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from the a-rising-ocean-floods-all-ports dept.
The University of New South Wales (Australia) is reporting on research [abstract;full article paywalled] by an international team led by Dr Nicholas Golledge, a senior research fellow at New Zealand's Victoria University's Antarctic Research Centre. According to the article, a jump in global average temperatures of 1.5°C–2°C will see the collapse of Antarctic ice shelves and lead to hundreds and even thousands of years of sea level rise. It goes on to say:
Using state-of-the-art computer modelling, Dr Golledge and his colleagues including researchers from UNSW simulated the ice-sheet's response to a warming climate under a range of greenhouse gas emission scenarios. They found in all but one scenario (that of significantly reduced emissions beyond 2020) large parts of the Antarctic ice-sheet were lost, resulting in a substantial rise in global sea-level. "The long reaction time of the Antarctic ice-sheet – which can take thousands of years to fully manifest its response to changes in environmental conditions – coupled with the fact that CO₂ lingers in the atmosphere for a very long time means that the warming we generate now will affect the ice sheet in ways that will be incredibly hard to undo," Dr Golledge said.
[...] "Around 93% of the heat from anthropogenic global warming has gone into the ocean, and these warming ocean waters are now coming into contact with the floating margins of the Antarctic ice sheet, known as ice shelves. If we lose these ice shelves, the Antarctic contribution to sea-level rise by 2100 will be nearer 40 centimetres." To avoid the loss of the Antarctic ice shelves, and a long-term commitment to many metres of sea-level rise, atmospheric warming needs to be kept below 2°C above present levels. "Missing the 2°C target will result in an Antarctic contribution to sea-level rise that could be up to 10 metres higher than today," Dr Golledge said. "The stakes are obviously very high—10 percent of the world's population lives within 10 metres of present sea level."
[...] "The striking thing about these findings is that we have taken the most conservative estimates possible," said co-author of the paper, Dr Chris Fogwill from UNSW Australia's Climate Change Research Centre. "In all IPCC global warming scenarios, only one (RCP2.6) saw Antarctic ice shelves avoid ongoing collapse. In every other case we saw significant collapse and rising sea levels continue for hundreds to thousands of years. "The results suggest Antarctic ice shelf stability has a tipping point dependent on a critical temperature threshold that can lead to substantial sea level rise even if we reduce emissions after that threshold has been reached." The findings raise an ethical decision for us all, according to Dr Golledge.
So, we have more research detailing the impact of AGW on sea levels. Interestingly, the paper's authors slam the IPCC's estimates of sea level rises due to Antarctic ice sheet melting as too modest.
(Score: 3, Interesting) by Sulla on Monday October 19 2015, @07:41PM
I have not been following this near as close as I should. But from years ago I remember hearing:
More emissions > more melting
More melting > more fresh water
More fresh water > gulf stream failure
Gulf Stream failure > Iceage
Has this changed? The methane releases tell us the ocean is warmer (unless unlikely isolated event) and the oceans pH changed from 8.2 to 8.1 if I recall tell me that we are headed for a gulf stream ending further south.
Is this still in the cards or are we doomed to death by heat/oceanic expansion.
Ceterum censeo Sinae esse delendam
(Score: 2) by BK on Monday October 19 2015, @07:49PM
Well, Bangladesh is doomed. Death by heat [wikipedia.org] is also possible.
...but you HAVE heard of me.
(Score: 2) by JoeMerchant on Monday October 19 2015, @09:30PM
>has this changed?
Um, no - it's just as possible as it ever was, maybe, maybe not, we're not really sure.
What is pretty sure is that we're creating change - the actual nature of that change is best described as "unknown, got some models based on data from before homo sapiens left Africa, we think they're good."
While sea level rise is scary and all, another ice age just might be worse, especially if we've pranged the system hard enough to get glaciers down to the Gulf of Mexico.
🌻🌻 [google.com]
(Score: 1) by WalksOnDirt on Monday October 19 2015, @11:23PM
There's a persistent cold area south of Greenland that may be a consequence of global warming. I don't think an ice age is a possible outcome, but parts of Europe may not warm as fast as the rest of the world.
(Score: 3, Informative) by Hawkwind on Monday October 19 2015, @11:53PM
(Score: 0) by Anonymous Coward on Tuesday October 20 2015, @12:15AM
That means the heat gets dumped somewhere else, doesn't it ?
North America & Europe get an ice age and the gulf becomes a living hell maybe, you are still getting a big change that the current infrastructure is not built for.
(Score: 0) by Anonymous Coward on Tuesday October 20 2015, @03:24AM
(Score: 2) by fritsd on Tuesday October 20 2015, @11:43AM
I think the Gulf Stream is a different issue: if you look at the map, you see that New York City is at the same latitude as Naples, Madrid and Thessaloniki (those are vacation destinations if you want to visit somewhere warm). So, they have the same insolation year-round. That means the difference in temperatures is explained by the Gulf Stream. If that circulation stops it would become equal, that would mean Scandinavia would freeze again (inland of Trondheim would look like inland of Nuuk, Miami like Morocco).
If it would reverse, I dunno.. maybe Morocco would get the climate of New York City and v.v., and Miami would get the climate of Sénégal and v.v.
Meanwhile, the trend line of global warming would just continue to creep up at 0.85 °C / ( 2012 - 1880 ) = 0.006 degrees per year, linear extrapolation for 2 degrees since 1990 is 0.14°C (since 1990) + Y * 0.006 = 2 °C => Y = 288, so at most 288 years since 2012 = in the year 2300.
That's a linear extrapolation from 1880, doesn't take into account any accelerations, such as that the ocean's heat capacity is huge but limited, or that the albedo of the planet changes when the North Pole melts 40 years from now, or if the Clathrate Gun Hypothesis [soylentnews.org] caused some of the famous mass extinctions (let's pray that that isn't true).
So, best case scenario is 285 years, to move the harbours and infrastructure and musea and palaces and courthouses and factories of Shanghai, Singapore, Shenzhen, Hong Kong, New York City, Rotterdam, Hamburg, Antwerp, Los Angeles, Amsterdam, Tokyo, Sydney etc. to a higher location.
How much would that cost?
(Score: 0) by Anonymous Coward on Tuesday October 20 2015, @02:07PM
Indeed, let's hope that a mere hypothesis does not cause any mass extinction. It's already bad enough if the hypothesized mechanism does. ;-)
(Score: 0) by Anonymous Coward on Tuesday October 20 2015, @02:02PM
Last I checked, the Gulf Stream didn't pass Antarctica.