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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...

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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 76 to 100 out of 195:

  1. Daniel Bailey #74: Do you have sources for those "cold records"? I quote from Met Office: "Last night saw November minimum temperature records fall across the country. Most notably both Wales and Northern Ireland recorded the coldest November night since records began. In Wales, temperatures fell to -18.0 °C at Llysdinam, near Llandrindod Wells, Powys. Northern Ireland recorded -9.5 °C at Loch Fea." Or check he article for yourself:
  2. Re: Argus (76) Thanks for the link. Ironically, another sign of a warming world: when the Arctic Oscillation goes negative, the Arctic experiences above-normal temps, enhancing the overall ongoing warming there. The downside, of course, is Europe and the UK gets hit with the cold polar airmass displaced from the Pole. Source here. The Yooper
  3. Talking of record colds... Quote Cold Record in the Antarctic Minus 50.2 degrees Celsius. 1:20 PM, JUL 22, 2010 • BY JOHN ROSENTHAL Courtesy of /.../ (NOAA), the news media has been full of reports in the last few days about last month being the “hottest June” yet recorded and 2010 being on track likewise to be the hottest year. /.../ When, however, actual temperature readings reveal record cold, this apparently is not news. So it was in May, when much of Europe was experiencing unseasonably cold weather. Germany, for instance, was hit with major snowstorms in May. In the middle of the month, the German Weather Service quietly acknowledged that the country was experiencing record cold: some 3-5 degrees Celsius below the long-term averages. And so it was also last week, when the Georg von Neumayer polar research station on the Antarctic coast recorded the lowest temperature reading since the station was first established in 1981: minus 50.2 degrees Celsius. Unquote
  4. It is winter again, and so the cherry-picking of cold temperatures, some of theme records, begins. Global warming, for now, does not mean the cessation of cold weather. Nor does it mean the end of winter (the planet is still tilted from the vertical)or that no record cold temperatures will be measured anywhere. What is does mean is that the planet as a whole is warming, and that fewer record lows will be set. That is a fact, and is exactly what has been happening. Another fact, until recently, 19 countries around the globe had set all-time record high temperatures in 2010, compared to zero record cold lows. See here. Maybe we will hit 20 before the year is out....
  5. Re: Argus (78) I had a real nice comment all lined up but I see Albatross beat me to it... :) Ah, well. Despite the focus on individual cooling trees (the weather), the forest surrounding us is still heating up nevertheless. The Yooper
  6. Sorry Daniel...
  7. # 73 Argus and #74 Yes it is unusually cold in Scandinavia for the moment, but take a look at Greenland. Yesterday they had +11C in some parts. Link It is rather well known that cold weather in Scandinavia means warm weather in Greenland.
  8. Re: Albatross (81) Old family saying:
    "The slow go hungry."
    Heh. The Yooper
  9. @Argus: we're used to such freezing cold here in Quebec (temperatures here are on average colder than in Sweden, even though we're more to the South), but so far the late Autumn has been quite mild. Nowhere near record cold here, despite being the land of Snow and Ice... :-) @SRJ: that's insane! There was a *25C* degree difference between Greenland's center and its western coast.
  10. Albatross (#79) and Daniel Bailey (#80), I like the wording in the article: "When, however, actual temperature readings reveal record cold, this apparently is not news. " The cherry-picking goes for hot temperatures as well as cold. It depends on what you want to see.
  11. Argus @85, You, it seems, do not wish to "see" the warming, and to that end latch onto every cold record to convince yourself that the warming is not occurring. Doing so is cherry-picking. The data and the scientists are not lying or deceiving you, nor are the scientists cherry-picking, they are looking at all the data. This is what Dr. Meehl had to say: “Despite the increasing number of record highs, there will still be occasional periods of record cold, Meehl notes. "One of the messages of this study is that you still get cold days," Meehl says. "Winter still comes. Even in a much warmer climate, we're setting record low minimum temperatures on a few days each year. But the odds are shifting so there's a much better chance of daily record highs instead of lows." Now that is the truth. You can choose to ignore it or distort it, but doing so does not change the facts nor the truth. And the cold weather currently affecting parts of Europe, is very much in the news.
    Response: Argus and everybody else, please put further comments about cooling on a more appropriate thread--even if you are responding to a comment on this thread.
  12. A special issue of the Philosofical Transactions of the Royal Society may be of interest. It's free through Tuesday 30.
  13. Hi Riccardo, Yes-- Joe Romm at CP has been featuring some of the results. Hopefully some of the papers will be discussed here at SS. They are pretty sobering papers in the special issue, and telling that they are now looking at a warming of +4 C or higher by 2100 and focusing on some of the high-end emission scenarios as BAU continues. It looks like AR5 is not going to make for "fun" reading.... PS: John Cook, sorry for wandering off topic.
  14. #85: "It depends on what you want to see. " Here is a rather objective way to portray this question of hot vs. cold. The high temp anomalies (marked at right) appear in more recent years. I've been playing with this type of display for GISSTemp data; its quite revealing. There's no dependence on wanting to see one thing or the other; its there in plain sight.
  15. Response to Argus taken to 2009-2010 winter saw record cold spells
  16. Reply to comment here. Sorry, you'll have to do better than the UK Telegraph. You snagged, out of context, a journalist's interview of a 'campaigner'. If you read the full sentence, he refers to 'resource wars' with large loss of life, not 'global warming killing billions.' Let's set some ground rules, or this will get stupid very quickly: Try looking at the actual research. Avoid misquotes, headlines and sound-bytes. If you want to be taken seriously, that is. Then we'll talk.
  17. #91: You asked for examples of hyperbole and I gave you one. If you look back at my original post you'll see I never said anything about hyperbole in peer reviewed papers, so I'm not exactly sure why you insist that I look only in the "actual research" for examples. I'm talking about people in the field making statements that in my opinion are hyperbole, regardless of venue. For example, when James Hansen says that CEOs of energy companies "should be tried for high crimes against humanity and nature" I would call that an example of hyperbole. The fact that he did not make the statement in a peer reviewed paper is irrelevant. He is a scientist in the field making statements that are non-scientific and arguably designed solely to garner press. Link to Hansen Statement: High Crimes Now, if you want to talk about why I believe that our understanding of climate sensitivity is insufficient to justify drastic action on climate change right now, I'll be happy to limit my links to actual research (or at the very least, links to sites like Real Climate that discuss actual research).
  18. Here's some hyperbole to match yours"


    [PW] Muoncounter, this link is now dead. You may wish to update it

  19. @Nederland: there is plenty of hyperbole on the denier side, with accusations of planned genocide and conspiracy theories involving a secret cabal of scientists and world government, etc. Considering that hyperbole is enough to convince you of the invalidity of a theory, will the blatant and repeated examples on the denier side turn you off of their position as well? In any case, hyperbole in itself is not a logical fallacy, neither are ad hominem if you don't use them in order to attack someone's credibility. The sentence "2+2=4, you arse!" may be uncouth and rude, but it's mathematically correct...
  20. #94: Considering that hyperbole is enough to convince you of the invalidity of a theory I never said that hyperbole was enough to convince me of the invalidity of a theory. In fact, I never said that I that AGW theory was invalid. I think it would be helpful if you understood my position before posting.
  21. @Nederland: why bring hyperbole up, then? Again, the science is quite sound - climate sensitivity is very likely to be within the 2.5-4.5C range. If you don't believe this, then you have to provide concrete, peer-reviewed evidence to the contrary.
  22. #95: "it would be helpful if you understood my position ..." Considering that you started here with buzzwords like 'catastrophic' and 'hysteria', you haven't exactly made your position clear. Nor have you provided any evidence to support that position.
  23. In another thread Albatross posted a graphic showing 18 weather-related deaths from cold per year (313 for heat). The CDC says 711 deaths back in 1979 before the recent global warming. The CDC also says 688 deaths per year for heath (1999-2003)
  24. Quietman @13 "Warmer means more like the world that we evolved in during the PETM (when prosimians first appear) in Asia." "We are from a tropical paradise, no polar ice caps and green pole to pole. Which do we wan't for our offspring? Warm and abundant or cold and starvation?" Things have changed a little in the past 250 million years. Modern humans have been around for what, 250 thousand years? I suppose you could also say we evolved in any climate since life began on earth. But the real point you are missing is the rate of change. Changes are happening in a human lifetime that normally would take thousands of years. And at no time in man's history were there 6 billion people with highly industrialized infrastructure near the coastline, burning a hundred million years worth of sequestered carbon and putting it back into the atmosphere. We are not nomadic hunter gatherers who can pick up our tents and move to higher ground or more hospitable climates. We depend on extensive modern agriculture, much of which is in coastal plains. Bruce Frykman "For the record "peer review" is simply a call for rudimentary error checking - it is not thesis confirming and it is by no means systematic, thorough, or even unbiased" I don't think anyone claims the peer review process is perfect. But I don't think you can claim the IPCC reports have not been thoroughly peer reviewed. "Climate Scientists Defend IPCC Peer Review as Most Rigorous in History" by Stacy Feldman - Feb 26th, 2010 "Nicholls, a professor at Monash University in Victoria, Australia, said the IPCC 2007 Fourth Assessment report was subjected to several rigorous tiers of review. The study cites over 10,000 papers from the scientific literature, "most of which have already been through the peer-review process to get into the scientific literature." "The report went through four separate reviews and received 90,000 comments from 2,500 reviewers, all of which are publicly available, along with the responses of the authors, Nicholls said."
  25. Monsoon-style flooding: Pakistan, Queensland and now there's ARkStorm: California’s other "Big One" ... scientists unveiled a hypothetical California scenario that describes a storm that could produce up to 10 feet of rain, cause extensive flooding (in many cases overwhelming the state’s flood-protection system) and result in more than $300 billion in damage. ... "We think this event happens once every 100 or 200 years or so, which puts it in the same category as our big San Andreas earthquakes. The ARkStorm is essentially two historic storms (January 1969 and February 1986) put back to back in a scientifically plausible way. The model is not an extremely extreme event."

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