Hi, It would be very helpful if someone could weigh in on what the latest research on CE and SLR actually indicates.
It seems as if early research on sunshade geoengineering found it promising for reducing ice melt. - But as Applegate and Keller (2015) wrote, with regards to Greenland, these groundbreaking earlier studies neglect feedbacks that may be vital for proper assessment of SRM's ability to reduce SLR. - Again in the Arctic, it seems that Jackson et al (2015) found that it was possible to remediate ice loss, but it would take a lot of SO2. - Looking at Antarctica, McCusker et al (2015) found that SRM could not preserve the West Antarctic ice sheet (because of upwelling of warm water, as I understand it). - Finally, Irvine et al’s review paper (2016) says that "While sunshade geoengineering could reduce sea-level rise, simulations employing more sophisticated models suggest that hysteresis in the response of the Greenland and Antarctic ice sheets to climate change could mean that there may be a limited ability to reverse some of the contribution to sea- level rise from the ice-sheets if deployment of solar geoengineering is delayed.” Attempting to read & assess this body of work leaves me with three outstanding questions: 1. Is preventing ice loss / ice restoration just one of those areas where we still don’t know how well SRM works? Or is there kind of an informal consensus about it? 2. If it’s still an unknown, is it even possible to better understand it — or will it always be relatively uncertain? About how much research (in years or papers) would we need to better understand it with some degree of consensus / certainty? Are there new approaches coming online to get a better handle on it? (I know these are hard questions). 3. Furthermore, I assume that SRM would help with the SLR from warming water and ocean expansion (?), but is the amount of expected SLR from ocean expansion low compared to the amount we get from melting ice? Thanks so much, Holly “not-a-climate-scientist" Buck > On Nov 3, 2017, at 08:21, Andrew Lockley <[email protected]> wrote: > > > https://www.washingtonpost.com/news/wonk/wp/2012/11/01/can-we-stop-the-seas-from-rising-yes-but-less-than-you-think/?utm_term=.7af0d50d549e > > <https://www.washingtonpost.com/news/wonk/wp/2012/11/01/can-we-stop-the-seas-from-rising-yes-but-less-than-you-think/?utm_term=.7af0d50d549e> > > > Subscribe > > <https://subscribe.washingtonpost.com/acquisition/?nid=top_pb_subscribe&promo=o3&oscode=RPWH&destination=http://www.washingtonpost.com/pb/news/wonk/wp/2012/11/01/can-we-stop-the-seas-from-rising-yes-but-less-than-you-think/&tid=nav_subscribe_logged_out> > Sign In > > <https://subscribe.washingtonpost.com/loginregistration/index.html#/loginhome/group/long?destination=https://www.washingtonpost.com/news/wonk/wp/2012/11/01/can-we-stop-the-seas-from-rising-yes-but-less-than-you-think/?nid=top_pb_signin&tid=nav_sign_in> > Newsletters & Alerts > <https://subscribe.washingtonpost.com/newsletters?tid=nav_acctmgnt_menu> > Gift Subscriptions > > <https://subscribe.washingtonpost.com/gift/?promo=digital_nav_gift&tid=nav_acctmgnt_menu> > Contact Us > > <http://help.washingtonpost.com/ics/support/ticketnewwizard.asp?tid=nav_acctmgnt_menu> > Help Desk > > <http://help.washingtonpost.com/ics/support/KBSplash.asp?tid=nav_acctmgnt_menu> > > <http://www.washingtonpost.com/pb/news/wonk/wp/2012/11/01/can-we-stop-the-seas-from-rising-yes-but-less-than-you-think/?outputType=accessibility&nid=menu_nav_accessibilityforscreenreader> > Wonkblog <http://www.washingtonpost.com/news/wonk/>Can we stop the seas from > rising? Yes, but less than you think. > By Brad Plumer > November 1, 2012 > One of the main concerns with climate change is that it's causing the oceans > to advance. Global sea levels have risen about seven inches > <http://en.wikipedia.org/wiki/File:Trends_in_global_average_absolute_sea_level,_1870-2008_%28US_EPA%29.png> > over the past century and that pace is accelerating. Not only does this > threaten coastal regions, but it also makes storm surges much worse — both > for huge hurricanes like Sandy and for smaller storms too. > > <> > We can hold back some of the tide, but not all of it. (Amanda Lucier/The > Washington Post) > And the oceans are likely to keep creeping up. Scientists project > <http://www.pnas.org/content/early/2009/12/04/0907765106.full.pdf+html> that > if we keep warming the planet at our current pace, sea levels could rise > between two and seven feet by 2100, particularly as the world's glaciers and > ice caps melt. So that raises the question: Is there anything we can do to > stop sea-level rise? How much would cutting greenhouse-gas emissions help? > > As it turns out, reducing our emissions would help slow the rate of sea-level > rise — but at this point, it's unlikely that we could stop further rises > altogether. That's the upshot of a recent study > <http://www.nature.com/nclimate/journal/v2/n8/full/nclimate1529.html?WT.ec_id=NCLIMATE-201208> > from the National Center on Atmospheric Research (NCAR). The study estimated > that aggressive steps to cut emissions could reduce the amount of sea-level > rise by somewhere between 6 and 20 inches in 2100, compared with our current > trajectory. That's quite a bit. But sea levels will keep rising for centuries > no matter what we do. We can't stop it entirely. We can only slow the pace. > > As NCAR's Gerald Meehl, a co-author of the study, explained to me by e-mail, > it's a lot easier to stabilize global temperatures by cutting carbon > emissions than it is to stabilize sea-level rise. The carbon-dioxide that > we've already loaded into the atmosphere will likely have effects on the > oceans for centuries to come. "But with aggressive mitigation," Meehl added, > "you can slow down the rate of sea level rise, which buys time for adaptation > measures." > > There are two ways that global warming causes sea levels to rise > <http://en.wikipedia.org/wiki/Current_sea_level_rise>. First, as > carbon-dioxide traps more heat on the planet, the oceans get warmer and > expand in volume. Second, ice caps in Greenland and Antarctica as well as > other glaciers start melting, pouring more water into the oceans. Once these > processes get underway, they won't stop quickly, even if we ceased putting > carbon-dioxide into the atmosphere tomorrow. > > The NCAR paper estimated that if emissions go unchecked, we could warm the > planet 4°C over pre-industrial levels by 2100, causing sea levels to rise > between two and five feet. By contrast, if we get really proactive at cutting > emissions, we could probably keep the temperature increase below 2°C. But sea > levels would still rise by between 11 inches and 3.5 feet. (The wide range is > due to the uncertainties in modeling the behavior of glaciers and ice > sheets—if the ice sheets destabilize, a bigger rise is possible.) That's > progress, but not total victory. > > In both scenarios, sea-levels continue to rise through 2300, though at very > different rates. The graph below shows the projected thermal expansion of the > oceans (this doesn't factor in glaciers and ice sheets, which are more > difficult to model). The red line is the "don't stop polluting" scenario. The > blue line is the "aggressive carbon-cutting" scenario. The green line is a > less aggressive cut: > > > <http://www.washingtonpost.com/blogs/ezra-klein/files/2012/10/sea-level-rise.jpg> > > <http://www.washingtonpost.com/blogs/ezra-klein/files/2012/10/sea-level-rise.jpg> > <> > > Other studies and modeling work have come to similar conclusions, albeit with > somewhat different numbers (see here > <http://www.sciencedaily.com/releases/2011/10/111017102601.htm> and here > <http://www.agu.org/pubs/crossref/2009/2008GL037074.shtml>). The basic idea: > Cutting emissions can make a modest difference in sea-level rise in the near > term, but the real impact comes after 2100. > > A few takeaways from these studies: > > 1) We're going to need to adapt to sea-level rise no matter what we do on > carbon emissions. Even the "optimistic" scenario in the NCAR paper still > envisions sea-levels rising roughly 11 inches by 2100. That's assuming we cut > emissions drastically and the ice sheets don't do anything too unpredictable. > Even then, New York City will have a bigger flood zone than it does today. > Storm surges on the coasts will be much larger > <http://iopscience.iop.org/1748-9326/7/1/014032/article>. Low-lying areas > will be at greater risk. In Bangladesh, for instance, the area prone to > severe flooding would increase by 69 percent > <http://www-wds.worldbank.org/servlet/WDSContentServer/WDSP/IB/2010/04/26/000158349_20100426144005/Rendered/PDF/WPS5280.pdf> > (pdf) with just a foot of sea-level rise. > > 2) That said, cutting emissions can make a significant difference this > century. Keeping sea-level rise a foot or two lower than it otherwise might > be is nothing to sneeze at. As this map > <http://www.nytimes.com/interactive/2012/09/11/nyregion/an-expanding-flood-zone.html>of > New York City shows, the flood zone increases dramatically with each > additional foot of sea-level rise. A city like Norfolk, Va. could get swamped > entirely > <http://www.scientificamerican.com/article.cfm?id=whatever-you-call-it-sea-level-rises-in-virginia&print=true> > by a Category 3 hurricane if ocean levels rose by two to five feet. > Florida's adaptation costs go up by billions of dollars with each additional > foot <http://www.ase.tufts.edu/gdae/Pubs/rp/Florida_hr.pdf> of sea-level > rise. Every little bit helps. > > 3) Sea-level rise is likely a much bigger problem for future generations. Not > to get too morbid, but I'll probably be dead by 2100. So will most people > reading this blog. So the main question at issue here is whether we want to > leave our descendants a relatively stable coastline or an unstable one. > > According to NCAR projections, sea levels could rise as much as 34 feet, or > nine meters, by 2300 if emissions continue unchecked (though modeling > projections that far out have very large uncertainties, so don't take this as > a definitive number). To get a sense of what a nine-meter rise would look > like, check out this interactive map <http://geology.com/sea-level-rise/>. > South Florida would be underwater. So would New Orleans. And Shanghai. And > the Netherlands. And Bangladesh. But this is also 200 years in the future. > That's a big reason why climate change is such a difficult problem to deal > with. > > Economy & Business Alerts > Breaking news about economic and business issues. > Sign up > Further reading: > > — Credit due to Roger Pielke Jr. for asking this question > <http://rogerpielkejr.blogspot.com/2012/10/how-much-sea-level-rise-would-be.html> > in the first place. His post cites a study showing a much smaller effect on > sea-level rise by 2100 if we cut emissions, though that study doesn't looking > at the impacts from melting glaciers and ice caps. The newer NCAR study tries > to include those effects (though, as noted, that increases the uncertainty). > > — A look at why the United States is unprepared > <http://www.washingtonpost.com/blogs/ezra-klein/wp/2012/10/31/why-the-united-states-is-so-unprepared-for-climate-disasters/> > to adapt to climate disasters like sea-level rise. > > — Why Hurricane Sandy should get us thinking more seriously > <http://www.washingtonpost.com/blogs/ezra-klein/wp/2012/10/29/yes-hurricane-sandy-is-a-good-reason-to-worry-about-climate-change/> > about climate change, sea levels, and storm surges. > > — A list of cities > <http://www.washingtonpost.com/blogs/ezra-klein/post/which-cities-get-screwed-by-rising-sea-levels/2011/10/13/gIQAPZrNhL_blog.html> > expected to get hit hardest by rising sea levels > > > -- > You received this message because you are subscribed to the Google Groups > "geoengineering" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected] > <mailto:[email protected]>. > To post to this group, send email to [email protected] > <mailto:[email protected]>. > Visit this group at https://groups.google.com/group/geoengineering > <https://groups.google.com/group/geoengineering>. > For more options, visit https://groups.google.com/d/optout > <https://groups.google.com/d/optout>. -- You received this message because you are subscribed to the Google Groups "geoengineering" group. 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