What caused the Little Ice Age?

By Phil Plait | February 1, 2012 7:00 am

Over the course of several hundred years – most notably in the 17th and 18th centuries — winter temperatures in western Europe were much lower than normal. Glaciers came much farther south than they had before, and a famous painting shows people ice skating on the Thames river — which hasn’t been frozen since. The period is known as the Little Ice Age, and its cause has always been something of a mystery.

However, new research by scientists at the University of Colorado-Boulder (yay team!) may have pegged it: the LIA appears to have started abruptly in the late 13th century, between the years 1275 and 1300. Radiocarbon dating of plants from Baffin Island (north of the Hudson Bay in Canada) and sediment samples from a lake in Iceland indicate that there was a rapid onset of severe cooling at that time. It’s been thought that the cooling started around then, but it’s been hard to pin down until now.

More importantly, this narrows down the cause of the LIA: four tropical volcanoes erupted violently in that period. The ash would have darkened the atmosphere, letting slightly less sunlight down. Some of the gases emitted by volcanoes also cool the air. It seems clear these volcanoes are what triggered the Little Ice Age. But why did it last so long?

That may be due to what happened after the volcanoes erupted. Most likely, the warmer temperatures would have melted the north polar sea ice. This fresh water is less dense than salty water, so it would flow on top of the oceans, and wouldn’t have mixed well with the deeper water. This would have slowed the transport of heat from the equatorial waters back up north, cooling them further. That system is what maintained colder temperatures for so long. There were variations — the Ice Age was more of as series of pulses of temperature drops than one long period — but for centuries the heating of the Earth was disrupted in that region.

For a long time it’s been suspected that the Sun played a role here, too. During the period of 1645 to 1715 there were few or no sunspots, a time called the Maunder Minimum. Sunspots are dark, but they’re surrounded by a region, a rim, that emits strongly in the UV. These faculae, as they’re called, actually more than make up for the darker regions of the spots, so in reality sunspots add to the amount of light and heat the Earth receives, by a fraction of a percent. So an active Sun, it’s thought, may warm the Earth a teeny bit more.


However, this study showed that even if the Sun were less active, and therefore not warming the Earth as much, it would have had little effect. The local issues of volcanoes and the additional fresh water were enough to account for the Little Ice Age. The Sun may have played a role, but now it’s less likely to have been a major one.

And when did the cold period finally stop? In the 19th century, at the same time as the rise of the Industrial Revolution. We’re now at or exceeding temperatures of the Medieval Warm Period that existed right before the Little Ice Age.

This work is extremely important, of course, because it has a direct impact on understanding the Earth’s climate. Even more obviously, if you’ve been reading my blog for more than about ten seconds, is that a lot of climate change deniers like to point to the Sun as being the culprit in the rapid warming of the Earth over the past century. However, even before this study was announced, we knew that’s dead wrong: there is nothing to link the Sun to the current rise in temperatures.

I’ll note that the dreadful Daily Mail article I tore apart the other day spends a lot of its time linking the Sun to the Little Ice Age. I find it particularly noteworthy that this Colorado study — years in the making — was announced the same day that article came out. The contrast between careful scientific study and the befuddling assertions of a climate change denier shows the intellectual bankruptcy of the latter. And even then, the Colorado research was hardly needed to show the Daily Mail article was baloney; its own internal failings were apparent when it grossly twisted the results from the UK Met Office (the weather service for the UK).

Also, ironically, around the very same time I was posting my article, NASA released more news that the Sun cannot be responsible for global warming.

The big picture here, the thing to remember and take home, is that real scientists are doing real work to learn more about what’s really going on with our home planet. A lot of folks out there are making careers (and a ton of money) trying to sow doubt on that work, twisting it in any way they can imagine to make it seem like either the Earth’s not warming up (but it is) or that humans are not to blame (but we are). The more we study the past, the more we can understand the present and future, despite any attempts at obfuscation.


Related posts:

- While temperatures rise, denialists reach lower
- Are we headed for a new ice age?
- New study clinches it: the Earth is warming up

Comments (98)

  1. Great work drawing all those different strands together. Keep it up.

  2. Gaebolga

    I’m going to give a pre-emptive “YES, DEAR!” just in case shunt1 shows up.

  3. David

    Phil:

    Is that a typo in the fourth paragraph? Shouldn’t that be “cooler” temperatures? Although how would cooler temperatures melt the polar ice?

  4. Daniel Snyder

    Thanks for your work on this, Phil! Your articles are always such a blast to read, even when the topic is pretty sobering.

  5. Patrick

    I have wondered about the effects of the LIA on other parts of the world, or were the worst effects limited to Europe and North America.

  6. A lot of folks out there are making careers (and a ton of money) trying to sow doubt on that work, twisting it in any way they can imagine to make it seem like either the Earth’s not warming up (but it is) or that humans are not to blame (but we are).

    These denialists are engaged in what I shall henceforth call: Trolling Science. Not troll science (which has applications in humour), but the trolling of science. Hopefully their reign of ignorance and lies will soon be put to rest…

  7. CJSF

    I agree with David (#3): There seems to be a disconnect or missing sentence in the fourth paragraph. What warmer temperatures melted the polar ice? Also, is sea ice fresh (i.e., does the salt not freeze with it)?

    CJSF

  8. Chris

    @7 CJSF
    When you freeze salt water, the water freezes out first and the remaining liquid is even more salty.

    Look at the binary phase diagram for salt water
    http://www.chemguide.co.uk/physical/phaseeqia/saltsoln.html
    Below 23.3% salt (the ocean is 3.5%), you’ll get solid ice and a salt solution till you get to -21.1 C, which probably wouldn’t happen except near the surface. So sea ice is fairly fresh.

  9. Lorenz

    @david: Phil shortened a part of the article at Boulder too much, I think. There it says:

    “The models showed sustained cooling from volcanoes would have sent some of the expanding Arctic sea ice down along the eastern coast of Greenland until it eventually melted in the North Atlantic.  Since sea ice contains almost no salt, when it melted the surface water became less dense, preventing it from mixing with deeper North Atlantic water.  This weakened heat transport back to the Arctic and creating a self-sustaining feedback system on the sea ice long after the effects of the volcanic aerosols subsided, he said.”

    So more saltless ice from the arctic gets transported to the warmer North Atlantic, melts, and weakens heat transport back to the arctic.

  10. Eric

    Good explanation, but I think I’m missing a step. You write:

    “But why did it last so long? Most likely, the warmer temperatures would have melted the north polar sea ice. . . .”

    Why was extra north polar ice melting during, or right before, the LIA?

  11. F16 guy

    Love the ongoing discourse…

    Perhaps I’ve missed this being discussed here, but:

    1. Over the course of the 4.5 billion years of earths history, what is the “right” temperature?
    2. Is global warming (by whatever source) always a bad thing?
    3. Are the following items as important as the negative effects of GW ?

    Advantages of Global Warming

    Arctic, Antarctic, Siberia, and other frozen regions of earth may experience more plant growth and milder climates.
    The next ice age may be prevented from occurring.
    Northwest Passage through Canada’s formerly-icy north opens up to sea transportation.
    Less need for energy consumption to warm cold places.
    Fewer deaths or injuries due to cold weather.
    Longer growing seasons could mean increased agricultural production in some local areas.
    Mountains increase in height due to melting glaciers, becoming higher as they rebound against the missing weight of the ice.
    Boundary disputes between countries over low-lying islands will disappear.

    Thoughts ?

  12. ethanol

    Check your paragraphs, Phil it seems like not all of them copied over.

  13. Daniel J. Andrews

    The input of fresh cold meltwater into the saline Atlantic that may have triggered the LIA may also be the same mechanism that triggered the Younger Dryas event (a very quick plunge into cold temperatures shortly after the warming that started the last ice age glaciers retreating. The cold was deep enough that glaciers began to advance again, at least in some regions).

    The Younger Dryas though seems to have been felt in much of the world (Australia seems to be an exception, see recent article by Tibby, 2012, (sciencedirect.com/science/article/pii/S1040618212000109), while the LIA seems to have mainly been northern hemisphere.

    Personally, I find this a fascinating area of research, and slightly off-topic, may I recommend After the Ice Age by E.C. Pielou about how things changed as the glaciers retreated. You feel like you were there witnessing the changes.

    Realclimate has a few articles on the Younger Dryas for anyone interested and links in the article (below) to previous writings about it.
    realclimate.org/index.php/archives/2010/07/revisiting-the-younger-dryas/

  14. Mika

    Wait, if we are indeed only “at the temperatures of the Medieval Warm Period” isn’t that evidence against global warming being caused by human actions? I mean, it cannot be mostly due to our work if there has been similar global temperatures in the last few millenia?

    I’ve always thought the evidence to human factor being an important cause of global warming was “rock solid”, but this sounds puzzling.

  15. The ice in both polar regions is fresh water because it falls as snow or freezing rain then accumulates on top of the existing ice. Salt water freezes in laboratory conditions but the sea does not provide the water for the ice caps.

    After the initial cooling period the subsequent warming melts the ice which then interferes with the convection of the warm water flowing North from Africa to Europe. Research published recently (about a year ago?) analyzed hundreds of ice-cores from the Himalayas shows that the LIA was a local phenomenon and not global.

    Just because it’s *relatively* warmer in one place does not mean – in and of itself – that such effect will make temperatures commensurately warmer everywhere else.

  16. Chuck

    You are correct… the Sun does not warm the planet… that is accomplished by tiny gnomes that live undeground firing carbon neutral furnaces…

  17. DigitalAxis

    @9. F16 guy

    Seas rise, flooding costal (often heavily populated) areas
    Deserts expand
    Wildfires increase
    More deaths due to heat
    Weather patterns change- long periods of drought in some areas, heavy flooding in others
    Animal Habitats change- some, like Polar bears, will have to adapt to new climates or they’ll go extinct
    Malaria, West Nile, Ebola and other insect-borne diseases will spread to new areas as the insect’s habitat changes.
    Coral reefs die
    (and that’s just from the heating. We’re also dumping all the chemicals and polluting the atmosphere)

    Much of this is merely different… but we’re talking massive extinctions and geopolitical upheavals. When Indonesia sinks, millions will be homeless. Parts of Africa have already been facing starvation due to its extremely long drought. Then there are diseases.
    No doubt life will continue, but don’t think we can all just move to Canada when the midwest cornfields dry up, Texas is permanently on fire, and yellow fever becomes an epidemic in South Carolina.

    Do we really want to do that?

  18. Hi Mika,

    I think I can answer your question with a metaphor. I come home one day to find half my house blown up. This could be due to a faulty water heater (natural variation a la medieval warm period) or it could be due to a pipe bomb (unnatural variation a la today). There were perfectly natural reasons for temperature to change in the past, but that doesn’t mean we are not changing temperatures now. Between our understanding of the climate, the chemistry of CO2, how much CO2 we’ve put in the air, and the correlation between CO2 rise and temperature rise, leads us to the conclusion that we are the ones causing the planet to heat up.

    Hope that helps!

  19. Jason

    Phil:

    I used to think of myself as a climate change denier. The last few years, I’ve become convinced that it is a real problem (science trumps flawed rhetoric). However, climate change scientists have not yet impressed me with a real solution to the problem.

    I’ll state the problem as this: Economy. It’s that simple. It is economical to not care about the environment. Here is an example: I just recently moved, and my commute to work is now half the time and 1/4th the distance. I’m saving gas money like crazy now that I live closer… but if, instead of moving closer, I could have saved that same amount of money by buying a new car that got much better gas mileage, would I have done it? NO! because a not having a car payment (I own my car) is much more economical for me. Science has done a pretty good job of identifying the problem… but science won’t convince 100% of the people that they need to change. Instead, science needs to now focus on ways to make environmentalism MORE economical than non-environmentalism. Appeal to the wallet, not the heart, because frankly, wallet appeal is what got us into this mess.

    P.S. Negative incentives never work. If government fines companies that exceed “threshold x” of pollutants, it is still easier to find a way to hide it from the government, than to fix the problem. If science could transform industrial waste into money… everyone would be doing it.

    P.P.S. I realize my above comments rank up there with alchemy, but in 1959 the idea of putting a man on the moon was also pretty far fetched. Then 10 years later willpower prevailed.

  20. Daniel J. Andrews

    @F16 guy. You raise some good points which have been discussed and studied (and are continuing to be discussed and studied) by the relevant experts.

    Here are a few of my nonexpert thoughts.

    1. Over the course of the 4.5 billion years of earths history, what is the “right” temperature?

    The “right” temperature is probably the one that has allowed agriculture and human civilizations to flourish (e.g. the last 8000-10,000 years). We and our agriculture have adapted to that and changing that temperature and precipitation patterns will not all be good news.

    2. Is global warming (by whatever source) always a bad thing?

    Not always. There will be winners and losers. See above. Extended droughts, more flooding, more precipitation, will all disrupt the society we’ve built during relatively stable periods. For the most part, warming will be mostly disruptive, hence more losers than winners.

    3. Are the following items as important as the negative effects of GW ?
    Advantages of Global Warming
    Arctic, Antarctic, Siberia, and other frozen regions of earth may experience more plant growth and milder climates.

    Living in northern Canada, I have to admit I like my winters a bit warmer especially as I age. Our warmer winters though are disrupting the lifestyles of the people of the north from those who depend on ice being in place to those who depend on the ice roads to last long enough to bring in supplies by truck. Last year the ice road was only good for 3 weeks instead of 6 and a state of emergency for the communities in northern Ontario was declared by the First Nations. Not sure why more plant growth in northern areas is an advantage though. Also, warming tundra regions will release more methane which along with less ice (less albedo) will feedback into more warming.

    The next ice age may be prevented from occurring.

    True. But that is 40,000 years in the future.

    Northwest Passage through Canada’s formerly-icy north opens up to sea transportation.

    More tourism too. Lots of pros and cons here with development vs pollution and exploitation vs ecosystem protection.

    Less need for energy consumption to warm cold places.

    Yes. But how does that balance against the need for more air conditioning?

    Fewer deaths or injuries due to cold weather.

    By far, there are more deaths due to heat than to cold. Compare the summer heat wave death toll in Europe with the current cold snap in Europe, for example. Also, this isn’t cold vs hot equation. Warming climate = more moisture in the air = more extreme precipitation events such as flooding rains, heavy snowfalls, all of which cause deaths, sometimes in the tens of thousands. See how the U.S. was hammered last year by numerous record floods and temperatures. Imagine how a poor or developing country would be affected (less resources, infrastructure, to deal with extreme events).

    And this doesn’t take into consideration the megadroughts that will be visited upon already arid places, resulting in further depletion of aquifers as people use more water for crops and livestock, and draw more water from rivers that are already running dry.

    Longer growing seasons could mean increased agricultural production in some local areas.

    There is an increased chance of crop-killing temperatures so longer seasons won’t help. Crop-killing hailstorms are also likely to increase. Our Canadian prairie provinces are already borderline drought in the summers combined with some pretty good floods in the spring. Climate change means those factors will be magnified in either direction (as we’re already seeing).

    Mountains increase in height due to melting glaciers, becoming higher as they rebound against the missing weight of the ice.
    Boundary disputes between countries over low-lying islands will disappear.

    heh. I suppose that is one way to deal with boundary disputes and complaints from skiers and mountain climbers about the mountains not being high enough.

  21. @F16 guy (#9), the earth will be fine. It’s us humans that will suffer. If we don’t mind going extinct, then there is nothing to worry about. ;)

  22. Tim Gaede

    The start of the fourth paragraph mentioning “the warmer temperatures” seems like a mistake.

    From the CU-Boulder article:

    The models showed sustained cooling from volcanoes would have sent some of the expanding Arctic sea ice down along the eastern coast of Greenland until it eventually melted in the North Atlantic.

  23. Quatguy

    Good article Phil, Here Here!

  24. Paul from VA

    @12 Mika If you click the link Phil provided, you’ll see that we are now way beyond the temperatures of the medieval warm period. It still remains debated whether the Medieval Warm period was global or local in extent, but it’s mostly irrelevant to the current and projected future warming due to human produced greenhouse gasses.

  25. Jeff

    http://www.eldoradocountyweather.com/world-mesomap.html

    just looking across a line of latitude passing through Reykjavik on above map, you can really see the big effect of the gulf stream warming northwestern Europe, I can easily imagine if that current stopped how Europe would freeze over.

  26. Doug Little

    Over the course of the 4.5 billion years of earths history, what is the “right” temperature?

    The right temperature is what it is right now, the question you should be asking is what is the maximum rate of change in temperature that we can handle.

  27. gss_000

    And in another climate-related study that came out that looks at the role of the sun over the past few years:

    http://content.usatoday.com/communities/greenhouse/post/2012/01/nasa-global-warming-caused-mostly-by-humans/1

    Of course, because Hansen is involved it will automatically be dismissed.

  28. Richard

    It appears that we’re missing something in the article since increased volcanic activity that cools the air shouldn’t lead to polar melting.

    The real question I have is why aren’t governments and scientist in general working to find effective ways to control and put out the runaway fires that exist in coal mines/veins and at some natural gas deposits. Several years ago it was estimated that the output from the runaway fires in China was equal to the US automotive pollutant output. A concentrated effort to put out these fires would not only allow for the re-opening of the associated mines, but it would also serve to dramatically drop the greenhouse gas production around the globe. It would also lead to the development of technology that can be used to keep such fires from impacting the population in their immediate vicinity. In the US we have towns that we’ve been forced to abandone, and highways that we’ve re-routed, due to the hazards created by such fires.

    It would also be an easier “sell” to the public/business/governments since you’re not telling them that they’re going to have to change their way of life in order to help reduce global warming.

  29. Theron

    “Boundary disputes between countries over low-lying islands will disappear.”

    Now that is some serious trolling. As entire low-lying nation disappear beneath the waves, will you be hosting the refugees at your house? And when we spend a few trillion on sea walls to protect our coastal cities, you’ll be picking up the bill, right?

  30. David

    One of the reasons the Thames used to freeze in London was because of how the Old London Bridge was built. The pilings and their protective supports (“starlings” or “cutwaters”) were so numerous (nineteen) and so wide that they restricted the water flow past the bridge — during low tide the water level could be as much as six vertical feet lower on the downstream side. Water wheels on some of the openings further restricted water flow. In cold weather, the sluggish water allowed ice chunks to form, even further restricting the flow and leading to freezeovers. London used to hold “Frost Fairs” on the river if the ice was thick enough. The last Frost Fair was in 1814; Old London Bridge was pulled down in 1832.

  31. rjbrash

    Check out Eric Klemetti’s blog “Eruptions” for a volcanologists take on the matter. Some very good info.

  32. Hather

    There’s actually another famous painting that shows the differences in temps from the late 18th Century and now.

    http://en.wikipedia.org/wiki/File:Washington_Crossing_the_Delaware_by_Emanuel_Leutze,_MMA-NYC,_1851.jpg

    In that painting, Washington’s men are seen pushing aside large chunks of ice that littered the Delaware River by Philadelphia. That does NOT happen anymore. In the past 3 decades I don’t think I’ve ever seen any ice floating down the Delaware, let alone so much ice that the river was almost blocked.

  33. gss_000

    “Northwest Passage through Canada’s formerly-icy north opens up to sea transportation.”

    Actually, this is bad because now ships can access areas where resources like oil can be reached. Now you are getting sovereignty battles over the arctic. See this article from 2010 that just shows it isn’t speculation but an ongoing fact. It will only get worse over time:

    http://www.cbc.ca/news/canada/story/2009/02/27/f-arctic-sovereignty.html

  34. Tony Mach

    I have just one request: Could you add more flames to earth? I don’t think it quite drives the message home yet.

    If there were smell-over-internet, you could add the smell of burned flesh! I think that would transport the message with clarity it deserves.

    Keep up the good work!

  35. Jeff

    #26: except this particular week, London is at freezing all week with chance of snow. It’s just that the Thames is not this cold all winter, so it doesn’t freeze in this part of history. I see one London BBC announcer talking about a dry continental polar air mass intruding into western Europe this week, but that comes from the east ; whereas here in USA it comes from Canada.

  36. Tim Gaede

    A number of people have noticed the non sequitur about “warmer temperatures”. I think Phil was thinking about the conjecture that accelerated melting of North Atlantic ice due to global warming also could lead to fresh water disrupting the thermohaline circulation in that region. The CU-Bolder article seems to suggest that ice sheets had expanded to where the meltwater more directly affected the circulation.

  37. Tom

    Periods of low solar activity indeed seem to have a minimal global effect, but there is good evidence of a stronger regional effect on both sides of the North Atlantic.

  38. CB

    @15 Mika

    Wait, if we are indeed only “at the temperatures of the Medieval Warm Period” isn’t that evidence against global warming being caused by human actions? I mean, it cannot be mostly due to our work if there has been similar global temperatures in the last few millenia?

    Um, that doesn’t follow. It is possible for the earth to warm up to a similar extent as it has due to non-human factors, but this doesn’t mean that therefore it’s impossible for the earth to warm up due to human factors. People die of natural causes, but you can’t use that fact alone to rule out homicide in any particular case. What matters is the specifics. And when they look at the natural sources of climate change, they aren’t sufficient to explain the current case of warming. Human factors are.

  39. And when did the cold period finally stop? In the 19th century, at the same time as the rise of the Industrial Revolution.

    Maybe it could be stated that the early part of the 20th century is within the natural range whereas the late 20th century, the main point of the AGU position statement and also in M03, is clearly outside.

  40. Looks good to me. It is one of these points where they can persuade journalists that they are ‘correct’ and it actually got into newspapers and finally to the senate floor this way. The more we are able to explain why the first half of the 20th century warmed up naturally, the more confidence we get on the detection of the anthropogenic signal afterwards.

  41. Kevin, Even without smoothing it is possible to get a trend of nearer 0.75 if the trend starts around 1920 (especially if the cold year of 1917 is at the start).

  42. DrFlimmer

    The more we study the past, the more we can understand the present and future, despite any attempts at obfuscation.

    And this is not only true for the climate, but also for a lot of other topics (politics as an example!). Too bad, that most people don’t think about history, and what one can learn from it.

  43. Ron Sharp

    There was a CERN experiment last year that suggested that cosmic rays are very important in cloud formation. I was wondering if a relatively close supernova could increase the level of cosmic rays hitting Earth and produce a climate effect?

    Recently discovered supernova remnant RX J0852.0-4622 is 650-700 light years away (debated), and the supernova should have been visible in 1250 or so. (Constellation Vela in the south.)
    http://www.nature.com/news/2011/110824/full/news.2011.504.html
    http://en.wikipedia.org/wiki/RX_J0852.0-4622

  44. VinceRN

    Uh, wasn’t this already what most people thought happened? Is this just more research confirming what what already the theory? Anywho, this seems to duplicate what I had already read about it some time ago.

    Oh, as for that “fail” picture, I’m pretty sure it would work if you could get a lens that big. It would be tricky to get the position just right, especially if you want it to follow the Earth around the sun, but it could be done. A lens with the right focal length at L1 would do it I think….

    Heck of a doomsday weapon, really.

  45. Gunnar

    Here we go again! Another good article that strengthens the case for AGW, which will surely be followed by a whole raft of deniers repeating bogus arguments that have already been often and devastingly refuted, and who will make fools of themselves by having not bothered to read previous posts to the thread that have already debunked their own fallacious and ill-informed comments. I love it! Every time this happens, the contratrians further erode their own credibility! I wonder how long it will take them to figure this out?

    I can’t help being reminded of the flat-earthers on the Flat Earth Research Society site who continue to claim that there is no compelling evidence for a flat earth, and that the idea of a round earth orbiting the sun is a long standing, centuries old and world-wide conspiracy by dishonest scientists, now led by NASA, in order to scam the government and the public into giving them billions of dollars which they pocket and use for their own selfish purposes.

  46. shunt1

    Why the heck would I give Phil a “Yes Dear” when he has finally recognized that there really was a Little Ice Age.

    “However, new research by scientists at the University of Colorado-Boulder (yay team!) may have pegged it: the LIA appears to have started abruptly in the late 13th century, between the years 1275 and 1300.”

    Perhaps Phil will need our support once Michael Mann learns about this! Did Phil forget that there was no such things as the little ice age?

    Step by step, eventually the original raw data will be validated and verified.

  47. Mark Schaffer

    shunt1 is a crank and adds nothing of value to this discussion.

  48. shunt1

    Darn, I guess you forgot that the Little Ice Age (as shown in paintings) was limited to England before the old London bridge was torn down. Once the Thames river was able to flow more rapidly, the river was no longer freezing.

    Mark Schaffer: Please keep to your script. It does get rather difficult for us to keep up, when previous statements about the Little Ice Age keep changing.

  49. shunt1

    The GOOD, because they used MEASURED raw data:

    “As part of the study, Miller and his colleagues radiocarbon-dated roughly 150 samples of dead plant material with roots intact collected from beneath receding ice margins of ice caps on Baffin Island. There was a large cluster of “kill dates” between A.D. 1275 and 1300, indicating the plants had been frozen and engulfed by ice during a relatively sudden event.”

    ….

    The BAD, because they used computer models:

    “The team used the NCAR-based Community Climate System Model to test the effects of volcanic cooling on Arctic sea ice extent and mass. The model, which simulated various sea ice conditions from about A.D. 1150-1700, showed several large, closely spaced eruptions could have cooled the Northern Hemisphere enough to trigger Arctic sea ice growth.”

    Obtaining and analyzing new raw data is a good thing. We need much more of that type of basic scientific inquiry. Models can only be evaluated and calibrated against known and verified raw data.

  50. Brian Too

    @16. Steven Dunlap,

    Re: “The ice in both polar regions is fresh water because it falls as snow or freezing rain then accumulates on top of the existing ice. Salt water freezes in laboratory conditions but the sea does not provide the water for the ice caps”.

    This is not entirely correct. While true for glaciers and essentially any polar region underlain by land (most of Antarctica and the northern polar islands like Greenland, Ellesmere and Baffin), sea ice routinely freezes directly from sea water. The process has a strong effect of desalinating the water. You can actually find small sources of super salinated water (brine) in and around the ice that are the remnants from the freezing process.

    This is not theoretical at all since the vast majority of the north polar regions are actually floating sea ice formed this way. Polar bears are notably dependent upon the annual freeze up to begin their winter hunting season.

  51. Jeff

    see the problem is, when politics get involved, it’s like putting one drop of poison in the drink, it ruins the whole drink.

    Which is why I took some time to meet and know Heidi Cullen, a head scientist at the climate central in New Jersey, formerly of TWC. I completely trust her intellect, integrity, and contacts in the biz, and she has written extensively, but summarizes her position as AGW as “actionable” and that is good enough for me. She means, we either act, or else, humans get ready for the consequences.

  52. mikel

    shunt1 @ 48:

    Why the heck would I give Phil a “Yes Dear” when he has finally recognized that there really was a Little Ice Age.

    And

    Perhaps Phil will need our support once Michael Mann learns about this! Did Phil forget that there was no such things as the little ice age?

    Do you have any evidence that Phil ever denied the LIA? Or the Medieval Warming Period? Can you point to any example of Mike Mann or any other prominent AGW accepting scientist denying either of these phenomena? You see, my understanding is that both of these have been part of Climate Science consensus, including AGW, for 2 or 3 decades now.

  53. KaoS

    — the Ice Age was more of as series of pulses of temperature drops than one long period — typo #2 :)

  54. Paul Pierett

    http://www.nationalforestlawblog.com/Pierett%20Cover.pdf

    http://www.nationalforestlawblog.com/Global%20Warming%20By%20Paul%20Pierett.pdf

    http://answers.yahoo.com/question/index?qid=20110912204701AAcqgEa

    nationalforestlawblog.com See Sun Hotz. License Plate

    Secrets of the Ice Ages by Robert G. Johnson, looks at ocean salt content for cause and affect

    http://joannenova.com.au/2012/01/global-cooling-coming-archibald-uses-solar-and-surface-data-to-predict-4-9c-fall/#more-19909

    Something to keep in mind, we are between ice ages and ice age study is only about as old as Darwin The Origin of Species. If you hang your hat on one item, you miss the whole picture. You also miss what is going on around you.

    I just show one piece of the puzzle that is dismissed for now by your beliefs, but the Russias are ahead of us by 7 years. PM Putin ordered that the electric grid be reviewed and corrected for they know a cooler century is ahead. Other scientists concur, including the MET of England that a cooler century is ahead.

    Somewhat In order:
    The Sun Activity
    Distance to the Sun
    Sunspot Activity, tied to earth heating and electromagnetic pull, influencing earthquakes and tied to Jupiter’s orbit
    Earth Axis Tilt, Your Mayan Calendar
    Volcanic Activity
    Ocean salt levels in different areas,
    Jet Streams
    Ice Sheets blocking Antartica and Chile Coastline
    Artic blocking surface currents
    Moon Gravitational pull
    Atlantic Ocean Conveyor Belt
    On and On the factors grow

    Don’t get too rapped up in man-made global warming or you will freeze to death before you wake up.

    Paul Pierett

  55. Cosmic dust from comet fragments (fireballs and the like) generated teh ice ages. Sometimes the fragments were large enough to even hit the Earth injecting more dust into the atmosphere. there is a half jovian mass body in our outer solar system that generates thes swarms of comet debris fragments. They orbit in a 3:2 resonate orbit. The orbit of this large body can be deduced by various means. One way is to investigate Ice Core and tree ring data at the nominal two period rate of 9938 years and see how close it fits to the theoretical orbital period. The impacts of these comet fragments can be fairly accurately predicted.

    Google: VULCAN REVEALED

  56. Gunnar

    Whoops! In my last post @ #47 I meant to say that the flat earthers claim there is no compelling evidence for a round earth, rather than a flat earth. I think it is very nearly as unreasonable and dishonest and/or ignorant to claim that there is no evidence for AGW.

  57. Um, shunt1, what the frak are you on about? I wrote about the LIA in my last book, back in 2008.

  58. Regner Trampedach

    Paul Pierett @ 57: Eh, – you didn’t even mention vaccines… :-)
    Regner

  59. Regner Trampedach

    Sorry – accidental double post
    – Regner

  60. TheBlackCat

    Obtaining and analyzing new raw data is a good thing. We need much more of that type of basic scientific inquiry. Models can only be evaluated and calibrated against known and verified raw data.

    Only someone who has never developed or used computer models for scientific research or engineering could possibly say something so completely bogus and downright nonsensical.
    Do you really think scientists and engineers spend years of their life and tens of thousands of dollars in computers just tell them what they already knew? Scientists and engineers use computer models because the models tell them something new, something they cannot learn through other means.

    You still seem to be stuck in this idea that computer models are simply statistical curve fits. Computer models, generally speaking (and including the climate models), are based on our understanding of the underlying physical principles. Any good computer model is not “calibrated” against anything, it is based on measured physical values and known physical interactions. The effect of free (unknown) parameters are usually estimated as best as possible and their effects are tested by varying them.

    Once the model has been tested against known data, it is then used to make predictions about unknown data. Not only is this not forbidden for computer models, it is an absolute requirement. A model that cannot tell us anything new is an utter failure and will be rightfully ignored by the scientific community as useless. Scientists and engineers are not into spending months, years, or even decades writing software that does absolutely nothing, which is what you are claiming.

    Of course the results of the models need to be verified by future data, but the climate models already have a couple decades of data behind them and the results have been well within their predicted values. So for the scientific community, they are considered good models that can be trusted as our best source of information about future events.

  61. shunt1

    Phil, if I am in error then please forgive me.

    What exactly did you publish in 1998 about the Little Ice Age and how was that in conflict with Michael Mann’s “hocky stick” that attempted to eliminate the LIA from the historical climate data?

    Does the movie “An Inconvenient Truth” ring any bells with you?

    Phil, it does get so confusing when historical data keeps changing…

  62. shunt1

    Of course, once you recognize the Little Ice Age, then the Medieval Warming Period must also be admited into the historical climate records.

    Phil, do you really want to go down this road?

  63. TheBlackCat

    @ shunt1: “Of course, once you recognize the Little Ice Age, then the Medieval Warming Period must also be admited into the historical climate records.”

    Both have been known for a long time. Do you seriously not realize that it is the climatologists that discovered the little ice age and the medieval warm period, the same people who discovered and overwhelmingly support AGW? Has it ever occurred to you that it might not be the smoking gun against AGW that you think?

  64. shunt1

    Have a nice day!

    I suggest that you rent the movie “An Inconvenient Truth” and report to us what was wrong with it in the morning.

    Actually, this is getting rather funny.

    Hopefully you have a copy of Phil’s 2008 book and can tell us exactly what he wrote about the Little Ice Age.

  65. shunt1

    (Sorry about the double posting – was trying to edit)

    I suggest that you rent the movie “An Inconvenient Truth” and report to us what was wrong with it in the morning.

    Hopefully you have a copy of Phil’s 2008 book and can tell us exactly what he wrote about the Little Ice Age.

    Actually, this is getting rather funny.

    I have been following Phil’s blog since it first started. As an astronomer, nobody on the internet can explain the complex better than him. Phil has earned my respect over the years and I will always consider him as someone I would call a friend. After moving from Minnesota to Colorado, Phil lives only 20 minutes away from me. I would love to take him and his wife out to dinner sometime.

    My one and only conflict with Phil is about data integrity and how that should be questioned, no matter what the scientific subject is.

  66. TheBlackCat

    @ shunt1: “I suggest that you rent the movie “An Inconvenient Truth” and report to us what was wrong with it in the morning.”

    No interest. I get my scientific information from scientists in the relevant fields, not from politicians and certainly not from random people on the internet.

    “My one and only conflict with Phil is about data integrity and how that should be questioned, no matter what the scientific subject is.”

    You keep saying this, but so far have consistently ignored any request to explain exactly what this “data integrity” problem is.

  67. shunt1

    Long story..

    When GISTEMP amd HadCRUT decided to alter historical temperature data that I personally recorded while serving at WSMR, I got damn angry.

    That data was quality controlled each and every day by a separate group of meteorologists.

    When my known historical temperature data is restored to it’s original quality, then I will finally back down.

    Until then, I will continue to bitch each and every time that Phil posts a data plot from GISTEMP or HadCRUT with this fictional data.

    A thermometer is a rather simple instrument and easily calibrated. When they alter the historical database, then there better be a very good reason.

    For instance: “that specific thermometer issued to the military during that time was known to be out of calibration by 0.05 C”

    Oh yes, it is very easy to show a warming on a data plot, when you are allowed to alter the historical data and make older records colder!

  68. shunt1

    Have you ever wondered why the GISTEMP and HadCRUT data showed a major increase in temperatures for the last 30 years, but none of the oceanic or satellite data have the same data slope?

    Why was there a very high temperature spike above Norway in their anomaly plots for last year, that the satellites and ARGOS data did not see?

    Never mind, you do not want to know…

    Once, I would love to see a data plot posted by Phil that actually agrees with other independent sources. When that day happens, I will be absolutly thrilled and tell him so.

  69. Monkey

    There was a comment earlier regarding “I used to be a climate change denier, but I listened to the evidence and changed”. Excellent, I applaud the honesty and clarity it takes to change such opinions.

    This was followed up by a statement regarding “but what I am not impressed with is how scientists are not solving the problem…”. Here I have to take pause and clarify something. Perhaps you didnt mean it as I will below interpret, but I have heard similar statements from family and I want to speak to this:

    If a scientist states that their research suggest ABC, and that future predictions of ABC are dire, that is a scientific discovery. Because the same scientists do not have a solution, this does not discount the science, does not decrease the reality of it. Further, if the scientist is also an ‘overweight idiot who is afraid to debate other scientists” (my fathers opinion of Al Gore), this does not change the science. If I discover cancer, the fact that I also do not co-discover a cure does not make cancer fake.

    PS – I know A. Gore is not a scientist….it was an example in the realm of the same topic that I have at the front of my head when I try to talk science with my family…

  70. 51 Shunt1: Obtaining and analyzing new raw data is a good thing. We need much more of that type of basic scientific inquiry. Models can only be evaluated and calibrated against known and verified raw data.

    Isn’t that exactly what they did? I know you have a hate-on for models, but no one would use them if they weren’t so damned useful for exploring raw data.

    @59 Gunnar: Heh… I was gonna say…

  71. @ Shunt1: What exactly did you publish in 1998 about the Little Ice Age and how was that in conflict with Michael Mann’s “hocky stick” that attempted to eliminate the LIA from the historical climate data?
    Does the movie “An Inconvenient Truth” ring any bells with you?
    Phil, it does get so confusing when historical data keeps changing…

    Ok, now I KNOW you’re a troll.
    Enjoy the revisionist world you’ve created for yourself. It sounds… colorful.

  72. @72 Monkey: If a scientist states that their research suggest ABC, and that future predictions of ABC are dire, that is a scientific discovery. Because the same scientists do not have a solution, this does not discount the science, does not decrease the reality of it. Further, if the scientist is also an ‘overweight idiot who is afraid to debate other scientists” (my fathers opinion of Al Gore), this does not change the science. If I discover cancer, the fact that I also do not co-discover a cure does not make cancer fake.

    I think we’ve been so inundated by this FoxNews-ization of media that many of us naturally default to thinking of any issue in terms of rhetorical debate rather than fact-finding. If you’re a candidate debating other candidates seeking an office, then yeah, if you criticize a plan, you’re expected to have an alternative. In pretty much every other situation, though, it’s important to make careful distinctions between issues, in this case, the phenomenon and our response to it.

    I wonder. If Al Gore never existed, would folks like your dad (and mine) be any less intransigent?

  73. TheBlackCat

    @ Shunt1:

    When GISTEMP amd HadCRUT decided to alter historical temperature data that I personally recorded while serving at WSMR, I got damn angry.

    You wouldn’t, by any chance, by referring to the statistical bias correction they applied to the data to compensate for issues introducing by gridding, would you? I sincerely hope not.

    Have you ever wondered why the GISTEMP and HadCRUT data showed a major increase in temperatures for the last 30 years, but none of the oceanic or satellite data have the same data slope?

    No, we know why the slopes aren’t exactly the same, and it is due to things like differences in sampling density in different regions.

    Have you ever wondered why they all show same general trend if you are right that some are intentionally falsified while others are not?

    Also, are you going to retract your misrepresentation of modeling or are you hoping we forgot about it. Because we haven’t.

  74. TheBlackCat

    duplicate post – please delete

  75. Messier Tidy Upper

    @30. Theron :

    “Boundary disputes between countries over low-lying islands will disappear.” [Quoting #12. F16 guy - ed.]
    Now that is some serious trolling. As entire low-lying nation disappear beneath the waves, will you be hosting the refugees at your house? And when we spend a few trillion on sea walls to protect our coastal cities, you’ll be picking up the bill, right?

    Plus there’s always the possibility of conflict happening over the salvage rights and underseas mining too. :-(

  76. Messier Tidy Upper

    @64. shunt1 :

    What exactly did you publish in 1998 about the Little Ice Age and how was that in conflict with Michael Mann’s “hocky stick” that attempted to eliminate the LIA from the historical climate data? Does the movie “An Inconvenient Truth” ring any bells with you? Phil, it does get so confusing when historical data keeps changing…

    Sometimes we learn things that change our views. Sometimes we find that what we used to think isn’t the case after all.

    Al Gore and his movie are latecomers to the issue. Gore didn’t invent climate change only exploited it. His Inconvenient Truth movie’ is irrelevant to the *science* of Human Induced Rapid Gobal Overheating although it is notable in the politics and histroy of rasing people’s awareness about it.

    HIRGO is based on basic physiscs of gases and an idea that Svante Arrrhenius had back in 1896. It has survived numerous peer-reviewed challenges and is supported by a mountain of multiple lines of evidence from oceanographic measurements to glacial records to biological studies to satellite observations etc ..

    We are learning more all the time. Some of what we’re learning is pretty worrying for instance the faster than expected decline in Arctic sea ice extent. :-(

    When the facts have changed, doesn’t it make sense to change our opinions to suit the facts rather than attempt the impossibility of changing the facts to suit our views?

    If you wish to disprove the consensus of 98% of climatologists you are going to need some extraordinary evidence to do so.

    Are you offering any of that or just a Yes dear shunt1? ;-)

    @71. shunt1 – February 2nd, 2012 at 3:15 am :

    Have you ever wondered why the GISTEMP and HadCRUT data showed a major increase in temperatures for the last 30 years, but none of the oceanic or satellite data have the same data slope? Why was there a very high temperature spike above Norway in their anomaly plots for last year, that the satellites and ARGOS data did not see?
    Never mind, you do not want to know…

    Actually I *do* want to know. Do you have a link or the name of a specific paper from apeer reviewed scientific journal or something like that to back up your seemingly unsupported word here please?

    @70. shunt1 Says:

    Long story.. When GISTEMP amd HadCRUT decided to alter historical temperature data that I personally recorded while serving at WSMR, I got damn angry.

    Please tell us. Specifically and with names and actual specifics.

  77. MartinM

    Have you ever wondered why the GISTEMP and HadCRUT data showed a major increase in temperatures for the last 30 years, but none of the oceanic or satellite data have the same data slope?

    Can we have a better class of troll, please? This one’s clearly never bothered to actually look at the data, or else assumes nobody else will.

  78. @64 shunt1 :”Does the movie “An Inconvenient Truth” ring any bells with you? “

    Gore’s flawed movie is examined – along with Durkins here :

    http://www.youtube.com/watch?v=WON-s00GIsU

    The Gore factor is also addressed here :

    http://www.skepticalscience.com/al-gore-inconvenient-truth-errors.htm

    with this :

    http://www.skepticalscience.com/medieval-warm-period-intermediate.htm

    dealing with the idea the Medieval Warm Period was warmer.

    Linked to my name is a videoclip running through the history of our growing understanding of the HIRGO issue including material from 1956 – fifty years before Gore’s movie.

  79. Gaebolga

    Shorter shunt1:

    I stand by my statement. The single most important factor in Earth’s climate, [sic] is the change in it’s [sic] albedo over time. Period.

    YES, DEAR!

  80. Messier Tidy Upper

    I stand by my statement. The single most important factor in Earth’s climate, [sic] is the change in it’s [sic] albedo over time. Period. .

    Hmm … So melting reflective ice at our planet’s poles and thereby replacing a surface that reflects 80% of the solar radiation hitting it with one that instead absorbs 80% of the same rays – changing from polar ice sheets to open ocean – would do what then?

    Albedo is a powerful feedback – once it starts. But it isn’t the sole factor in determining our climate.

    ***

    “Without our atmosphere the Earth’s average temperature would be minus eighteen degrees Celsius.”
    - Dr Alan Longstaff, ‘Astronomy Now’ magazine July 2007.

  81. Nigel Depledge

    F16 guy (12) said:

    Love the ongoing discourse…

    Perhaps I’ve missed this being discussed here, but:

    1. Over the course of the 4.5 billion years of earths history, what is the “right” temperature?

    There isn’t one, unless you have built a massively interdependent social infrastructure that depends on the climate being the same all the time.

    Oh, look what we humans have gone and done . . .

    2. Is global warming (by whatever source) always a bad thing?

    No, unless you have built a massively interdependent social infrastructure that depends on the climate being the same all the time.

    Most particularly, GW that occurs naturally tends to occur over many thousands of years, which gives life more time to adapt. Having said that, most of the large swings of climate in Earth’s history coinicde with mass extinctions.

    3. Are the following items as important as the negative effects of GW ?

    Advantages of Global Warming

    Arctic, Antarctic, Siberia, and other frozen regions of earth may experience more plant growth and milder climates.

    This does not outweight any of the principle negative effects (at least, not from a human perspective).

    The next ice age may be prevented from occurring.

    Hey, if an ice age is starting, we know how to prevent it (dig up sequestered CO2 and burn fossil carbon), so the possibility that we have already prevented its occurence does not outweigh the principle negative effects of GW (at least, not from a human perspective).

    Northwest Passage through Canada’s formerly-icy north opens up to sea transportation.

    This is trivial.

    Less need for energy consumption to warm cold places.

    This is outweighed by the increased energy consumption to cool warm places (even now, Californians use more energy on air conditioning than they do on heating). Remember that the Tropics cover a substantially larger area of the globe than areas within the Arctic and Antarctic Circles.

    Fewer deaths or injuries due to cold weather.

    Outweighed by the greater number of deaths due to heatstroke etc.

    Even now, a particularly hot summer in Europe (2010) has been identified as the cause of several tens of thousands of deaths.

    Longer growing seasons could mean increased agricultural production in some local areas.

    Substantially outweighed by (a) the loss of some of the world’s most fertile land to rising sea level; (b) the loss of some of the world’s most fertile land to persistent drought, and (c) loss of agricultural yields due to more frequent extreme weather events (floods, hurricanes, droughts etc.).

    Mountains increase in height due to melting glaciers, becoming higher as they rebound against the missing weight of the ice.

    In what way is this any kind of advantage?

    Boundary disputes between countries over low-lying islands will disappear.

    Outweighed by many orders of magnitudes by the disputes that will be caused by migrating refugees and wars over water supplies.

    In short, your proposed benefits of GW are all trivial in comparison with the most likely drawbacks of GW.

  82. Nigel Depledge

    Steven Dunlap (16) said:

    The ice in both polar regions is fresh water because it falls as snow or freezing rain then accumulates on top of the existing ice. Salt water freezes in laboratory conditions but the sea does not provide the water for the ice caps.

    The polar sea ice does indeed have a low salt content, but it is wrong to say that none of it comes from the sea.

    Sea water does freeze. As it freezes, the salt gets concentrated in patches of very salty brine that remain liquid. I have seen video footage of downpours of brine from accumulating sea ice in the Antarctic. As the brine, being denser than the seawater around it, descends, several phenomena are observable:

    1. You can see the refractive effect of the denser fluid travelling down from the newly-forming sea ice (rather like a heat haze, but the density gradient that causes ths refraction is due to cold, not heat).

    2. Because the brine is so cold (typically between 0 °C and -15 °C), it often forms tubes of ice as water freezes out of the less-salty water around the brine current. They look like stalactites, but form rather more rapidly, and have freezing-cold brine pouring out of their open ends.

    3. Where these currents meet the sea floor, everything freezes, so you get patches of ice on the sea floor, and the ice encases everything that is too slow to move out of the way.

  83. Nigel Depledge

    Jason (20) said:

    I used to think of myself as a climate change denier. The last few years, I’ve become convinced that it is a real problem (science trumps flawed rhetoric). However, climate change scientists have not yet impressed me with a real solution to the problem.

    Eh?

    Why should it be up to climatologists to come up with solutions to a man-made problem that they have identified but are being obstructed in disseminating?

    As it happens, there are a great many talented scientists and engineers working on various solutions, from sustainable energy generation to carbon sequestration to geoengineering.

  84. Reading 1493 by Charles Mann I came upon a theory that William Ruddiman from the University of Virginia proposes which claims that the destruction of American Indian societies by European epidemics severely impacted the massive and frequent land-clearing and regular burning and thus removed an atmospheric carbon source.

    The reforestation of land in American tropical regions alone would have accounted for 1/4 of the temperature drop.

    Interesting.

  85. MNP

    I’m really disappointed in this.

    I’m writing an alternate history and when it gets to the LIA, there is no huge Mongolian conquest. This references the theory that Genghis Khan contributed to LIA by the slaughter of so many people. I was counting on the people staying alive to prevent reforestation and reducing the severity (or delaying the severity) of the LIA for some time.

    This really shoots my grand plan in the foot. DAMN IT. DAMN IT. DAMN IT.

  86. Gary Ansorge

    “Most likely, the warmer temperatures would have melted the north polar sea ice. ”

    I just wonder if the dilution of the Atlantic current is what’s driving the cold winter in Europe this year,,,or is that just another side effect of el nino/la nina?(dang, I have trouble keeping those two compartmentalized)(and spelling them right)

    Gary 7

  87. JP

    The Thames hasn’t frozen since the 17th or 18th century? Really? What about 1963…there are plenty of easy to find photos of a frozen Thames from that year. I wouldn’t be surprised if it happens again this year, which has been a very cold winter for Europe. Drop the freezing Thames myth…it doesn’t help your argument.

  88. Paul Pierett

    Tx R.

    Vaccines!

    I guess that is why they call this blog. Discover.

  89. @ MTU: Sometimes I think Al Gore did more harm than good with his personal HIRGO crusade. Sure, he may have raised awareness among a few people, but it seems like he distanced others from the issue because of his politics, and gave the deniers a handy straw man to attack.

  90. The next ice age may be prevented from occurring.

    I love this particular optimistic little tidbit. Sure, I guess. Eventually.
    Still, that seems kinda like cheerfully telling someone whose home is submerged by floodwaters “Hey! As long as it’s like this, it’ll never catch on fire!”

    @85 Nigel Depledge: 1. You can see the refractive effect of the denser fluid travelling down from the newly-forming sea ice (rather like a heat haze, but the density gradient that causes ths refraction is due to cold, not heat).
    2. Because the brine is so cold (typically between 0 °C and -15 °C), it often forms tubes of ice as water freezes out of the less-salty water around the brine current. They look like stalactites, but form rather more rapidly, and have freezing-cold brine pouring out of their open ends.
    3. Where these currents meet the sea floor, everything freezes, so you get patches of ice on the sea floor, and the ice encases everything that is too slow to move out of the way.

    Wow! Sounds like an underwater version of the “Killer cold wind” from “The Day After Tomorrow” :)

  91. Nigel Depledge

    Joseph G (93) said:

    Wow! Sounds like an underwater version of the “Killer cold wind” from “The Day After Tomorrow”

    Kind of, except for lacking the impossibility of TDAT’s killer cold wind!

    In fact, all of the sea-floor organisms in the seas fringing Antarctica are poikilothermic (sp?), i.e. their bodies will be at approximately the same temperature as their environment. This means that their metabolism tends to be pretty slow and therefore also their locomotion is slow. The effect is not so fast that a human diver (for example) would get encased in ice, but for a starfish that has a top speed of less than 1 cm/s it can be a real hazard.

  92. Total

    The Thames hasn’t frozen since the 17th or 18th century? Really? What about 1963…there are plenty of easy to find photos of a frozen Thames from that year.

    I’m assuming he means in London, where the Thames did *not* freeze over in 1963:

    http://en.wikipedia.org/wiki/Winter_of_1962–1963_in_the_United_Kingdom

  93. mikel

    JosephG check this out.

  94. Kevin Mudd

    If we are at the same temperature as before the lia then aren’t we at the normal temperature ?

NEW ON DISCOVER
OPEN
CITIZEN SCIENCE
ADVERTISEMENT

Discover's Newsletter

Sign up to get the latest science news delivered weekly right to your inbox!

ADVERTISEMENT

See More

ADVERTISEMENT
Collapse bottom bar
+

Login to your Account

X
E-mail address:
Password:
Remember me
Forgot your password?
No problem. Click here to have it e-mailed to you.

Not Registered Yet?

Register now for FREE. Registration only takes a few minutes to complete. Register now »