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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.

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Can animals and plants adapt to global warming?

What the science says...

Select a level... Basic Intermediate Advanced

Human-caused climate change is occurring too rapidly for species to be able to adapt. Plants and animals are currently dying off at a rate that is 100 to 1000 times faster than the average rate of extinction over geological timescales. Because of this, there is mounting evidence that we are heading towards a mass extinction event.

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)

The five biggest mass extinction events in Earth’s history, and most of the smaller extinction events, were driven by rapid climatic change. When climate changes too fast for species to be able to adapt, extinctions are bound to occur. Figure 1 shows prior extinction events and atmospheric CO2 concentration over the last 420 million years. Each colored circle denotes an extinction event, with the “Big Five” mass extinctions in red (end-Ordovician, which occurred 444 million years ago, is not shown) and lesser extinction events in pink.

Most extinctions have been linked to immense volcanic events, called Large Igneous Province (LIP) eruptions. These events spew billions of metric tonnes of carbon dioxide (CO2) and sulfur dioxide (SO2) into the atmosphere, in many cases triggering marine anoxia (oxygen loss) and ocean acidification due to rapid greenhouse warming. Of the Big Five mass extinctions, the one exception is the end-Cretaceous event. The current scientific consensus is that the end-Cretaceous mass extinction (that wiped out the dinosaurs 66 million years ago) was primarily caused by a large meteor strike (and a resulting, jarring change in climate). In Figure 1, the past three events (end-Permian, end-Triassic, and end-Cretaceous) are positioned at their respective, estimated short-term CO2 spike levels. These CO2 spikes which triggered their respective mass extinctions are not captured in the grey CO2 concentration curve due to its coarser temporal resolution. 

Extinction Events and Background CO2

The largest of the mass extinctions, the Permian Mass Extinction (also known as the “Great Dying), resulted in the loss of nearly 80% of all species at the end of the Permian Era 252 million years ago. During this event, which was triggered by an LIP eruption in modern-day Siberia, global temperatures warmed by nearly 10 °C and the world’s oceans lost up to 80% of their oxygen content. This eruption, which waxed and waned over about 2 million years, is estimated to have released as much as 106,000 gigatonnes (Gt) of carbon into the atmosphere. Even at the peak of carbon emissions from the Siberian eruptions (about 0.7 GtC per year), the LIP was emitting 14 times less than our current rate of emissions (9.9 GtC per year). This current trend is not expected to change. Worrisomely, current projections show that global emissions are only going to increase in the near future. 

One myth argues that this change is fine, because animals and plants have adapted to shifts in CO2 concentration or temperature of similar magnitude. For example, dinosaurs thrived when CO2 levels were much higher than today in an ice-free world with high sea levels. It's not the level of CO2 levels that's harmful, or even slow shifts in climate that unfold gradually over millions of years. It's when CO2, and consequently climate, shift so abruptly that life is unable to adapt fast enough. In the end-Permian Mass Extinction CO2 levels jumped from around 500-800 ppm before the extinction, rising to around 4,400 ppm over 40,00 years or so.

When contrarians argue that species will be able to adapt to current climate change because they have adapted to “routine” climate changes in the past, they are committing the fallacy of false equivalence. We cannot compare how species adapted to gradual climate shifts (like ice age cycles) to how they will adapt to future, human-caused change because they take place over different timescales. Comparing rapid, human-caused climate change to the slow, natural climate change of the past is like comparing apples to oranges.

Most large, natural shifts in CO2 concentration have occurred over tens to hundreds of thousands of years or longer. For example, the periods between ice ages and warm periods occur over about 10,000 years (Figure 2), with a total warming of up to 6°C in each cycle. Comparatively, state-of-the-art climate models predict that global mean temperatures will warm by 2-6 °C in the next 100 years due to anthropogenic climate change. This current rate of warming would be 20-60 times faster than the natural warming rate after ice ages. Today’s shifts in CO2 concentration and global mean temperature due to human emissions are occurring too fast for plants and animals to be able to adapt. To use an analogy: most species may have been able to float through the shallow waves of natural climate variation, but they are not ready for the tsunami of rapid climate change to come. 

CO2 concentration over the last 800000 years.

Future climate change aside, the natural world has already been under attack for centuries. Since the discovery of agriculture, humans have massively transformed the globe through the expansion of modern civilization, to the detriment of Earth’s biodiversity. More recently, this transformation was kicked into high gear with the Industrial Revolution of the late 1800s. 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 in South America and Africa are now on the front line. Human-assisted species invasions of pests, competitors, and predators are rising exponentially, and overexploitation of fisheries and forest animals for meat have already driven many species to the point of collapse.

The ways plants and animals adapt to changes in their environment have also been severely hampered. In order for many species to migrate large distances – one of the main ways animals adapt to climatic shifts – they would have to cross large areas of human influence. Mass migration in areas of large human population – entwined with crisscrossing, high-speed highways and polluted, dammed-up rivers – is a challenging task. Along with this, it has been shown that climate change has already had an impact on the environmental cues that animals use to determine the timing and navigation of their migratory patterns. Subsequently, these changes in animal migratory behavior have also been shown to have a detrimental effect on the animal’s average lifespan and overall health.

There is much evidence that we are already on the brink of a sixth mass extinction event. Because of human activity, the number of species on the planet is already decreasing. According to the Millennium Ecosystem Assessment (an international environmental report with the goal of assessing the impact of ecosystem change on human well-being), 60% of the world’s ecosystems are now degraded and the global rate of extinction is already at 100 to 1000 times that of the “normal” background rate on geological timescales. Because mass extinction events take place over a long time period compared to human life spans, this evidence alone is not enough to definitely conclude the occurrence of such an event. However, we can say with certainty that rapid, anthropogenic climate change will only make things worse for Earth’s biodiversity.

If we fail to prevent catastrophic climate change, there will be many regions of the world (some of which are highly populated) which will become uninhabitable to even us humans. This is based on human physiology and future temperature and humidity predictions under climate change. When temperature and humidity levels are too high – indicated by something scientists call a high “wet bulb temperature” – the human body is not able to cool itself by sweating. Extended periods of these high wet bulb temperatures increase the rate of heat stroke and death in humans. Here in the U.S., large areas of the Mississippi Valley, the South, and Arizona could have almost a month’s worth or more of these dangerously hot and humid days by the year 2050 (Figure 3). When we zoom out to the entire globe, it gets worse, specifically in tropical regions. Right now, only 1% of the Earth’s land is considered a “barely livable” hot zone, mainly within the Sahara and other deserted regions. If emissions continue unregulated and climate change continues unmitigated, this fraction could increase to 19% by 2070. Billions of people live in these potential, future hot zones. Due to the current state of the global economy, many disadvantaged people residing in these potentially deadly places may not be able to move away or adapt.

Harmful Wet Buld days in the US

In summary, the current outlook on Earth’s biodiversity is gloomy. We know that most mass extinctions in the fossil record have been triggered by the rapid onset of global warming due to an increase in carbon dioxide emissions to the atmosphere. In the past, these emissions were usually due to large, volcanic episodes which occurred over tens to hundreds of thousands of years. On a geological timescale, these changes occurred in the blink of an eye, and this is why they were so costly. The human-caused climate change that is occurring today is similar; since 1850, we have increased atmospheric CO2 levels to the highest they have been in the last 3 to 5 million years. Humans are changing the Earth’s climate faster than animals and plants are able to adapt, and a multitude of evidence points to the occurrence of a sixth mass extinction. Even though this may be depressing, there is still hope. There is still time to reverse the worst effects of man-made climate change, and to do so we must support conservationist efforts and transition to renewable energy. For all of human history we have depended on Earth’s biodiversity, and it now depends on us to save it.

Update: In the course of our Rebuttal Updates Project the previous intermediate version published by Finlay Hay-Chapman (fhaychap) on 13 November 2020 became this advanced version in May 2023.

Last updated on 29 May 2023 by fhaychap. View Archives

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Further reading/viewing

Here are related lecture-videos from Denial101x - Making Sense of Climate Science Denial

Additional videos from the MOOC

State of the Wild, A Global Portrait of Wildlife, Wildlands, and Oceans by James Hansen


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Comments 1 to 25 out of 66:

  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.

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