Talk:Effects of climate change/Archive 2

Benefits?

Why no benefits? Surely for any climate change to occur, there must be some benefits?--Rotten 20:02, 3 August 2007 (UTC)

Backyard swimming hole for the win. Ball of pain 21:06, 18 August 2007 (UTC)

I agree. What about access to resources in the Arctic? Or the creation of arable land in areas such as Canada or Russia? I'm not making any claim that the benefits outweigh the negative effects, but surely they exist. Here's a good article that I found: Global Warming's Silver Lining Mgerb (talk) 19:19, 16 December 2007 (UTC)

Agreed in principle, but the fact that the article you cite quotes Peiser and Singer isn't a good sign. Surely they can do better than those two. (Probably it's just because the reporter was lazy, and knew P and S can always be counted on for a contrarian take.) Raymond Arritt (talk) 19:22, 16 December 2007 (UTC)

Greenland ice sheet irreversible melting? (moved from "Global warming" discussion page)

Both Lovelock´s latest book and the BBC documentary on global dimming claim that the Greenland ice sheet will continue melting until nothing´s left of it once the temperature rises above a certain limit, and that there is nothing that can be done to stop this once it´s started. I can find absolutely no information on this on Wikipedia. Are the claims unfounded?

Totally unfounded. We are in an interglacial. And when you are in an interglacial what comes next is the glacial period. Ask yourself if they came up with any evidence for what they were saying? In fact the leftists refuse to come up with evidence. Its rude to ask them for evidence any more. —The preceding unsigned comment was added by 122.148.183.191 (talk) 08:53:03, August 19, 2007 (UTC)

I would have thought that effects of global warming might be the place. Answer: yes, fairly soon we will be committed to melting Greenland, if we aren't already William M. Connolley 21:06, 17 July 2006 (UTC)

More or less. With ice sheets, strong melting does tend to provoke more melting so once it gets significantly started it is likely to continue for quite a while. However, there are also matters of degree to this. Some scenarios suggest that one could stabalize with an ice sheet of roughly half the present mass. The rate and degree to which Greenland melts still depends on how climate change and greenhouse gas emissions play out over the next century. Dragons flight 21:37, 17 July 2006 (UTC)

One good method of checking the rate at which ice is receeding is to use Google Earths dated flyovers. You can easily see the difference over just the last five years. Sea level 14:14, 28 December 2006 (UTC)

As a separate issue the synergystic effects of temperature increase include not just the ice melt but also the rising coefficient of expansion of the water in the oceans. Sea level 14:14, 28 December 2006 (UTC)

American data from all sources is generally more conservative than the IPCC, but taking into account changes in fossil fuel use now that we can no longer produce as much light sweet crude as we consume and are increasingly dependent on burning things like coal with a higher carbon footprint, and the death of the oceans, and the rising consumption of countries like China, the use of a target date a century off for the effects to be felt seems very conservative indeed.Sea level 14:14, 28 December 2006 (UTC)

Negative feedback

Aren't there any negative feedback effects? Narssarssuaq 11:33, 29 July 2006 (UTC)

All the feedbacks are magnificently and powerfully negative. Perhaps the only exception being land ice. —The preceding unsigned comment was added by 122.148.183.191 (talk) 08:56:22, August 19, 2007 (UTC)

As the world gets warmer, the atmosphere will be able to carry more moisture. Consequently, one might expect more clouds and, thus, increase reflectance of short-wave radiation. However, moisture is also a greenhouse gas itself, so will trap long-wave radiation. I'm not aware of the precise balance of these processes, but the former could be construed as negative feedback.

As could, for instance, increase terrestrial plant growth removing more atmospheric CO2. This process is facilitated by the improved water-use efficiency a high CO2 atmosphere allows, and also by warmer temperatures. However, again this apparent negative feedback is believed to be counteracted by increased terrestrial soil respiration in a warmer world.

I'm afraid both of these examples lie well outside my expertise, but you could poke around on the web to try to quantify them better. From my reading of the literature, I believe the positive feedbacks listed above outweigh the negative ones. But I think there's still some ignorance on the processes in question. Cheers, --Plumbago 15:38, 29 July 2006 (UTC)

The main -ve feedback is that as T rises thermal radiation rises (to the 4th power, but thats not so important over the fairly small range concerned) William M. Connolley 18:59, 29 July 2006 (UTC)

Also, is the mechanism of atmospheric CO2 dissolving into the sea mentioned anywhere on Wikipedia? It's rather essential for understanding the long-term scenarios. I know it's a negative feedback effect from increasing CO2 and not from global warming, but that also applies to the "ocean acidification" part listed in this article. Narssarssuaq 08:21, 31 July 2006 (UTC)

See the articles on the solubility pump and ocean acidification. --Plumbago 10:02, 2 August 2006 (UTC)

I added it, which I guess makes the article more NPOV. My entry, however, is very crude, so I hope for improvements. If any of the points I mentioned are negligible, I hope experts could comment this in the article. Narssarssuaq 10:51, 7 August 2006 (UTC)

People consume less energy for domestic heating. Bendž|Ť 06:28, 28 June 2007 (UTC)

evap para

I cut:

In addition, as the world gets warmer, the atmosphere will be able to carry more moisture. However, over the course of the 20th century, evaporation rates have reduced worldwide [1]; this is thought by many to be explained by global dimming. As the climate grows warmer and the causes of global dimming are reduced, evaporation will increase. With increased moisture in the air, one might expect more clouds and, thus, increased reflectance of short-wave radiation. But moisture being a greenhouse gas itself, it will trap long-wave radiation.

Firstly, the atmos doesn't "carry" moisture, but thats trivia. More importantly, atmos moisture doesn't directly depend on the pan evap rates - what matters is precip - evap. AFAIK there is evidence for an increasing trend in atmos moisture, so the nature link is just confusing. And most evap is from the sea anyway. With increased moisture in the air, one might expect more clouds - this is just idle speculation and unsourced. Conversely, clouds depend on relative humidity, which to first order remains constant, so one might expect to see no changes in clouds William M. Connolley 22:12, 13 August 2006 (UTC)

Thanks for your help. That paragraph bothered me. Still, "one might expect to see no changes in clouds" --you may be right in this context, but - out of curiosity - isn't cloud formation scenarios still one of the big issues to be looked into, and doesn't it make up a significant part of the insecurity surrounding temperature estimates? Narssarssuaq 10:57, 14 August 2006 (UTC)

Yes, clouds are still a big issue. However, which way they go is less than clear - certainly, first-order arguments like "more absolute moisture = more clouds" is too crude William M. Connolley 11:01, 14 August 2006 (UTC)

50% reduction in total surface area of glaciers worldwide?

From the article:

"The total surface area of glaciers worldwide has decreased by 50% since the end of the 19th century [43]."

I checked the reference linked at http://www.munichre.com/ and it is an insurance site that does not list it's sources. The statement is grossly incorrect if taken at face value. Does anybody know where they got the information? Is it possible that by glacier they are excluding continental ice sheets? It is indisputable that the overwhelming majority of the total surface area of glaciers is comprised of continental ice sheets and it is equally certain that these have not decreased anywhere *near* 10 percent much less 50 percent since the end of the 19th century.

I think this comment needs to be removed or qualified if the original intended meaning of 'glacier' in the referenced site can be identified. Zebulin 22:24, 21 November 2006 (UTC)

That glaciers are retreating is not in doubt. [2] [3] The question is by how much. Looking at the cite, Munich Re has a pretty high reputation and would seem to be a disinterested party. OTOH, "worldwide" would seem to include Antarctica (well, maybe not to insurance companies, who likely insure very little there), and I believe we would have heard of a 50% reduction there (we certainly heard when an ice shelf calved off). I think the thing to do is to write to Munich Re and clear up the confusion, so I will do that. Simesa 01:14, 22 November 2006 (UTC)

Okay, I just wrote off to them. Let's give them a little time to reply. Simesa 01:26, 22 November 2006 (UTC)

I received an autoreply. The appropriate press contact will out until November 28. Simesa 06:05, 22 November 2006 (UTC)

This may be true for mountain glaciers. It is not true for continental ice sheets (Antarctica/Greenland), whose volume has not changed substantially in the last 10,000 years. --Agnana 01:05, 23 November 2006 (UTC)

It is likely correct that on average glaciers world-wide have not lost as much as 50% of their surface area, but this is an encyclopedia and we have a reputable source that says they have. We are questioning that source, but a source that disagrees would certainly be appreciated. Until we get clarification or a different source, I suggest we should leave the statement as is. Simesa 03:31, 23 November 2006 (UTC)

The current rate of sea level rise is 180 mm/century. 30 to 70 mm is estimated to be due to thermal expansion. 20 to 40 mm is thought to be due to mass loss from glaciers and ice caps. The sum is in agreement given the error estimates. Complete melting of glaciers, ice caps and ice sheets would cause a rise of 68.8 meters. [4][5][6] Munich Re may well be correct that half the glacier area has disappeared. Loss during the first half of the 20th century was probably more due to the end of the Little Ice Age than GW. GW came to dominate in the second half. The areas of ice caps and ice sheets were little changed in the 20th century, however, and the fractional mass loss has been tiny. See also Retreat of glaciers since 1850. --Walter Siegmund (talk) 04:59, 23 November 2006 (UTC)

Certainly the Munich Re figures can only refer to exclusing the ice sheets: Antarctica and Greenland comprise most of the area otherwise and have lost very little in fractional terms: Antarctica certainly less than 1%; Gr probably too. I don't think I believe the 50% figure even for non-polar glaciers William M. Connolley 08:32, 23 November 2006 (UTC)

Munich Re never responded. I suggest the 50% figure be removed. Simesa 00:22, 7 December 2006 (UTC)

We are already seeing glacier retreats. Just over the summer of 2007, about 3/4's of the Northern Ice Cap melting due to the rising land and sea temps. WE NEED TO TAKE ACTION NOW!!!!!!! gameplaya 9:27 18, September 2007

Global warming and ocean life

[7] "New Data Show Global Warming Kills Marine Life" Simesa 00:22, 7 December 2006 (UTC)

Question on Negative feedback effects

Following Le Chatelier's principle, the chemical equilibrium of the Earth's carbon cycle will shift in response to anthropogenic CO2 emissions. The primary driver of this is the ocean, which absorbs anthropogenic CO2 via the so-called solubility pump. At present this accounts for only about one third of the current emissions, but ultimately most (~75%) of the CO2 emitted by human activities will dissolve in the ocean over a period of centuries (Archer, 2005; "A better approximation of the lifetime of fossil fuel CO2 for public discussion might be 300 years, plus 25% that lasts forever"). However, the rate at which the ocean will take it up in the future is less certain, and will be affected by stratification induced by warming and, potentially, changes in the ocean's thermohaline circulation.

Also, as temperature rises, the Earth's thermal radiation rises.

Call me crazy, but I did some searching on thermal radiation.

Thermal radiation is electromagnetic radiation emitted from the surface of an object which is due to the object's temperature

-Wikipedia (Thermal radiation)

Okay, so, global warming heats up the Earth, and thermal radiation is released. How is this negative feedback? Does the radiation counteract the Global warming?
If not, then should this statement be in the negative feedback section?

Thanks very much! --AveryJ 04:50, 14 January 2007 (UTC)

From the GW page

I just chopped a pile of stuff out of the global warming article, as the effects section there had bloated. Its in Talk:Effects of global warming/temp if you want it William M. Connolley 20:05, 15 January 2007 (UTC)

Risks and Impacts Figure

thumb|right|Original lead image

Recent replacement

The figure shown at right (based on the IPCC) was removed from the article and replaced by the current lead image showing an increase in reported natural disasters. Personally, I find the IPCC figure much more informative and covering a broader range of information. By contrast the reported natural disasters figure is problematic since, as the embedded text says, most of the risk in natural disasters during the last hundred years is related to increased reporting and awareness, and it is only the much smaller differences over the last ~20 years that might indicate anthropogenic interference.

I make it a point not to restore figures that I have created when they are removed, but I would ask people to seriously consider whether removing the Risks and Impacts figures was a good idea in this case. Dragons flight 18:36, 17 March 2007 (UTC)

I'm very much in favor to reinstate the original lead image. The catastrophe-diagram should not be deleted, however, but be placed lower. Hardern 10:11, 21 March 2007 (UTC)

The original lead image from the 2001 IPCC contains no quantitative information: the shade of orange is not related to any particular number of events. It is particularly difficult to read, with each category along the x-axis being broken out in a legend. The embedded text does not say "most" of the risk in natural disasters during the last hundred years is related to increased reporting and awareness -- it says "much" is, and the baseline of earthquakes (which have presumably remained constant) is there to call out just such a comparison. James S. 16:09, 26 March 2007 (UTC)

I have made a change to the description on the graph from:
"Global warming is responsible for some trends in natural disasters such as extreme weather."
To:
"Global warming is believed by many to be responsible for some trends in natural disasters such as extreme weather."
I made this change on the grounds that I feel it better reflects what is actually presented in the graph:
"How, we must ask, is global warming affecting the frequency of natural hazards?"
A question not a statement. The article that is linked also does not choose to make any sort of definitive statements, only strong evidence of the likely causal relationship between global warming and extreme weather. I also believe this better reflects the introduction to Section 2, which states:
"Increasing temperature is likely to lead to increasing precipitation [3] [4] but the effects on storms are less clear. Extratropical storms partly depend on the temperature gradient, which is predicted to weaken in the northern hemisphere as the polar region warms more than the rest of the hemisphere [5]."--David C 02:33, 27 March 2007 (UTC)

Is there an update of the 2001 figure with numeric estimates of quantities? Until then, I would ask that the 2004 figure remain. Do any of the most recent IPCC publications include any such graphics? James S. 05:44, 5 April 2007 (UTC)

I believe that the 2001 figure provides a better overview of possible impacts and should be the lead image, with the 2004 figure belonging in the Effects on Weather section. If you have no objection to that, I would like to make those moves.Hal peridol 16:33, 5 April 2007 (UTC)

Developments section

A section which I put in was recently totally deleted. Sorry, I totally disagree with your approach. Exactly where did you get the idea that Wikipedia is not able or meant to chronicle continuing historical developments? I'm sure you are aware that there are many Wikipedia articles which chronicle current or recent history. So why do you feel that it is not possible to include that, or that it is necessary to delete others efforts to do so. --Steve, Sm8900 00:35, 19 March 2007 (UTC).

I am open to anyone's comments and input on this issue. I would like to think that we can discus things constructively, rather than simply deleting various contributions. Thanks. --Steve, Sm8900 00:52, 19 March 2007 (UTC)

The same principles already discussed at Talk:Global_warming#Recent_findings_section apply here. Raymond Arritt 00:58, 19 March 2007 (UTC)

SLR

The article used to say Sea level is generally expected to rise 50-200 cm in the next century (Dean et al. 1987). Such a rise would inundate 7,000 square miles of dry land in the United States (an area the size of Massachusetts) and a similar amount of coastal wetlands; erode recreational beaches 100-200 meters; exacerbate coastal flooding; and increase the salinity of aquifers and estuaries (Titus 1989).. Using a 1987 ref is weird - the obvious one to use is the AR4. how 50-200 translated into just one number (7000) for dry land I don't know; but that needs new numbers if it is to go in William M. Connolley 15:31, 13 April 2007 (UTC)

I assume we would also mention the lack of consideration of most melting scenarios encompassing Antarctica and Greenland in AR4?

--Skyemoor 15:52, 13 April 2007 (UTC)

I'm not sure exactly what is in AR4. Presumably the sea level rise should be updated first - or rather, that this article should reflect what is there William M. Connolley 16:34, 13 April 2007 (UTC)

Off bit re desertification

Theres a lot I dislike about the extreme weather bits of this article, but

As the climate grows warmer and the causes of global dimming are reduced, evaporation will increase due to warmer oceans. Because the world is a closed system this will cause heavier rainfall and more erosion, and in more vulnerable tropical areas (especially in Africa), desertification due to deforestation.

seems especially weird, as it apparently attributes desertification to heavier rainfall. I *think* it is trying to say that increased evap, if the rain falls elsewhere, leads to drying? If so it should be made much clearer; and also this is (unsourced) special pleading: the Because the world is a closed system is an invalid argument; the ppn could all fall over the sea William M. Connolley 20:23, 21 April 2007 (UTC)

It *may* be trying to say that an effect of heavier rainfall (over land) is a greater rate of soil erosion, which ceteris paribus is also greater in deforested areas than in forested areas. The combined effect is to erode soil resources needed by vegetation to the extent that vegetation is unsustainable. Of course, this would be confusing desert with a land cover classification rather than a precip one. More likely that the whole confusing para is the result of edit creep. I'm sure it could all be made clearer if there was a source for it... Deditos 12:37, 23 April 2007 (UTC).

Forest Fires

Global warming will increase the amount of CO2 and water vapor in the air right? So how would the amount of forest fires increase? 71.161.48.4 03:17, 11 May 2007 (UTC)

Fine then, if someone can't give an explanation, I'll delete the section. 71.161.41.63 13:28, 17 May 2007 (UTC)

How about reading the references - such as the EPA one? --Kim D. Petersen 13:41, 17 May 2007 (UTC)

ok, that's fine, but I didn't get a response for 6 days, by the way, there's something wrong with the footnotes in that section now, and I looked at what the first link was in the history and the article says that summers will be hotter (true) and drier (false). while the temperature may increase, more water will evaporate from the ocean, increasing the humidity. just thought I'd point that out. 71.161.41.63 19:38, 18 May 2007 (UTC)

I can't access those refs either. --Dean1970 10:25, 24 June 2007 (UTC)

One billion refugees?

See [8]. Reliable enough for inclusion? Ultramarine 20:32, 14 May 2007 (UTC)

I've never heard of Christian Aid, so I can't comment their reliability. If one does choose to include the information, it should come from the Christian Aid Report, not the blog. ~ UBeR 20:37, 14 May 2007 (UTC)

Connection to other areas of human interest

Global warming is a big deal. Most people don't get that this stuff is important. I did a speech on the topic for my speech class, and anyone could tell that the classs couldn't care less. I think the main reason we are having such a problem is because most people don't understand the consequences of global warming. Even more people scorn scientists' opinions. It's like evolution. The evidence is right in front of these ignoramuses, and yet they deny it. If we're to do something to save human civilization, our species as a whole has to go back to the main instinct of all animals: trusting only emperical andd scientific evidence, not basing beliefs on texts written millenia ago. An interesting fact is that most modern devout theists only accept the 'good' side of their corresponding scriptures. Most ancient texts, including the Bible, the Koran, and others, preach the killing of non-believers. Look at the Crusades. It's all right to have a belief in a higher power, but allowing it to interfere with others and society is unacepptable. It defies nature's law of natural selection. Think of the scientific advances that could have been made if Galileo's theory was accepted. If Bruno wasn't burned at the stake. If Copernicus wasn't forced to do his work in secrecy. If cloning research was and is accepted by the American government. If quantam mechanics was openly embraced. Just think. Perhaps it may lead you somewhere. We don't live on a flat earth. And to think that people still believe this.

                                                                                                                                    [Edit]

Well the human race isn't expected to go extinct anytime soon, so I don't know where you're getting that bit from. Second, this isn't an article on theism, and it really bears no relevance here. Third, did you say killing defies the law of natural selection? ~ UBeR 18:08, 22 May 2007 (UTC)

South American Hurricane

At first I thought this was vandalism, but the hurricane in the South Atlantic occurred March 26-28, 2004. Simesa 02:50, 25 May 2007 (UTC)

Thanks for the edit. Sometimes it's hard to spot mistakes like that, and even more so when the reference cited doesn't work. I've replaced it with a news link dated from around the time the storm happened. ~ UBeR 03:02, 25 May 2007 (UTC)

Rising Water

"sea level rise of not more than 0.5 m (1.6 ft) is expected through the 21st century, with an average annual rise of 0.0004 m (0.0013 ft) per year"

This doesn't make any sense. If the sea level is expected to rise .5 m over the course of 100 years, the average annual rise would be .005 m.

spread of disease

I removed one link, it misrepresented an actual "disease control expert". One link leads nowhere. Another link to Sarah Boseley, health editor at the guardian. Her article covers NHS contingency plans in the event of a heatwave more than anything. Her profile @ guardian: won journalism awards for covering the spread of AIDS in Africa. AIDS is not linked to climactic weather. --Dean1970 04:43, 24 June 2007 (UTC)

EcoSystems

Ref #43. "grass established in antarctic for the first time" - is that factually correct?, i'm not sure. Person he interviewed said grass was taking hold in areas he hasn't observed it to grow before (so it does grow there?). Also Link [9]. --Dean1970 13:01, 25 June 2007 (UTC)

Pine beetles

There is an ongoing massive Mountain pine beetle outbreak in British Columbia, which at least in part is blamed on the recent reduction in the severity of winters: temperatures down to -30°C to -40°C for at least several days kill most mountain pine beetles and have kept outbreaks in the past contained. The numbers are quite shocking: while most pine trees are effected, 80% of BC's mature lodgepole pine trees, the province’s most abundant commercial tree species, are expected to be dead by 2013. Almost half are dead already. No kidding. Other Canadian states are fearing (and observing) a spread East. Both the ecological and economical impact are great, and the effect is very visible and immediate. I've been looking for a mention of it on any of the "effects of global warming" sites, but haven't found any, nor am I quite sure where the best place is to insert it. Any Canadians out there wanna rectify this? An Effects of global warming on Canada article like the existing Effects of global warming on Australia page may be warranted (hey, you also have your polar bears and Northwest passage). Afasmit 08:39, 20 August 2007 (UTC)

I've seen some conference papers on this but don't recall the author. There's published documentation out there somewhere; feel free to go ahead and find it and cite it here. Raymond Arritt 13:26, 20 August 2007 (UTC)

The pine beetle population would be killed by the colder Candian climate which spreads into the Norhtern US. That has been happening for centuries. It's how nature works, but now due to Global Warming, which causes warmer winters, the Pine Beetle population is not drastically killed, now its only some. So, do to that the Pine Beeltes destroy more Pine trees in the Northern US and Canada. gameplaya 9:31 18 September 2007

Loss of Arctic ice leaves experts stunned

Not sure where this news item fits in -- the only mention of sea ice is under positive feedbacks. Some quotes:

The Arctic ice cap has collapsed at an unprecedented rate this summer.... Experts say they are "stunned" by the loss of ice, with an area almost twice as big as the UK disappearing in the last week alone. So much ice has melted this summer that the Northwest passage across the top of Canada is fully navigable, and observers say the Northeast passage along Russia's Arctic coast could open later this month.

Dr Serreze said: "If you asked me a couple of years ago when the Arctic could lose all of its ice then I would have said 2100, or 2070 maybe. But now I think that 2030 is a reasonable estimate. It seems that the Arctic is going to be a very different place within our lifetimes, and certainly within our childrens' lifetimes."

Wow. ←Ben^B4 02:47, 6 September 2007 (UTC)

You may need a better source. Brusegadi 03:43, 6 September 2007 (UTC)

Are you referring to The Guardian, David Adam, the US National Snow and Ice Data Centre, or Mark Serreze? Dr. Serreze seems to be an expert. ←Ben^B4 04:18, 6 September 2007 (UTC)

To the guardian. The other sources seem better suited to report on science stuff; I failed to locate the links to them on your initial post. Also, please excuse my ignorance on British media. The guardian seems to be more prominent then I thought. Cheers, Brusegadi 04:38, 6 September 2007 (UTC)

Mark is definitely an expert on this topic. As with anyone else his outlook may turn out to be wrong, but his views certainly count as a reliable source. Raymond Arritt 04:36, 6 September 2007 (UTC)

Since August 23, I've been updating the retreat of the Arctic ice in the Polar ice packs article and a link to it would be fitting here. The figures there are way outdated though (2005); if anyone could supply newer graphs that would be great. Afasmit 05:36, 6 September 2007 (UTC)

I went ahead and added a few lines to the "positive feedback, retreat of sea Ice" section, though the accelerating loss also effects ecologies and the thermohaline circulation perhaps.Afasmit 06:12, 6 September 2007 (UTC)

Recent comments by some of the scientists contributing to the IPCC report evidence their concern that what they are observing now is outside the range of all the scenarios being considered. Global warming is not a theory, its an observation. What's theoretical is how fast its accelerating, and how much the observed acceleration is outside the modeled range on which the consensus of scientists was agreed even a few years ago.

The rate of loss accelerating

The Arctic has now lost about a third of its ice since satellite measurements began thirty years ago, and the rate of loss has accelerated sharply since 2002. Dr Serreze said: "If you asked me a couple of years ago when the Arctic could lose all of its ice then I would have said 2100, or 2070 maybe. But now I think that 2030 is a reasonable estimate. It seems that the Arctic is going to be a very different place within our lifetimes, and certainly within our childrens' lifetimes."

Rktect 11:44, 5 September 2007 (UTC)

The above has been reverted three times to remove it from the more conservative main global warming article Rktect 11:49, 6 September 2007 (UTC)

Over on Intergovernmental Panel on Climate Change#History and studies suggesting a conservative bias, understating dangers there are some things indicating that the consensus estimates are likely low. There is also this paragraph, the status of which I'm unsure of:

The CO₂ emissions growth rate from 2000 to 2004 was greater than for the most fossil-fuel intensive of the IPCC emissions scenarios developed in the late 1990s. Arctic ice cover is retreating more rapidly than estimated by any of the eighteen computer models used by the IPCC. Climate models used by the IPCC are overestimating how much carbon the oceans are absorbing and underestimating the rate at which CO₂ will rise in future.

←Ben^B4 14:58, 6 September 2007 (UTC)

Should the sea ice bit be split? There seems two things to me: 1) a the positive feedback and 2) The effects of less sea ice affecting polar bears, ecosystems etc. etc. The recent acceleration would be more appropriate in this part. The positive feedback should also be expanded to indicate this only has an effect in summer and there are also other feedbacks eg on evaporation from open sea which affects clouds. Ice albedo effect probably dominates in summer. Some refs for this would be needed. crandles 12:42, 6 September 2007 (UTC)

I would think so. ←Ben^B4 14:58, 6 September 2007 (UTC)

How do the record maximums of the antarctic ice sheet fit into all of this? Zoomwsu 18:55, 9 October 2007 (UTC)

Source for the "record maximum"? Antarctic sea ice patterns are changing. Some parts are metting, some parts are increasing. There currently is some net increase that is caused by increased precipation (simplified, warmer air carries more humidity, which, because it is still f*ing cold there, falls as snow onto the existing ice and increases its thickness, thus keeping it around somwehat longer). See e.g. [10]. --Stephan Schulz 19:12, 9 October 2007 (UTC)

(a) there is no max (b) you're confusing ice sheet and sea ice William M. Connolley 19:10, 9 October 2007 (UTC)

A source for the record extend of the Antarctic sea ice. It's only 1% over the previous max and there basically is no data pre-1979, but it seems somewhat befuddling. Afasmit 19:46, 9 October 2007 (UTC)

Ah, sorry. I was confused because the same site had already announced a max earlier this year but then recalculated and decided it wasn't quite. This must be a new one.I'd caution about believing this too much as well before it has time to be confirmed. Nonetheless I'm perfectly happy with the idea that Antarctic sea ice is close to a max (within the satellite era; it was almost undoubtedly higher earlier, before 1979, but we don't have good obs for then) William M. Connolley 20:03, 9 October 2007 (UTC)

Negative feedback in GCMs?

The negative feedback section details natural carbon cycle absorbtion then follows with:

The impact of these negative feedback effects in relation to the positive feedback effects are part of IPCC's global climate models.

I think this is (or is close to being) incorrect. GCM generally don't have carbon cycle feedback built in - they are just told what GHG levels to use. Obviously the GHG figures the models are told to work with do take account of natural absorbtion of carbon but is saying 'part of GCMs' wrong? crandles 15:08, 10 September 2007 (UTC)

Since the GCM results depend on the positive feedback adjustments of their inputs, I think it's fine. ←Ben^B4 15:45, 10 September 2007 (UTC)

"like nuclear war"

Dear experts, please tell me how much of this is hyperbole:

LONDON, Sept 12 (Reuters) - Climate change could have global security implications on a par with nuclear war unless urgent action is taken, a report said on Wednesday.

The International Institute for Strategic Studies security think-tank said global warming would hit crop yields and water availability everywhere, causing great human suffering and leading to regional strife....

"The most recent international moves towards combating global warming represent a recognition ... that if the emission of greenhouse gases ... is allowed to continue unchecked, the effects will be catastrophic -- on the level of nuclear war," the IISS report said....

Overall, it said 65 countries were likely to lose over 15 percent of their agricultural output by 2100 at a time when the world's population was expected to head from six billion now to nine billion people.

I don't know what nuclear war would be like, but 15% less crops seems pretty mild. Where agriculture is already sufficient, diets will simply move from meat to vegetable proteins, because crop price increases will be amplified in livestock. Where people were starving to begin with, more will starve. But it's hard to imagine that by 2100 all of the world's farming won't be industrialized.

The report is at http://www.iiss.org/publications/strategic-survey-2007 -- this is the only thing in the the executive summary about global warming:

Climate Change: Security Implications and Regional Impacts

International moves towards combating global warming indicate recognition of the need to curb emissions of greenhouse gases. Even if eff ective measures are adopted, there will still be unavoidable impacts on the environment, economies and human security. This essay examines likely consequences of climate change for individual regions, and the implications for security. It says: ‘The security dimension will come increasingly to the forefront as countries begin to see falls in available resources and economic vitality, increased stress on their armed forces, greater instability in regions of strategic import, increases in ethnic rivalries, and a widening gap between rich and poor.’

I take it when the press goes overboard, it doesn't help the cause of mitigation much because it gives deniers ammunition? ←Ben^B4 19:11, 12 September 2007 (UTC)

Apocalypse possible?

It may be that I have not read the article good enough, but I think it fails to discuss the potential of global warming leading to a future apocalypse (meaning that the Earth eventually becomes uninhabitable to human life). If this is a real possibility in the future, it needs to be addressed explicitly. I don't know its likelihood (let alone whether it is even scientifically plausible), but at least it is not hard to fantasize about a Venus-like scenario where the situation spirals out of control (one bad thing leads to another bad thing and so on). For instance, increased temperatures make the tundras release more greenhouse gases, further raising sea levels, affecting the Earth's albedo, increasing temperatures even more, and so on. Relrel (talk) 06:40, 19 November 2007 (UTC)

Never heard such scenario being possible. Brusegadi (talk) 06:54, 19 November 2007 (UTC)

Thanks for responding. OK, if it's true, I think it would be a good idea to state explicitly that no studies have suggested that a runaway greenhouse effect is possible on Earth. However, take a look at this quote that suggests otherwise:

We have to be extremely concerned about processes such as burning of fossil fuels in large volumes that might (we don't know for sure because the scientific questions are complex) have the potential to trigger a runaway greenhouse effect and produce on the Earth atmospheric conditions such as those found on Venus.

— http://csep10.phys.utk.edu/astr161/lect/venus/greenhouse.html

--Relrel (talk) 09:51, 19 November 2007 (UTC)

• Much pain and agony has resulted from astronomers commenting on Earth's climate. Raymond Arritt (talk) 15:43, 20 November 2007 (UTC)

Agreed! Brusegadi (talk) 00:48, 21 November 2007 (UTC)

A simple calculation leads to this scenario: In about 0.5 to 1 billion years the solar luminosity is about 5 to 10 per cent higher than today. It is believed that about this time Earth will become uninhabitable due to a runaway greenhouse effect and evaporating oceans. According to the Stefan-Boltzmann law this will be equivalent to a rise in temperature of about 3.5 to 7 °C. This is not really far from the more pessimistic estimates for 2100. One may conclude that a greenhouse-related shift in Earth's thermal radiation equilibrium equivalent to a 10 per cent higher luminosity might lead to a similar runaway-effect. And if this will eventually be the case, a few millennia (from energy conservation) might be sufficient to evaporate all oceanic water. The atmospheric pressure will then be about 20 times higher with the atmosphere consisting mainly of water vapor (95 per cent) and surface temperatures between 300 and 400 °C (Venus at Earths orbit would have about 360 °C). Thus, I am actually surprised that this terrifying scenario seems to be no topic in science or even in the yellow press.--SiriusB (talk) 12:07, 20 November 2007 (UTC)

If the yellow press has not fed on it, then perhaps the calculations are way too simple... Brusegadi (talk) 00:48, 21 November 2007 (UTC)

The Earth with its greenhouse effect is far from a S-B blackbody. A 10% shift in luminosity (~40 W/m^2) would represent a 25 °C increase in temperature ignoring additional positive feedbacks. Yes, a 25 °C would be dire, but it is much different from the ~3 °C temperature change expected from the ~4 W/m^2 radiative forcing expected from CO2 increases. Dragons flight (talk) 01:19, 21 November 2007 (UTC)

Do you know any references (that might be cited in the article)? Especially where do the 25 °C come from (it suggests an almost linear relationship between solar input and absolute temperature)? Anyway, your estimate suggests that the expected temperature increase in the 21st century can reach at least 10% of the critical limit beyond that Earth would be "killed". What would happen if not only petroleum but also methane hydrate would be consumed by industry, or, even worse, large amounts of methane escapes from the oceans, maybe due to a new Storegga Slide (e.g. as shown fictionally in Frank Schätzing's "Der Schwarm")? Methane has a much higher greenhouse potential then CO_2, thus in a rule-of-the-thumb estimate a factor 10 increase of the 2000-2100 greenhouse boost might be easily achievable. Or would negative feedbacks push the critical limit to far beyond anything, mankind can do to Earth?--SiriusB (talk) 08:58, 21 November 2007 (UTC)

The Permian–Triassic extinction event is interesting. One of the possible causes is a volcanic release of CO2 which may have doubled the atmospheric concentration of the gas. Feedbacks kicked in and led to an increase of 6C at the equator, the global average would have been higher. It wasn't a runaway to Venusian conditions, but under analogous conditions a trip to the grocery store would likely be quite disappointing. But how much it relates to the Earth today is a good question: the continents were arranged differently, and the thermohaline may have functioned differently. It is, however, food for thought. Sagredo^Discussione? 05:37, 1 December 2007 (UTC)

From my (admitedly 8 years ago) geology degree, I think the Late Palaeocene Thermal Maximum would be a better comparison than the End-Permian extinction. There is (or was, when I studied it) good evidence that the LPTM was caused by global warming casued by Methane Hydrate release (which itself had been triggered by earlier global warming). (Unfortunatley, there is no Wiki article on the subject, and I haven't found a decent one by Googling). The cause of the End-Permian event, I believe, is still not resolved, and has been attributed to a wide variety of causes.

At any rate, the earth has experienced natural global warming comparable to and greater than that predicted as a result of human activity, without triggering a Venus-like runaway greenhouse effect. IMO, the world could easily survive and recover from the worst (likly) case scenarios, and humanity - being tough and adaptable - would survive as well. (That's not to say we wouldn't get the extinctions of numerous species, collapse of civilization, mass human casulties, etc. But the Earth, and at least some humans, would survive). Wardog (talk) 16:24, 20 December 2007 (UTC)

After reading this interesting discussion, it seems (to me) that the issue of a runaway greenhouse effect is debatable, implying that the likelihood of this event occurring is non-zero. Isn't this a convincing case for including a section on this (or at the very least a mentioning) in the article? --Relrel (talk) 16:45, 9 December 2007 (UTC)

Uncited sources

This article has a list of sources in the "References" section, though they are not referenced to in the text of the article. Please cite them in the text, or consider moving them to an "Additional reading" section or simply deleting them. ~ UBeR 23:19, 30 November 2007 (UTC)

Hello, UBeR. I agree - I eliminated the ones not being used and fixed the duplicates. The other references are still in fairly bad shape, though - I'll try and fix them up over the next while. Thanks, Hal peridol 03:34, 1 December 2007 (UTC)

Hey, get work, Hal peridol. Appreciate it. I can also fix some refs. Overall the article is pretty messy though. ~ UBeR 07:01, 1 December 2007 (UTC)

Lead Image

User:Boehner removed the lead image in this article in two edits, with the first edit asking for a source of the image, and the second edit removing the caption along with the image. I restored the image with a new caption stating the source of the image as the third assessment report of the IPCC. If anyone would like to improve the caption, there is quite a significant essay on its origin and meaning on the image description page. - Enuja (talk) 19:20, 24 December 2007 (UTC)

Thanks! Brusegadi (talk) 20:07, 24 December 2007 (UTC)