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Hi Veli, Thanks for your detailed reply, however I think my original point still stands in that radiocarbon dating is only used on its own in palaeoclimate dating for only very recent (less than 40 thousand years ago) time and not on its own - for most palaeoclimate dating (especially beyond 40 ka) astro-tuning, palaeomagnetism and biological markers are the primary dating tools, none of which would suffer from isotope dilution effects. Re. the tropical plants in ice-rafted debris (IRD), your hypothesis is certainly interesting but I suspect that the simpler hypothesis may be that this material is sourced from sediments lain down during the Palaeogene (65 to 34 millions years ago) or during later brief episodes of warmth when the Arctic was ice free and sub-tropical in temperature and ecology. Of course if it was fresh plant material that would indeed suggest a modern-day source of warmth, but if it's old and then it seems more likely to be sourced from erosion of Greenland sediments by iceadvance. Re. the flood basalts, one of my research areas happens to be the impact of flood basalt volcanism on long-term climate change, and although it's definitely an important source of heat and affects the climate I'm not sure it works in the way you're proposing. For one thing, as partial melting of mantle to produce basalt at the seafloor is constantly occurring at mid-ocean ridges presumably you'd have to be mooting a big upshoot in melt production, but such increases would also result in a big increase in volcanic CO2 release - certainly past flood volcanism is associated with episodes of long-term global warmth, which is something I'm currently working on. Basalt weathering does draw down CO2 but on a timescale much longer than it releases the initial CO2, although projects are ongoing though to find ways of speeding up basalt weathering artificially to mop up CO2. Another point to make is that in the global scale Surtsey is a rather small outpouring in the grand scheme of things (as shown here http://en.wikipedia.org/wiki/Large_igneous_province#Examples_of_Large_Igneous_Provinces). I may well be missing something from your argument, but if the eruptions were big enough to cause enough of the lake-snow effect you invoke to cause ice growth then it seems likely to be large enough to also cause greeenhouse warming that would counter ice growth too? If you've written about this elsewhere in greater depth with some quantitive estimates then that would be good to see - further debate/discussion would probably best be not on the crisis forum list so as not to flood biogeochemistry jargon and nitty-gritty over everyone! Cheers, Dave A. McKay >________________________________ > From: Veli Albert Kallio <[log in to unmask]> >To: [log in to unmask]; Crisis Forum <[log in to unmask]> >Sent: Tuesday, 26 February 2013, 15:49 >Subject: RE: Major methane release is almost inevitable - New Scientist > > > >Hi Dave, > >Professor Sir Ghillean Prance, FRS, who is currently the science director of the Eden Project Cornwall, and was previously the director of Royal Botanical Gardens at Kew, London nominated me for the international Guru Nanak Peace prize together with 5 other academics for: sea level rise risks for global security and economic stability on the following basis: > >The radiocarbon dating (carbon-14) is possible because the plants inhalate though the stomata in their leaves which in the process exhalate their body metabolism by product, oxygen (O2). As such carbon-14 transit pathway is through the leaves at the time of the plant is conducting its photosynthetising activity from the air. On the contrary, due to the body metabolism of the plants, the other nutrients or building blocks of the plant enter the organism through their root systems. This happens when the plant is drawing water from the ground using its roots. As a result of this, the other radioisotopes in the plant are more of a reflection of age of the soil and rocks where the plant has been grown, as such, these other cosmogenic isotopes i.e. radioboron, or the uranium series isotopes, can have a vast pre-existence to the time plant actually grew and was photosynthetising (from the very beginnigs of the solar system until the point the plan actually grew depending how long their half life is). > >The above, therefore, necessitates that a variety of radioisotope dates can be obtained depending which radioisotope is chosen. This arises a possibility of a circular argument as it comes down to the assumptions and judgement to choose which particular isotope is being measured for the purpose, carbon-14 from half-life of 5,730 years to uranium series isotopes that live billions of years. The problem now arises from another observation of the ice berg debris having been found: the moraine drop stones from the melting ice bergs being deposites with a plant material known as Apectodinium. The metabolism of this aquatic plant is such that it dies whenever the temperature dips below +24C and is a common plant today in the Amazonia and seen sometimes drifting north from the mouth of the river Amazon. This plant grew massively at one time on the North Pole and above the Gaggel Ridge where it has been found. Yet there were ice bergs in the area raining moraine from the bases of melting ice bergs that fell of the surrounding land masses. In addition another tropical plant, Azolla, is found with vast amounts of pebbles that the floating ice had lifted up from the coastal beaches before melting and re-depositing them onto the Arctic Basin. Azolla, survives a slightly cooler water, but like Apectodinium, not as cold as that where sea ice can be forming. It dies whenever the tempearature drops below +18C at any given time and is clearly another tropical water plant. > >I came to suggest a solution to this seeming impossibility of the tropics meeting in the Arctic as the subsea lava floods on the Greenland Sea where the world's largest volcanic island, Iceland, sits as cause of the tropical plant sustaining heat - while the surrounding continents were cold enough to build up glaciers and calve ice bergs. Or, when parts of the Arctic Ocean coasts were cold enough for the sea ice to form and then drift over the same waters where tropical Azolla was blossoming. I suggested that the Surtseyan eruptions during the ice ages were exceedingly large and the ice ages may have been producing their huge snow deposits because of subsea warming, producing a geothermally induced lake-snow effect, which may have formed a thight feedback loop to drive out fluids from beneath the developing glaciers. Because of this, I have been proposing for the UN General Assembly complainant nations that there is need to take out carbon-14 sampling from beneath deep polar glaciers to check out the possible role of major subsea lava flooding contributing to ocean warming and the large Pleistocene era precipitation events. There are large bulk samples of organic matter in high polar regions that can be run for test under Accelerated Mass Spectrometer (AMS) for any presence of carbon-14, and if found, would prove the complainant nations worries right. > >The ultimate cause of the ice ages then being the compromised gravity separation of crust that keeps hydrosphere separate from the asthenosphere, the topmost layer of mantle where there is a very heavy mineral called peridotite that is water soluble under the high temperatures that prevail beneath the continental plates. If the techtonical movements shred the continental plates in the far north, the water incursion to the fault could have started a runaway process due to subcontinental peridotite being under higher pressure than that under the ocean. Its breakdown product in a process called partial melting is basalt, a rock that is found plentiful under the oceans. Our aim remains for the UN to investigate the possibility of this material being leaked onto the sea floor to trigger the ice ages precipitations and carbon-14 could possibly be found to explain all the above. > >Kind regards, > > > > > >________________________________ >Date: Tue, 26 Feb 2013 09:56:54 +0000 >From: [log in to unmask] >Subject: Re: Major methane release is almost inevitable - New Scientist >To: [log in to unmask] > > >Just a quick note to say that as someone working in the palaeoclimate field I can confirm that no-one uses radiocarbon dating for anything older than about 40 ky (as it get's worse the further it goes back) and so only covers the last glacial termination - standard practice is to date timings of palaeoclimatic changes through graphic correlation and astro-tuning (as planetary orbital mechanics are very stable) or with other non-carbon cosmogenic isotopes. As such, the big permafrost melt detailed by the New Scientist article shouldn't suffer from the same problem, described below, and the last glacial termination I believe is dated not just from radiocarbon either. > >Re. earlier discussions, I'd also write longer about John's claims about Tim Lenton and the rate of permafrost melt, but from previous exchanges on similar matters I suspect I'd have better luck not! Suffice to say the key question about permfrost carbon impact is in the rate of melt and subsequent rate of CO2eq release - simply calculating the total carbon content of permafrost and assuming an effectively instantaneous and total release is not good enough - and is something which is not well understood yet. For a good palaeoclimate example of this, see the paper written about here: http://www.skepticalscience.com/Petmpf.html - note the surprising result of extensive permafrost coverage even in warmer Eocene times. > >Dave A. McKay > > > >>________________________________ >> From: Kevin Coleman <[log in to unmask]> >>To: [log in to unmask] >>Sent: Tuesday, 26 February 2013, 7:47 >>Subject: Re: Major methane release is almost inevitable - New Scientist >> >> >>So in other words we have got all the time scales wrong? If what you say is correct, and looking at what you say I feel sure it is correct, then carbon 14 as a means of dating events is totally null and void. >>I think we are in for some serious trouble. If the time scales are skewed because of carbon 12 and 13 dilution we have absolutely no idea when events will start or finish. We won't even have any idea how long the changes will endure either. The geological record is virtually useless in this regard. >>Oops! >>Kev C >> >>Veli Albert Kallio <[log in to unmask]> wrote: >> >> >>The problem is exemplified by the very fact that there is a high risk of circular argument in timing the ending of the ice ages: >> >>When sea levels kept changing during the ice ages, and then the permafrost sea bed and Siberian tundra started thawing, these released copious amounts of most ancient carbon-12 and carbon-13 which diluted the relatively fixed proportion of cosmically-generated carbon-14 in the air. As a result of radiocarbon-dilution the time scales were stretched longer as it has been presumed that the fallen c-14 levels in samples resulted only from the half-life decay of carbon-14 isotope which halves its content each 5,730 year period. Everything else is calibrated to this bench mark. >> >>But as carbon-14 benchmark was diluted during the Ice Ages, and until Holocene Thermal Maximum, when Siberia melted last time extensively, then the processes assigned by carbon-14 date with very long time period, happened much faster (the more diluted atmospheric carbon-14) became from the discharges originating from the ocean bed and permafrost. Carbon coming from geological deposits has lost all carbon-14. >> >>There are 21,000 methane craters on the Arctic Ocean sea bed with sizes from hundreds of metres to one kilometre. The largest methane ice melting crater is 750 km2 in area on the ocean bed, representing huge methane dumping during and at the end of the ice ages. Here is an animation of the problem which occurred during the Ice Ages (destabilisation of methane clathrate deposits by depressurisation triggered by sea level dropping, and then warming and melting of the permafrost terrains and sea beds): >> >>http://www.youtube.com/watch?v=LBDJNGSufO4 >>So there is a great potential for things ending up much faster, much worse than generally thought due to radiocarbon-dilution effect: >>http://arctic-news.blogspot.com/2013/01/high-methane-levels-persist-in-january-2013.html >> >> >>________________________________ >>Date: Mon, 25 Feb 2013 12:45:54 -0800 >>From: [log in to unmask] >>Subject: Re: Major methane release is almost inevitable - New Scientist >>To: [log in to unmask] >> >> >>Hi Graham it has been predicted that global warming will increase the spread of most infectious diseases and bring about new ones. >> >>I don’t think the diseases idea from thawed permafrost has been studied. >> >>I it is a small risk compared with what we know the combined emission of all 3 GHGs from thawing permafrost will do. >> >>So I think one more risk to add to the insanity of just watching and recording the development of runaway climate change. >> >>Peter C >> >> >>From: Independent Scientist >>Sent: Sunday, February 24, 2013 10:22 PM >>To: Peter Carter ; P. Wadhams >>Cc: John Nissen ; Nigel Wylde ; john ecologist ; [log in to unmask] ; Brian Orr ; [log in to unmask] ; [log in to unmask] >>Subject: RE: Major methane release is almost inevitable - New Scientist >> Dear Peter, >>Thank you for Your email. Sometimes, doing this work, I feel very isolated, and it's good to receive some words of encouragement. But Your news of the enhanced release of Nitrogen Oxide is a shock. I had overlooked this completely. We might all literally die laughing.......Joking apart, the mass emission of N2O is bad news. The trillions of tonnes of rotten permafrost organic debris, in some places kilometres thick, will vent now for several thousand years, perhaps. (it will take that long, to warm it all up, down to bedrock.) I might also add that the bacteria will feed of the Methane voraciously, and the airborne bacteria will be subjected to enhanced Ultra Violet light radiation, a known mutagen. This is a pathway to mutations spreading their deadly microbial life. But at the same time, it will break down the Methane. But clearly this is a long process. it is now unstoppable. >> >>I think its worth putting on the list as a study area, as the spread of bacteria is explosive, and the effects on the biosphere are unknown, it seems, in some aspects. I want to know what breathing a deadly bacterial soup does to my lungs, and those of all the other animals. >>Regards >>Graham >> >> >> >>> From: [log in to unmask] >>> To: [log in to unmask]; [log in to unmask] >>> CC: [log in to unmask]; [log in to unmask]; [log in to unmask]; [log in to unmask]; [log in to unmask]; [log in to unmask]; [log in to unmask] >>> Subject: Re: Major methane release is almost inevitable - New Scientist >>> Date: Sun, 24 Feb 2013 10:35:05 -0800 >>> >>> The bacteria release CO2 methane and N2O from thawing permafrost. >>> By the way N20 is now rising much faster than the others and research >>> indicates very large emission from thawing permafrost. . >>> Peter C >>> >>> Microbes in thawing permafrost - Climate Change Science Institute ... >>> climatechangescience.ornl.gov/system/files/graham_et_al__2011.pdf >>> >>> -----Original Message----- >>> From: P. Wadhams >>> Sent: Sunday, February 24, 2013 4:11 AM >>> To: Independent Scientist >>> Cc: John Nissen ; Nigel Wylde ; john ecologist ; [log in to unmask] ; >>> [log in to unmask] ; Brian Orr ; [log in to unmask] ; >>> [log in to unmask] >>> Subject: RE: Major methane release is almost inevitable - New Scientist >>> >>> Dear Graham, re. Plague. This is either a complete non-starter or something >>> incredibly important. I havent heard of anybody considering this before. >>> But the possibility could easily be tested - melt some typical permafrost >>> samples in a secure biochemical facility (ie a spooky place like Porton >>> Down or Fort Dettrick), and see if any viable bacteria, viruses or nasties >>> of any kind are being given off. According to this recent stalagmite study, >>> the last time that permafrost melted in large quantities was during the >>> last interglacial, about 100,000 years ago. Something resembling Man was >>> around at that time, but does not appear to have been wiped out, otherwise >>> we wouldn't be here, Best wishes Peter >>> >>> >>> On Feb 24 2013, Independent Scientist wrote: >>> >>> > >>> > >>> > >>> > Hullo All,The situation re permafrost is actually worse than realised. I >>> > had a long conversation with a bio-scientist friend yesterday, who had >>> > been brooding on the subject. The permafrost is in some areas about 4km >>> > deep. It is very old. It contains deep frozen bio-wastes, such as rotted >>> > trees, bushes, animal remains, etc, all of which have saturation levels of >>> > frozen bacteria and virus's. The methane venting is going to release into >>> > the atmosphere ancient virus and bacterial agents that have not been >>> > "loose" for up to 500,000 years. Both human and animals will have no >>> > immune response to these agents. I will spell it out simply: PLAGUE. >>> > RegardsGraham Ennis >>> > >>> > >>> >Date: Sat, 23 Feb 2013 20:27:14 +0000 >>> >From: [log in to unmask] >>> >To: "petercarter46"@shaw.ca >>> >CC: [log in to unmask]; [log in to unmask] >>> >Subject: Re: Major methane release is almost inevitable - New Scientist >>> > >>> > >>> > >>> > Hi all, >>> > >>> > >>> > They have found from stalagmite that the permafrost has only melted >>> > once in the last 500,000 years, when the temperature was only 1.5 >>> > degrees higher than today. This is stunning news, because we have >>> > already passed that threshold. >>> > >>> > >>> > As we would expect, Tim Lenton has downplayed the danger [1], as he >>> > did in giving evidence to the Environment Audit Committee last >>> > year. He says the greatest danger is for the buildings built on >>> > permafrost. My foot! What about those emissions of methane into >>> > the atmosphere? He dismisses the danger without any good argument >>> > to do so. He knows the quantity of organic material, and that most >>> > of it will emitted as methane when the permafrost thaws, because the >>> > conditions are essentially anaerobic. He also knows that the >>> > permafrost will thaw quite quickly, because the Arctic is warming at >>> > about a degree a decade - far faster than global warming. Thus the >>> > 1.5 degrees is already exceeded, as regards the local temperature. >>> > >>> > >>> > I don't think he is lying. Rather he is under the delusion that the >>> > sea ice will last for decades, and everything will happen slowly. He >>> > won't admit it, but he is terrified by the sea ice volume trend >>> > (with September 2015 virtually sea ice free), and this has led to >>> > subconscious suppression of the "bad news" about the permafrost, >>> > methane, etc. >>> > >>> > >>> > But it's not just Tim Lenton in denial. Among many scientists who >>> > study the Arctic, one sees this suppression of the reality of the >>> > vicious cycle of warming and melting in the Arctic because it is >>> > just so frightening. And if this problem continues to be ignored, >>> > we will all suffer the consequences of inaction - the most immediate >>> > being a worsening disruption of the jet stream, with the escalation >>> > in climate extremes precipitating a monumental food crisis. >>> > >>> > >>> > The good news is that we are not too late to cool the Arctic, if >>> > only we were prepared to consider emergency geoengineering this >>> > summer. We need some scientists who are brave enough to confront >>> > the reality of the situation, cut through the crap from the danger >>> > deniers, and demand international action at top priority. >>> > >>> > >>> > Cheers, >>> > >>> > >>> > John >>> > >>> > >>> > [1] >>> > >>> > http://www.newscientist.com/article/dn23205-major-methane-release-is-almost-inevitable.html?cmpid=RSS|NSNS|2012-GLOBAL|environment >>> > >>> > >>> > [Quote] >>> > >>> > >>> > What are the consequences? The greatest concern, says Tim >>> > Lenton of the University of Exeter in the UK, is the regional >>> > landscape. Buildings and infrastructure are often built on hard >>> > permafrost, and will start subsiding. "Ice roads won't exist any >>> > more." >>> > >>> > >>> > The increasingly soggy permafrost will also threaten the pipelines >>> > that transport Russian gas to Europe. "The maintenance and upkeep of >>> > that infrastructure is going to cost a lot more," says Schuur. >>> > >>> > As for the methane that could be released into the atmosphere, >>> > Schuur estimates >>> > that emissions will be equivalent to between 160 and 290 billion >>> > tonnes of carbon dioxide. >>> > >>> > That sounds like a lot, but is little compared to the vast amount >>> > humans are likely to emit, says Lenton. "The signal's going to be >>> > swamped by fossil fuel [emissions]." >>> > >>> > He says the dangers of the permafrost greenhouse gases have been >>> > overhyped, particularly as much of the methane will be converted >>> > to carbon dioxide by microbes in the soil, leading to a slower >>> > warming effect. >>> > >>> > Schuur agrees with Lenton that the methane emissions are "not a >>> > runaway effect but an additional source that is not accounted in >>> > current climate models". >>> > >>> > >>> > [End quote] >>> > >>> > >>> > -- >>> > >>> > >>> > On 23/02/2013 07:08, Peter Carter wrote: >>> > The fuse to the Arctic methane time bomb has been >>> > burning a long time, and without drastic emergency intervention >>> > the future is committed to planetary catastrophe. This latest >>> > research proves are right out of time. >>> > >>> > >>> > The Arctic methane time bomb is warming peatlands, thawing >>> > permafrost and melting sea floor frozen solid methane hydrate. >>> > >>> > Thawing permafrost generates its own heat so reaches a stage where >>> > the thawing is self increasing irreversible. >>> > >>> > >>> > This Arctic methane is at least three times all atmospheric >>> > carbon. >>> > >>> > >>> > There is a way out, but we have to act now or there won't be- for >>> > today's young generation. >>> > >>> > >>> > Our commitment is way over 1.5C. >>> > >>> > 1.5C is also the end of the coral reefs. >>> > >>> > >>> > The ocean heat lag alone commits us to 1.4C by 2100. >>> > >>> > >>> > Our unavoidable commitment to more warming is at least 2.4C >>> > (published). >>> > >>> > (Ramanathan Feng 2008 PNAS On Avoiding Dangerous Anthropogenic >>> > Interference with the Climate System) ... even the most >>> > aggressive CO2 mitigation steps as envisioned now can only limit >>> > further additions to the committed warming, but not reduce the >>> > already committed GHGs warming of 2.4°C. >>> > >>> > >>> > The Ramanathan commitment is from the ocean heat lag (more than >>> > doubles todays warming) and unmasking of air pollution aerosol >>> > cooling. >>> > >>> > >>> > The warming incurred by the time it will take to stabilize >>> > atmospheric GHGs and the added warming from terrestrial carbon >>> > (excludes Arctic carbon) feedback warming has to be added to that >>> > to get the total committed warming, which is at least 3C. >>> > >>> > >>> > Robert Watson has stated we are committed to 3C may be up to 5C. >>> > >>> > The World Back says we are rapidly committing ourselves to 4C. >>> > >>> > >>> > Today's combined national UN filed emissions reduction pledges >>> > commit us the 4.4C by 2100, and nations have not acted on these >>> > pledges (Climate Interactive) >>> > >>> > >>> > An emergency response now can get us below 1.5C >>> > >>> > >>> > 1) rapidly stabilize Arctic albedo snow and ice cooling and >>> > thereby Arctic methane by regional Arctic cooling >>> > >>> > This also prevents American food producing regions being ruined by >>> > drought. >>> > >>> > >>> > 2) zero carbon emissions mitigation on a rapid emergency basis. >>> > That is total conversion off all fossil fuels to 100% clean >>> > energy. >>> > >>> > >>> > Zero carbon takes care of most black carbon but there is further >>> > black carbon mitigation from other sources of soot like biomass >>> > burning and open cook stoves. As black carbon is second only to >>> > soot in global warming this can drop the warming 0.5C. >>> > >>> > Zero carbon also takes care of most ground level ozone- another >>> > much smaller added drop of warming. >>> > >>> > >>> > Zero carbon decarbonization could be done within 20 years by a >>> > total conversion off all fossil fuel energy and a halt to >>> > deforestation. >>> > >>> > >>> > Once virtual zero carbon is reached (we cannot achieve actual >>> > zero) atmospheric CO2 concentration is stabilized. >>> > >>> > >>> > 3) World afforestation would remove and store some carbon out of >>> > the atmosphere so achieving zero carbon - for many decades at >>> > least >>> > >>> > 4) Biochar would sink carbon for a couple of centuries. >>> > >>> > 5) Remove CO2 directly from the air (doable in theory) would >>> > maintain negative carbon in order to drop atmospheric CO2 below >>> > 350 ppm. >>> > >>> > >>> > It will take a hundred years for atmospheric CO2 to get below 350, >>> > but if we act now we may leave a legacy of a sustainable future. >>> > >>> > If we fail to act now our legacy is a short dark age and no >>> > future. >>> > >>> > >>> > The only hope is to convince people of the planetary Arctic >>> > warming emergency- we have to acknowledge how bad this is and then >>> > act for our survival. >>> > >>> > >>> > Peter C >>> > >>> > >>> > >>> > -----Original Message----- From: Oliver Tickell >>> > >>> > Sent: Friday, February 22, 2013 5:56 AM >>> > >>> > To: [log in to unmask] >>> > >>> > Subject: Major methane release is almost inevitable - New >>> > Scientist >>> > >>> > >>> > Abstract link >>> > >>> > >>> > http://m.sciencemag.org/content/early/2013/02/20/science.1228729.abstract?sid=d26b1542-62e0-4aa0-9239-a82abda2d1ad >>> > >>> > >>> > Major methane release is almost inevitable >>> > >>> > >>> > 19:00 21 February 2013 by Michael Marshall >>> > >>> > >>> > We are on the cusp of a tipping point in the climate. If the >>> > global >>> > >>> > climate warms another few tenths of a degree, a large expanse of >>> > the >>> > >>> > Siberian permafrost will start to melt uncontrollably. The result: >>> > a >>> > >>> > significant amount of extra greenhouse gases released into the >>> > >>> > atmosphere, and a threat - ironically - to the infrastructure that >>> > >>> > carries natural gas from Russia to Europe.The Arctic is warming >>> > faster >>> > >>> > than the rest of the planet, and climatologists have long warned >>> > that >>> > >>> > this will cause positive feedbacks that will speed up climate >>> > change >>> > >>> > further. The region is home to enormous stores of organic carbon, >>> > mostly >>> > >>> > in the form of permafrost soils and icy clathrates that trap >>> > methane - a >>> > >>> > powerful greenhouse gas that could escape into the atmosphere.The >>> > >>> > Siberian permafrost is a particular danger. A large region called >>> > the >>> > >>> > Yedoma could undergo runaway decomposition once it starts to melt, >>> > >>> > because microbes in the soil would eat the carbon and produce >>> > heat, >>> > >>> > melting more soil and releasing ever more greenhouse gases. In >>> > short, >>> > >>> > the melting of Yedoma is a tipping point: once it starts, there >>> > may be >>> > >>> > no stopping it.For the first time, we have an indication of when >>> > this >>> > >>> > could start happening. Anton Vaks of the University of Oxford in >>> > the UK >>> > >>> > and colleagues have reconstructed the history of the Siberian >>> > permafrost >>> > >>> > going back 500,000 years. We already know how global temperatures >>> > have >>> > >>> > risen and fallen as ice sheets have advanced and retreated, so >>> > Vaks's >>> > >>> > team's record of changing permafrost gives an indication of how >>> > >>> > sensitive it is to changing temperatures. >>> > >>> > >>> > Stalagmite record >>> > >>> > >>> > But there is no direct record of how the permafrost has changed, >>> > so Vaks >>> > >>> > had to find an indirect method. His team visited six caves that >>> > run >>> > >>> > along a south-north line, with the two southernmost ones being >>> > under the >>> > >>> > Gobi desert. Further north, three caves sit beneath a landscape of >>> > >>> > sporadic patches of permafrost, and the northernmost cave is right >>> > at >>> > >>> > the edge of Siberia's continuous permafrost zone.The team focused >>> > on the >>> > >>> > 500,000-year history of stalagmites and similar rock formations in >>> > the >>> > >>> > caves. "Stalagmites only grow when water flows into caves," Vaks >>> > says. >>> > >>> > "It cannot happen when the soil is frozen." The team used >>> > radiometric >>> > >>> > dating to determine how old the stalagmites were. By building up a >>> > >>> > record of when they grew, Vaks could figure out when the ground >>> > above >>> > >>> > the caves was frozen and when it wasn't.As expected, in most of >>> > the >>> > >>> > caves, stalagmites formed during every warm interglacial period as >>> > the >>> > >>> > patchy permafrost melted overhead.But it took a particularly warm >>> > >>> > interglacial, from 424,000 and 374,000 years ago, for the >>> > stalagmites in >>> > >>> > the northernmost cave to grow - suggesting the continuous >>> > permafrost >>> > >>> > overhead melted just once in the last 500,000 years.At the time, >>> > global >>> > >>> > temperatures were 1.5 °C warmer than they have been in the last >>> > 10,000 >>> > >>> > years. In other words, today's permafrost is likely to become >>> > vulnerable >>> > >>> > when we hit 1.5 °C of global warming, says Vaks."Up until this >>> > point, we >>> > >>> > didn't have direct evidence of how this happened in past warming >>> > >>> > periods," says Ted Schuur of the University of Florida in >>> > Gainesville.It >>> > >>> > will be very hard to stop the permafrost degrading as a warming of >>> > >>> > 1.5 °C is not far off. Between 1850 and 2005, global temperatures >>> > rose >>> > >>> > 0.8 °C, according to the 2007 report of the Intergovernmental >>> > Panel on >>> > >>> > Climate Change. Even if humanity stopped emitting greenhouse gases >>> > >>> > tomorrow, temperatures would rise another 0.2 °C over the next 20 >>> > years. >>> > >>> > That would leave a window of 0.5 °C - but in fact our emissions >>> > are >>> > >>> > increasing. What's more, new fossil fuel power stations commit us >>> > to >>> > >>> > several decades of emissions. >>> > >>> > >>> > Soggy permafrost >>> > >>> > >>> > What are the consequences? The greatest concern, says Tim Lenton >>> > of the >>> > >>> > University of Exeter in the UK, is the regional landscape. >>> > Buildings and >>> > >>> > infrastructure are often built on hard permafrost, and will start >>> > >>> > subsiding. "Ice roads won't exist any more."The increasingly soggy >>> > >>> > permafrost will also threaten the pipelines that transport Russian >>> > gas >>> > >>> > to Europe. "The maintenance and upkeep of that infrastructure is >>> > going >>> > >>> > to cost a lot more," says Schuur.As for the methane that could be >>> > >>> > released into the atmosphere, Schuur estimates that emissions will >>> > be >>> > >>> > equivalent to between 160 and 290 billion tonnes of carbon >>> > dioxide.That >>> > >>> > sounds like a lot, but is little compared to the vast amount >>> > humans are >>> > >>> > likely to emit, says Lenton. "The signal's going to be swamped by >>> > fossil >>> > >>> > fuel [emissions]."He says the dangers of the permafrost greenhouse >>> > gases >>> > >>> > have been overhyped, particularly as much of the methane will >>> > >>> > be converted to carbon dioxide by microbes in the soil, leading to >>> > a >>> > >>> > slower warming effect.Schurr agrees with Lenton that the methane >>> > >>> > emissions are "not a runaway effect but an additional source that >>> > is not >>> > >>> > accounted in current climate models".Journal reference: Science, >>> > DOI: >>> > >>> > 10.1126/science.1228729 >>> >>> >> >> >> > >