Climate Science Glossary

Term Lookup

Enter a term in the search box to find its definition.

Settings

Use the controls in the far right panel to increase or decrease the number of terms automatically displayed (or to completely turn that feature off).

Term Lookup

Settings


All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

Home Arguments Software Resources Comments The Consensus Project Translations About Donate

Twitter Facebook YouTube Pinterest

RSS Posts RSS Comments Email Subscribe


Climate's changed before
It's the sun
It's not bad
There is no consensus
It's cooling
Models are unreliable
Temp record is unreliable
Animals and plants can adapt
It hasn't warmed since 1998
Antarctica is gaining ice
View All Arguments...



Username
Password
Keep me logged in
New? Register here
Forgot your password?

Latest Posts

Archives

Can animals and plants adapt to global warming?

What the science says...

A large number of ancient mass extinction events have been strongly linked to global climate change. Because current climate change is so rapid, the way species typically adapt (eg - migration) is, in most cases, simply not be possible. Global change is simply too pervasive and occurring too rapidly.

Climate Myth...

Animals and plants can adapt
[C]orals, trees, birds, mammals, and butterflies are adapting well to the routine reality of changing climate." (source: Hudson Institute)

Humans are transforming the global environment. Great swathes of temperate forest in Europe, Asia and North America have been cleared over the past few centuries for agriculture, timber and urban development. Tropical forests are now on the front line. Human-assisted species invasions of pests, competitors and predators are rising exponentially, and over-exploitation of fisheries, and forest animals for bush meat, to the point of collapse, continues to be the rule rather than the exception.

Driving this has been a six-fold expansion of the human population since 1800 and a 50-fold increase in the size of the global economy. The great modern human enterprise was built on exploitation of the natural environment. Today, up to 83% of the Earth’s land area is under direct human influence and we entirely dominate 36% of the bioproductive surface. Up to half the world’s freshwater runoff is now captured for human use. More nitrogen is now converted into reactive forms by industry than all by all the planet’s natural processes and our industrial and agricultural processes are causing a continual build-up of long-lived greenhouse gases to levels unprecedented in at least the last 800,000 years and possibly much longer.

Clearly, this planet-wide domination by human society will have implications for biological diversity. Indeed, a recent review on the topic, the 2005 Millennium Ecosystem Assessment report (an environmental report of similar scale to the Intergovernmental Panel on Climate Change Assessment Reports), drew some bleak conclusions – 60% of the world’s ecosystems are now degraded and the extinction rate is now 100 to 1000 times higher than the “background” rate of long spans of geological time. For instance, a study I conducted in 2003 showed that up to 42% of species in the Southeast Asian region could be consigned to extinction by the year 2100 due to deforestation and habitat fragmentation alone.


Figure 1: Southeast Asian extinctions projected due to habitat loss (source: Sodhi, N. S., Koh, L. P., Brook, B. W. & Ng, P. K. L. 2004)

Given these existing pressures and upheavals, it is a reasonable question to ask whether global warming will make any further meaningful contribution to this mess. Some, such as the sceptics S. Fred Singer and Dennis Avery, see no danger at all, maintaining that a warmer planet will be beneficial for mankind and other species on the planet and that “corals, trees, birds, mammals, and butterflies are adapting well to the routine reality of changing climate”. Also, although climate change is a concern for conservation biologists, it is not the focus for most researchers (at present), largely I think because of the severity and immediacy of the damage caused by other threats.

Global warming to date has certainly affected species’ geographical distributional ranges and the timing of breeding, migration, flowering, and so on. But extrapolating these observed impacts to predictions of future extinction risk is challenging. The most well known study to date, by a team from the UK, estimated that 18 and 35% of plant and animal species will be committed to extinction by 2050 due to climate change. This study, which used a simple approach of estimating changes in species geographical ranges after fitting to current bioclimatic conditions, caused a flurry of debate. Some argued that it was overly optimistic or too uncertain because it left out most ecological detail, while others said it was possibly overly pessimistic, based on what we know from species responses and apparent resilience to previous climate change in the fossil record – see below.

A large number of ancient mass extinction events have indeed been strongly linked to global climate change, including the most sweeping die-off that ended the Palaeozoic Era, 250 million years ago and the somewhat less cataclysmic, but still damaging, Palaeocene–Eocene Thermal Maximum, 55 million years ago. Yet in the more recent past, during the Quaternary glacial cycles spanning the last million years, there were apparently few climate-related extinctions. This curious paradox of few ice age extinctions even has a name – it is called ‘the Quaternary Conundrum’.

Over that time, the globally averaged temperature difference between the depth of an ice age and a warm interglacial period was 4 to 6°C – comparable to that predicted for the coming century due to anthropogenic global warming under the fossil-fuel-intensive, business-as-usual scenario. Most species appear to have persisted across these multiple glacial–interglacial cycles. This can be inferred from the fossil record, and from genetic evidence in modern species. In Europe and North America, populations shifted ranges southwards as the great northern hemisphere ice sheets advanced, and reinvaded northern realms when the glaciers retreated. Some species may have also persisted in locally favourable regions that were otherwise isolated within the tundra and ice-strewn landscapes. In Australia, a recently discovered cave site has shown that large-bodied mammals (‘megafauna’) were able to persist even in the arid landscape of the Nullarbor in conditions similar to now.

However, although the geological record is essential for understanding how species respond to natural climate change, there are a number of reasons why future impacts on biodiversity will be particularly severe:

A) Human-induced warming is already rapid and is expected to further accelerate. The IPCC storyline scenarios such as A1FI and A2 imply a rate of warming of 0.2 to 0.6°C per decade. By comparison, the average change from 15 to 7 thousand years ago was ~0.005°C per decade, although this was occasionally punctuated by short-lived (and possibly regional-scale) abrupt climatic jolts, such as the Younger Dryas, Dansgaard-Oeschger and Heinrich events.

B) A low-range optimistic estimate of 2°C of 21st century warming will shift the Earth’s global mean surface temperature into conditions which have not existed since the middle Pliocene, 3 million years ago. More than 4°C of atmospheric heating will take the planet’s climate back, within a century, to the largely ice-free world that existed prior to about 35 million years ago. The average ‘species’ lifetime’ is only 1 to 3 million years. So it is quite possible that in the comparative geological instant of a century, planetary conditions will be transformed to a state unlike anything that most of the world’s modern species have encountered.

C) As noted above, it is critical to understand that ecosystems in the 21st century start from an already massively ‘shifted baseline’ and so have lost resilience. Most habitats are already degraded and their populations depleted, to a lesser or greater extent, by past human activities. For millennia our impacts have been localised although often severe, but during the last few centuries we have unleashed physical and biological transformations on a global scale. In this context, synergies (positive or self-reinforcing feedbacks) from global warming, ocean acidification, habitat loss, habitat fragmentation, invasive species, chemical pollution (Figure 2) are likely lead to cascading extinctions. For instance, over-harvest, habitat loss and changed fire regimes will likely enhance the direct impacts of climate change and make it difficult for species to move to undamaged areas or to maintain a ‘buffer’ population size. One threat reinforces the other, or multiple impacts play off on each other, which makes the overall impact far greater than if each individual threats occurred in isolation (Brook et al 2008).


Figure 2: Figure from the Millennium Ecosystem Assessment

D) Past adaptation to climate change by species was mainly through shifting their geographic range to higher or lower latitudes (depending on whether the climate was warming or cooling), or up and down mountain slopes. There were also evolutionary responses – individuals that were most tolerant to new conditions survived and so made future generations more intrinsically resilient. Now, because of points A to C described above, this type of adaptation will, in most cases, simply not be possible or will be inadequate to cope. Global change is simply too pervasive and occurring too rapidly. Time’s up and there is nowhere for species to run or hide.

Last updated on 22 December 2011 by Daniel Bailey. View Archives

Printable Version  |  Offline PDF Version  |  Link to this page

Further reading

Acknowledgements

This is a guest post by Professor Barry Brook, an international research leader in global ecology and conservation biology. He holds the Foundation Sir Hubert Wilkins Chair of Climate Change and is Director of the Research Institute for Climate Change and Sustainability at the University of Adelaide. He has published two books and over 120 scientific papers on various aspects of human impacts on the natural environment and biodiversity, including climate change, deforestation and overexploitation of populations. In 2006, he was awarded both the Australian Academy of Science Fenner Medal for distinguished research in biology and the Edgeworth David Medal by the Royal Society of New South Wales, and in 2007, the H.G. Andrewartha Medal by the Royal Society of South Australia and was listed by Cosmos as one of Australia's top 10 young scientists. The principal motivation for his research is to identify ways and means of reducing extinctions and mitigating the worst ravages of global change. Read more at Brave New Climate.

Comments

Comments 1 to 33:

  1. Good article. The only fault I see is "The IPCC storyline scenarios such as A1FI and A2 imply a rate of warming of 0.2 to 0.6°C per decade." which just has not happened but it does not change the message or impact of the article. Kudos to Professor Barry Brook.
  2. England: Little egrets have been observed nesting
    (previously seen but in winter migrated to southern Europe/Africa) and in 2008 cattle egrets ( from Africa) have also been filmed, although not nesting.
    In S.England green lizards and brown rock lizards, both mediterranean species are now resident.
    An illustration of species movement as conditions allow.
    ( and in the case of the lizards, ably assisted by transcontinental traffic)
  3. I would like to invite readers to my blog witsendnj dot blogspot dot com and especially the early post, Effects of Climate Change, where I give an overview of my concerns. I see very prominent and deleterious effects on vegetation around my home in NJ and I would be very interested to learn of other observers who would be willing to compare notes.

    Why is this important? Because many of the prominent and influential policy makers live on the Eastern Seaboard and maybe if they become enlightened enough to recognize the collapse of the ecosystem around their own homes, they might finally realize how urgent it is to eliminate carbon emissions.

    Thank you!
  4. When there is a end, there is always (mostly) a new beginning.
  5. #4. New beginnings? Just look at much of the Middle East. Large areas were once fertile crop producing lands supporting substantial populations in cities. Now the deserts, mostly caused by abandoning age-old water management practices, barely support an assortment of goats and lizards. Not a fruit tree or a grain crop in sight. There are similar places elsewhere in the world. Once lost, always lost.

    As for evolution taking care of the problem. Evolution for changed climate consitions takes many generations - maybe centuries, maybe millennia, maybe millions of years. The big difference for substantial impact on species this time round is the lack of places to go. Even where human population is sparse, the lands in question are surrounded by urban or agricultural developments inimical to the free movement and re-establishment of existing or changing species.

    Change *is* natural - when it occurs on natural time-scales. This time we're changing things in the space of a few human generations rather than a few thousand or million years.
  6. Good news,Adelady.
    Snippet from National Geographic:-

    "Desertification, drought, and despair—that's what global warming has in store for much of Africa. Or so we hear.
    Emerging evidence is painting a very different scenario, one in which rising temperatures could benefit millions of Africans in the driest parts of the continent.
    * Ancient Cemetery Found; Brings "Green Sahara" to Life
    * Exodus From Drying Sahara Gave Rise to Pharaohs, Study Says
    Scientists are now seeing signals that the Sahara desert and surrounding regions are greening due to increasing rainfall.
    If sustained, these rains could revitalize drought-ravaged regions, reclaiming them for farming communities.
    This desert-shrinking trend is supported by climate models, which predict a return to conditions that turned the Sahara into a lush savanna some 12,000 years ago"

    More info available at Nat Geographical website. Use their search button and key in"Satellite greening".
    Acacias spreading and thriving in Sudan. Nomads in Western Sahara say "We've never had it so good."

    As for rapidity of evolution. Check out Howard Bloom's website and in the black column on the left, click on"Instant Evolution:the effect of the city on human genes"
    He cites some thought - provoking examples of rapid evolution.
  7. Africans will move to the Sahara? Problem solved? Rather than rely on some quotes from National Geographic Kids, better to delve into the literature and get the big picture, as usual.

    Here's a continental-scale review for Africa, a little long in the tooth but a good starting point:

    African climate change: 1900–2100

    Continental-scale scenario for surface water:

    Changes in Surface Water Supply Across Africa with Predicted Climate Change

    Meanwhile, it's best to take changes on the timescale mentioned in National Geographic w/a grain of salt because of course there's always natural variability in play:

    The impact of decadal-scale Indian Ocean sea surface temperature anomalies on Sahelian rainfall and the North Atlantic Oscillation
  8. Replying to Doug Bostrom,
    Like most folks I generally accepted that a battle against the encroaching sands was being lost, so the evidence of a reversal, especially in a magazine(kiddies?) as pro-AGW as Nat Geographic, came as a surprise.
    I am familiar with the PROJECTIONS and PREDICTIONS, and very plausible they sounded too.
    HOWEVER.....this report as to what is ACTUALLY happening on the ground, is at odds with that which was predicted.
    What would be a reasonable attitude towards people that make predictions, in your opinion, that don't come to pass?
  9. @AWoL: it is common practice here to provide links to your sources. Do you have the link handy, so we can evaluate how accurate the NatGeo Kids article really is?
  10. A reasonable thing to do would be to read articles by researchers rather than a massively compressed synopsis in a kid's magazine, AWoL.

    It's worth noting that climate models have a tough time w/predicting precipitation in N. Africa. If you read the literature, you'd know that. You'd also have some idea of the ease with which decadal natural variation can slew precipitation in the region of the Sahara.

    By the way, are you having some sort of trouble with your caps-lock key?
  11. Sorry ASteel, haven't provided a direct link but if you refer to my earlier post on this subject I do give instructions as to how to reach it. Just checked it.Up and running.Don't go to the kids section for it ain't there.
    Yes it is probably massively compressed, but by a climate researcher who has been working in the region for 20yrs.....which was why I brought the matter to the attention of this forum.
    Google National Geographic, type "satellite greening" in the search box, then select title with "Sahara" in it.
  12. AWoL - Here's the link to the Sahara Desert Greening Due to Climate Change article in National Geographic.

    The article appears to be based on Hickler et al 2005, "Precipitation controls Sahel greening trend". The article also (indirectly) points to Haarsma et al 2005, "Sahel rainfall variability and response to greenhouse warming" indicating increased Sahara rainfall of 1-2mm/day.
  13. @AWoL: I think Doug said it best. Climate models do disagree on N. Africa, and the article acknowledges this:

    "Even so, climate scientists don't agree on how future climate change will affect the Sahel: Some studies simulate a decrease in rainfall.

    "This issue is still rather uncertain," Haarsma said.

    Max Planck's Claussen said North Africa is the area of greatest disagreement among climate change modelers.

    Forecasting how global warming will affect the region is complicated by its vast size and the unpredictable influence of high-altitude winds that disperse monsoon rains, Claussen added.

    "Half the models follow a wetter trend, and half a drier trend."


    Whether it is increased desertification or a greening of some of its regions due to increased hydrological activity, however, it's hard no to see the effects of AGW at work.

    Obviously, the best outcome would be sustained greening, as this would introduce a vast new carbon sink, however it's unwise to count on this happening.

    Here is the direct link, if anyone is interested.
  14. Replying to ASteel
    Yes I take your points.
    Nevertheless that which has taken place,whilst not condemning outright AGW and its proponents, is however at odds with mass media output.
    ie we haven't had any glowing reports of this (benign) change in the Sahel.
    When brought to the attention of Joe Public, invariably his first utterance is "Why haven't we heard of this?"(because he still depends for the most part, but increasingly suspiciously, on the mass media for his information)
    I think you may have problems like this in the future. Time is wearing on, after all.Time was always a bit of a problem for soothsayers and fortune-tellers.
  15. AWOL I'm absolutely certain that there's some good news for some species aroung the place. I notice some of the things you refer to involve plants and animals moving to more congenial circumstances.

    Your example of an "exodus" leading to a good outcome is great for a historical example. But there are 2 problems for me there. One, such movements are now highly constrained by the hugs human population, and the effects of habitation and agriculture on grasslands and forests.

    Two, where I live the only way for existing animals to move is south - not many plants and animals will migrate inland to even more inhospitable conditions. Unfortunately, there's not a lot of south to move to. Unless someone's come up with a few generations evolution schema for land animals to imitate seals and penguins.
  16. I wonder how any of our European readers feel about being so near the tip of the spear:

    From MacKenzie and Schiedek 2007:
    ... trends in surface temperatures in the North and Baltic Seas now exceed those at any time since instrumented measurements began in 1861 and 1880. Temperatures in summer since 1985 have increased at nearly triple the global warming rate which is expected to occur during the 21st century and summer temperatures have risen 2-5 times faster than those in other seasons. These warm temperatures and rates of change are due partly to an increase in the frequency of extremely warm years. The recent warming event is exceeding the ability of local species to adapt and is consequently leading to major changes in the structure, function and services of these ecosystems. [emphasis added]

    From Devictor et al. 2008:
    ... a 91 km northward shift in bird community composition, which is much higher than previous estimates based on changes in species range edges. During the same period, temperature increase corresponds to a 273 km northward shift in temperature. Change in community composition was thus insufficient to keep up with temperature increase: birds are lagging approximately 182 km behind climate warming.
  17. AWoL, situations such as you have illustrated in the Sahara will (have?) allow the more astute observers to bring together the rapidly accumulating knowledge of drought tolerant plant species suitable for agricultural exploitation, and the cyclic changes as they occur in various locations.
    Establishing deep rooted perennials that can tap into water reserves well below the surface, that also bring essential nutrients to the surface, will help re-establish ground cover leading to a rebuilding of the top soil and then to the expansion of the cropping or grazing into new areas.

    One of the limiting factors to plant growth in arid areas is the cold night temperatures, but with increased rain comes increased cloud cover that should see some improvement there.

    Much may be happening now, there are many enterprising advances happening that fly below the radar with research often trailing practice by a considerable margin due to the tendency to think laterally by those who have to contend in practice with the vagaries of nature and take whatever opportunities as they present themselves, even if it has not been peer reviewed.
  18. @AWoL: I'm sorry, I have a hard time understanding your point. The fact that AGW is apparently causing some greening of the Sahara desert due to increased rainfall is *not* an argument against AGW theory. I'm also unaware that the Sahara is often cited in Mass Media stories about AGW.

    Furthermore, this is another piece of evidence showing that AGW is real. I don't see how this could "cause problems" for AGW proponents. To the contrary, it goes to show that we are, in fact, having a serious impact on our environment through CO2 emmissions.

    I also don't get your comment about soothsayers and fortune-tellers. I suggest you stick to the science and not try to divine how public opinion will react to an observed greening of the Sahel.
  19. "Nevertheless that which has taken place,whilst not condemning outright AGW and its proponents, is however at odds with mass media output."

    As others have pointed out in different ways, Sahel greening will never "condemn" AGW outright or implicitly. You need to work on larger processes if you want to try to find evidence against a warming planet. If you want to be taken seriously, point to single instances, but do so by looking at the single instances within the context of the whole.

    "ie we haven't had any glowing reports of this (benign) change in the Sahel. When brought to the attention of Joe Public, invariably his first utterance is "Why haven't we heard of this?"(because he still depends for the most part, but increasingly suspiciously, on the mass media for his information)"

    Invariably? Where is your evidence for this response? And if you think mass media news is in collusion with climate science, you aren't paying attention.

    "I think you may have problems like this in the future. Time is wearing on, after all. Time was always a bit of a problem for soothsayers and fortune-tellers."

    Ahhh, the old "modeling a complex system is impossible" game. You do note that you're playing the game, too, yes? You make the implicit claim that the planet is not warming--and certainly not because of humans--because the Sahel is greening. And yet you make this claim without any sort of evidence. Soothsaying indeed!

    Don't be so provincial. The Sahel may be greening, but the oceans are dying and pine mountain beetles are munching my bloody pine trees.
  20. I think one of the points being made by the article goes back in part to what was quoted by archiesteel at 06:35 AM, that being
    "Half the models follow a wetter trend, and half a drier trend."

    Whilst some may feel that this greening is not causing problems for AGW, however it certainly must be causing some problems for some of the modelers.

    If anyone now accepts that the trend of increasing rainfall validates those half of all models that are predicting a wetter trend, then they must also be accepting that it also invalidates those other half of the models predicting a drier trend which obviously have been built around some rather incorrect assumptions.
    If those assumptions are now being found to be incorrect, which one must now be willing to accept in this particular case, then wherever the same assumptions have been inputted into other modeling makes those outcomes produced perhaps somewhat similarly suspect also.
  21. @johnd: in order to invalidate *any* model, we'll need to have sustained greening over a significant area of the desert. It's a bit early to start calling out specific models.

    Your last paragraph is simply an attempt to invalidate climate models in general by introducing a bit of FUD about their precision. However, as the article clearly spells out, it is *North Africa* that is difficult to model. Models tend to agree a lot more about other regions, and there's no reason to believe that the models that eventually get it wrong on North African impact are any less accurate in the rest of their predictions.

    It seems to me you're fishing for a pretty convoluted argument, here.
  22. The article starts quite factual with stating that biodiversity is under constant thread from direct human interference, Most prominently by destroying (slowly but surely) land for industrial use (food industry) with the latest addition of biological fuels as well as destroying the oceans by depleting them of marine live and using them as trash bins at the same time.

    In my opinion that needs to be stopped and as far as possible reversed. Reducing CO2 emissions (unless they stem from deforestation) will not help a bit.

    Besides, if I am not mistaken it is still the tropical rain forests that boast the richest biodiversity which happen to occur where this world counts the highest temperatures. Therefore I completely fail to see how rising temperatures may cause general losses in biodiversity.
  23. h-j-m wrote: "Reducing CO2 emissions (unless they stem from deforestation) will not help a bit."

    CO2 emissions are causing global warming, which is causing habit loss for species all over the planet. Thus, reducing CO2 emissions definitely would help, and more than 'a bit'.

    Also: "Therefore I completely fail to see how rising temperatures may cause general losses in biodiversity."

    Which is happening faster, climate change or the evolution of new species?

    That is, unless you think that evolution happens over the course of a few decades, it should be entirely obvious that 'warmer = more biodiversity' is an invalid assumption. Species which cannot adapt to the warmer conditions will become extinct and new species will not evolve at the same rate... ergo declining biodiversity.
  24. CBDunkerson, if you can tell me how reducing CO2 emissions can help reforesting the destroyed rainforests all over the world and help to regain the lost top soils (destroyed due to monoculture farming) and regain the lost wildlife habitats destroyed in the process I would like to believe you.
  25. h-j-m, setting aside the primary point that CO2 emissions ALSO causes loss of biodiversity and thus is every bit as worth addressing on that front as the other problems you list... there are also several studies showing that rising CO2 levels may further threaten the rainforests by increasing evaporation and decreasing precipitation in the region. Thus, addressing CO2 emissions can also help prevent further rainforest loss. That would also cause rainforest recovery, but only if the land were allowed to revert.
  26. CBDunkerson, I just wanted to point out that at the current time loss of biodiversity is due to direct human intervention by far outranking that what can be attributed to global warming. Chances that tropical rainforests are threatened by it are rather slim as studies show that in the tropics forestation is the main factor governing local weather patterns(i. e. they show that deforestation leads to major changes in weather patterns). Some small scale endeavours on the other hand show that rainforest farming (using the biological productivity of rainforests to support the local population) is a viable and sustainable alternative - capable not only to fight poverty but even to allow for modest prosperity -, but they are not getting a chance due to the profits that biological fuels are promising. So far I can only see that in result the global warming theory has led to nothing but an increasing pace of destroying the ability of this globe to support human life.
  27. h-j-m,

    A problem is not rendered inconsequential if an implementation of a proposed (partial) solution may cause more harm in a given area than it aleviates. Arguing against biofuel farming practices is in no way a valid argument against the effects of global warming.
  28. Hydrogen sulfide is thought to have been a major player in the Permian mass extinction 250 million years ago, because CO2 emissions from the Siberian Traps warmed the atmosphere and oceans, causing the oceans to lose oxygen. With less oxygen, the anaerobic bacteria produce hydrogen sulfide that spreads through the ocean and into the atmosphere and poisons most of the animals on the planet. When we hear about the potentially dire consequences of global warming, why don't we ever hear about hydrogen sulfide emissions from the warming oceans as a result of decreasing oxygen?
  29. The link to "a study I conducted in 2003" doesn't work (http://www.skepticalscience.com/docs/Brook_2003_Extinctions.pdf).

    It may be this one?:
    http://www.dbs.nus.edu.sg/lab/cons-lab/documents/Brook_etal_Nature_2003.pdf
  30. Another link that doesn't work is in "it left out most ecological detail" (http://www.mncn.csic.es/pdf_web/maraujo/Thuiller_et_al_2004Nature.pdf).

    It may be this one:
    http://stephenschneider.stanford.edu/Publications/PDF_Papers/ThuillerEtAl2004.pdf
  31. Continuing from here.

    "the 10k bp mark"

    From Wikipedia:

    Identifying the exact origin of agriculture remains problematic...

    ... grains of rye with domestic traits have been recovered from Epi-Palaeolithic (10,000+ BC) contexts at Abu Hureyra in Syria, but this appears to be a localised phenomenon resulting from cultivation of stands of wild rye, rather than a definitive step towards domestication.

    ... By 7000 BC, sowing and harvesting reached Mesopotamia, and there, in the fertile soil just north of the Persian Gulf, Sumerians systematized it and scaled it up. By 8000 BC farming was entrenched on the banks of the Nile River.


    So, yes, the last glacial retreat was a good thing for the development of agriculture. But your contention that this development took place during a time of rapidly rising temperatures and sea levels is not well supported -- and really makes no difference.

    However, there is a clear difference in conditions described by Bettinger et al 2009:


    Ice age climates varied at very short timescales (Richerson, Boyd, and Bettinger 2001). Ice core data show that last glacial climate was highly variable on timescales of centuries to millenia ...

    In comparison, the Holocene after 11,600 BP has been a period of comparatively very stable climate.


    So it appears to have been stability that gave birth to civilization. What we have provoked is rapid change and instability: deeper droughts, worse flooding, wilder extremes from winter to summer.

    Anecdotally, from a recent trip west: it is clear that the only people who will get a crop this year are those who can afford to buy lots of water. Poor farmers have abandoned their fields; buildings and other infrastructure are in decay. Everywhere you go, creekbeds and streams are dry and people are saying 'it's never been this bad.'

  32. What may be of conversely great concern to this topic is plants and animals that adapt exceptionally well but are pests - most insects, rodents, and weeds will and are adapting to warming trends exceptionally well, in some cases becoming invasive species on entire continents due to the change of climate allowing new habitation.

    In the same light, the change in climate is putting pressure on "friendly" and "neutral" species, as well as a strong increase is invasive and pest species, which does not bode well for our species even in the short term. It certainly doesn't bode well in terms of comfort - longer term, it won't sit well for meeting the basic needs of all of society as species relied upon for necessities are pushed out by species regarded as pests.
  33. The link to Univ of Texas climate change impact article (marked by the text "timing of breeding, migration, flowering, and so on") is broken. It looks like they've moved the article. I think the link was to this article http://web5.cns.utexas.edu/news/2004/11/global-warming-2/

Post a Comment

Political, off-topic or ad hominem comments will be deleted. Comments Policy...

You need to be logged in to post a comment. Login via the left margin or if you're new, register here.

Link to this page



The Consensus Project Website

TEXTBOOK

THE ESCALATOR

(free to republish)

THE DEBUNKING HANDBOOK

BOOK NOW AVAILABLE

The Scientific Guide to
Global Warming Skepticism

Smartphone Apps

iPhone
Android
Nokia

© Copyright 2014 John Cook
Home | Links | Translations | About Us | Contact Us