Talk:Climate change

IPCC models are also "uncertain" in that they do not include all feedbacks

First reversion

Here is a diff for the first reverted text under discussion. NewsAndEventsGuy (talk) 12:13, 4 December 2012 (UTC)

I removed this recent addition to the lede by User:NewsAndEventsGuy:

"(...) (AR4 temperature projections) omit the effect of any climate system feedbacks that were not included in the models, i.e., greenhouse gas releases from thawing permafrost or methane hydrates."

I don't agree that this issue should be explained like this. In my opinion, the risks of climate change should be explained in a more generalized fashion, e.g., from effects of global warming#Physical impacts: "Human-induced warming could potentially lead to some impacts that are abrupt or irreversible (see the section on Abrupt or irreversible changes). The probability of warming having unforeseen consequences increases with the rate, magnitude, and duration of climate change." See also economics of global warming#Temperature. Enescot (talk) 01:55, 21 November 2012 (UTC)

Back up please and let us define what the "issue" is. The issue is not methane hydrates per se. The issue is certainty vs uncertainty with the specific temp ranges IPCC projected. We have not listed a single qualifier. For example, we only listed the ranges for the highest and lowest emissions scenarios IPCC used - there are others, especially higher ones, but we did not say that. We also did not say that the highest scenario used was run in AR4 without the available GCMs. When Betts (et al) did that later they bumped up the likely amount of warming. In listing these ranges we say nothing about the specific hedges IPCC stated. So the issue here is NOT about teaching about methane hydrates. The issue here is integrity in our coverage: we must not mislead readers into thinking the stated temp rangers are really rock solid except for one (and only one) unknown, the dangling issue of climate sensitivity. The issue is that the ranges were based on the best assumptions at the time, and in light of limited computing power. This creates an "uncertainty" in the layman's sense of the word. We have to address that to avoid giving a false sense of "certainty" in the lay reader's take-home message. Subsequent to your reverting my first attempt UNEP has released a new report, and I have incorporated additional RSs a revised attempt to address "the issue". Please see the article for the new attempt. NewsAndEventsGuy (talk) 16:07, 3 December 2012 (UTC)

BTW, the Warren paper is a literature review. NewsAndEventsGuy (talk) 16:18, 3 December 2012 (UTC)

The body text contains qualifiers, and the feedbacks section (undue weight in my opinion) also discusses uncertainty. You are selecting two sources which have not gone through the rigorous IPCC or US National Research Council peer-review and consensus process. I agree that the uncertainty in projections could be better explained, but I do not agree that you edit is an improvement in this regard. I should also note that the IPCC's best estimates are below the upper end of the "likely" ranges. Additionally the "likely" range is not based solely on model results, but reflects the expert judgement of IPCC authors of all available information, including uncertainty in the carbon cycle feedback.

You argue that the lede is misleading in its coverage of uncertainty. However, the lede uses the same word ("likely") as the IPCC to describe the likelihood of the projected range being correct. You imply that the IPCC's projections are out-of-date, but as I have commented previously, numerous other reliable sources are consistent with the IPCC's findings. If I can make a suggestion, perhaps you could post a draft revision here so that we can discuss the issue further. Changes to the lede are especially important, and I'm sure that other editors will be interested in any changes you propose. Enescot (talk) 04:49, 4 December 2012 (UTC)

Agree. Until we have an assessment of the weight of these uncertainties in comparison with the actual model uncertainties, it belongs in the in-depth articles. As it stands it provides (imho) undue weight/focus (literature wise) - it might turn out to be significant, but we as wikipedians are not the arbiters of this. --Kim D. Petersen (talk) 06:24, 4 December 2012 (UTC)

Re the Warren review. Methane release is not a primary focus of the paper (it is a short notice), and the timescales considered by Warren for methane release does not match the timescales considered here. (ie. methane over 1,000-100,000 years is not directly comparable to a timescale of 100 years). --Kim D. Petersen (talk) 06:31, 4 December 2012 (UTC)

Second reversion

Here is a diff for the second reverted text under discussion. NewsAndEventsGuy (talk) 12:16, 4 December 2012 (UTC)

For ease of reference, the reverted text reads (or should one say "read"?) as follows:

In addition, the models used in their report did not include various climate feedbacks that could greatly exacerbate these projections. According to the UNEP, even the climate projections in the IPCC’s next assessment "are likely to be biased on the low side relative to global temperature because none of the participating models include the permafrost carbon feedback."

This text was also reverted and the discussion is below NewsAndEventsGuy (talk) 12:33, 4 December 2012 (UTC)

Yes, it was reverted, and for good reasons - some already given above. But here is a major one: You cut down Warren's text about interaction factors into "climate feedbacks" - this is simply not correct. Of the 8 interactions that Warren summarizes in the introduction, only 1 of them is feedbacks. Feedback processes are a factor - but your focus/undue weight on this is not warrented (pun intended). And as i pointed out above - the timescales of some of these feedbacks is not comparable to the timescales that are discussed here .. or more clearly you cherry-pick from Warren here. --Kim D. Petersen (talk) 21:03, 4 December 2012 (UTC)

References for this thread

Reflist for above:

--Kim D. Petersen (talk) 06:19, 4 December 2012 (UTC)

Continuation of feedbacks discussion

As I've already stated, I do not agree with how uncertainty in the IPCC's temperature projections are discussed in the lede. One revision I've thought of is to simply move the quantitative IPCC projections from the lede to the "climate model" section, and replace them with "Continued greenhouse gas emissions at or above current rates would cause further warming the 21st century that would very likely be larger than that observed during the 20th century"[1]. The main text of the article has more information on the IPCC projections/feedbacks. As a result, my suggested revision would indirectly address the issue that NewsAndEventsGuy has raised. Enescot (talk) 05:23, 19 December 2012 (UTC)

Background observations, at this time I am not endorsing Enescot's suggestion nor proposing any other changes.

(A) IPCC's use of "likely" for these temp ranges means >66% certain, per ref footnote 4 in this version.

(B) Media usually talks about the chance that IPCC has over-estimated, however, in the absence of reasons to think one way or the other NPOV requires equal treatment of the possibility that their >66% certainty range is an under-estimate. See last section of this non-RS blog post (offered here for background purposes only)

(C) IPCC has more uncertainty for more warming. Each range started with a "best estimate", from which IPCC generated the range for which they have >66% certainty. To create the range, they subtracted a bit (40%) from the best estimate, but they added more (60%). See ref footnote 8 in this version.

(D) To my knowledge, IPCC AR4 (2007) has no discussion of mechanisms that might unexpectedly cause substantial reductions to atmospheric greenhouse gas concentrations or climate system responses, but they most certainly do talk about mechanisms that might possibly increase both.

(E) We say the different ranges exist due to use of models with differing climate sensitivity but that's just one factor. IPCC says there are different types of uncertainties, including "structural" ones. Examples include but are not limited to incomplete modeling of some feedback processes and not including others at all.

(F) IPCC's guidance note to AR4 authors observed that "Experts tend to underestimate structural uncertainty arising from incomplete understanding of or competing conceptual frameworks for relevant systems and processes."

(G) Arctic albedo is changing much faster than apparently expected. From sea ice loss, to Greenland's melt ponds and dusting of particulate from fires, to reduced extent and duration of snowfall, to timber-stand replacement (spruce in place of larch), the cryosphere appears to be sucking up heat it used to reflect back to space at an ever-faster rate.

We agree we need to treat uncertainty better. And that means better coverage of the possibilities IPCC could be under-estimating as well as over. The ranges after all are only stated with ">66% certainty". NewsAndEventsGuy (talk) 15:23, 19 December 2012 (UTC)

See the related thread below Talk:Global warming#Section on feedbacks NewsAndEventsGuy (talk) 07:01, 25 December 2012 (UTC)

Section on solar activity

This section contains useful content but I am concerned about some aspects of it. For a start, Svenmark's hypothesis gets a full paragraph, which I think is somewhat questionable. The article implicitly gives Svenmark's views considerably more weight than the extensive evidence supporting attribution to human activities (see attribution of recent climate change). Additionally, I don't see why James Hansen's views need to be mentioned. I can't see any reason why he needs to be directly quoted. Enescot (talk) 01:53, 3 December 2012 (UTC)

Its scar tissue from old wars. Probably time to revise it William M. Connolley (talk) 08:44, 3 December 2012 (UTC)

In addition to Svenmark's bit seeming overblown, in the current version the paragraph on the stratosphere and troposhere behaving differently seems out of place. Maybe some more glue could anchor it in this section better, or maybe it should be moved out.... maybe being revised to fit with observed temps?

As for Hansen, he has not provided "views" so much as a reference-able statement regarding a key observation from this last solar minimum.... it was a really low minimum, and yet the place still got warmer overall, contrary to the usual skeptical arguments that increases in temp are driven by sunspots. We did see such a minimum, we did see a temp increase, and if we are to mention this observation we need an RS from someone. If not an RS attributed to Hansen, what RS do you suggest be substituted in place of it? Or do you think we should not say anything at all about the skeptical argument being apparently contradicted with observation during this last solar cycle? NewsAndEventsGuy (talk) 09:46, 3 December 2012 (UTC)

I would like to keep the stuff about changes in the stratosphere and troposphere, but perhaps the issue could be explained more clearly. As for the Svenmark's hypothesis, I think it could be moved to attribution of recent climate change. The section on "views on global warming" could be revised, e.g., "However, some scientists and non-scientists question aspects of climate-change science, see list of scientists opposing global warming consensus."

I do not think it is necessary to quote Hansen. Personally I would prefer that information was added on the small contribution of solar activity to radiative forcing, as compared to anthropogenic forcings. In my opinion, the graph of changes in radiative forcing should be added to the article (below). The article states - "The effect of changes in solar forcing in recent decades is uncertain, but small, with some studies showing a slight cooling effect,[90][91] while others studies suggest a slight warming effect". I think this is quite a weak statement. Compare this with the EPA's comments on attribution [2][3], which I think are pretty robust.

Radiative forcing graph.

Enescot (talk) 01:34, 7 December 2012 (UTC)

I did not mean to suggest deleting the troposphere/stratosphere bit, just that it seems out of place under "solar activity". I mean, we're not talking about solar activity, we're talking about responses of different atmospheric layers. It would seem more at home in this section with just a bit of introductory glue.... something about how some have said warming is just due to "solar activity", but these different responses tell us otherwise. That would make it seem more at home in this section. If I come up with further comments on anything else you said, I will add them later. NewsAndEventsGuy (talk) 02:23, 7 December 2012 (UTC)

I've put together a draft replacement for the solar activity section. It's taken from attribution of recent climate change#Solar activity (sources are cited in that article). I've arranged the images to stop them from spilling over into the next thread. If other editors agree with my revision, I would arrange the images vertically inside the relevant section of the article:

Satellite observations of Total Solar Irradiance from 1979–2006.

Contribution of natural factors and human activities to radiative forcing of climate change. Radiative forcing values are for the year 2005, relative to the pre-industrial era (1750). The contribution of solar irradiance to radiative forcing is 5% the value of the combined radiative forcing due to increases in the atmospheric concentrations of carbon dioxide, methane and nitrous oxide.

"Since 1978, output from the Sun has been precisely measured by satellites.[6]:6 These measurements indicate that the Sun's output has not increased since 1978, so the warming during the past 30 years cannot be attributed to an increase in solar energy reaching the Earth. In the three decades since 1978, the combination of solar and volcanic activity probably had a slight cooling influence on the climate.

Climate models are unable to reproduce the rapid warming observed in recent decades when they only take into account variations in solar output and volcanic activity. Models are, however, able to simulate the observed 20th century changes in temperature when they include all of the most important external forcings, including human influences and natural forcings.

Another line of evidence against the sun having caused recent climate change comes from looking at how temperatures at different levels in the Earth's atmosphere have changed.[65] Models and observations show that greenhouse warming results in warming of the lower atmosphere (called the troposphere) but cooling of the upper atmosphere (called the stratosphere).[66] Depletion of the ozone layer by chemical refrigerants has also resulted in a strong cooling effect in the stratosphere. If the sun was responsible for observed warming, warming of both the troposphere and stratosphere would be expected."

Enescot (talk) 04:58, 13 December 2012 (UTC)

Sock comment removed

This is the Michigan-based IP sock again, from their alternative hangout (NW region of Florida). Effective now, I'm going to just work on article content so if this sock's external link-farm spam seems to spike (nature abhors a vaccuum) some of you may want to help patrol, revert his ext link spam, and most important of all, make sure to ask the involved eds to tell the server the block-clocks have restarted before the server erroneously thinks they expire. Here is the log and there is a lot of history on my talk page. NewsAndEventsGuy (talk) 00:28, 21 December 2012 (UTC)

Section on feedbacks

In my opinion, the "feedbacks" section of the article would benefit from revision. In particular, I'm concerned about how the section describes carbon cycle feedbacks. It makes some pretty bold statements, and implies that the IPCC's projections are biased downwards. While this may reflect the view of some experts, I am not convinced that it reflects a consensus view.

There is also the issue of how much space is devoted to carbon cycle feedbacks in relation to other important feedbacks. For example, refer to these summaries by the UK Royal Society (pp8-10) and US National Research Council pp26-27p200. Carbon cycle feedbacks are not the only factor that affect projections of future climate change. The water vapor feedback is important, yet it gets very little space. The same is true of the Stefan-Boltzmann law.

There is very little information on abrupt or large-scale changes in climate system. This issue has featured in the IPCC reports [4][5][6] and other assessments [7]. I think that this article should provide a better summary of the issue. Enescot (talk) 04:05, 25 December 2012 (UTC)

Distinction should be made between feedbacks that were

• well-quantified in the AR4 models, like the two you mentioned (water vapor feedback and Stefan-Boltzmann law),
• poorly quantified or not included in them, like large components of the carbon cycle and faster-than-expected albedo reduction in the cryosphere, which ties this discussion to our sister thread on "uncertainty".

I too would like to see better discussion of abrupt or large-scale changes in the climate system. NewsAndEventsGuy (talk) 05:57, 25 December 2012 (UTC)

I've put together a draft revision which I hope we can discuss.

"The climate system includes a range of "feedbacks" which alter the response of the system to changes in external forcings. Positive feedbacks amplify the response of the climate system to the initial forcing, while negative feedbacks dampen the response of the climate system to the initial forcing.

There are a range of feedbacks in the climate system, including water vapor, changes in ice-albedo (snow and ice cover affect how much the Earth's surface absorbs or reflects incoming sunlight), clouds, and changes in the Earth's carbon cycle (e.g., the release of carbon from soil). The main negative feedback is the energy which the Earth's surface radiates into space as infrared radiation (US NRC, 2003). According to the Stefan-Boltzmann law, if temperature doubles, radiated energy increases by a factor of 16 (2 to the 4th power).

Feedbacks are an important factor in determining the sensitivity of the climate system to increased greenhouse gas concentrations. Other factors being equal, a higher "climate sensitivity" means that more warming will occur for a given increase in greenhouse gas forcing (US NRC 2006). Uncertainty over the effect of feedbacks is a major reason why different climate models project different magnitudes of warming for a given forcing scenario. More research is needed to understand the role of clouds (NASA) and carbon cycle feedbacks in climate projections (American Meteorological Society).

The IPCC projections given in the lede span the "likely" range (greater than 66% probability, based on expert judgement) for the selected emissions scenarios. However, the IPCC's projections do not reflect the full range of uncertainty. The lower end of the "likely" range appears to be better constrained than the upper end of the "likely" range (Meehl et al 2007).

Large-scale and abrupt impacts

Climate change could result in global, large-scale changes in natural and social systems (Smith et al 2001). Two examples are ocean acidification caused by increased atmospheric concentrations of carbon dioxide, and the long-term melting of ice sheets, which contributes to sea level rise.

Some large-scale changes could occur abruptly, i.e., over a short time period, and might also be irreversible. An example of abrupt climate change is the rapid release of methane from permafrost, which would lead to amplified global warming. Scientific understanding of abrupt climate change is generally poor (US NRC, 2010, p3). However, the probability of abrupt changes appears to be very low (IPCC, 2001;CCSP, 2008, pp.2-6). The probability of abrupt climate change may increase with larger magnitudes of global warming. Additionally, more rapid global warming may increase the probability of abrupt climate change."

Enescot (talk) 04:15, 5 January 2013 (UTC)

Questions

• 1. Do you propose this draft to replace the entire feedback section in the current text?
• 2. Should your draft be evaluated in context that it is a complete response to the issues in our "uncertainty" thread, or in context that more draft text is coming with respect to "uncertainty"?

NewsAndEventsGuy (talk) 14:03, 6 January 2013 (UTC)

http://en.wikipedia.org/wiki/File:All_palaeotemps.png

Shouldn't an article on global warming include this picture http://en.wikipedia.org/wiki/File:All_palaeotemps.png for reference? I'm not particularly good with editing in images and it's a touchy subject, so figured I'd see if someone more knowledgeable would help out. For the record I believe humans are definitely affecting our climate in a warming manner (...words, not good with I am). Pär Larsson (talk) 18:47, 25 December 2012 (UTC)

As the hat-note says, "This article is about the current change in Earth's climate." It might be that that graph, going back more than 500 million years, would be more relevant at Climate change, which takes a longer view. This is such a vast subject area that we cannot cover much of it in any one article. --21:33, 25 December 2012 (UTC)

Magnetic field strength

I undid this addition [8]:

Magnetic field strength

Some recent (2006+) analysis suggests that global climate is correlated with the strength of Earth's magnetic field.

I don't think that fringe views should be discussed in this top-level article. The section on "other views" already states "some scientists and non-scientists question aspects of climate-change science,[194][196][197] see: list of scientists opposing global warming consensus." I've revised and moved the above edit to attribution of recent climate change. Enescot (talk) 04:17, 7 January 2013 (UTC)

Since when is the view "fringe"? -- Has any body of reputable scientists disparaged, in general, the idea that a relationship between climate and magnetic field strength can exist, or, in particular, the work of Courtillot, et al (who, in their conclusion, were careful to point out that magnetic field influences are only factor of many affecting climate; i.e., their work isn't the denialist polemic it seems you're attempting to imply)?--Mike18xx (talk) 19:23, 7 January 2013 (UTC)