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The IPCC sea level numbers



What does IPCC say?


Sea Level Rise
(m at 2090-2099 relative to 1980-1999)
Case Model-based range
excluding future rapid dynamical
changes in ice flow
B1 scenario 0.18 – 0.38
A1T scenario 0.20 – 0.45
B2 scenario 0.20 – 0.43
A1B scenario 0.21 – 0.48
A2 scenario 0.23 – 0.51
A1FI scenario 0.26 – 0.59






• Contraction of the Greenland ice sheet is projected to continue to contribute to sea level rise after 2100. Current models suggest ice mass losses increase with temperature more rapidly than gains due to precipitation and that the surface mass balance becomes negative at a global average warming (relative to pre-industrial values) in excess of 1.9 to 4.6°C. If a negative surface mass balance were sustained for millennia, that would lead to virtually complete elimination of the Greenland ice sheet and a resulting contribution to sea level rise of about 7 m. The corresponding future temperatures in Greenland are comparable to those inferred for the last interglacial period 125,000 years ago, when paleoclimatic information suggests reductions of polar land ice extent and 4 to 6 m of sea level rise. {6.4, 10.7}


• Current global model studies project that the Antarctic ice sheet will remain too cold for widespread surface melting and is expected to gain in mass due to increased snowfall. However, net loss of ice mass could occur if dynamical ice discharge dominates the ice sheet mass balance. {10.7}


(The above quotes document everything the SPM says about future sea level rise. The numbers in wavy brackets refer to the chapters of the full report, to be released in May.)

What is included in these sea level numbers?

Let us have a look at how these numbers were derived. They are made up of four components: thermal expansion, glaciers and ice caps (those exclude the Greenland and Antarctic ice sheets), ice sheet surface mass balance, and ice sheet dynamical imbalance.

1. Thermal expansion (warmer ocean water takes up more space) is computed from coupled climate models. These include ocean circulation models and can thus estimate where and how fast the surface warming penetrates into the ocean depths.

2. The contribution from glaciers and ice caps (not including Greenland and Antarctica), on the other hand, is computed from a simple empirical formula linking global mean temperature to mass loss (equivalent to a rate of sea level rise), based on observed data from 1963 to 2003. This takes into account that glaciers slowly disappear and therefore stop contributing – the total amount of glacier ice left is actually only enough to raise sea level by 15-37 cm.

3. The contribution from the two major ice sheets is split into two parts. What is called surface mass balance refers simply to snowfall minus surface ablation (ablation is melting plus sublimation). This is computed from an ice sheet surface mass balance model, with the snowfall amounts and temperatures derived from a high-resolution atmospheric circulation model. This is not the same as the coupled models used for the IPCC temperature projections, so results from this model are scaled to mimic different coupled models and different climate scenarios. (A fine point: this surface mass balance does include some “slow” changes in ice flow, but this is a minor contribution.)

4. Finally, there is another way how ice sheets can contribute to sea level rise: rather than melting at the surface, they can start to flow more rapidly. This is in fact increasingly observed around the edges of Greenland and Antarctica in recent years: outlet glaciers and ice streams that drain the ice sheets have greatly accelerated their flow. Numerous processes contribute to this, including the removal of buttressing ice shelves (i.e., ice tongues floating on water but in places anchored on islands or underwater rocks) or the lubrication of the ice sheet base by meltwater trickling down from the surface through cracks. These processes cannot yet be properly modelled, but observations suggest that they have contributed 0 – 0.7 mm/year to sea level rise during the period 1993-2003. The projections in the table given above assume that this contribution simply remains constant until the end of this century.

As an example, take the A1FI scenario – this is the warmest and therefore defines the upper limits of the sea level range. The “best” estimates for this scenario are 28 cm for thermal expansion, 12 cm for glaciers and -3 cm for the ice sheet mass balance – note the IPCC still assumes that Antarctica gains more mass in this manner than Greenland loses. Added to this is a term according to (4) simply based on the assumption that the accelerated ice flow observed 1993-2003 remains constant ever after, adding another 3 cm by the year 2095. In total, this adds up to 40 cm, with an ice sheet contribution of zero. (Another fine point: This is slightly less than the central estimate of 43 cm for the A1FI scenario that was reported in the media, taken from earlier drafts of the SPM, because those 43 cm was not the sum of the individual best estimates for the different contributing factors, but rather it was the mid-point of the uncertainty range, which is slightly higher as some uncertainties are skewed towards high values.)

How do the new numbers compare to the previous report?

Sea level rise as observed (from Church and White 2006) shown in red up to the year 2001, together with the IPCC (2001) scenarios for 1990-2100. See second figure below for a zoom into the period of overlap.

The TAR showed sea level rise curves for a range of emission scenarios (shown in the Figure above together with the new observational record of Church and White 2006). The range was based on simulations with a simple model (the MAGICC model) tuned to mimic the behaviour of a range of different complex climate models (e.g. in terms of different climate sensitivities ranging from 1.7 to 4.2 ºC), combined with simple equations for the glacier and ice sheet mass balances (“degree-days scheme”). This model-based range is shown as the grey band (labelled “Several models all SRES envelope” in the original Figure 5 of the TAR SPM) and ranged from 21 to 70 cm, while the central estimate for each emission scenario is shown as a coloured dashed line. The largest central estimate of sea level rise is for the A1FI scenario (purple, 49 cm).
In addition, the dashed grey lines indicate additional uncertainty in ice sheet behaviour. These lines were labelled “All SRES envelope including land ice uncertainty” in the TAR SPM and extended the range up to 88 cm, adding 18 cm at the top end. One has to delve deeply into the appendix of Chapter 11 of the TAR to find out what these extra 18 cm entail: they include a “mass balance uncertainty” and an “ice dynamic uncertainty”, where the latter is simply assumed to be 10% of the total computed mass loss of the Greenland ice sheet. Note that such an ice dynamic uncertainty was only included for Greenland but not for Antarctica; instability of the West Antarctic Ice Sheet, a scenario considered “very unlikely” in the TAR, was explicitly not included in the upper limit of 88 cm.

As we mentioned in our post on the release of the SPM, it is apples and oranges to say that IPCC reduced the upper sea level limit from 88 cm to 59 cm, as the former included “ice dynamic uncertainty” (albeit only for Greenland, as rapid ice flow changes in Antarctica were considered too unlikely to bother at the time), while the latter discusses this ice flow uncertainty separately in the text, stating it could add 10 cm, 20 cm or even more to the 59 cm in the table.

So is it better to compare the model-based range 21 – 70 cm from the TAR to the 18 – 59 cm from the AR4? Even that is apples and oranges. For one, TAR cites the rise up to the year 2100, the AR4 up to the period 2090-2099, thus missing the last 5 years (or 5.5 years, but let’s not get too pedantic) of sea level rise. For 2095, the TAR projection reduces from 70 cm to 65 cm (the central estimate for A1FI reduces from 49 cm to 46 cm). Also, the TAR range is a 95% confidence interval, the AR4 range a narrower 90% confidence interval. Giving the TAR numbers also as 90% ranges shaves another 3 cm off the top end.

Sounds complicated? There are some more technical differences… but I will spare you those. The Paris IPCC meeting actually discussed the request from some delegates to provide a direct comparison of the AR4 and TAR numbers, but declined to do this in detail for being too complicated. The result was the two statements:




(In fact delegates were told by the IPCC authors in Paris that with the new AR4 models, the central estimate for each scenario is slightly higher that with the old models, if numbers are reported in a comparable manner.)

The bottom line is thus that the methods have significantly improved (which is the reason behind all those methodological changes), but the expectation of how much sea level will rise in the coming century has not significantly changed. The biggest change is that ice sheet dynamics look more uncertain now than at the time of the TAR, which is why this uncertainty is not included any more in the cited range but discussed separately in the text.

Critique – Could these numbers underestimate future sea level rise?

There’s a number of issues worth discussing about these sea level numbers.

The first is the treatment of potential rapid changes in ice flow (item 4 on the list above). The AR4 notes that the ice sheets have been losing mass recently (the analysis period is 1993-2003). Greenland has contributed +0.14 to +0.28 mm/year of sea level rise over this period, while for Antarctica the uncertainty range is -0.14 to +0.55 mm/year. It is noted that the mass loss of Antarctica is mostly or entirely due to recent changes in ice flow. The question then is: how much will this process contribute to future sea level rise? The honest answer is: we don’t know. As the SPM states, by the year 2095 it could be 10 cm. Or 20 cm. Or more. Or less.

The IPCC included one guess into the “model-based range” provided in the table: it took half of the Greenland mass loss and the whole Antarctic mass loss for 1993-2003, and assumed this would remain constant ever after until 2100. This assumption in my view has no scientific basis, as the ice-flow is almost certainly highly variable in time. The report itself states that this ice loss is due to a recent acceleration of flow, and that in 2005 it was already higher, and that in future the numbers could be several times higher – or they could be lower. Adding such an ill-founded number into the “model-based” range degrades the much more reliable estimates for thermal expansion, mountain glaciers and mass balance. Even worse: to numbers with error estimates, it adds a number without proper error estimate (the observational uncertainty for 1993-2003 is included, but who would claim this is an error estimation for future ice flow changes?). And then it presents only the combined error margins – you will notice that no central estimate is provided in the above table. If I had presented this as an error calculation in a first-semester physics assignment, I doubt I would have gotten away with it. The German delegation in Paris (of which I was a member) therefore suggested taking this ice-flow estimate out of the tabulated range. The numbers would have become slightly lower, but this approach would not have mixed up very different levels of uncertainty, and it would have been clear what is included in the table and what is not (namely ice flow changes), rather than attempting to partially include ice flow changes. The ice flow changes could have been discussed in the text – stating there that at the 1993-2003 rate, this term would contribute 3 cm by 2095, but it is bound to change and could turn out to be 10 cm or 20 cm or more. However, we found no support for this proposal, which would not have changed the science in any way but improved the clarity of presentation.

As it is now, because of the complex and opaque way of combining the errors, even I could not tell you by how much the upper limit of 59 cm would be reduced if the questionable ice flow estimate was taken out, and one of the reasons provided by the IPCC authors for not adopting our proposal was that the numbers could not be calculated quickly.

A second problem with the above range is that the models used to derive this projection significantly underestimate past sea level rise. We tried in vain to get this mentioned in the SPM, so you have to go to the main report to find this information. The AR4 states that for the period 1961-2003, the models on average give a rise of 1.2 mm/year, while the data show 1.8 mm/year, i.e. a 50% faster rise. This is despite using observed ice sheet mass loss (0.19 mm/year) in the “modelled” number in this comparison, otherwise the discrepancy would be even larger – the ice sheet models predict that the ice sheets gain mass due to global warming. The comparison looks somewhat better for the period 1993-2003, where the “models” give a rise of 2.6 mm/year while the data give 3.1 mm/year. But again the “models” estimate includes an observed ice sheet mass loss term of 0.41 mm/year whereas ice sheet models give a mass gain of 0.1 mm/year for this period; considering this, observed rise is again 50% faster than the best model estimate for this period. This underestimation carries over from the TAR models (see Rahmstorf et al. 2007 and the Figure below) – this is not surprising, since the new models give essentially the same results as the old models, as discussed above.

Comparison of the 2001 IPCC sea-level scenarios (starting in 1990) and observed data: the Church and White (2006) data based primarily on tide gauges (annual, red) and the satellite altimeter data (updated from Cazenave and Nerem 2004, 3-month data spacing, blue, up to mid-2006) are shown with their trend lines. Note that the observed sea level rise tends to follow the uppermost dashed line of the IPCC scenarios, namely the one “including land ice uncertainty”, see first Figure.

We therefore see that sea level appears to be rising about 50% faster than models suggest – consistently for the 1961-2003 and the 1993-2003 periods, and for the TAR models and the AR4 models. This could have a number of different reasons, and the discrepancy could be considered not significant given the error ranges of observations and models. It is no proof that models underestimate future sea level rise. But it is at least a plausible possibility that the models may underestimate future rise.

A third issue worth mentioning is that of carbon cycle feedback. The temperature projections provided in table SPM-3 of the Summary for Policy Makers range from 1.1 to 6.4 ºC warming and include carbon cycle feedback. The sea level range, however, is based on scenarios that exclude this feedback and thus only range up to 4.5 5.2 ºC. This could easily be misunderstood, as in table SPM-3 the temperature ranges including carbon cycle feedback are shown right next to the sea level ranges, but the latter actually apply to a smaller temperature range. As a rough estimate, I suggest that for a 6.4 ºC warming scenario, of the order of 20 15 cm would have to be added to the 59 cm defining the upper end of the sea level range.

A final point is the regional aspects. Planners of coastal defences need to be aware that sea level rise will not be the same everywhere. The AR4 shows a map of regional sea level changes, which shows that e.g. European coasts can expect a rise by 5-15 cm more than the global mean rise – that is a model average, not including an uncertainty range. The pattern in this map is remarkably similar to that expected from a slowdown in thermohaline circulation (see Levermann et al. 2005) so probably it is dominated by this effect. In addition, some land areas are rising and some are subsiding in response to the end of the last Ice Age or due to local anthropogenic processes (e.g. groundwater withdrawal), which local planners need to account for.

The bottom line

The main conclusion of this analysis is that sea level uncertainty is not smaller now than it was at the time of the TAR, and that quoting the 18-59 cm range of sea level rise, as many media articles have done, is not telling the full story. 59 cm is unfortunately not the “worst case”. It does not include the full ice sheet uncertainty, which could add 20 cm or even more. It does not cover the full “likely” temperature range given in the AR4 (up to 6.4 ºC) – correcting for that could again roughly add 20 15 cm. It does not account for the fact that past sea level rise is underestimated by the models for reasons that are unclear. Considering these issues, a sea level rise exceeding one metre can in my view by no means ruled out. In a completely different analysis, based only on a simple correlation of observed sea level rise and temperature, I came to a similar conclusion. As stated in that paper, my point here is not that I predict that sea level rise will be higher than IPCC suggests, or that the IPCC estimates for sea level are wrong in any way. My point is that in terms of a risk assessment, the uncertainty range that one needs to consider is in my view substantially larger than 18-59 cm.

A final thought: this discussion has all been about sea level rise until the year 2095. Sea level rise does not end there, as the quotes from the SPM at the beginning of this article show. Over several centuries, without serious mitigation efforts we may expect several meters of sea level rise. The Advisory Council on Global Change of the German government (disclosure: I’m a member of this body) in its recent special report on the oceans has proposed to limit long-term sea level rise to a maximum of one meter, as a guard-rail to guide climate policy. But that’s another story.

Update: I was just informed by one of the IPCC authors that the temperature scenarios without carbon cycle feedback range up to 5.2 ºC, not 4.5 ºC as I had assumed. This number is not found in the IPCC report; I had tried to interpret it from a graph, but not accurately enough. My apologies! The numbers in the text above that had to be corrected are marked by strikethrough font. -stefan

308 Responses to “The IPCC sea level numbers”

  1. 301
    steven mosher says:

    Hi gareth,

    RE 291:

    You wrote:

    “As someone else has pointed out, you ignore or drastically underestimate the impacts of warming. ”

    Acually you get this exactly wrong. My argument is THIS.

    A1F1 ( fossile fuel intensive future SRES ) shows a Global GDP that is DOUBLE that of green futures. The scenario (A1F1) is internally inconsistent. Here is what I mean, if we burn fossile fuel at the rate assumed in A1F1, the economic activity it assumes cannot be sustained BECAUSE OF the enviromental impact. Garbage in; garbage out. I don’t underesimate the impacts of warming, A1F1 does!

    Like I said in other posts. If you ask me to guess about future warming, I’d say +1-3C at 2100. Less than 1 degree C over the next century has Zero probablity (according to the SRES) , more than 4C has a POSITIVE probablity. Ok, wanna bet? Looks like I would get infinite odds by betting less than 1C against your bet of >4C. Right? Again, the issue is the SPREAD of the projections. This is a function of two things: The error in the models and the assumptions of the scenarios. The error or uncertainty within a scenario is half of the uncertainity between scenarios.

    just look at the sea level data in the data set above.See the spread within the scenarios… 18, 23 25 20 27. That variation is within model varition.

    Now look at the range between SCENARIOS. 18CM to 59CM.

    Its a rather simple observation.

    So, I would think, that better policy would be supported by better projections, and better projections could be had by doing better scenarios. read the SRES, you’ll see that they have serious self admitted uncertainity about the data sets. yet, it gets stuffed into a physically based, validated, scientific model. Garbage in.

    Now, you want to improve projections, improve the SRES. reduced the biggest source of error and uncertainity first.

    Now, be honest have you read the entire SRES?

    You went on:

    “If you are so keen to hand out reading lists, then I will respond with only one: start with the Summary For Policymakers of the IPCC’s WG2 report (available here), ”

    Thanks I’ve read every report in full the day they hit . THAT is what got me interested in the SRES. (So I read that too.. did you?). I looked at the graphs. what the heck is this B1 scenario? what is A1T, A1B….. Look at the error band around B1… hmm looks like the error band around A1T.. but why is one scenario so far away from the other? INPUT ASSUMPTONS. What are the input assumptions? Who made up this data? garbage in.

    To repeat I think the high emission scenarios are unrealistic. BUT as the SRES makes clear every scenario is given equal weight in making the projections.

    So, simply, I would suggest that people take more care in selecting input scenarios and look at issue like internal consistency. Namely, a scenario that assumes the that increased C02 will lead to a doubling of C02, ASSUMES that there will be no negative economic feedback. This is my other complaint.. no feedback between climate outputs and economic inputs. Simple feedback. See you first point. I dont under estimate the impact of warming, A1F1 does. A1F1 assumes that
    we can output c02 with impunity. THIS, as you point out, makes no sense. So A1f1 makes no sense. This is your position.
    but you don’t realize it.

    You conclude:

    “then move on to the full report when it’s out in May. With luck you might change your tune. But I won’t be holding my breath. ”

    To reapeat. I don’t question the science. Let me make this very simple.
    A GCM tells me this: “If c02 goes up 2X, sea level will go up xy cm”
    I would not question it. Seems rather silly to question the climate science.

    That is not my issue. Let me answer laconically. IF…..

    IF c02 goes up 2x. what about 1 X, what about 2.76547X what about 3X, what about 4X. The SRES. the IFs. So, that has been my focus. I read the report. made sense. My issue is the inputs. Were the scenarios self consistent.

    1. the green scenarios with less C02, had lower GDPs. Green is poor.
    2. The dirty future (A1f1) had twice the C02 and twice the GDP.

    Now, I ask you. Do you think that greener will be poorer? I dont. Do you think we can sustain economic growth AND
    destroy the enviroment as A1f1 suggests? I don’t.

    Personally I’d focus on an A1T future, high GDP, low emmissions. Green and rich. Put another way, A1F1 is just a scare tactic. I’m not confortable with this. Strikes me as a eco version of you’ll go to hell.

    And then beyond this, the issue is the policy. What’s the right sea level? if it’s rising, and rising is bad, then what exactly is the correct level? what’s the “natural” level? ( like there is an unnatural level) Funny question huh? But one really can’t attempt to control something without a goal. I mean one has to close the loop on something right? What is the exact right temp? We can’t realy close the loop on a target level because of the time lags, so do we implement a rate controller? First order lag? how much overshoot? steering an oil tanker is way different than steering a jetski.

    Honest question. Is having a radiative balance a good goal? Do you think that we can actually control the enviroment with enough fidelity to manage the radiative balance. What would be the best things to measure.. air temp? ocean heat storage etc etc. THAT would be a cool probem for a control systems guy. Lots of measrement errors and long time lags for control inputs.. anyways..

  2. 302


    In the long run, radiative balance, at least at the top of the atmosphere, will be enforced by conservation of energy. If the temperature stabilizes, solar energy input to the planet will equal reflected and emitted energy output.

  3. 303
    ER Barker says:

    Anyway you cut it, that is a lot less then the 27 ft. Al Gore quoted [edit] in Senator Boxer’s Senate hearings on Global Warming.

    [Response: 20ft is the rise (from ice sheet melt) that eventually occurred during the last interglacial when global temperatures were maybe only a degree or so warmer than today. But the timescale over which that plays out is uncertain. -gavin]

  4. 304
    Mike Donald says:


    On the subject of books hereâ??s one I recommend â??The Last Generationâ?? by Fred Pearce (Eden project books Â£8.99). Itâ??s got that famous (?) picture of a river acting like a thermal lance in Greenland (p85). Pearce also states â??In all probability, the Pine Island and Thwaites glaciers are already the biggest causes of sea level worldwideâ??.

    If thatâ??s true I think it shouldâ??ve got a mention in a thread about sea levels.

    Has anyone seen my pet glacier? It was there a few days ago and itâ??s gone! Iâ??ve reported its disappearance to the police and RSPCG. If you have kidnapped it please donâ??t mistreat it. It responds well to ice cubes and cold temperatures. It answers to â??Glassieâ??.

  5. 305
    John L. McCormick says:

    I did not make this up.. It appeared in the Bangkok Post

    Expert predicts no local rise in sea

    (dpa) Global warming is not likely to cause the sea level in the Gulf of Thailand to rise because the body of water is too far from melting glaciers, a leading Thai hydrologist claimed on Monday.

    Recent forecasts by the United Nations’ Inter-governmental Panel on Climate Change (IPCC) – which predict a 40 centimetre rise in sea levels by the end of the century will cause flooding for up to 94 million Asians living in coastal areas – may not apply to the Gulf of Thailand, according to Suphat Vongvisessomjai, a former professor in water resources engineering at Bangkok’s Asia Institute of Technology.

    “The climate change panel’s projection was wrongly accepted to apply to the Gulf of Thailand,” Suphat told The Nation newspaper. “We are too far from melting glaciers or ice sheets.”

    Suphat added that, in fact, recent research shows that the average sea levels along some coastal provinces on the gulf have declined 0.3 to 0.6 centimetres over the past eight years.

    The hydrologist, now an employee of Team Consulting Engineering, called on the public not to panic over the IPCC findings.

    “The climate change panel did not deceive us or exaggerate. Its scientific findings are just based on the environment of their scientists, most of who live in Europe,” he told the English-language daily.

    [Response: oh dear…. – gavin]

  6. 306
    John Mashey says:

    re: #305

    Clearly a complete wacko ….

    OOPS: turns out, it is very likely that he isn’t, and in fact, this is a good reminder to be really careful, especially when an expert tries to explain something complex to a reporter writing a tiny summary in the popular press, and how over-simplifications may come back to bite.

    When I saw this, I laughed, but then, from personal experience, I know how things sometimes get mangled by newspapers, especially with potential language issues. Since I’m in the middle of Naomi Oreskes’ fine book “The Rejection of Continental Drift” (about why American geoscientists resisted this theory so long in the face of mounting evidence for it), I thought “I know SouthEast Asia is complex geologically (colliding plates), could some of Thailand be rising? Maybe this guy isn’t crazy?”

    Searching for the author Suphat Vongvisessomjai in Google Scholar [easier than Joe Smith :-)], I find that he actually has a good multi-decadal record of scholarly publications, and at least looks a like a serious expert on anything to do with water around Thailand.

    Then I found:
    “Will Sea-Level Really Fall in the Gulf of Thailand?”
    [Abstract in both English & Thai, but the article is in English].

    This is a reasonably clear discussion of the various issues that affect local sea-level change, followed by a lot of discussion about the Gulf of Thailand’s specifics. It may or may not be right, and a few of the words describing it may be poorly chosen (stuff about glaciers) but it’s certainly neither denialist nor uninformed.

    This paper, at least, is *not* making a generic claim that there is no sea level rise in the world [i.e., he is not doing the denialist “No Sea level rise near Stockholm” trick.] He is really just pointing out that average sea level rises aren’t seen anywhere, and there are specific data and reasons to not expect much rise in he Gulf of Thailand.

  7. 307
    Mike Donald says:

    #305 #306

    Still oh dear. Someone will have to tell The Onion about this.

  8. 308
    stormboy says:

    I am learning day by day from reading these posts and everything I can find about global warming. To me the time has come to begin the radical transitions needed to mitigate the damages. Here are my top ten ways to slow global warming. Let’s see how they compare to the IPCC’s recommendations.

    Preamble: Our one and only planet is heating up, fast. CO2 burned 200 years ago is still lingering up above us, warming the planet, compounded every day by still increasing tonnage that won’t go away for a thousand years, melting ice caps and glaciers, heating and acidifying oceans, decimating phytoplankton that grows best in cold water, removing the foundations of Earth’s entire biotic ecosystem, from crab larvae to terrestrial mammals like us. The bountiful oceans have been strip-mined and are now losing their ability to grow back.
    Sea levels are rising. According to an IPCC climatologist on

    “59 cm (23 inches by 2095) is unfortunately not the â��worst caseâ��. It does not include the full ice sheet uncertainty, which could add 20 cm or even more. It does not cover the full â��likelyâ�� temperature range given in the AR4 (up to 6.4 ÂºC) â�� correcting for that could again roughly add 15 cm. It does not account for the fact that past sea level rise is underestimated by the models for reasons that are unclear. Considering these issues, a sea level rise exceeding one metre can in my view by no means ruled out… Greenland ice is good for 7 metres and the WAIS for 6 metres of sea level rise. 20 feet is about 6 metres so either ice sheet alone, or half of each, could lead to a 20 feet rise.â��

    A blogger points out that: â��The rise will continue rising and there is no possibility for the sea rise to retreat….not in centuries or longer.â��
    These rising waters will soon, in coming years, not decades, wipe out massive human populations (The low countries, northern Europe and especially Bangladesh, come to mind, but coastal communities everywhere will be flooded) while disrupting the most productive tidal nurseries needed for life in both land and sea.
    Droughts are already drying up wide swaths of tropical and temperate latitudes, where most of Earth’s 6,708,290,000 humans live, (on 04/30/07). That’s at least three times, and probably ten times, the number of people this planet can support for more than one or two generations, and land surface suitable for human habitation is rapidly shrinking. See E.O Wilson on Acting now to save life on Earth. Rising seas, droughts and floods will push 100’s of millions, maybe billions, of surviving refugees to ever-shrinking higher, greener ground, overwhelming those habitats and inhabitants, the stores, schools, hospitals, and criminal justice systems, creating lawless gang warfare and warlords dominating the daily lives of survivors. It’s gonna be bleak. Public awareness of the realities of global warming is ramping up every day, but we’re still deep in the darkness of denial about what’s really starting to happen

    So here, for all leaders and citizens alike all around this imperiled planet, by the wonders of global internet broadcasting, are the top ten things that truly will need to be accomplished while we still have functioning societies, that should have been started generations ago, if we desire to keep our lives tolerable and intact:

    1) Stop having so many wars. Wars, and the buildup for wars, burn more oil and create more CO2 than any other single human endeavor. As resources become harder to find, the tendency will be to start more wars, but if we can stop having wars now, and accomplish the other nine items on this list, we won’t consume nearly as much of Earth’s natural resources, so we won’t be so tempted to start wars. Wars also justify the entire military/industrial complex, which directly and indirectly burns oil without reflection on the consequences, by the millions of barrels daily. Wars are interactions – “they” say or do something bad, like own a resource we think should be ours, or we think they did, so “we” answer with something bad toward them, and the spiral descends into uncontrollable war. We need a better way to respond and interact with each other, a new modus operandi in our society and government, new philosophies at colleges and think tanks, new conversations everywhere, etc. That’s impossible, you say? OK then, welcome to the world of Mad Max Mutual Murder worldwide. Or, we can change our ways and get along, if we try.

    2) Stop having so many babies. This is also contrary to our habits and customs known as “human nature,” but let’s face it, one way or another the human race is about to be drastically reduced. It’s far better to take some control over our sheer numbers by reducing births rather than by increasing deaths. We need an international resolve to distribute clear educational truth on the realities of global warming and overpopulation, and condoms and IUDs, etc. on every streetcorner, and in every school, tea room and post office, worldwide.

    3) Stop traveling so much. Overconsumption of resources leads to global warming and wars, so we’ll need to radically reduce our travels in every way possible. Games, concerts, vacations, family visits, conferences, weekend getaways, and other important occasions, need to be severely reduced, worldwide. Like almost everything else on this list, we’re talking about major personal and economic disruptions, with lots of people out of work while transitions are made to resettle into more integrated communities with our families and our daily needs close by. Hard to imagine? So is Mad Max.

    4) De-throne the corporate rulers. When you’ve got the political muscle, you don’t have to make sense, apparently. We need to see some investigation into exactly who is orchestrating the campaigns to lie about global warming to sell oil, who is pushing unnecessary drugs on people, who is poisoning the Earth with pesticides, who is weakening the will of the people to have livable, logical societies by corrupting our democracies. Of course we have their chosen political officers like Cheney and Bush, and the lobbyists and the “industry reps,” but behind them have to be actual individuals with names and faces, who own the industries, or own the investment groups that own the industries, who hand down their wishes through boards and CEOs, who hire think tanks, media conglomerates and PR firms who hire lobbyists who then say they represent “the industry.” They proclaim their faith in Reaganite simplicity: “Government is bad, taxes are bad, corporations are good.” “For every complex problem, there is a solution that is simple, neat, and wrong. –H. L. Mencken
    I’d like to pull back the curtain and see exactly who is shaping the campaigns to overpower elected officials and shape the consciousness of the public to accept their faulty, simplistic logic. I think we need a public conversation with these individuals. They have a big influence on our lives and our future, and yet they’re just people like the rest of us, once we can see them and talk to them.
    Who are they? They have a big influence on our lives and our future. I want names, faces, bios and contact information. Who set up the think tanks and endowed positions that spew out the pundits that are nothing but loyal team players who have no standards of truth to fall back on, but only allegiance to the captain and to making the scores and claiming moral superiority over the other team? Who does Rupert Murdoch, for instance, have dinner with, meet at the club, go hunting with? The campaign to declare that global warming is a hoax perpetrated by corrupt scientists and greedy environmentalists was not just spontaneously concocted by Sean, Rush and Glenn Beck, to name a few. These hired guns were carefully taught to tell such preposterous lies by….who? These lies are immensely damaging to the consensus we all desperately need if we are to change our lifestyles rapidly, and for the major industries to take seriously the increasingly obvious threats of global warming, or we will indeed cook in our own exhaust fumes. It’s as if we’re all on a train that is headed over a cliff, and some of us see the danger, but we can’t get the engineer to stop or turn, because the crowd in the club car are laughing at us and calling us kooks, in an orchestrated, coordinated fashion, like a trained choir. Who trained them?

    5) Return to simple pleasures, like playing music, making love (using birth control), reading and writing, drinking beer, smoking grass, bird-watching, woods-walking, wood-carving, knitting, yoga, jogging, card-playing, story-telling and listening, rowing, swimming, walking the dog, visiting friends and old folks for no good reason. These are the positives that have been mostly lost due to wars, over-population, over-consumption, social fragmentation and alienation, and obedience to corporate masters.

    6) Conserve power. Buy and use florescent light bulbs, low-power appliances. Use less water, replant lawns with gardens or native ground cover, etc. Enjoy the sounds of nature and the natural relaxation of darkness. Recycle, re-use, reduce. Obvious, I know.
    7) Find locally grown food, building material and everything else as much as possible. Corporate agriculture and those container ships and trucks bringing cheap goods (such as polluted pet food) from far away places, like Mexico and China, are destroying the air, the climate, and our health. Again, there will be personal and economic disruption, worldwide, while we make transitions, but we have no other choice.

    8) Use wind and solar power for homes, industries, businesses, offices and public buildings, every chance you get. This should be politically mandated and demanded by consumers.

    9) Demand inexpensive, plug-in biodiesel hybrid cars, and get as few of them as possible and use them as little as possible. Walk or ride bicycles whenever possible, which also provides strength and vitality and reduces health care costs.

    10) Support Earth-bound politicians, organizations, businesses, teachers, friends and relatives, and avoid religions and philosophies that degrade Earth in favor of any supernatural heaven or afterlife. We won’t know what’s after life until we get there, but our life, and all life, on Earth is too important to let it burn up in our own exhaust fumes, toxic chemicals, radioactivity, etc.

    Iâ��m sure others can think of additions to these ten items, but before we can do these things in a scale to meet the effects of global warming, we’ll need to talk about them.

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