Prepare for global temperature rise of 4C continued...
March 22, 2009 - 11:59am
The IPCC predicted ~10 inches over the next century. I don't think that's enough to put Vancouver under water, and it's four generations from now.
Apparently you, along with a great many other people, overlooked this very explicit caveat within the 4th Assessment Report itself:
Models used to date do not include uncertainties in climate-carbon cycle feedback nor do they include the full effects of changes in ice sheet flow, because a basis in published literature is lacking. The projections include a contribution due to increased ice flow from Greenland and Antarctica at the rates observed for 1993-2003, but these flow rates could increase or decrease in the future.
In reality, the published literature on changes in ice sheet flow even before the 4th Assessment Report was finalized and released in 2007 made it quite clear that the rate of ice sheet melt in both Greenland and the Antarctic Peninsula/West Antarctica had accelerated beyond the observed rate for 1993-2003, and that the IPCC projection of 18 to 59 cm (7 to 23 inches) of sea level rise severely underestimated the most likely range of rise that can be expected. Subsequent published literature puts the estimate at 89cm to well over 1 meter for this century, with an upper bound of around 2 meters, based on the fastest rate of melt observed in the paleo record.
Science continually moves forward. Citing a report based on data from before 2006 (the cut-off for the IPCC 4th Assessment) misrepresents the current scientific understanding, not to mention the reality of the potential threat of sea level rise.
The question was what would it take, not could it happen ;) And as others have mentioned, it could.
Would famine and drastic events in other nations be enough, or will something catastrophic and local be needed?
And as one of the regular commenters at Realclimate.org often points out, sea level doesn't need to rise into the streets to render a city unlivable, it just has to rise up into the storm sewers far enough to render them inoperable.
I can't help but think about the Penguins when I read something like this.
Ice bridge ruptures in Antarctic
http://news.bbc.co.uk/2/hi/science/nature/7984054.stm
Antarctica's tumultuous past revealed
The Andrill drilling project is showing that the West Antarctic Ice sheet has retreated and regrown at least 60 times over the past 14 million years, suggesting that it is prone to rapid and catastrophic collapse over as little as 1000 years at atmospheric CO2 concentrations of 400 to 450 ppm. (We're currently at 387 ppm.) That translates into a rate of .5 to 1 meter of sea rise per century.
That's from the WAIS alone. Add in the Greenland Ice Sheet and thermal expansion and we are looking at closer to three times that, although as an average and not in the next century.
A new paper in Nature presents evidence of rates of sea level rise of 5+ cm per year over a 50 year period (2.5+ meters total) 121,000 years ago during the last interglacial (the Eemian). By comparison, current sea level rise is just over 3 mm per year, projected to increase to .3 to 1.4 cm per year as polar melting accelerates.
Story at Climate Progress.
Abstract at Rapid sea-level rise and reef back-stepping at the close of the last interglacial highstand.
I'm watching The 11th Hour (2007), folks are talking about the consequences of increasing temps - pretty scary.
The next time some one tries to tell you that global warming is a myth or hoax, that it's just the urban heat island effect in populated areas and that there hasen't been any warming, show them this little interactive map that shows the northward shift in plant hardiness zones since 1990.
"Control greenhouse emissions or face trade sanctions, panel tells governments"
http://www.google.com/hostednews/canadianpress/article/ALeqM5hScgRIhbPfvMTwVjDMlQoz7JUIdg
OTTAWA — Canada has no choice but to implement a national hard cap-and-trade system on carbon that would set uniform standards for all industries and provinces, says a government advisory panel.
The report, by the National Round Table on the Environment and the Economy, has been a year in the making and gives a detailed road map for meeting Ottawa's greenhouse gas targets in a manner it says is the most efficient and least costly.
The report says so-called intensity targets, which the Harper government has recommended as the way forward until at least 2017, won't work and that Canada should put in place a hard cap regime on emissions by 2015, with auctioning of carbon permits to businesses by 2020 ...
It's not just the Arctic and Antarctic that are melting:
Snow Cover Turning to Lakes in the Himalayas
http://www.ipsnews.net/news.asp?idnews=46761
"These are the world's greatest repositories of snow and ice outside of the polar regions, and yet they may melt away in just 20 to 30 years, leaving more than a billion people desperately short of water...."
Six of the world's major rivers rise in the Himalayas and the Tibetan plateau (Indus, Ganges, Brahmaputra, Yangtze, Yellow, Mekong). We're talking about the water source for over a billion people.
It's not just the Arctic and Antarctic that are melting:
Snow Cover Turning to Lakes in the Himalayas
http://www.ipsnews.net/news.asp?idnews=46761
"These are the world's greatest repositories of snow and ice outside of the polar regions, and yet they may melt away in just 20 to 30 years, leaving more than a billion people desperately short of water...."
Six of the world's major rivers rise in the Himalayas and the Tibetan plateau (Indus, Ganges, Brahmaputra, Yangtze, Yellow, Mekong). We're talking about the water source for over a billion people.
Some might plug for the St. Elias Icefields in the Yukon or the Southern Ice Cap in Chile/Argentina, but they are all disappearing.
Some might plug for the St. Elias Icefields in the Yukon or the Southern Ice Cap in Chile/Argentina, but they are all disappearing.
Indeed they are, but it's those billion plus people, and their nuclear weapons, that makes the situation in the Himalayas and the Tibetan plateau just a wee bit more critical, don't ya think?
Some might plug for the St. Elias Icefields in the Yukon or the Southern Ice Cap in Chile/Argentina, but they are all disappearing.
Indeed they are, but it's those billion plus people, and their nuclear weapons, that makes the situation in the Himalayas and the Tibetan plateau just a wee bit more critical, don't ya think?
I didn't say it wasn't, just questioning that the Himalayan snow and icefields were the worlds largest.
OK, now I see what you meant.
The southern Patagonia and Kluane ice fields are both claimed to be the largest continuous ice fields outside of Greenland and Antarctica by different refernces, but given that the Himalaya cover an arc of 2400 km by 150 to 400 km it could well be that they contain more total ice volume.
Regardless of the true record holder, the Himalaya clearly eclipse the other two by far in terms of potential geopolitical impact.
I wonder what the effect will be on the local weather when the Himalayen ice is gone. I wonder if it would streghten the monsoon on the Idian continent and bring in more Arctic air from the north. Making for a more violent weather in general.
Looks like 2009 Arctic sea ice extent has caught up to the record 2007 melt, at least for the moment, but it's still early.
Not at all surprising since most of the thicker, denser, less saline multi-year ice melted or was simply flushed out of the Arctic basin over the last two seasons.
ETA: Here's a visual comparison of the melt on or near this date for 2009, 2008 and 2007.
Looks like 2009 Arctic sea ice extent has caught up to the record 2007 melt, at least for the moment, but it's still early.
Not at all surprising since most of the thicker, denser, less saline multi-year ice melted or was simply flushed out of the Arctic basin over the last two seasons.
ETA: Here's a visual comparison of the melt on or near this date for 2009, 2008 and 2007.
The melt for May was rather precipitous, as it was much closer to normal than the 2007 coverage at the beginning of the month. The rate of decline has decreased though. The thickness and salinity of the young ice will have an impact, but the weather conditions still have to be right (or wrong) to set another record.
Human-caused warming has overtaken and reversed 2,000 years of natural cooling in the Arctic
A new paper in Science shows that human-caused enhancement of the greenhouse effect has reversed the long, slow natural cooling of the Arctic of the past 2000 years. (Actually, since the Holocene Climate Optimum of ~6000 years ago.)
Recent Warming Reverses Long-Term Arctic Cooling
Science 4 September 2009: Vol. 325. no. 5945, pp. 1236 - 1239
Kaufman et al
Abstract:
The temperature history of the first millennium C.E. is sparsely documented, especially in the Arctic. We present a synthesis of decadally resolved proxy temperature records from poleward of 60°N covering the past 2000 years, which indicates that a pervasive cooling in progress 2000 years ago continued through the Middle Ages and into the Little Ice Age. A 2000-year transient climate simulation with the Community Climate System Model shows the same temperature sensitivity to changes in insolation as does our proxy reconstruction, supporting the inference that this long-term trend was caused by the steady orbitally driven reduction in summer insolation. The cooling trend was reversed during the 20th century, with four of the five warmest decades of our 2000-year-long reconstruction occurring between 1950 and 2000.
Extracted graphs at Desdemona Despair
In-depth reports at:
Climate Progress
Andy Revkin's Dot Earth
NYT
WaPo
Four Degrees of Devastation
by Stephen Leahy [excerpt]
Eighteen months ago, no one dared imagine humanity pushing the climate beyond an additional two degrees C of heating, but rising carbon emissions and inability to agree on cuts has meant science must now consider the previously unthinkable.
"Two degrees C is already gone as a target," said Chris West of the University of Oxford's UK Climate Impacts Programme.
"Four degrees C is definitely possible...This is the biggest challenge in our history," West told participants at the "4 Degrees and Beyond, International Climate Science Conference" at the University of Oxford last week.
A four-degree C overall increase means a world where temperatures will be two degrees warmer in some places, 12 degrees and more in others, making them uninhabitable. It is a world with a one- to two-metre sea level rise by 2100, leaving hundreds of millions homeless. This will head to 12 metres in the coming centuries as the Greenland and Western Antarctic ice sheets melt, according to papers presented at the conference in Oxford.
Four degrees of warming would be hotter than any time in the last 30 million years, and it could happen as soon as 2060 to 2070.