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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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Positives and negatives of global warming

What the science says...

Select a level... Basic Intermediate Advanced

Negative impacts of global warming on agriculture, health & environment far outweigh any positives.

Climate Myth...

It's not bad

"By the way, if you’re going to vote for something, vote for warming. Less deaths due to cold, regions more habitable, larger crops, longer growing season. That’s good. Warming helps the poor." (John MacArthur)

At a glance

“It's not going to be too bad”, some people optimistically say. Too right. It's going to be worse than that. There are various forms this argument takes. For example, some like to point out that carbon dioxide (CO2) is plant-food – as if nobody else knew that. It is, but it's just one of a number of essential nutrients such as water and minerals. To be healthy, plants require them all.

We know how climate change disrupts agriculture through more intense droughts, raging floods or soil degradation – we've either experienced these phenomena ourselves or seen them on TV news reports. Where droughts intensify and/or become more prolonged, the very viability of agriculture becomes compromised. You can have all the CO2 in the world but without their water and minerals, the plants will die just the same.

At the same time, increased warming is adversely affecting countries where conditions are already close to the limit beyond which yields reduce or crops entirely fail. Parts of sub-Saharan Africa fall into this category. Elsewhere, many millions of people – about one-sixth of the world’s population - rely on fresh water supplied yearly by mountain glaciers through their natural melt and regrowth cycles. Those water supplies are at risk of failure as the glaciers retreat. Everywhere you look, climate change loads the dice with problems, both now and in the future.

Please use this form to provide feedback about this new "At a glance" section. Read a more technical version below or dig deeper via the tabs above!

Further details

Most climate change impacts will confer few or no benefits, but may do great harm at considerable costs. We'll look at the picture, sector by sector below figure 1.

IPCC AR6 WGII Chapter 16 Figure FAQ 16.5.1

Figure 1: Simplified presentation of the five Reasons for Concern burning ember diagrams as assessed in IPCC AR6 Working Group 2 Chapter 16 (adapted from Figure 16.15, Figure FAQ 16.5.1).


While CO2 is essential for plant growth, that gas is just one thing they need in order to stay healthy. All agriculture also depends on steady water supplies and climate change is likely to disrupt those in places, both through soil-eroding floods and droughts.

It has been suggested that higher latitudes – Siberia, for example – may become productive due to global warming, but in reality it takes a considerable amount of time (centuries plus) for healthy soils to develop naturally. The soil in Arctic Siberia and nearby territories is generally very poor – peat underlain by permafrost in many places, on top of which sunlight is limited at such high latitudes. Or, as a veg-growing market gardening friend told us, “This whole idea of "we'll be growing grains on the tundra" is just spouted by idiots who haven't grown as much as a carrot in their life and therefore simply don't have a clue that we need intact ecosystems to produce our food.” So there are other reasons why widespread cultivation up there is going to be a tall order.

Agriculture can also be disrupted by wildfires and changes in the timing of the seasons, both of which are already taking place. Changes to grasslands and water supplies can impact grazing and welfare of domestic livestock. Increased warming may also have a greater effect on countries whose climate is already near or at a temperature limit over which yields reduce or crops fail – in parts of the Middle East and sub-Saharan Africa, for example.


Warmer winters would mean fewer deaths, particularly among vulnerable groups like the elderly. However, the very same groups are also highly vulnerable to heatwaves. On a warmer planet, excess deaths caused by heatwaves are expected to be approximately five times higher than winter deaths prevented.

In addition, it is widely understood that as warmer conditions spread polewards, that will also encourage the migration of disease-bearing insects like mosquitoes, ticks and so on. So long as they have habitat and agreeable temperatures to suit their requirements, they'll make themselves at home. Just as one example out of many, malaria is already appearing in places it hasn’t been seen before.

Polar Melting

While the opening of a year-round ice-free Arctic passage between the Atlantic and Pacific oceans would have some commercial benefits, these are considerably outweighed by the negatives. Detrimental effects include increased iceberg hazards to shipping and loss of ice albedo (the reflection of sunshine) due to melting sea-ice allowing the ocean to absorb more incoming solar radiation. The latter is a good example of a positive climate feedback. Ice melts away, waters absorb more energy and warming waters increase glacier melt around the coastlines of adjacent lands.

Warmer ocean water also raises the temperature of submerged Arctic permafrost, which then releases methane, a very potent greenhouse gas. The latter process has been observed occurring in the waters of the East Siberian Arctic Shelf and is poorly understood. At the other end of the planet, melting and break-up of the Antarctic ice shelves will speed up the land-glaciers they hold back, thereby adding significantly to sea-level rise.

Ocean Acidification

Acidity is measured by the pH scale (0 = highly acidic, 7 = neutral, 14 = highly alkaline). The lowering of ocean pH is a cause for considerable concern without any counter-benefits at all. This process is caused by additional CO2 being absorbed in the water. Why that's a problem is because critters that build their shells out of calcium carbonate, such as bivalves, snails and many others, may find that carbonate dissolving faster than they can make it. The impact that would have on the marine food-chain should be self-evident.

Melting Glaciers

The effects of glaciers melting are largely detrimental and some have already been mentioned. But a major impact would be that many millions of people (one-sixth of the world’s population) depend on fresh water supplied each year by the seasonal melt and regrowth cycles of glaciers. Melt them and those water supplies, vital not just for drinking but for agriculture, will fail.

Sea Level Rise

Many parts of the world are low-lying and will be severely affected even by modest sea level rises. Rice paddies are already becoming inundated with salt water, destroying the crops. Seawater is contaminating rivers as it mixes with fresh water further upstream, and aquifers are becoming saline. The viability of some coastal communities is already under discussion, since raised sea levels in combination with seasonal storms will lead to worse flooding as waves overtop more sea defences.


Positive effects of climate change may include greener rainforests and enhanced plant growth in the Amazon, increased vegetation in northern latitudes and possible increases in plankton biomass in some parts of the ocean.

Negative responses may include some or all of the following: further expansion of oxygen-poor ocean “dead zones”, contamination or exhaustion of fresh water supplies, increased incidence of natural fires and extensive vegetation die-off due to droughts. Increased risk of coral extinction, changes in migration patterns of birds and animals, changes in seasonal timing and disruption to food chains: all of these processes point towards widespread species loss.


Economic impacts of climate change are highly likely to be catastrophic, while there have been very few benefits projected at all. As long ago as 2006, the Stern Report made clear the overall pattern of economic distress and that prevention was far cheaper than adaptation.

Scenarios projected in IPCC reports have repeatedly warned of massive future migrations due to unprecedented disruptions to global agriculture, trade, transport, energy supplies, labour markets, banking and finance, investment and insurance. Such disturbances would wreak havoc on the stability of both developed and developing nations and they substantially increase the risk of future conflicts. Furthermore, it is widely accepted that the detrimental effects of climate change will be visited mostly on those countries least equipped to cope with it, socially or economically.

These and other areas of concern are covered in far more detail in the 36-page Summary for Policymakers from the IPCC AR6 Synthesis Report, released in March 2023. The report spells out in no uncertain terms the increasingly serious issues Mankind faces; the longer that meaningful action on climate is neglected, the greater the severity of impacts. The report is available for download here.


Last updated on 21 April 2023 by John Mason. View Archives

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Further reading

National Geographic have an informative article listing the various positives and negatives of global warming for Greenland.

Climate Wizard is an interactive tool that lets you examine projected temperature and precipitation changes for any part of the world.

A good overview of the impacts of ocean acidification is found in Ken Caldeira's What Corals are Dying to Tell Us About CO2 and Ocean Acidification

Denial101x video

Here is a related video lecture from Denial101x - Making senses of climate science denial


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Comments 351 to 375 out of 405:

  1. Earthling: "It would seem that we humans have probably done ourselves a favour by acting to avoid a decline in global temperature."

    What, by missing the next glacial period 1500 to 5000 years from now?  Sure, the LIA sucked, but so did the PETM and end-Permian.  The PETM event involved a change in global average temp of 5C over 12,000 years.  That's what extreme looks like.  We're doing about 40x the rate of PETM warming.  In what shape will we be when the time comes for us to miss the next glacial period?  When is the best time to develop sustainable energy and greenhouse management technology?  When the world is rich in energy resources and relatively stable politically, economically, and socially?  Or when cheap energy is diminishing, food prices are rising, climate is persistently unstable, and many more people are on the move trying to find a better place to live?  I think the idea is that we reach the next "missed" glacial period without having gone through the school of hard knocks and instead having shown that we're mature enough to drive the family car.

  2. "Increased deaths to heatwaves - 5.74% increase to heatwaves compared to 1.59% to cold snaps (Medina-Ramon 2007)"

    SO? This has no context in terms of the general population mortality. The CDC figures on US death rates (2007-8) are quite clear, 900 more people per million die in cold weather, at temperatures below 12 degrees, that's in excess of 250000 people annually! Intermittent Heatwave 'costs' in terms of mortality are insignificant compared to the 'benefit' of a warmer continental US. You must excuse me but without appropriate context, noting studies like this distorts our necessary perception and responses to climate change.


  3. @Ray Coleman #352

    You blithely assert, 

    Intermittent Heatwave 'costs' in terms of mortality are insignificant compared to the 'benefit' of a warmer continental US.

     Please provide documentation to support your statement.

  4. Hmm.  Available evidence shows that it is the human adaptation to weather extremes that is key in limiting mortality.  Evidence for that assertion:

    "Adaptation measures have prevented a significant increase in heat-related mortality and considerably enhanced a significant decrease in cold-related mortality. The analysis also suggests that in the absence of any adaptive processes, the human influence on climate would have been the main contributor to both increases in heat-related mortality and decreases in cold-related mortality."


    "With regard to heat-related mortality, projected future increases in the frequency and intensity of heat waves may exert a stress beyond the adaptive limits of the population."

    Causes for the recent changes in cold- and heat-related mortality in England and Wales
    Nikolaos Christidis, Gavin C. Donaldson, Peter A. Stott; Climatic Change, October 2010


    That's called supporting an assertion with evidence.

  5. without appropriate context noting studies like this distorts our necessary perception and responses to climate change

    You mean such as, say, omitting the peak season for influenza in the United States from consideration?

    With studies such as this, or news articles such as this, it appears much of the seasonal mortality in winter is the result of not the weather, but of the seasonal variation in influenza circulation.

    Or perhaps you mean, say, referring strictly to seasonal trends in mortality in a single country rather than from a global perspective?

  6. an additional contribution to reduced heat in the near term can be derived from the cooler sea surface temperatures which reduces the amount of tropical thunderstorm activity which results in a decrease in moisture transport to the lower stratosphere.  This effect is also compounded by a recent decline in stratospheric ozone.  When there is less water vapor in the lower stratosphere the radiative forcing declines.  this is seen as contributing to the reduction in atmospheric heating.  Jeff Masters wrote an excellent article on this on his blog:


  7. Russ, what you define as the "consensus research" never set out to measure consensus on the danger, so why complain about it? After all, the IPCC has already established a level of consensus in WG II, a report that summarizes much of the existing research on impacts (citing over 12,000 publications). How much more of a consensus do you want? Do you find that none of the WG II conclusions constitutes a significant adverse impact?

  8. Link to Nyegaard 2007 is broken. I even tried to google it, but there's too little information to begin with. If someone could provide a new link, or at least more info (like the name of the paper), it would be greatly appreciated.

  9. What if a reduction in CO2 emissions doesn't prevent further global warming?

  10. Hoges,

    When you are stuck in the bottom of a hole the first rule is always to Stop Digging.  There is nothing we can do about pollution already released.  If we reduce what we currently produce the final temperature will be lower than if we dig up as much carbon as possible.  The stronger the steps we take now, the smaller the final problem we will have to deal with.  Scieentists believe that if we stop polluting now the problem will not be too bad, we have to work on the presumption that they are correct.

  11. @343-347 discussing the 2009 Tol research review of overall impact to humans of climate change, quantified in dollars. 

    This article needs to be part of the Further Reading associated with this argument. It reflects the state of economic knowledge about climate change impacts, published in the premier economics journal used to summarize research to date. To my knowledge the Tol research review hasn't been updated. 

    I am not sure if AR4 or AR5 incorporates this review or the studies it summarizes/synthesizes. If not would like to understand reasons for exclusion.  If so, the SKS write up needs to do a better job incorporating the research into this part of its site. The current write up doesn't fairly represent uncertainty that exists in the current science focused on quantifying net impacts of climate change. That said, the science still shows that rational decision makers should be willing to pay to reduce carbon emissions, which goes toward debunking the claim that we do not yet know enough to act. 

  12. There is an update to Tol 2009.  See Jourrnal of Economic Perspectives 28(2): 221-26, Spring 2014. Update corrects errors in 2009 article and adds 5 new studies. Shows that GDP impact is negative for any increase in temperature anomaly. Previous paper showed positive impact up to 2degC anomaly. While Tol 2014 does not update estimate of optimal carbon tax, guessing it will be substantially higher than the original $45 per ton. 

  13. Good article and comments on Tol's corrections at And Then There's Physics.

  14. Good working paper summarizing research on social cost of carbon (SCC). SCC is basically the amount of an optimal tax that would "internalize" the negative impacts of carbon, expressed as $ per ton of carbon emissions. See Havranek et al. 2014 CUDARE Working Papers #1139.  Correcting for publication bias, estimates of SCC are in the range $0 - $130 per tC, in 2010 USD for emission year 2015.  Still a lot of uncertainty, but still suggests that optimal policy involves a positive tax on carbon, as high as $130 per ton. 

  15. I hope I am not posting in the wrong thread, but: instead of aiming for a less than 2 degree rise in temperature shouldn't we be talking in terms of sea level rise?


    For instance I live on a hill and 5 metres isn't going to get to where I live but it will decimate the city and every supporting resource for the best part of 100 square kilometres, minimum!


    The answer could be quickly retorted that we don't know what kind of temperature that equates to and seeing as 2 degrees is a nice round figure that a population of billions can understand we'll go with that...


    Thus, the problem can now be seen as an inability to communicate at the most basic level making this a very bad problem indeed! Further, I am saying that the inability to respond to this basic communication problem will lead to panic when the problem becomes understood by the masses yet the lack of communication skills to be able to indicate that it has been appreciated and understood becomes the more pressing issue.

    .. I'm saying the important issue of the clear and present danger involved, i.e. a numerical value for sea level rise, is missing from the conversation!

  16. ...and 'that' is bad!!

  17. As an example: if a man on upon hearing about this climate thingy were to question if a 4 metre sea level rise were already locked in by 2300, what sort of answer would he receive?

    I'm not being flippant, I'm directly asking if he would only receive waffle or would he be able to get a direct answer?

    This is what I mean by the communication breakdown arising from the fact sea-levels are not being communicated and thus engaged with. (Yes- I do have method!!)

  18. Great to see such a clear overview of the advantages and disadvantages of climate warming. I've shared this with several people I know that don't believe global warming is a serious problem.



    [PS] Removed link. Periliously close to SPAM which remove all posts and posting priviledges

  19. little birdy told me that there is no money for Glacier Research. Is this true?

    If it is this can't be good can it?? If the myth being addressed is that the problem is not bad then can some mention of this be made in a revision of the answer to this skeptical questioning of the science.

    I don't want to push the point and it's not my site but it would seem appropriate is all I'm saying.

    I'm just saying it gives me the chills to hear that this could be a reality: that there is indeed no money for Glacier Research at a time when we are seeing funny rates of change to other indicators of climate change, namely the sea ice in the Arctic.

    Isn't science all about corroboration?


    Of course, this is an excellent web-site and we all enjoy using it.

  20. Loss of sea ice is currently the greatest in the Barents Sea area, York explained, where the summer ice-free period is now 20 weeks longer than when records began in 1979.


    How can a "summer ice-free period" being 20 weeks longer than 36 years ago be a good thing

  21. On the matter of the "goodness" or "badness" of outcomes, scepticism in the scientific sense is not relevent - because it is not a scientific question. It would be scientific to ask whether a given outcome is more or less likely under different global climate conditions (but sadly, few such predictions are scientifially checked, on either side of the debate). 

    It is elightening, though, to look at the stats. Cliamte change alarm supporters invariably cite all or virtually all consequences as "bad". They will fargue the toss each and every time a "good" outcome is found.

    Statistically speaking, is it reasonable for a small change in climate to have 10, 100 or 1000 times more "bad" consequences than "good"? No. Even if there was some underlying mechanism skewing the true outcomes toward "bad", it could not possibly be as extreme as the alarmists from the IPCC to this site and everywhere in between claim... and one can easily show to an adequate statistical significance that they are biassed. 

    How could bias creep in? Well, the individual negative outcomes are often fabrications (do you have time to check them all? There are thousands!). They are cherry-picked in type, methodology and location. You can see this by taking one and asking "how many other kinds of scenarios could be looked at, that differ in some way from this case?". And you will usually find *those* outcomes are far less "bad". Many, maybe 50%, will be "good". So naturally you wonder how the one that was published (and included in alarming lists on the internet) was chosen.

    What *true* underlying skew might there be? Well, the most obvious one is that more human beings are harmed by cold then by warm, and that more of the world becomes fertile when it is warm. Beyond that, the question rapidly bifurcates into less and less generally applicable effects, operating in both "good" and "bad" directions, with no "force majeure" to make them skew in either direction.

    So by the (very few) arguments that are sufficiently general to produce an overall skew, warming is a net "good". The remainder of arguments should be randomly distrinuted, or at least close to that. So people who claim they are mostly bad (or mostly good) are biassed (we can be confident of that).

    Of course, there are other moral positions. An actor changes something, another actor suffers as a result even though many actors benefit. What's your position on that? Well, in the case of global warming, it isn't even clear who is the actor making the change. Is it the humams who emitted CO2? OR the other humans trying to stop the first humans? Because both groups' actions will hurt *somebody*. 

  22. A.R.S.Says @ #371 :

    The question here of "good" or "bad" [regarding Global Warming effects] is very straightforward, really! It is viewed from the point of view of the human race (and which largely co-incides with the beneficial aspect to terrestrial & marine lifeforms).

    Worse heatwaves, droughts, floods, and rising sea levels encroaching on land which is heavily settled and/or fertile agricultural. In addition, agricultural scientists point to an overall reduction of staple food production (worsening with each degree of warming).

    Please read and educate yourself, in the appropriate section of this website.

    (btw, I must commend your sense of humour in choice of your nom-de-plume ~ the abbreviation is priceless.)


    [JH] Inflamatory & off-topic.

  23. Winter deaths will decline as temperatures warm (HPA 2007)

    may need an update partly because the link no longer works. You might want to use refs 4 through 8 from

    and you may want to note that the above link disputes this for England and Wales.

  24. Eclectic @ #372: It is viewed from the point of view of the human race...

    Yes, that is the easy part.  Rising sea levels are clearly bad.  Worse heatwaves, droughts and floods are clearly bad.  The hard part is knowing whether the effects will be good or bad, and if bad, what is the cost of adaptation compared to giving up fossil fuels.

    We have to look at the effects one-by-one:

    1) Sea level rise.  Clearly bad, but we have a few decades to adapt.  Do not rebuild in the flood zones of New Orleans.  Do some careful planning on the costs of relocating Miami, lower Manhattan, etc.

    2) Average temperature rise.  We have a few decades for a migration to cooler areas.

    3) Shifting climate patterns.  This seems like the biggest worry, because it can happen rapidly, and rapid change can be costly.

    I think we make a mistake by assuming all shifts will be in a bad direction.  I live in the Southeast part of Arizona, and the hot summers here have been getting milder on the eastern edge of the Sonoran Desert.  Over a larger area (California and Arizona) the drought is getting worse.  A few more years, and the Tucson area could be cut off from its life supply, water from the Colorado River.  That would be an economic disaster, and it could happen in just a few years.  The resulting collapse in the real estate market could happen instantly.

  25. I come on this forum as not a skeptic about climate change nor do I deny that we have some impact. However, as a scientist myself I am very skeptical that it is magically reversible or reversible to the degree some say it would be

    One of my issues with the whole hostile shouting down of skeptics, is that I have still to find a single man made climate change believer, who is balanced enough in their argument to give a single positve about climate change, i.e. apparantly it is all 100% bad!!

    This is simply not possible and I suspect is indicative of an agenda that can't allow any good to be admitted, for fear of undermining the argument

    Logically, that can only be because the climate change want everyone to think that "we're doomed" unless we agree with them  - which is a poor way to have a debate


    [JH] Blatant sloganeering snipped. 

    [TD] Click the Intermediate tab of this post to see a list of positives and negatives. Then read the Advanced tabbed pane. If you want more resources, inquire politely here.

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