tag:blogger.com,1999:blog-3046701423623795423.post3233271501166659463..comments2024-03-25T04:43:08.153-07:00Comments on Arctic News: How much will temperatures rise?Sam Caranahttp://www.blogger.com/profile/12376449209858411775noreply@blogger.comBlogger7125tag:blogger.com,1999:blog-3046701423623795423.post-57451366064349987452013-04-07T18:00:30.587-07:002013-04-07T18:00:30.587-07:00One thing I am becoming aware of is that senior wr...One thing I am becoming aware of is that senior writers in the Earth science community (eg Tim Lenton and Will Steffen) distinguish between "tipping points" (TP) and "tipping elements" (TE). In their writing and thought, positive feedbacks such as release of old carbon from the Arctic may be a TE , but not a TP. Tipping points are much larger events, eg transition to an ice free world. I think this is confusing. <br /><br />The following paper may avoid both terms - at least the abstract does: van Huissteden J, Dolman AJ. Soil carbon in the Arctic and the permafrost carbon feedback. Current Opinion in Environmental Sustainability. 2012; 4(5): 545-51.<br /><br />Lenton in a new paper (Lenton T. Arctic Climate Tipping Points. AMBIO. 2012; 41(1): 10-22) states: "There is widespread concern that anthropogenic global warming will trigger Arctic climate tipping points. The Arctic has a long history of natural, abrupt climate changes, which together with current observations and model projections, can help us to identify which parts of the Arctic climate system might pass future tipping points. Here the climate tipping points are defined, noting that not all of them involve bifurcations leading to irreversible change. {CB comment - if so then they would seem more TEs?} Past abrupt climate changes in the Arctic are briefly reviewed. Then, the current behaviour of a range of Arctic systems is summarised. Looking ahead, a range of potential tipping phenomena are described. This leads to a revised and expanded list of potential Arctic climate tipping elements, (CB: sic) whose likelihood is assessed, in terms of how much warming will be required to tip them. Finally, the available responses are considered, especially the prospects for avoiding Arctic climate tipping points"<br /><br />Or, more clearly, in Lenton TM. Early warning of climate tipping points. Nature Climate Change. 2011; 1: 201-9.): A climate ‘tipping point’ occurs when a small change in forcing triggers a strongly nonlinear response in the internal dynamics of part of the climate system, qualitatively changing its future state. Human-induced climate change could push several large-scale ‘tipping elements’ past a tipping point. Candidates include irreversible melt of the Greenland ice sheet, dieback of the Amazon rainforest and shift of the West African monsoon. Recent assessments give an increased probability of future tipping events, and the corresponding impacts are estimated to be large, making them significant risks. Recent work shows that early warning of an approaching climate tipping point is possible in principle, and could have considerable value in reducing the risk that they pose." <br /><br />Lenton et al's best known paper on this topic is probably Lenton TM, Held H, Kriegler E, Hall JW, Lucht W, Rahmstorf S, et al. Tipping elements (sic) in the Earth’s climate system. Proceedings of the National Academy of Science USA. 2008; 105(6): 1783-5.<br /><br />This refers to TEs yet the map in that paper seems to suggest large-scale transformations..<br /><br />To me it seems a matter of degree, with TE at one end of the spectrum and TP at the other - and everything in between being a mixture - but I think many people will use the two terms as synonyms<br /><br />BTW there is very little published on the "ecosocial" TPs likely to arise from Earth system TEs/TPs; I am working on that.Global Change Musingshttps://www.blogger.com/profile/10414537060472660654noreply@blogger.comtag:blogger.com,1999:blog-3046701423623795423.post-41518493285947354692013-04-07T15:07:19.874-07:002013-04-07T15:07:19.874-07:00Quite frankly, I think we're just lucky that m...Quite frankly, I think we're just lucky that methane has as yet not entered the Arctic atmosphere in large quantities. <a href="http://arcticmethane.blogspot.com/p/quotes.html" rel="nofollow">Shakhova et al.</a> in 2008 considered release of up to 50 Gt of predicted amount of hydrate storage as highly possible for abrupt release at any time. By comparison, the total amount of methane currently in the atmosphere is about 5 Gt. Back in 2002, Malcolm Light, contributor to this blog, warned about the hazard of seismic activity in the Arctic at a Geophysical Congress on methane hydrates, earthquakes and global warming (see poster at the bottom of <a href="http://arctic-news.blogspot.com/p/seismic-activity.html" rel="nofollow">this post</a>).Sam Caranahttps://www.blogger.com/profile/12376449209858411775noreply@blogger.comtag:blogger.com,1999:blog-3046701423623795423.post-89611714685454373512013-04-07T14:31:17.467-07:002013-04-07T14:31:17.467-07:00What timescale would you give for that?
Would th...What timescale would you give for that? <br /><br />Would the amount of time taken be cut in half, for example the runaway occurs in around 2020 or something along those lines, or would it happen during the months following the melt out or earth quake in the Arctic. Liam Lynchhttps://www.blogger.com/profile/05889435638378730093noreply@blogger.comtag:blogger.com,1999:blog-3046701423623795423.post-55928966683895994082013-04-07T13:59:23.418-07:002013-04-07T13:59:23.418-07:00The white line in image 4 gives a projection of ho...The white line in image 4 gives a projection of how runaway global warming could eventuate, based on a business-as-usual scenario. As you say, things could happen sooner, e.g. if the Arctic melted out this year, which is within the margin of errors of projections based on observations, or if seismic activity in the Arctic caused hydrate destabilization and subsequent release of huge amounts of methane into the atmosphere. Sam Caranahttps://www.blogger.com/profile/12376449209858411775noreply@blogger.comtag:blogger.com,1999:blog-3046701423623795423.post-7146707716741287542013-04-07T13:36:42.278-07:002013-04-07T13:36:42.278-07:00If the Arctic melted out this year, what changes w...If the Arctic melted out this year, what changes would ensue in the projection to the increase in Arctic temperature and the onset of Runaway global Warming.<br /><br />I suppose things would happen somewhat sooner. <br /><br /> Liam Lynchhttps://www.blogger.com/profile/05889435638378730093noreply@blogger.comtag:blogger.com,1999:blog-3046701423623795423.post-48707412837078429142013-04-06T11:09:20.917-07:002013-04-06T11:09:20.917-07:00Really, Today is an all hands on deck moment to sa...Really, Today is an all hands on deck moment to save Earth.<br />We need to shield the Arctic from incoming radiation this year, get a handle on stopping methane release from sea floor and temperature rise. We need to stimulate the world's oceans by adding proper nutrients to stimulate biological productivity in an effort to both sequester carbon and to provide food for mankind.<br />To do this effectively so Earth survives involves alteration to the value of money by Act of God'..<br />The fact Antarctic is showing huge methane anomaly and Arctic is showing huge plumes of heat indicates time is short indeed to take action. If we can see what's obviously happening and mankind can act together and hold the peace in an effort to stop this in a full tilt attempt to zoom up economy and potential hope then our earth lives. But this is what needs war upon today.Dale Lananhttps://www.blogger.com/profile/05409842680440987251noreply@blogger.comtag:blogger.com,1999:blog-3046701423623795423.post-10826901679481281702013-04-06T08:10:46.141-07:002013-04-06T08:10:46.141-07:00Isn't runaway global warming already here? Isn...Isn't runaway global warming already here? Isn't the evidence of this fact already found in the temperature record and positive feedbacks now occurring?<br /><br />There is also the massive methane releases being measured -- this doesn't happen unless we've already passed the tipping points.<br /><br />The IPCC cannot be considered the authority anymore on what will happen, due to their gigantic oversight (which was a deliberate political decision) and the years-long delay at publishing results.<br /><br />I am puzzled by the false optimism that I read online. There is nothing in the record to indicate this is justified other then "hopium". I think we are seriously deceiving ourselves at what has <b>already</b> occurred and what it means for our future.<br /><br />Anonymousnoreply@blogger.com