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Speed of tipping in Greenland
@Pinkygonzales: you've changed the lede a couple of times, saying that the speed of a tipping point in Greenland may take centuries rather than millennia. The source says A complete disappearance of the Greenland ice sheet would occur over a period of several millennia due to increased melting of the ice sheet
. You may be confused with tipping points in Antarctica, where worst-case scenarios indicate that tipping under medium global warming levels may take place faster than that. Femke (talk) 10:34, 23 April 2022 (UTC)
That Nature paper also indicates that the Greenland ice sheet is set to melt on a timescale of millennia, see figure 2b. Misrepresenting sources is a form of WP:disruptive editing, which may get you blocked from editing. Femke (talk) 13:55, 23 April 2022 (UTC)
- @Femke:The wikipedia entry states: "Tipping points are not *necessarily* abrupt. For example, with a temperature rise between 1.5 and 2 degrees Celsius, large parts of the Greenland ice sheet are *likely* to melt, yet the melting process *may* take centuries." This is a qualitative statement. It is not a statement of fact.
- From the cited reference at Journal Nature: "*Even if* anthropogenic warming were constrained to less than 2 °C above pre-industrial, the Greenland and Antarctic ice sheets will continue to lose mass this century, with rates similar to those observed over the past decade. However, *nonlinear responses cannot be excluded*, which *may* lead to larger rates of mass loss."
- In other words, assumptions are being made that Earth's climate will stay below 2C in the first place, which it may not, and that the rate of melt will be linear, which it may not be. If the temperature rises above 2C and/or melt rate occurs in non-linear fashion, estimates that melting could take "thousands of years" are simply not accurate.
- Please cite a reliable source that states that ice melt in Greenland will take millennia based on current environmental factors and/or scientific consensus. The initial reference article was published in 2018 and was an editorial take on the actual research paper I posted. This article is about tipping points, not complete ice loss. Tipping points are predicted to lead to complete ice loss, not the other way around. Complete ice loss is not a prerequisite for tipping points to occur. Pinkygonzales (talk) 14:54, 23 April 2022 (UTC)
- placed back after being deleted by Pinkygonzales, response to earlier version of comment The 2018 nature paper does assume nonlinearities in its estimate of timescales in figure 2b, which is a figure actually about tipping. This is evidenced by the paragraph starting with
On longer timescales
, which talks about various nonlinearities they have included in their model. The sentence about mass loss this century does not refer to the tipping characteristics of the Greenland ice sheet, and is irrelevant to this discussion.
- placed back after being deleted by Pinkygonzales, response to earlier version of comment The 2018 nature paper does assume nonlinearities in its estimate of timescales in figure 2b, which is a figure actually about tipping. This is evidenced by the paragraph starting with
- The IPCC confirms this, indicating that even with sustained warming of between 3 and 5 °C, a near-complete melt of Greenland will take millennia:
At sustained warming levels between 3°C and 5°C, near-complete loss of the Greenland Ice Sheet and complete loss of the West Antarctic Ice Sheet is projected to occur irreversibly over multiple millennia (medium confidence)
(page 71) Femke (talk) 14:31, 23 April 2022 (UTC)- Deletion was due to a formatting mistake in my original comment, my apologies. Your original point was that I had "changed the lede a couple of times," which I have not done. The lede was qualitative. It is no less accurate to say that a tipping point "could" occur within centuries as it is to say that it "could" take millennia. Both statements are true, yet they are not equally likely to occur based on current climate trends. The original reference was to a 2018 publication. The reference I have cited in this reply was published on April 5, 2022. My edit does not violate Wikipedia policy. Pinkygonzales (talk) 16:59, 23 April 2022 (UTC)
- No worries, it seems like you made the same mistake in the article too, removing multiple improvements in this edit: [1].
- The Greenland tipping point is a change in state from having ice to being almost ice-free, so the statement about complete iceloss is a statement about the timescale of this tipping point (see f.i. definition in this carbon brief article. The IPCC explicitly gives this as an example of non-abrupt tipping, with high confidence.[1] The NSIDC reference you cited does not mention the Greenland ice sheet tipping point, so is again irrelevant. Femke (talk) 18:21, 23 April 2022 (UTC)
- How about we agree to split the difference with the statement, "could take centuries to millennia"?
- Your newly cited reference is from February 2020. Meanwhile in this reference from PNSAS in May 2021, they state:: "We reveal early-warning signals for a forthcoming critical transition from ice-core-derived height reconstructions and infer that the western Greenland Ice Sheet has been losing stability in response to rising temperatures. We show that the melt-elevation feedback is likely to be responsible for the observed destabilization. Our results suggest substantially enhanced melting in the near future." The title is, "Critical slowing down suggests that the western Greenland Ice Sheet is close to a tipping point."
- "Near future" does not imply "millennia" before a tipping point is reached. Many experts are currently debating whether it has actually already happened. At very least, it is reasonable to agree that there are scientific opinions that differ on the matter, and range from "already happened" to "thousands of years from now."
- On a personal note, you have questioned my motivations, accused me of having committed a potentially ban-able offense, and called my sources irrelevant. I would appreciate it if we could keep the conversation to the facts at hand. Pinkygonzales (talk) 18:58, 23 April 2022 (UTC)
- Deletion was due to a formatting mistake in my original comment, my apologies. Your original point was that I had "changed the lede a couple of times," which I have not done. The lede was qualitative. It is no less accurate to say that a tipping point "could" occur within centuries as it is to say that it "could" take millennia. Both statements are true, yet they are not equally likely to occur based on current climate trends. The original reference was to a 2018 publication. The reference I have cited in this reply was published on April 5, 2022. My edit does not violate Wikipedia policy. Pinkygonzales (talk) 16:59, 23 April 2022 (UTC)
- The IPCC confirms this, indicating that even with sustained warming of between 3 and 5 °C, a near-complete melt of Greenland will take millennia:
There is a difference between a tipping point having passed (the moment tipping becomes inevitable) and a system having tipped into a new state. For Greenland, the tipping point may have passed, but it'll still take thousands of years to tip to its new state. My edit to clarify this difference was reverted. Femke (talk) 19:06, 23 April 2022 (UTC)
- Apologies if I've been too harsh here. I recently had a bad experience with an editor who misused multiple accounts to disrupt this article, and I wasn't quite sure if that scenario was repeating itself. (I now know you're not the same person.) From here onwards, I'll make sure to be more mindful, as new editors should make mistakes to learn :). Femke (talk) 16:59, 25 April 2022 (UTC)
References
- ^ Lee, June-Yi; Marotzke, Jochem; Bala, Govindasamy; Cao, Cao; et al. (2021). "Chapter 4: Future global climate: scenario-based projections and near-term information" (PDF). IPCC AR6 WG1. Table 4.10.
Thwaites
I propose deleting the last sentence of the lede (However, a 2021 study by the American Geophysical Union states that the Thwaites ice shelf in Antarctica had the potential to shatter by 2025.
because
- It's based on a pre-print and a conference abstract, not on a peer-reviewed paper. It's primary, whereas we should be the lede primarily on secondary sourcing / review papers.
- Neither source describes the ice shelf disappearing as a tipping point, and the body of our article does neither. As I understand it, the Thwaites glacier is a tipping element, not the ice shelf.
- I can't find anything about the year 2025 in either source. Five years from December 15 2021 is December 15 2026.. Femke (talk) 19:45, 23 April 2022 (UTC)
- The actual statement made by AGU was "two to five years" from the time of the report, meaning collapse could realistically occur by late 2023. The report is published for review, and unless you can provide a recent study that conflicts with their findings, there is no reason the citation should be considered insufficient.
- Official Presentation: https://www.youtube.com/watch?v=uBbgWsR4-aw&t=2255s (Bookmarked at 37:35 for specificity)
- Associated Research: https://tc.copernicus.org/preprints/tc-2021-288/
- As for the comment about the Thwaites Ice Shelf being a tipping element and not a tipping point, it is the only thing keeping the Thwaites Glacier from imminent collapse into the sea, and potentially the Pine Island glacier with it. Your opinion of its severity vs. other tipping points is not relevant. The collapse of a tipping element is by definition the indication that a tipping point has been crossed. They are not separate and unrelated. Pinkygonzales (talk) 20:05, 23 April 2022 (UTC)
- The use of WP:PREPRINTs is generally discouraged on Wikipedia. The same goes for panel discussions. So we need a better source, which should be doable, even if its a bit older.
- What I meant to say is that the Twaites glacier has a tipping point and is a tipping element. The Thwaites ice shelf itself I've never seen described as a tipping element / having a tipping point. The Thwaites glacier is one the riskiest tipping points on the short term, but we need better sourcing to state this. I'm not sure if tipping of this glacier is guaranteed if the ice shelf is melted: the sources don't seem to make this claim. Femke (talk) 20:39, 23 April 2022 (UTC)
- I'm fine to remove the citation of the panel discussion as long as the study itself remains. Unless there is different/better/more recent research on the topic, the validity of the source should be recognized. It's not a media article or editorial, and their announcement itself was covered by the media as well. See also:
- NBC: https://www.nbcnews.com/science/environment/antarctic-ice-shelf-crack-raise-seas-feet-decade-scientists-warn-rcna8918
- BBC: https://www.bbc.com/news/science-environment-59644494
- Nature: https://www.nature.com/articles/d41586-021-03758-y
- USA Today: https://www.usatoday.com/story/news/world/2021/12/16/antarctica-glacier-collapse-raise-sea-levels/8924940002/
- (etc)
- The report makes clear that based on recent verified measurements, Thwaites ice shelf will likely melt and/or shatter within the decade, and specifically as soon as late 2023. It is also a fact that the Thwaites shelf is what holds the Thwaites Glacier back, and Pine Island vicariously through Thwaites. No shelf, no breaks. No breaks, a tipping point has been achieved. It was stated in the video presentation listed above that they don't know if complete collapse will take "decades or up to a century," but that collapse is unstoppable once the shelf goes.
- I'm not interested in an extended debate based on technicalities and personal opinions. Thwaites ice shelf is structurally critical to Thwaites Glacier. Without it, Thwaites Glacier will 100% collapse into the sea, and likely draw Pine Island Glacier with it. There is no transition point between the loss of the ice shelf and the collapse of the Glacier that would be considered "the real tipping point." Again, this entire article is about tipping points, not complete ice loss, so how long it takes for Thwaites and Pine Island to recede is secondary from the fact that they will, and therefore tipping points will have been reached. Pinkygonzales (talk) 21:30, 23 April 2022 (UTC)
- From Rosier 2021, it seems like the disintegration would take centuries for Thwaites, which I believe is considered abrupt in this context. Femke (talk) 20:45, 23 April 2022 (UTC)