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Climate Hustle

Are we heading into a new Ice Age?

What the science says...

Select a level... Basic Intermediate

Worry about global warming impacts in the next 100 years, not an ice age in over 10,000 years.

Climate Myth...

We're heading into an ice age
"One day you'll wake up - or you won't wake up, rather - buried beneath nine stories of snow. It's all part of a dependable, predictable cycle, a natural cycle that returns like clockwork every 11,500 years.  And since the last ice age ended almost exactly 11,500 years ago…" (Ice Age Now)

According to ice cores from Antarctica, the past 400,000 years have been dominated by glacials, also known as ice ages, that last about 100,000. These glacials have been punctuated by interglacials, short warm periods which typically last 11,500 years. Figure 1 below shows how temperatures in Antarctica changed over this period. Because our current interglacial (the Holocene) has already lasted approximately 12,000 years, it has led some to claim that a new ice age is imminent. Is this a valid claim?

Figure 1: Temperature change at Vostok, Antarctica (Petit 2000). The timing of warmer interglacials is highlighted in green; our current interglacial, the Holocene, is the one on the far right of the graph.

To answer this question, it is necessary to understand what has caused the shifts between ice ages and interglacials during this period. The cycle appears to be a response to changes in the Earth’s orbit and tilt, which affect the amount of summer sunlight reaching the northern hemisphere. When this amount declines, the rate of summer melt declines and the ice sheets begin to grow. In turn, this increases the amount of sunlight reflected back into space, increasing (or amplifying) the cooling trend. Eventually a new ice age emerges and lasts for about 100,000 years.

So what are today’s conditions like? Changes in both the orbit and tilt of the Earth do indeed indicate that the Earth should be cooling. However, two reasons explain why an ice age is unlikely:

  1. These two factors, orbit and tilt, are weak and are not acting within the same timescale – they are out of phase by about 10,000 years. This means that their combined effect would probably be too weak to trigger an ice age. You have to go back 430,000 years to find an interglacial with similar conditions, and this interglacial lasted about 30,000 years.
  2. The warming effect from CO2 and other greenhouse gases is greater than the cooling effect expected from natural factors. Without human interference, the Earth’s orbit and tilt, a slight decline in solar output since the 1950s and volcanic activity would have led to global cooling. Yet global temperatures are definitely on the rise.

It can therefore be concluded that with CO2 concentrations set to continue to rise, a return to ice age conditions seems very unlikely. Instead, temperatures are increasing and this increase may come at a considerable cost with few or no benefits.

Basic rebuttal written by Anne-Marie Blackburn

Update August 2015:

Here is a related lecture-video from Denial101x - Making Sense of Climate Science Denial


Last updated on 7 August 2015 by MichaelK. View Archives

Printable Version  |  Offline PDF Version  |  Link to this page

Further reading

Tamino discusses predictions of future solar activity in Solar Cycle 24.


Many thanks to Sami Solanki for his invaluable advice and feedback as well as John Cross for his very helpful comments.


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Comments 251 to 300 out of 389:

  1. Randy, setting aside the fact that we have absolutely NO idea what technology will be like in 50,000 years... the CO2 we have already released into the atmosphere is sufficient to prevent the next glaciation cycle. Basically, instead of the next Milankovitch swing taking us into a global glaciation it is now more likely to see a return to the sort of climate we had two hundred years ago. If we continue increasing atmospheric CO2 levels we may actually skip the next several glaciation events. However, again, we are talking about time-frames so large that circumstances could change completely due to things we cannot predict.
  2. 'good chance that the arctic melting will stop the Atlantic conveyer by dumpling lots of fresh (therefore lighter) water into the North Atlantic.'

    I dont believe there is any science supporting this, but please feel free to cite some. There is a postulate (and evidence) that the massive dump of fresh water from ice sheet melting caused a slow down and thus the YD event. However, this was an extremely rapid dump of a lot of water. Summer melt of seaice over many years is in a different order.

    Even if the Milankovich cycles were strong enough to cause another glacial with CO2 levels this high, the onset is extremely slow - 2 orders of magnitude less than current rate of change. It not a question of whether we would prefer warm or cold - its the rate of change that is dangerous.
  3. scaddenp @252, this press release from NASA details some of the latest research. In essence, models predict a slowing of the Atlantic Conveyor with increased melt water because fresh water is less dense than salty, and hence less prone to sink. Josh Willis has used buoy data and satellite data to show the Atlantic Conveyor sped up by 20% from 1993 to 2009, contradicting earlier ship-based data. There has been no statistically significant change from 2002-2009.

    The acceleration is attributed to a possible natural cycle. However, I would note that Greenland ice melt has primarily been in areas where it would feed the Labrador current. Further, because of the reducing volume of sea ice, it is not clear the more extensive summer melt back results in more fresh water being introduced to the Arctic Ocean. The point is that there are obvious complexities in this issue, not all of which I have covered (or are competent to cover). If you want to become up to date on the issue, this google scholar search will get you started ;)
  4. Tom, this seems to back my view - current melting isnt going to do anything dramatic, especially not another ice age.

    From the release:
    "No one is predicting another ice age as a result of changes in the Atlantic overturning," said Willis.

    In short, worry about warming, not a coming ice age.
  5. Randy Subers @248, you are missing the obvious point that well before the 50 K years the Greenland Ice Sheet will have melted away, as will the Arctic Sea Ice (much earlier). Therefore in 50 K years there will not be massive charges of melt water to slow the conveyor because there will be no melt water remaining from our entry into the anthropocene.

    Whether we could return to an ice age in 50,000 years depends critically on how much CO2 we emit in the coming 100 to 200 years. If we keep it below 1000 tonnes of carbon, then in 10,000 years CO2 levels may have declined enough so that Milankovitch cycles can restart the recent pattern of glacials and interglacials. Should we continue at business as usual, however, even 50 thousand years from now, CO2 levels may still be too high for that process to recommence.
  6. Phil/Tom, there's also this paper: Effect of the potential melting of the Greenland Ice Sheet on the Meridional Overturning Circulation and global climate in the future - Hu (2011). I always save copies of papers that interest me when I'm trawling the internet, and your discussion rang a few bells.

    The modelling shows that even high rates of Greenland icesheet melt over the coming centuries will only slow global warming by a few tenths of a degree. Hardly enough to start a new ice age. If only eh?
  7. OK this is stupid, we can predict things, but only to a degree. Apparently we are also long overdue for a super volcano eruption under yellow stone park, but it hasnt happened yet. The only thing that we have actually proved right from prediction, is that there is 365 days in a year, not counting leap years, So everyone can calm down, I dont think we will be in an ice age in any time soon.
  8. "The degree" varies wildly however. You can predict sunrise etc with very high degree of accuracy. You can also predict the changes in insolation due to the Milankovitch cycles which drive the ice cycle with a very high degree of accuracy, but climatic effect of that change also depends on other factors - especially level of GHGs.
    On the other hand, volcanoes are unpredictable with no known physical basis to a "cycle". A statistical recurrance period should never be confused with a prediction. Saying we are "long overdue" for an eruption smacks of pop-sci documentaries, and I would be interested if you have a science paper that says that.

    The basis for saying that there wont be an iceage soon is a/ Berger, A. and Loutre, M. F. (2002) which consider that orbital drivers, and b/ our GHG levels are getting to Pliocene levels - too high for an iceage.
  9. This is very interesting. In the past there were short and "very warm", but now we are in a semi long "warm" phase. According to the chart global temperatures were way higher in the past than they are now so the heat doesn't seem so bad compared to back then.
  10. Depends on your definition of bad. Global sea level was many metres higher during the last interglacial, the Eemian, despite global temperatures being equivalent to either, the mid-twentieth century, or perhaps 1-2°C warmer than now.

    When one considers the amount of infrastructure put at risk by such a rise in sea level, I'd classify that as bad. And that is but one consequence of a future warmer world.
  11. qwop, it never was about the absolute temperature. It's about the rate of change. Go back through the data and see how many periods you find that feature a 3C global temp increase over 300 years. You might check out the PETM event for starters. Of course, that event was 24x slower.
  12. The isotope proxies for temperature and glacial ice volume correlate with the Earth’s orbital variations, but the correlations are far from perfect. The “internal” climate drivers of glacial-ice area, oceanic circulation, and water vapor transport interact to cause the large 100,000-year spikes and other noise variation in the long-term records of Vostok ice and ocean sediments. One such driver is the loss of northern perennial polar ocean sea ice due to CO2 warming. That ice may be gone by 2020 according to a simple extrapolation. There is a plausible connection between its loss and the initiation of the last ice age 120,000 years ago, and the next ice age may likewise begin in the next decade – because of our current warming. I am working on it, so stay tuned.
  13. Nonsense. You forget about the most important forcing present today, the previously-sequestered, anthropogenically-derived fossil-fuel CO2 slug we are injecting back into the carbon cycle. This forcing simply wasn't present at previous interglacial/glacial transitions.

    But then, actual scientists have already looked into this (as opposed to semimythical cycles); let's examine the facts, shall we:

    The oceans have been absorbing an extra 2 Hiroshima-bombs-worth of energy, PER SECOND, since 1960. That warming continues to this day, unabated.

    Per Tzedakis et al 2012
    glacial inception would require CO2 concentrations below preindustrial levels of 280 ppmv
    (for reference, we are at about 391 right now…and climbing).

    Earlier, Tyrrell et al 2007 examined this, concluding that we have already skipped the next glacial epoch. Furthermore, Tyrrell concludes that if we continue our present fossil fuel consumption,
    "Our research shows why atmospheric CO2 will not return to pre-industrial levels after we stop burning fossil fuels. It shows that it if we use up all known fossil fuels it doesn't matter at what rate we burn them. The result would be the same if we burned them at present rates or at more moderate rates; we would still get the same eventual ice-age-prevention result."
    "Burning all recoverable fossil fuels could lead to avoidance of the next five ice ages."
    So no glacial epochs the next million years…

    Facts, like tiggers, are wonderful things, for those who have them.
  14. Daniel, all facts are not relevant, but this fact is: lower temperatures did not trigger the last ice age, 120,000 years ago. The severe climate with its winter sea ice vanished in northern Baffin Bay in a warming implied by unusual willow pollen and the more negative oxygen isotope ratios at the bedrock base of the Devon ice core (Koerner et al, 1988). East of southern Baffin Island at the site of sediment core HU75-58, 60% of the foraminifera were warm water species, now absent in today’s cold seas (Fillon, 1985). The warmer waters west of Greenland imply a cyclonic circulation and cloudy weather with heavy snowfall over Baffin Island, Quebec and Labrador. The heavy precipitation increased erosion that is confirmed by the large abrupt ~500 year pulse of hematite-containing sediment in a deep-sea record (Adkins et al., 1997). During that 500-year interval glacioeustatic sea level fell about 2.5 m, as measured on presently uplifted Barbados (Johnson, 2001) at the Cane Vale B site. Ice-free seas west of Greenland may again trigger an ice age. Ice-free seas can be established only if there is no sea-surface stratification there, and that only if the less dense polar water inflow through the Nares Strait ceases, and that only if the perennial sea ice on the polar ocean goes away, consequently enabling a warmer polar atmosphere in winter and a lower atmospheric pressure that reduces or eliminates polar water inflow through the Nares Strait.
    Indeed, the increasing atmospheric CO2 may eventually terminate our next ice age hundreds of years later, but during the first century after year 2020 when the perennial polar sea ice is gone, it is very likely that Canada will see widespread thickening snow fields on now bare summer tundra, and temperate climate trees in northern Europe will vanish, like their pollen vanished from the record 120,000 years ago (Field et al., 1994). You only need to wait another ten years to see if this triggering prediction is right or wrong.
  15. Again, human fossil fuel bolus injections were not around in previous interglacials so you still are comparing apples to guavas.

    I'll trust what the science has to say about this current interglacial. And the verdict is that ice ages are not recurring anytime soon. Not while human activities are acting to retard their formation. Not on our watch, as they say.

    See? No waiting necessary.
  16. Robert,

    Can you provide a citation to peer reviewed data supporting your wild hand waving or is this original thought of yours unsupported by actual data?
  17. As a wise man once said: “ It’s not what we don’t know that slows our progress, it’s what we think we know that isn’t true.” Conventional wisdom says that the last ice age began by cooling in the Baffin Island area, but a detailed examination of the evidence shows that it began by a large precipitation increase under warmer oceanic conditions. Please note that the Penney and Barnes ice caps on Baffin Island and the Devon Island ice cap have survived to this day, and would surely grow if they had a large moisture supply. To argue the next ice age climate change about the year 2020, we need to consider the known evidence for the last initiation, explain that evidence, and apply that explanation to the next decade or so. There are two parts to this argument: (1) the evidence, and (2) the explanation. Here are the references for Part 1:
    For a warmer ice-free Baffin Bay precisely when new glaciation began:
    Koerner, R.M., Bourgeois, J.C., and Fischer, D.A., 1988, Pollen analysis and discussion of time-scales in Canadian ice cores: Annals of Glaciology, v. 110, p. 85-91.
    For extreme warmth in the Labrador Sea east of southern Baffin Island:
    Fillon, R.H., 1985, Northwest Labrador Sea Stratigraphy, sand input and
    paleoceanography during the last 150,000 years: in Andrews, J.T., ed., Quaternary Environments: Eastern Canadian Arctic, Baffin Bay and Western Greenland, Boston: Allen and Unwin, p. 210-247.
    For the ~500 year pulse of clay and hematite showing heavy regional precipitation and erosion:
    Adkins, J.F., Boyle, E.A., Kegwin, L., and Cortijo, E., 1997, Variability of North Atlantic thermohaline circulation during the last interglacial period: Nature, v. 390, p. 154-156.
    For the glacioeustatic sea level fall in that ~500 year interval, see the Cane Vale B transect in fig. 2 in :
    Johnson, R.G., 2001, Last interglacial sea stands on Barbados and an early anomalous deglaciation timed by differential uplift: Journal of Geophysical Research, v. 106, no. C6, p. 11543-11551.
    In Part 2, the key to the explanation was the collection of data in 2011 using the ESA ENVIISAT system that showed that atmospheric pressure differences dominate the flow of polar water into Baffin Bay, and the realization that a lower polar pressure could cause an ice-free Labrador Sea and Baffin Bay. The ice-free Baffin Bay in the absence of polar water stratification has a perfect analog in the ice-free Greenland Sea extending northward to Svalbard to where the ice on the polar ocean can form due to the river discharge stratification there. The timing of year 2020 is obtained from the web site: where you can draw your own curve through the points of seasonal minimum sea-ice area, a curve that I extrapolate to zero about 2020. The reason why and when the warm Baffin-Labrador Sea conditions ended, together with the other physical, meteorological and oceanic parts of the explanation, are embodied in a paper too long for this forum and which was rejected recently by “Geology,” perhaps because of the wise man effect, above. The next ice age may not last for thousands of years under rising CO2 concentrations, but a short-term validation of this prediction will make Canada and northern Eurasia much more unpleasant and will result in very difficult political and societal problems. It would be better to recognize the coming change sooner than later.
  18. Sorry, I omitted the Field et al. reference for the absence of temperate climate trees in northern Germany:

    Field, M.H., Huntley, B., and Müller, H., 1994, Eemian climate fluctuations observed in a European pollen record: Nature, v. 376, p. 779-783.
  19. Robert,

    Why did scientists stop producing papers that you can cite over a decade ago? Can you cite a paper that suggests that warm temperatures over Baffin Island initiated the ice ages?

    The Milankovitch cycles are generally presumed to initiate the ice ages by cooling the Northern Hemisphere. This slow cooling allows snow to accumulate in Northern Canada. Please provide a recent citation that claims warm water in the Baffin area initiated the ice ages. Your supposition that an ice free arctic, deduced by eyeballing the Cyrosphere Today graph, will cause snow to accumulate is the opposite of the snow records observed at the National Snow lab at Rutgers. Those records show a dramatic decrease in the summer snow levels across the Northern Hemisphere.
  20. Further to Michael Sweet's comment @269, Milankovitch cycles are supposed to initiate glacials by cool summers failing to melt snow, thereby increasing albedo with a progressive cooling over time as a result. Merely piling more snow onto a preexisting ice cap will not increase albedo, and so cannot initiate an glacial. As it happens, with a warmer world, NH summer snow extent has decreased significantly, the reverse of that required to initiate a new glacial (July shown):

    What is more, ice caps are not accumulating ice on Baffin Island, rather they are melting.

    Zdanowicz et al (2012) report:

    "At latitude 67°N, Penny Ice Cap on Baffin Island is the southernmost large ice cap in the Canadian Arctic, yet its past and recent evolution is poorly documented. Here we present a synthesis of climatological observations, mass balance measurements and proxy climate data from cores drilled on the ice cap over the past six decades (1953 to 2011). We find that starting in the 1980s, Penny Ice Cap entered a phase of enhanced melt rates related to rising summer and winter air temperatures across the eastern Arctic. Presently, 70 to 100% (volume) of the annual accumulation at the ice cap summit is in the form of refrozen meltwater. Recent surface melt rates are found to be comparable to those last experienced more than 3000 years ago. Enhanced surface melt, water percolation and refreezing have led to a downward transfer of latent heat that raised the subsurface firn temperature by 10°C (at 10 m depth) since the mid-1990s. This process may accelerate further mass loss of the ice cap by pre-conditioning the firn for the ensuing melt season. Recent warming in the Baffin region has been larger in winter but more regular in summer, and observations on Penny Ice Cap suggest that it was relatively uniform over the 2000-m altitude range of the ice cap. Our findings are consistent with trends in glacier mass loss in the Canadian High Arctic and regional sea-ice cover reduction, reinforcing the view that the Arctic appears to be reverting back to a thermal state not seen in millennia."

    Fisher et al (2012) report:

    "There has been a rapid acceleration in ice-cap melt rates over the last few decades across the entire Canadian Arctic. Present melt rates exceed the past rates for many millennia. New shallow cores at old sites bring their melt series up-to-date. The melt-percentage series from the Devon Island and Agassiz (Ellesmere Island) ice caps are well correlated with the Devon net mass balance and show a large increase in melt since the middle 1990s. Arctic ice core melt series (latitude range of 67 to 81 N) show the last quarter century has had the highest melt in two millennia and The Holocene-long Agassiz melt record shows that the last 25 years has the highest melt in 4200 years. The Agassiz melt rates since the middle 1990s resemble those of the early Holocene thermal maximum over 9000 years ago."

    Sharp et al (2011) report:

    "Canada's Queen Elizabeth Islands contain ∼14% of Earth's glacier and ice cap area. Snow accumulation on these glaciers is low and varies little from year to year. Changes in their surface mass balance are driven largely by changes in summer air temperatures, surface melting and runoff. Relative to 2000–2004, strong summer warming since 2005 (1.1 to 1.6°C at 700 hPa) has increased summer mean ice surface temperatures and melt season length on the major ice caps in this region by 0.8 to 2.2°C and 4.7 to 11.9 d respectively. 30–48% of the total mass lost from 4 monitored glaciers since 1963 has occurred since 2005. The mean rate of mass loss from these 4 glaciers between 2005 and 2009 (−493 kg m−2 a−1) was nearly 5 times greater than the 1963–2004 average. In 2007 and 2008, it was 7 times greater (−698 kg m−2 a−1). These changes are associated with a summer atmospheric circulation configuration that favors strong heat advection into the Queen Elizabeth Islands from the northwest Atlantic, where sea surface temperatures have been anomalously high."

    Finally, Schrama et al, (2011) report:

    "In this paper we discuss a new method for determining mass time series for 16 hydrological basins representing the Greenland system (GS) whereby we rely on Gravity Recovery and Climate Experiment (GRACE) mission data. In the same analysis we also considered observed mass changes over Ellesmere Island, Baffin Island, Iceland, and Svalbard (EBIS). The summed contribution of the complete system yields a mass loss rate and acceleration of −252 ± 28 Gt/yr and −22 ± 4 Gt/yr2 between March 2003 and February 2010 where the error margins follow from two glacial isostatic adjustment (GIA) models and three processing centers providing GRACE monthly potential coefficient sets. We describe the relation between mass losses in the GS and the EBIS region and found that the uncertainties in all areas are correlated. The summed contribution of Ellesmere Island, Baffin Island, Iceland, and Svalbard yields a mass loss rate of −51 ± 17 Gt/yr and an acceleration of −13 ± 3 Gt/yr2 between March 2003 and February 2010. The new regional basin reconstruction method shows that the mass loss within the southeastern basins in the GS has slowed down since 2007, while mass loss in western basins increased showing a progression to the north of Greenland."

    The reported ice mass loss for Baffin Island alone is -10.8 Gt/year.

    In sum, ice sheets and ice caps in the Canadian archipelago are loosing ice with warmer weather, the opposite to the effect predicted by Robert. His theory is therefore falsified.
  21. Tom,
    Thanks for the references.

    I checked the Rutgers snow lab and only 0.16 million km2 of snow cover remained in week 31 this year, not counting Greenland. At least the anomaly will stop going up, since all the snow is gone. A lot of permafrost is also melting, but I do not have a reference at hand. NSIDC probably has something.

    Robert, what is your response to this data?
  22. Wait, didn't I see a movie about this once?
  23. Michael,
    Response: [DB] Ignoring the proof citation challenges and the challenges of physical reality contravening your hypothesis put forth earlier by Michael Sweet and by Tom Curtis, it is not helpful to avoid dealing with those challenges and to blithely comment away. You must first deal with those before moving on. Soliloquy snipped.
  24. Worry about global warming impacts in the next 100 years, not an ice age in over 10,000 years.


    Looking at fig1,it appears that an ice age is due any minute, not in 10,000 years. 

    Another bit of information to take from fig 1, it looks as if  all the previous interglacials were warmer than the current one.  Who decided that the temp after the industrial revolution was the "accurate" temperature the earth should be at, and that we are exceeding that perfect temp?

  25. @ Kevin

    "Looking at fig1,it appears that an ice age is due any minute, not in 10,000 years. "

    Umm, got any physical basis for that?  Any at all?  "Eyecrometers" do not count.

    Frankly, your entire above comment is an example of simplistic thought, tired fake-skeptic talking points and unsupported rhetoric constituting sloganeering (a violation of the Comments Policy here).

  26. As a followup to my previous comment, real scientists doing real studies have already looked into whether the Earth will warm or cool, long-term. As opposed to empty assertions, let's examine the facts, shall we:

    Per Tzedakis et al 2012,

    glacial inception would require CO2 concentrations below preindustrial levels of 280 ppmv

    For reference, we are at about 394 right now…and climbing, so we can be relatively sure the next glacial epoch won't be happening in our lifetimes.

    But what about further down the road? What happens then? Per Dr Toby Tyrrell (Tyrrell 2007) of the University of Southampton's School of Ocean and Earth Science at the National Oceanography Centre, Southampton:

    "Our research shows why atmospheric CO2 will not return to pre-industrial levels after we stop burning fossil fuels. It shows that it if we use up all known fossil fuels it doesn't matter at what rate we burn them.

    The result would be the same if we burned them at present rates or at more moderate rates; we would still get the same eventual ice-age-prevention result."


    "Burning all recoverable fossil fuels could lead to avoidance of the next five ice ages."

    So no ice ages and no Arctic sea ice recovery the next million years...

    Facts, like Tiggers, are wonderful things, for those who have them.

    Also covered by Stoat, here.

    Given the radiative imbalance at the TOA is still present and that CO2 levels are still increasing (and that human emissions are not ending anytime soon), it is reasonable to presume that the impacts of a warming planet will increasingly impact the most vulnerable aspects of our remaining cryosphere: the Arctic sea ice (a goner), the Greenland Ice Sheet and the West Antarctic Ice Sheet.

    We are, through our own actions, effectively locking-in a world of another 8-12 meters SLR above present. Unless we can magically arrest our emissions and also initiate methods to draw-down atmospheric concentrations of CO2.

  27. Kevin You might find this paper interesting, the question of the regularity of glacials is apparently not quite as straightforward.

    As to the question "Who decided that the temp after the industrial revolution was the "accurate" temperature the earth should be at, and that we are exceeding that perfect temp?", that really is a canard that has been answered here repeatedly.

    A reasonable answer to that would be "the perfect temperature of the Earth is that to which our civilisation (and especially agricultural practices) has become highly adapted".  It is the change in climate that is the principal problem, as adapting to change has costs. It seems likely that mitigation will reduce the cost of adaptation, so that would appear to be the rational strategy. It isn't rocket science.

    Do you accept that answer?

  28. A reasonable answer to that would be "the perfect temperature of the Earth is that to which our civilisation (and especially agricultural practices) has become highly adapted". 


    OK.  But then, the LIA was quite cold, and people adapted, agriculture adapted, but at cost (which is part of your point - in other direction but applicable).  During the Roman optimal, wine grapes were grown in Great Britain.  During the Medieval Warm period, grains were reported to be much more bountiful. 


    On another note, how is it that you were able to respond to my post, yet my post does not appear?

  29. the appearance issue was regarding my second post, sorry about that.

  30. "During the Roman optimal, wine grapes were grown in Great Britain"

    Prove it.  We await the links to the reputable sources.

  31. Kevin There are plenty of historical precedents for civilisations not surviving climate change (e.g. Egyptian Old Kingdom).  At the time of the LIA, global population was much lower, and agricultiral land less over-exploited, which made adaption very much easier than it is now.  There are large parts of the world that are relatively poor, where large populations exist with marginal subsistence agriculture.  Adapting for us will be much easier than it will for them.  There is also the point that the rate of change is also relevant to adaption.  Even then the LIA caused great hardship for many, the natural climate change we can do little about, but that doesn't make it O.K. to cause some more for ourselves.

    The point is that questioning whether there is a perfect temperature for the Earth is a straw man - nobody is claiming that there is one, and it isn't really relevant anyway, it is the change that is important. 

    Now if you have evidence to show that we will have no problem adapting to the projected climate change, then I am sure there is a relevant post at SkS on which to discuss it, but this isn't it.

    The post to which I responded is still there (at least I can still see it).

  32. Kevin:

    Wine production appears to have been more-or-less continuous in the UK since the Roman invasion, albeit patchily implemented at commercial scales and vulnerable to sociopolitical changes.

    As far as I am aware (courtesy of a survey of the Met Office and Environment Canada sites), the UK, and in particular southern England, has had, for some centuries, a climate that is comparable to current wine-growing regions in southern Ontario and British Columbia, despite being at a comparatively higher latitude.

    IMO the significance of Roman viticulture in the UK is overstated in the context of climate change discussions.

  33. While England had 42 vineyards at the time of the Domesday Book, as is well known, there are now over 300 commercial English vineyards today.  So the climate today in England is much more conducive to wine-making than during the Roman occupation of England, consistent with the proxy reconstructions of temperatures covering those times.

    Last 2,000 years


    Without a link to a source for that claim I must conclude that Kevin just made that claim up. Especially given that it took me all of 3 minutes to look up the material for this comment...and that Kevin has had more than 4 hours to do likewise...

  34. Also apparent from DB's graph, is that rate of temperature change (which strongly influences our ability to adapt) is much faster now than going into the LIA.  Accounts of the time suggests adapting to LIA wasnt all beer and skittles either. I'd rather avoid that kind of pain and paying more for my energy is certainly acceptable. We adapted pretty well to change in oil price to $15 to $80 and projected energy change costs not in that league.

  35. Kevin:

    1)  Figure 4 of the intermediate version of the above article shows expected future temperatures based on milankovithch cycles and CO2 concentration.  Even by eyeball it is evident that at preindustrial CO2 levels, no new glacial is imminent for thousands of years.

    2)  I will see you your "wine in England", which as Daniel points out, is a very current phenomenon, and raise you three vinyards in Scotland (one indoors), and four commercial vinyards in Sweden!   I will note that traditionally grapes were grown in England not because they produced good wine, but because wine was needed for sacramental reasons, and until recently, wines turned to vinigar if transported any distance.

  36. DB @ 280:

    "It is said that Julius Caesar brought the vine to England. Nice though that story is, some scholars think it apocryphal - wine was certainly brought to Britain by the Romans, but it is less certain whether the vine was grown here, or if it was, whether it was in sufficent quantity to satisfy the local requirement for wine or just as an ornament to remind Romans of home and wealthy Romano-Britons of the source of their civilisation and prosperity."


  37. Here is a source for wine in UK CfA Press Release
    Release No.: 03-10
    For Release: March 31, 2003 20th Century Climate Not So Hot

    Cambridge, MA - A review of more than 200 climate studies led by researchers at the Harvard-Smithsonian Center for Astrophysics has determined that the 20th century is neither the warmest century nor the century with the most extreme weather of the past 1000 years. The review also confirmed that the Medieval Warm Period of 800 to 1300 A.D. and the Little Ice Age of 1300 to 1900 A.D. were worldwide phenomena not limited to the European and North American continents. While 20th century temperatures are much higher than in the Little Ice Age period, many parts of the world show the medieval warmth to be greater than that of the 20th century.

    Smithsonian astronomers Willie Soon and Sallie Baliunas, with co-authors Craig Idso and Sherwood Idso (Center for the Study of Carbon Dioxide and Global Change) and David Legates (Center for Climatic Research, University of Delaware), compiled and examined results from more than 240 research papers published by thousands of researchers over the past four decades. Their report, covering a multitude of geophysical and biological climate indicators, provides a detailed look at climate changes that occurred in different regions around the world over the last 1000 years.

    "Many true research advances in reconstructing ancient climates have occurred over the past two decades," Soon says, "so we felt it was time to pull together a large sample of recent studies from the last 5-10 years and look for patterns of variability and change. In fact, clear patterns did emerge showing that regions worldwide experienced the highs of the Medieval Warm Period and lows of the Little Ice Age, and that 20th century temperatures are generally cooler than during the medieval warmth."

    Soon and his colleagues concluded that the 20th century is neither the warmest century over the last 1000 years, nor is it the most extreme. Their findings about the pattern of historical climate variations will help make computer climate models simulate both natural and man-made changes more accurately, and lead to better climate forecasts especially on local and regional levels. This is especially true in simulations on timescales ranging from several decades to a century.

    For more information, contact:

    David Aguilar, Director of Public Affairs
    Harvard-Smithsonian Center for Astrophysics
    Phone: 617-495-7462 Fax: 617-495-7468

    Christine Lafon
    Public Affairs Specialist
    Harvard-Smithsonian Center for Astrophysics
    Phone: 617-495-7463, Fax: 617-495-7016

    Response: [DB] Further to DM's comments below, your claim also pertained to the Roman optimal, not the Medieval Warm Period. Try again.

    [Sph] Original comment edited to correct formatting issues.
  38. Kevin, that is not proof, Bauliunas says that vinyards flourished in England, but that doesn't make it true.  Is there evidence in the paper on which the press article was based?

    BTW you do know that Energy and Environment is not a science journal, but a social sciences journal, don't you?

  39. DM, you're being generous.  Kevin might want to take a look at some of the other studies that E&E has published.  

    Kevin, you might also look at the Soon & Baliunas (2003) affair, and also what Willie Soon is capable of trying to pull over on his target audience.  What a world it would be if fake skeptics gave the same level of scrutiny to those they pedestalize as they do to the studies that do not support their worldviews.  

  40. source for grain abundance is
    Response: [DB] Non sequitur. The Domesday reference does not cover the period in question nor is there any references to wine or vineyards in the linked article. Try again.
  41. As far as I can see, that source provides no real evidence (references to primary sources?) and provides only rather equivocal support for your assertion, e.g.:

    "More people meant smaller acreage of land per person and this led to "harvest sensitivity." In years of poor harvests (such as the wet summers of 1315-1316) insufficient grain was grown and the poor starved."

    "English agricultural methods and productivity remained stagnant throughout the Middle Ages. The "strip" system of farming was equitable and extremely inefficient. Yields of grain per acre remained stagnant."

    "Food production was only increased by bringing more land under the plow - a process that stopped once all available waste land had been improved."

    Also the graph of population (reproduced below) suggests that a fair proportion of the population didn't adapt to the LIA (except perhaps by dying).

    Regarding grain abundance, your source emphasises a point I was making: "More people meant smaller acreage of land per person and this led to "harvest sensitivity." In years of poor harvests (such as the wet summers of 1315-1316) insufficient grain was grown and the poor starved." That sitation is far worse now in a world with 9 billion mouths to feed.  As far as I can see you have provided very little evidence to suggest that the past suggests we can adapt to future climate change without substantial hardship.

    Response: [DB] Nor does it cover his claimed time period of the Roman optimal.
  42. Here is one for the Roman Optimal

    The last source was for the Medieval Period, for grain.


    [DB] It is noted that your referenced source does not support your earlier contention. Therefore, the conclusions reached in this comment apply and you tacitly agree to its conclusion:

    "So the climate today in England is much more conducive to wine-making than during the Roman occupation of England, consistent with the proxy reconstructions of temperatures covering those times."

    By agreeing, you concede you earlier comment was in error and therefore invalid. If you disagree, you will need to then further support it here before being allowed to comment elsewhere on this site.

  43. If I can end the game between Kevin and the Moderators, this is evidence of viticulture in Roman Britain:

    "This article presents stratigraphic and palynological data from Wollaston in the Nene Valley, England, which provides conclusive evidence of viticulture on an large scale. The spread of Viticulture through the Roman World and the extent to which it supplanted beer brewing can be seen as an essential element in the consideration of the Romanization of northwest Europe. The pollen assemblage suggests hoeing or ploughing was used, presumably to reduce grass and weed growth around the vines. The distribution of known and probable sites and of suitable pruning tools has a distinct southeastern bias, as might be expected from the spatial variation of climate in the British Isles."

    (My emphasis)

    So also does this article about the same site, but note that while "...the apparent lack of viticultural tools and wine presses in the archaeological record in Britain is not reliable evidence for the absence of viticulture at that time", it must be considered evidence that viticulture was not widespread.

    Regardless, as I have noted on other occassions, the presence or absence of vinyards is a poor proxy of climate as human and economic factors play too large a role.  Is the decline (but not absence) of viticulture in Anglo-saxon Britain and indication of cooler climates, or just an indication that the Anglo-saxons has a taste for ale in preference to wine?  Does the post norman decline in viticulture in England reprsent a decline in climate or the fact that improvements in wine manufacture and transport made French wine cheaper in Britain?

    More importantly, if you are going to use viticulture as a proxy for climate in the past, then you must be consistent and do so in the present.  So, if viticulture in England in Roman and Norman times is evidence of warm climates at that time, then viticulture in Scotland and Sweden now must be considered evidence that it is warmer now than in Roman or Norman times.  The extent to which deniers cherry pick data rather than following evidence is shown by their refusal to follow the clear logic of this argument.

  44. Dikran Marsupial @291, the very sharp decline in population in the 14th century has almost nothing to do with climate, and everything to do with the Bubonic Plague.  Much of the increase before that had little to do with climate, and much to do with the adoption of the horse collar in Europe.

  45. Kevin pretty much scored an own goal here.

  46. Tom, yes you are absolutely right about the cause of the decline in European populations, doh!  The info on English wine growing was also very interesting, ISTR there is something about it in the book on the British Climate compiled a few years ago, I think in honour of Hubert Lamb, but it is back in the library now, so I can't check. I hope Kevin learns from this exercise that perhaps his information on the topic of climate isn't perhaps all it could be, and will moderate the attitude in his posts somewhat.  We are all happy to discuss science here, but generally those who arrive with a bit of an attitude tend to provoke a correspondingly confrontational response.



    Try this source for Roman Optimal Wine production n UK.

  48. Kevin, thanks for the link, it is a shame that the article is paywalled - it looks interesting (see also Toms comment).  Please do take on board my comments in the previous post.  We are happy to discuss science here, but you will get a much better reception if you make your points in a measured scientific, rather than a confrontational hubristic manner, especially as your previous comments suggest a lack of understanding of some important issues

  49. There is a free-access, text-only version of that paper available here

  50. Cheers Andy, very interesting, the differing standards of acceptable evidence in archaeology and climatology is very evident (of course this is inevitable and not an indication of a problem with archaeology)!

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