sheets, with only a small contribution from melted mountain glaciers and small ice caps," McKay said.

According to co-author Bette Otto-Bliesner, senior scientist at the National Center for Atmospheric Research (NCAR) in Boulder, Colo., getting the same estimate of the role ocean expansion played on sea level rise increases confidence in the data and the climate models.  

"The models allow us to attribute changes we observe in the paleoclimate record to the physical mechanisms that caused those changes," Otto-Bliesner said. "This helps tremendously in being able to distinguish mere correlations from cause-and-effect relationships."

The authors cautioned that past evidence is not a prediction of the future, mostly because global temperatures during the Last Interglacial were driven by changes in the Earth's orbit around the sun. However, current global warming is driven by increasing greenhouse gas concentrations.

The seasonal differences between the northern and the southern hemispheres were more pronounced during the Last Interglacial than they will be in the future. 

"We expect something quite different for the future because we're not changing things seasonally, we're warming the globe in all seasons," McKay said.

"The question is, when we think about warming on a global scale and contemplate letting the climate system change to a new warmer state, what would we expect for the ice sheets and sea levels based on the paleoclimate record? The Last Interglacial is the most recent time when sea levels were much higher and it's a time for which we have lots of data," McKay added.

"The message is that the last time glaciers and ice sheets melted, sea levels rose by more than eight meters. Much of the world's population lives relatively close to sea level. This is going to have huge impacts, especially on poor countries," he added.

"If you live a meter above sea level, it's irrelevant what causes the rise. Whether sea levels are rising for natural reasons or for anthropogenic reasons, you're still going to be under water sooner or later."

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Comments 51 to 59 out of 59:

  1. Pirate, it's not hard to make an assessment for what 50-80cm of sealevel rise will do locally. Since is low-end of expectation, I take it you arent actually in denial that this will happen? It's real easy to ignore sealevel effects if your position is that it is not happening.

    This was subject of public meeting for our city who are already battling a number issues (coastal erosion, salt water excursion in low lying farmland and rising water table in southern suburbs). 50-80cm is no cause for panic but it is a considerable cost to the city and complicated because you have to solve a number of problems all at the same time. Who's paying?

    Making pious statements about problems of people living on unstable areas is pure diversion. We are only talking about EXTRA pressure created by sealevel rise. This in addition to existing problems. Fertile deltas are always going to be heavily populated.

    Now lets look at how much displacement from say 80cm of rise, divide by 100 years and work out the required immigration per year. Is your country prepared to take to avoid that conflict?
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  2. Muoncounter

    Your assessment of the effects of SLR are spot-on, particularly the certainty that they will cause flooding of low coastal land and river deltas – often among the more heavily populated areas of the planet and certainly among the major food producing areas.

    The effects on a global population of 10 billion, of whom 7 billion now live in such areas, is not difficult to imagine.

    What intrigues me is that so many commentators assume that the rate of SLR is either static or linear. It can be neither.

    SLR is primarily caused by loss of land based snow and ice, particularly polar ice. Even a casual glance at polar ice mass loss data should be sufficient to show that the rate of loss is non-linear, increasing and expected to go on increasing for the rest of this century.

    Consequently SLR will continue to increase and do so at an increasing rate this century and for centuries to come. The question is how much will it rise by 2100? The answer varies from 1-5m depending on which authority you listen to.

    What is clear is that even a conservative estimate of 1m SLR by 2100 has the potential to be tremendously damaging since there us no effective defence against SLR which is continuous – and it is certainly not going to stop in 2100.
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  3. Pirate - just to be clearer, supposing you are wrong - sealevel rise causes significant costs for adaptation - do you accept the principle that your country should be taking responsibility for your countries share of the emissions that caused the problem? This is a question of principle not science - that of assuming responsibility for actions.
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  4. Agnostic#52: "there us no effective defence against SLR which is continuous"

    The only defense I've heard continuously on this thread is a variant of 'I can't see it happening to me right now' aka 'it's not my problem'.

    A series of talks given at an SLR conference in the US last year are available here. These slide shows are well worth a browse. One author described the economic effects to the Galveston Bay area of 0.69m and 1.5m SLR -- when combined with a 100 year storm. That's exactly the scenario we've been labeling 'conservative;' the results will cripple the region's economy (which is already not doing too well).

    Another author stressed the need to begin making decisions now. That's not going to happen if the prevailing attitude is a hand-waving 'we can adapt.'

    But the east bank of New Orleans is resting easier behind what they are calling a 100 year floodwall; claims by the Army Corps of Engineers (who designed it - as well as the prior failed levees/canal system) are that they included both SLR and subsidence potential in their calculations.

    So with enough money, concrete and 6 years of hard work, it seems possible to defend one location. Unfortunately for the surrounding area, doesn't a wall in one spot just mean more flooding someplace else?
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  5. scaddenp#51: "it's not hard to make an assessment for what 50-80cm of sealevel rise will do locally."

    Those sorts of assessments already exist:

    The impact of sea level rise on coastal flooding is amply demonstrated by comparing Hurricane Isabel of 2003 with another major storm: the hurricane of August 1933, widely regarded as the “storm of the century” for Hampton Roads.

    The 1933 hurricane was more powerful than Isabel and produced a storm surge (rise in water level due to the effects of the storm) of 1.8 m (5.8 feet) as compared to 1.5 m (4.8 feet) for Hurricane Isabel in Hampton Roads. Yet the maximum water level or storm tide (sum of the storm surge and the astronomical tide) for both storms was about the same: 2.4 m (8.0 feet) for the 1933 hurricane and 2.4 m (7.9 feet) for Isabel.

    The reason the weaker of the two storms produced an equivalent storm tide is that monthly mean sea level during Isabel stood about 0.43 m (1.4 feet) higher than the monthly mean during the August 1933 hurricane. Most of the difference is due to sea level rise during the 70 years between these two storms.
    -- emphasis added

    Hurricane Isabel was 'only' Cat 2 at landfall in North Carolina (south of the Hampton Roads, Virginia location discussed above); the Outer Banks storm of 1933 was Cat 3 at its first landfall in about the same location.

    Regarding Isabel's effects on Virginia alone:

    The hurricane caused about $1.85 billion (2003 USD, $2.17 billion 2008 USD) in damage and 36 deaths in the state — 10 directly from the storm's effects and 26 indirectly related.

    Too bad those folks just didn't adapt.
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  6. Muon@50
    Well, obviously moving away from the water's edge as it continues it's inexorable creep upwards is a start. That is until the next ice age starts and then the land can be reclaimed.

    It's not "we can adapt", it's about "we must adapt."

    I am interested in hearing your ideas.
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    [DB] "Well, obviously moving away from the water's edge as it continues it's inexorable creep upwards is a start. That is until the next ice age starts and then the land can be reclaimed."

    So your suggestion is to walk uphill for the next 60,000+ years...some, obviously, will run out of "uphill" and will need a boat...

  7. Sphaerica,

    I think you are dodging pirate's question. Just because the possibilty of something happening exists, does mean that drastic measures should be taken now to prevent it. I think he has a legitimate issue. Is there an ecosystem that is threatened by current SLR? If so, then we can take steps to counter the threat. Absent any specifics, the only general reply is to move away from the coast, or at least far enough so that if the seas were to rise by a foot in your lifetime, you will not be negatively affected.
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  8. Pirate - moving is not cost free (especially if it say a slum in Dacca). And this "until the next ice age" - even without extra CO2, another ice age isnt expected for around 50,000 year (see Berger & Loutre 2002. On top of that, it's not clear that climate will go into ice age with CO2 at 400ppm. This looks like a "look squirrel" to avoid answering questions about taking responsibility.

    And for "we must adapt" - adapting to 20cm of sealevel is a lot easier than adapting to 1m. Its a choice - mitigate the emission or take responsibility for the costs of adaption.
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  9. Scaddenp@58
    What country do you live in?

    How do you plan on assessing how much to "bill" each country?

    How will that cost be passed on to the average citizen?

    How will the procured funds be distributed?

    We can go on and on with these questions - but, I think its obvious that it is a practical impossibility.

    The USA might be tops on your list for "responsibility", but that is because we are a developed country that has industry. We make stuff for people worldwide, so based on your thought pattern anybody who buys our products needs to pay up too.

    Ain't going to happen.
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  10. Eric the Red
    Thanks for stating my point better than me. I honestly want to know about the ecosystems that are definitely in danger due to SLR, not the ones that may be.

    It is a much more prudent path to take to address issues that may arise. SLR is going to be slow in human terms regardless of how fast it may be in geological terms.

    And, again, let me state that there are an awful lot of actions that we should be doing anyway that are helpful for the "health" of this planet. Many of those actions would be beneficial in reducing CO2 emissions.
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  11. pirate - I live in NZ.

    And yes, those are difficult questions. That is whole point. Americans in particular push the viewpoint of individual liberty of action and with it goes the responsibility for the consequences. However, responsibility can be very difficult to assign, especially for inter-generational debt hence the need to governement action. You cannot find a way to cost the responsibility, therefore you limit your emissions. Either solve the problems of assignment of responsibility or dont incur the liability.

    You dont seriously entertain the idea that western world should enjoy the benefit of FF use while the rest of the world pays for the consequences?
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  12. scaddenp @ 61
    Americans are reducing our emissions. There is a lot of pushback and a lot of that is from environmental groups whether it concerns solar or wind or nuclear.

    I get my power from nuclear and hydroelectric.

    I am not sure where you are coming from on your last sentence. Everyone on Earth should be able to enjoy the benefits of electricity and transportation. I am quite sure you do. Food lasts longer, living conditions are more tolerable, medicine can be properly maintained, etc... I will leave it up to you to tell villagers in Asia, Africa, or South America that they can't have that because CO2 emissions lead to AGW and that leads to SLR.

    Certainly, there are smarter ways to do manage our use of FF. Certainly, mistakes have been made. But, I feel quite certain in the next few decades new sources of energy will come online and be dependable and affordable.
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  13. pirate#60 and EtR: "I honestly want to know about the ecosystems that are definitely in danger due to SLR"

    There's an ample list of ecosystems among the papers I referenced here. Do the homework.

    "SLR is going to be slow in human terms"

    Do you still refuse to accept the well-documented conclusion that SLR, however slow,
    a. Has already had serious effects
    b. Shortens the return time of the '100 year storm'
    c. Makes storm surges worse?

    I suspect so, because you're still going on about this being a slow problem, one that can be postponed for someone else to solve. If so, you've proved my point here. Or as a wise man once said, if you're not part of the solution, you're part of the problem.
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  14. muoncounter @ 40
    I was intriqued by your link to the CNA document. I talked to two of my friends who are active duty military. One is a Lt. Colonel in the US Army and has served extensively overseas in combat sitatutions. The other is a Lt. Commander in the US Navy and has served stateside only in various functions.

    The Army officer has never heard of this document, and further stated that he has never been briefed on any security issues relating to climate change.

    The Naval officer had heard of this study. He did not know who it was commissioned by. He said the USN is looking at contingency plans for their ports and bases as it pertains to sea level rise. However, he had no knowledge of security issues related to SLR.
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  15. pirate#64: "I talked to two of my friends..."

    Is that what constitutes research? Let's try the Google machine:

    Here's a .mil website about SLR impact that cites the CNA study.

    A recent study directed by a board of senior retired military officers also recommended that the DoD conduct assessments of the impact on United States military installations of rising sea levels, extreme weather events, and other projected climate change impacts over the next 30 to 40 years.

    Here's a DoD workshop:

    The project’s sea level rise risk assessment moves beyond the arguments of cause and effect and begin planning to address its potentially devastating effects. The consequences of climate change and sea level rise are clear, the disruption of the organization, training, equipping, and planning of the military services.

    This from Defense News:

    A sea-level rise in the Arctic over the next two decades is "highly certain to occur and highly certain to come with economic costs" in a region thought to hold more than one-fifth of the world's untapped hydrocarbons, it said.

    I don't know who CNA is, nor do I care. The fact is that the US military recognizes this problem, whether you do or not.
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  16. mufon@63
    Thank you for the link. I followed it and found many interesting papers. Some of the research was actually done in my state and at research centers that I have worked at. Very cool!

    I have not had time to read more than a few of the presentations. But, at least one them mentioned something that I have been thinking about. Of course SLR will eventually cause freshwater marshes to convert to saltwater marshes and then the saltwater marshes to disappear as the water gets deeper. However, it should be remembered that that new marshes will be created at the same time. Simple arithmetic will confirm that overall there will be a loss of wetlands because of shrinking land mass, but they just don't go away. The pluses have to be factored in with the minuses. I think too many times the minuses only are focused on.

    And, I am providing a link to my thesis to show you that I really have studied and worked with these people. I am not sure if the thesis will pull up or not. My focus was on crawfish, but I did a tremendous amount of work with redfish and oysters as well.
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  17. "I will leave it up to you to tell villagers in Asia, Africa, or South America that they can't have"

    Their rights, like yours, like mine, only extend as far as not constricting the rights of others. As far as I can see, that means reducing CO2 emissions much faster than now. The Western world is responsible for almost all of the current increase in CO2 in the atmosphere and so it seems to me that we are beholden to the most to reduce. Whatever you personal choices, I would say US government action has been exceedingly ineffective.

    And by the way, looking USA trade deficit, how much of the very modest reduction in emissions is from exporting these emissions to China?
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  18. muon @ 65
    I plaiinly stated that the Navy at least is developing contingency plans for SLR. I don't understand your confuion. Bases built in areas of low elevation are going to have to address any possible future changes in sea level.

    Think about this: at some point in the future the oceans will recede again and the naval bases will have to extend instead of retreat.
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  19. Pirate -"Think about this: at some point in the future the oceans will recede again and the naval bases will have to extend instead of retreat.'

    I doubt very much there'll be a US navy in the years 2200 -2500.
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  20. Walk to work, send kids to schools they can walk to, public transport, renewable electricity purchase, (NZ is 73% renewable anyway), dont fly overseas - dont attend conferences, converted from gas heating to wood pellet heating, double-glazed and double-insulated (rare here), minimize on gadgets - especially from coal-fired sources - paying more for goods that will last longer, advocate for renewable energy (eg this article.

    Answering my last question should be question of amount of embodied energy imported from China (especially compared to say 1992 which was last time USA had a trade surplus I think?).
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  21. "at some point in the future the oceans will recede again" planning for 10,000+ years in future seems somewhat impractical.
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  22. pirate#68: "the Navy at least is developing contingency plans for SLR"

    Confusion? Hardly.

    Eglin is a large Air Force Base in 'panhandle' Florida. Camp LeJeune is a Marine Corps base on the coast of North Carolina. And who is building all those floodwalls in New Orleans? The US Army Corps of Engineers.

    The other branch of the service is called the Coast Guard; I think they're up to speed as well.
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  23. Muon@73
    You are so predisposed to find fault in anything I write, that you are not reading what I write.

    I typed "the Navy AT LEAST". That doesn't exclude the other branches of the US Military.

    Earlier in July I was in the panhandle of Florida and drove through Tyndall AFB on the way out. It is a very low lying area and will obviously be affected by any SLR down the road. I plan on doing IronMan Florida there in 2012.

    One would expect the US Army with most of their bases being inland to be the least concerned about SLR.
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    [DB] It strains credulity beyond the breaking point that the Joint Chiefs would have all of the branches developing contingency plans except for one.

  24. pirate#74,
    Sorry, nothing personal. I read the 'at least' in "the Navy at least is developing contingency plans" as a qualifier on what they were doing (at least they are developing plans).

    But this is now wayyy off topic.
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  25. pirate,

    I appreciable the compliment. It appears that we are searching for similar problems and solutions to specific, rather than generic, issues. SLR has been an issue for mankind since we first started migrating about this planet. Some, like New Orleans and the Netherlands have adopted large engineering feats to combat this issue, while Blangladeshis moved to neighboring lands. You may be interested in this paper.

    Never underestimate mother, mother ocean.
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  26. DB at 73
    I never stated that the US Army was not. I stated that my friend who is a Battalion Commander has never heard of any climate related security issues. So, if the Army is working on something it has not filtered down yet.
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    [DB] Speaking in generalities tends to draw unwanted attention; had you been more precise, I would not have intruded.

    That said, expecting the rank-and-file to be kept "in-the-loop" by the powers-that-be is not credible.

  27. EtR#75: "You may be interested in this paper"

    Yes, there are some interesting conclusions drawn. Forgive the lengthy quote, but it's always fun to read exactly what we've heard as skeptic arguments demolished point-by-point:

    Critics may argue that climate change is slow, providing ample adjustment time. However, climate change is expected to raise the frequency and intensity of extreme weather events, which play a role in migrations. Critics may also argue that economic growth in LDCs will solve the problem, financing mitigation and adaptation, and reducing dependence on the environment. However, this will considerably raise their demand for energy, and with the current technology, accelerate climate change. Facing this conundrum, I propose that we take initiative early on, defending against climate change problems before they grow. This effort should focus on LDCs most vulnerable to environmental migration and conflict. For example, vulnerable LDCs could lessen their dependence on the environment for livelihood or protect certain areas against rising sea level. These programs will likely be lengthy, complex, and expensive ...

    Nevertheless, assuming we decide to implement this effort, who would fund it? The ‘‘polluter pays’’ principle which DCs implement at home, suggests that DCs should finance most of the effort required to defend the LDCs against the effects of climate change, as over-reliance of the DCs on fossil fuels is the primary cause of climate change.
    -- emphases added, albeit hardly necessary
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  28. Muon,

    Quite interesting. He is basically saying that migration caused by past weather events has led to conflict in many cases; particularly when the migration crosses ethnic or cultural borders. Therefore, migration should be avoided. In order to avoid this type of migration, the least developed countries (LDC) should reduce their dependence on the land, i.e. increase modern development. Also, these countries should invest (with help from the developed world) in infrastructure to withstand environmental changes.
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  29. DB at 76
    The Lt. Col. in the Army is hardly rank and file. He has a top secret security clearance, reports directly to a 4 star General, and is the G4 at Fort Jackson.

    The US Army may well have contingency plans for sea level rise as it pertains to national security. I really don't know and don't claim to know. I'm just saying that a high ranking officer has neither been briefed nor seen any documents on SLR or Global Warming related security issues. The Army has contingency plans for just about everything. One of their main concerns right now is what to in the event of an EMP.
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    [DB] We are seriously OT here.  And yes, your friend, despite his level, position, clearance, etc, is hardly in a "need-to-know" position as a warrior in the field.  And that is no slam on him.

    FWIW, I carried a Sec Clear well above the TS level in my time with the DoD and much dialogue went on "above my pay grade", even though serving on the nation's Crisis Support team for more than a decade.

  30. Yes, its OT, but let's put this to rest. Once again, to the Google machine. Note I included .mil in the search phrase.

    On March 30-31, 2007, the Strategic Studies Institute (SSI) and the Triangle Institute for Security Studies (TISS) held a colloquium on “Global Climate Change: National Security Implications.” The 2-day event took place in Chapel Hill, North Carolina, and was well-attended by both academics and members of the U.S. Government and the Armed Forces.

    FYI, SSI is a division of the US Army War College, Carlisle, PA

    Of course, the Army Corps of Engineers builds floodwalls and that's more to the point of SLR. But did you know that new budget proposals in our right-tilted House of Reps would prevent the CoE from including climate change adaptation in their planning? How's that going to work with 'we must adapt'?
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  31. EtR at 78 and muon at 77
    Interesting article. It does create a conundrum. I am not sure how the DCs are supposed to invest their money in helping the LDCs defend against climate change. One thing is for sure - we can't improve their quality of life by supplying them with electricity because that will supposedly lead to faster warming and faster SLR. They are also need to give up their jobs that depend on local marine resources. Now, I am a huge supporter of properly managing our natural resources, but what are these people going to do? Does that mean that basically we take wealth from the polluting DCs and give it to the LDCs to keep them up in their current modes so they don't contribute to further global warming?
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  32. I don't know if it is too late to turn the tide, or not. I really don't think it is possible to turn the tide. Even if we eliminate all of our FF use and land altering activities, there is still good ole Mother Nature to deal with and she will continue her cycle of warming and cooling.

    I firmly believe that the most prudent path for addressing current perceived negative climate change issues, and possible future negative climate change issues is to use technology and innovation. We can easily address the current rate of SLR, and the anticipated increased rate over the next few decades. In the meantime we should be working diligently on developing dependable, affordable and emission free energy sources.
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  33. " In the meantime we should be working diligently on developing dependable, affordable and emission free energy sources"

    And does that include providing effective incentives for their development? Especially removal of ALL FF subsidies?

    You also keep bringing natural SL change as if this would make any appreciable difference in the scale of 1000's of years. What is your evidence for this? Specifically what natural forcing can produce global sealevel change of more than 1-2mm/yr given the planet's current configuration?
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  34. scaddenp@83

    "And does that include providing effective incentives for their development?"
    A resounding NO. The market will take care of that. Point being, if you offered me an equally or even closely equally cost-effective method of generating electricity to heat and cool my home and place of work that is dependable and genuinely more "friendly" to the environment, I would gladly accept it. So would most end users.

    "Especially removal of ALL FF subsidies?"
    Please define before I comment.

    Of course natural SL changes over 1,000's of years will be appreciable. I am sure you realize by looking at long-term history that number may go up or down.

    "You also keep bringing natural SL change as if this would make any appreciable difference in the scale of 1000's of years. What is your evidence for this? Specifically what natural forcing can produce global sealevel change of more than 1-2mm/yr given the planet's current configuration?"

    Well, I am not sure about those natural forcings. I know they happened. Just go back and look at the graphs posted at #12 of this topic. The Agricultural Revolution occurred during the middle of the sharpest rise. Human impact obviously had noting to with that, AND during that time we prospered an grew as a multitude of civilizations.
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  35. "I would gladly accept it." -unfortunately, it would appear that most in fact would buy on price only. Especially industry where there is sense that to do otherwise would risk competitiveness. Industry use outweighs residential use.
    "Please define before I comment"
    As detailed in this IEA Report (Translation, if you remove subsidies you will pay more for energy but you argue for less tax).

    "I know they happened."
    Sorry, but I dont see anything on those graphs to support that conclusion. You get high rates during the collapse of ice sheets but they are gone. What can give you that now? (well aside from melting of the polar ice sheets but you wont do that from natural forcings as paper I pointed you earlier shows).
    0 0
  36. A new paper from Oregon State University states:

    "If water were to warm by about 2 degrees under the ice shelves that are found along the edges of much of the West Antarctic Ice Sheet, Marcott said, it might greatly increase the rate of melting to more than 30 feet a year. This could cause many of the ice shelves to melt in less than a century, he said, and is probably the most likely mechanism that could create such rapid changes of the ice sheet."
    0 0
  37. Scaddenp@85
    I must be misunderstanding you in your last paragraph. Can you explain what you mean.

    "Sorry, but I dont see anything on those graphs to support that conclusion. You get high rates during the collapse of ice sheets but they are gone. What can give you that now? (well aside from melting of the polar ice sheets but you wont do that from natural forcings as paper I pointed you earlier shows)."
    0 0

    [DB] Scaddenp refers to the SLR which occurred during the demise of the Laurentide Ice Sheet, which is long gone now.

  38. Sean at 87
    From the article you linked to, please note that key words in bold:

    We don’t know whether or not water will warm enough to cause this type of phenomenon,” said Shaun Marcott, a postdoctoral researcher at Oregon State University and lead author of the report. “But it would be a serious concern if it did, and this demonstrates that melting of this type has occurred before.”

    If water were to warm by about 2 degrees under the ice shelves that are found along the edges of much of the West Antarctic Ice Sheet, Marcott said, it might greatly increase the rate of melting to more than 30 feet a year. This could cause many of the ice shelves to melt in less than a century, he said, and is probably the most likely mechanism that could create such rapid changes of the ice sheet.
    0 0

    [DB] Do you have a point with this?  Sean was merely relaying new info.  Or are you merely advancing an agenda...?

  39. Pirate, when you say agricultural revolution, I assume you mean 10k BP?
    0 0
  40. scaddenp @ 89
    Yes, I do. When modern humans began transitions from the hunter-gatherer lifestyle to agrarian societies. And, this was during a time of (compared to today) of extremely rapid SLR.
    0 0

    [DB] Actually, human agriculture and civilization emerged due to unusual climate stability:

    Sweet Spot

    A period nearing the end of its "natural cycle"...

    C'est la vie

  41. DB @88
    I am not sure of the difference between making a point, or advancing an agenda. If you can enlighten me, I would appreciate it.

    I was trying to make a point (you may inform me differently) that when reading scientific articles the wording is very important. You see people on both sides of the argument that latch on to certain papers as if they were the gospel. This paper Sean posted was full of words that in the scientific lexicon do not imply that the stated effect will happen, but merely that it is possible.
    0 0

    [DB] And no one other than you was implying that it was.  Please let us return the dialogue to that of the OP.

  42. Rapid sea level rise 10K was caused by milankovich operating on ice sheets that are now long gone. No mysteries and that forcing isnt going to change sealevel one way or the other anytime soon. Note also that rate of temperature change then was at least 10x less than current rate of change.
    0 0
  43. DB @ 90
    From Oregon State University World Food Crops: Origins of Agriculture.

    So, if we go back to the 10K BP mark you see from your post that it is at the beginning of the Younger Dryas. A period of relatively rapid temperature rise and sea level rise. Those were the seeds (pun intended) of the development of civilization. It is hard to tell on that quasi-log scale where exactly that point is. And, yes we did flourish in that sweet spot. There are no historical indicators that say we stay there.

    "About 10,000 years ago, in the delta of the Tigris and Euphrates rivers in Mesopotamia (today Iraq), people began to grow crops and to adopt a more sedentary lifestyle."

    "Why did the revolution occur? The shift to food production is related to the end of the Pleistocene era and beginning of the Holocene era. The ice age retreated, and the world became warmer and generally wetter beginning about 14,000 BC. Parts of the Fertile Crescent became drier, making it possible to farm. By 10,000 BC, climates were essentially modern. While the Pleistocene had strong climate fluctuations over periods of 1,000 years or less, these fluctuations have been much smaller in magnitude in recent times. It has been suggested that the past 10,000 years have been a "lucky break" in terms of climatic extremes and volcanic activity."
    0 0
  44. pirate#83:
    You are basing an awful lot on 'the 10k bp mark' as the exact origin of agriculture. But this is a thread about sea level rise.

    Continuing here.
    0 0
  45. I fail to see the relevance of this. The natural forcing causing that past climate change is well known. The milankovitch forcings are entirely predictable, very slow compared to anthropogenic forcings, and from the published paper, not about to produce any changes, any time soon. Looking at past ice-ages cycles we can indeed see that the periods when an ice age ends is subject to wild variation in climate (YD, Heinrich events etc), but these appear to be related to ice sheet collapse and we lack evidence of such wild extremes in interglacials (like now). Furthermore, the milankovich cycles were still going on in pre-Pleistocene climates but didnt cause ice-ages. Best guess as to why? CO2 level too high to produce glaciation.
    0 0
  46. Scaddenp,

    I was in Utah where there is a Honnaker Trail formation that records sea level rise and fall, presumably in response to fluctuating southerh hemisphere glaciation, for th entire Pennsylvanian.

    I was interested because geologists have determined the fluctuation period over this vastly longer timeline to be 200,000 years, matching none of the Milankovitch cycles.

    I was delighted to run into Adam Maloof while hiking the trail. He is not convinced that the fluctuations are entirely due to glaciation, but he is carefully studying the formation using modern techniques. His work is in its early stages, but in a few years we should have a very good referedum on Milankovitch.

    In a subsequent email he noted that a worker in Russia using radiometric dating on a similar formation found a period of 400,000 years, matching the longest and most stable Milankovitch cycle, but as you know, this cycle seems to have no power at all in the Pleistocene.
    0 0
  47. trunkmonkey#96:

    There are many reasons for sea level rise/fall over the geologic past; Milankovitch cycles are just one of these. The continents were in a vastly different configuration; oceanic circulation must be a factor in any discussion of past era glacial cycles.
    0 0
  48. Echoing muoncounter on that, but it is very hard to comment without knowing about what you refer to. Some references would help.
    0 0
  49. Regarding the discussion of our transition from hunter gatherers to nomadic pastorialists and then settled urban populations, One of the costs of rising sea levels is the destruction of infrastructure.

    Most of our oldest cities are built as ports at river mouths. Nuclear facilities which use oceans for cooling are very hard to service underwater but so are water treatment and sewage facilities; street utilities, power stations, lpg terminals, roads, bridges, subways, commuter rail, and most of our communications facilities.

    Doesn't the cost of replacing all of that make mediating climate change a bargain we should jump at?
    0 0
  50. rktect#99:"a bargain we should jump at? " More people should think like you. Fig 7 here demonstrates comparative costs of early action vs. inaction.

    What we usually hear are far-sighted statements like 'they can just move' or 'let them build walls' and of course, the ever-popular 'its not happening to me.'

    Here is a set of planning maps for the eastern US. You can see roads, ports, power plants, sewer plants, oil refineries, airports etc, all in need of some level of protection; all just waiting for the next disaster.
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