Please support this Forum and Neven's Blog

Author Topic: Hansen et al paper: 3+ meters SLR by 2100  (Read 137639 times)

sidd

  • ASIF Upper Class
  • Posts: 1257
    • View Profile
Re: Hansen et al paper: 3+ meters SLR by 2100
« Reply #650 on: April 26, 2017, 06:46:00 PM »
Hansen not so farfetched: 3m SLR by 2100 doi: 10.1088/1748-9326/aa6512

I see Drijfhout is an author. They put in DeConto-Polard model for Antarctica and a couple other tweaks. Open access. Read all about it

sidd

AbruptSLR

  • ASIF Emperor
  • Posts: 12040
    • View Profile
Re: Hansen et al paper: 3+ meters SLR by 2100
« Reply #651 on: May 05, 2017, 09:53:51 AM »
The linked reference indicates that freshwater hosing events in the North Atlantic can result in warming of the Nordic Seas (see the attached image); which can accelerate Arctic Amplification:

Mélanie Wary et. al. 92017), "Regional seesaw between North Atlantic and Nordic Seas
during the last glacial abrupt climate events", Clim. Past Discuss., doi:10.5194/cp-2017-14

http://www.clim-past-discuss.net/cp-2017-14/cp-2017-14.pdf

Abstract. Dansgaard-Oeschger oscillations constitute one of the most enigmatic features of the last glacial cycle.  Their cold atmospheric phases have been commonly associated with cold sea-surface temperatures and expansion of sea ice in the North Atlantic and adjacent seas. Here, based on dinocyst analyses from the 48-30 ka BP interval of four sediment cores from the northern Northeast Atlantic and southern Norwegian Sea, we provide direct and quantitative evidence of a regional paradoxical seesaw pattern: cold Greenland and North Atlantic phases coincide with warmer sea-surface conditions and shorter seasonal sea-ice cover durations in the Norwegian Sea as compared to warm phases. Combined with additional paleorecords and multi-model hosing simulations, our results suggest that during cold Greenland phases, reduced Atlantic meridional overturning circulation and cold North Atlantic sea-surface conditions were accompanied by the subsurface propagation of warm Atlantic waters that re-emerged in the Nordic Seas and provided moisture towards Greenland summit.
« Last Edit: May 05, 2017, 05:17:00 PM by AbruptSLR »
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

  • ASIF Emperor
  • Posts: 12040
    • View Profile
Re: Hansen et al paper: 3+ meters SLR by 2100
« Reply #652 on: May 05, 2017, 06:42:10 PM »
The linked video entitled: "Climate Change: Hansen Paper: Multimeter Sea Level Rise by 2075?", provides an easily accessible overview of the key points of Hansen et al (2016):

https://www.youtube.com/watch?v=tHV2j8Hypes
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

  • ASIF Emperor
  • Posts: 12040
    • View Profile
Re: Hansen et al paper: 3+ meters SLR by 2100
« Reply #653 on: July 10, 2017, 04:31:17 AM »
The linked reference indicates that much of the weaker polar amplification of Antarctica as compared to the Arctic is due to its (high) surface elevation.  This makes me wonder how much the Antarctic polar amplification will increase if/when the WAIS collapses:

Salzmann, M. (2017) The polar amplification asymmetry: Role of antarctic surface height, Earth Systems Dynamics,doi:10.5194/esd-8-323-2017

http://www.earth-syst-dynam.net/8/323/2017/esd-8-323-2017.pdf

Abstract: “Previous studies have attributed an overall weaker (or slower) polar amplification in Antarctica compared to the Arctic to a weaker Antarctic surface albedo feedback and also to more efficient ocean heat uptake in the Southern Ocean in combination with Antarctic ozone depletion. Here, the role of the Antarctic surface height for meridional heat transport and local radiative feedbacks, including the surface albedo feedback, was investigated based on CO2-doubling experiments in a low-resolution coupled climate model. When Antarctica was assumed to be flat, the north–south asymmetry of the zonal mean top of the atmosphere radiation budget was notably reduced… between 24 and 80%… of the polar amplification asymmetry was explained by the difference in surface height, but… might to some extent also depend on model uncertainties.”
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson

AbruptSLR

  • ASIF Emperor
  • Posts: 12040
    • View Profile
Re: Hansen et al paper: 3+ meters SLR by 2100
« Reply #654 on: July 18, 2017, 07:49:00 PM »
The linked reference finds that: "The increase in the number of extreme El Niño events projected for the twenty-first century could expose the WAIS to more frequent major melt events.":

Julien P. Nicolas et. al. (2017, "January 2016 extensive summer melt in West Antarctica favoured by strong El Niño", Nature Communications 8, Article number: 15799, doi:10.1038/ncomms15799

http://www.nature.com/articles/ncomms15799

Abstract: "Over the past two decades the primary driver of mass loss from the West Antarctic Ice Sheet (WAIS) has been warm ocean water underneath coastal ice shelves, not a warmer atmosphere. Yet, surface melt occurs sporadically over low-lying areas of the WAIS and is not fully understood. Here we report on an episode of extensive and prolonged surface melting observed in the Ross Sea sector of the WAIS in January 2016. A comprehensive cloud and radiation experiment at the WAIS ice divide, downwind of the melt region, provided detailed insight into the physical processes at play during the event. The unusual extent and duration of the melting are linked to strong and sustained advection of warm marine air toward the area, likely favoured by the concurrent strong El Niño event. The increase in the number of extreme El Niño events projected for the twenty-first century could expose the WAIS to more frequent major melt events."
“It is not the strongest or the most intelligent who will survive but those who can best manage change.”
― Leon C. Megginson