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Tuesday 4 August 2015

Climate change: sea levels rising

When it comes to climate change, iconic monuments have long been pictured underwater:



And putting expensive real-estate under water can be even more provocative:



Last month, the latest predictions were even more dire.

This is from the Daily Mail:

Sea levels may rise by 10 FEET in the next 50 years: Climate change targets could still lead to 'highly dangerous' global warming, warn scientists

  • Study warns ice sheets are melting 10 times faster than originally believed
  • Climate expert Dr James Hansen says paper is most important of his career
  • Scientists warn circulation of heat around oceans could collapse entirely
  • They way this could lead to more powerful storms than currently seen 
Sea levels could rise by as much as 10 feet in the next 50 years due to 'highly dangerous' global warming, a leading climate scientist has warned.
Dr James Hansen, one of the world's leading climate scientists, and 16 other researchers are preparing to publish new projections for how the oceans may respond to climate change.
They warn an increase in average global temperatures of just 1°C could result in dramatic changes in sea level and an increase in powerful storms.
A new scientific paper has warned that melting of ice sheets in West Antarctica and Greenland may be happening 10 times faster than was previously predicted. This could lead to sea levels rise of up to 30 feet within 50 years, they warn. A picture of an iceberg which calved off from the Greenland ice sheet is pictured
A new scientific paper has warned that melting of ice sheets in West Antarctica and Greenland may be happening 10 times faster than was previously predicted. This could lead to sea levels rise of up to 30 feet within 50 years, they warn. A picture of an iceberg which calved off from the Greenland ice sheet is pictured
They conclude that 2°C of warming – the international target for limiting global warming – will be 'highly dangerous' to humanity.
The study warns that glaciers in Greenland and the Antarctic could melt 10 times faster than projections put forward by the UN's Intergovernmental Panel on Climate Change, which predicted sea levels would rise by around one metre (three feet) by the end of the century.

RISING SEAS COULD DESTROY TURTLE POPULATIONS 

Rising sea levels could destroy many of the nesting sites used by endangered sea turtles around the world, a new study has warned.
Researchers have found that as coastal nesting sites become flooded with sea water more often, many turtle populations will struggle to produce sufficient young.
They found that green turtles on Raine Island on the Great Barrier Reef, are now regularly being swamped with sea water.
This is leading to just 10 per cent of the eggs hatching into turtles, while in other parts of the world usually around 90 per cent of eggs hatch.
The researchers found that eggs submerged in sea water for up to six hours had a far reduced chance of hatching as the embryos struggled to get enough oxygen to survive. 
The scientists said: 'Social disruption and economic consequences of such large sea level rise could be devastating.
'It is not difficult to imagine that conflicts arising from forced migrations and economic collapse might make the planet ungovernable, threatening the fabric of civilization.'
Dr Hansen, who was Nasa's lead climate scientist until 2013 when he retired and now holds a post with Columbia University's Earth Institute, has described the paper as his most important to date.
Dr Hansen was one of the first scientists to publicly highlight the risk of global warming during evidence he gave to the US congress in 1988.
He said he now plans to take the results of the latest study to policymakers in an attempt to make them realise the importance of taking action to curb climate change.
Last year the UN's IPCC warned world leaders they need to restrict global warming to 2°C above pre-industrial targets by cutting carbon emissions.
However, the new study by Dr Hansen and his colleagues, which is to be published by the online journal Atmospheric Chemistry and Physics Discussion, suggests even keeping climate change within these limits may not save the world from disaster.
The 66-page long report highlights evidence that ice loss in many parts of the planet is accelerating.
Global temperatures have risen since postindustrial times, as shown in the graph above, and world leaders have been urged to restrict further warming to within two degrees. However, the new research warns this could led to 'highly dangerous' warming even if this target is achieved
Global temperatures have risen since postindustrial times, as shown in the graph above, and world leaders have been urged to restrict further warming to within two degrees. However, the new research warns this could led to 'highly dangerous' warming even if this target is achieved
Previous estimates of sea level rise have assumed ice loss would occur at a consistent rate, but the new evidence suggests it can double within 10 years.
They warn that as ice loss increases, the ice sheets could suffer large scale disintegration and it could change the circulation of the oceans due to large amounts of cold fresh water appearing in the seas.
Last winter, widely seen as the warmest on record across much of the world, saw the water in the North Atlantic reaching the coldest temperatures on record, perhaps due to ice loss from Greenland.
Dr Hansen and his colleagues claim this could eventually lead to the ocean currents that circulate warm and cool water around the globe shutting down.
This would lead to the tropics warming more without the ocean to pull heat away towards the poles and this could also lead to more powerful storms.
Their paper notes that in the Eemian period, an interglacial period around 120,000 years ago, there is evidence that gigantic waves moved huge boulders from the seafloor to the top of hills in the Bahamas.
While many parts of the world experienced an unusually warm winter and spring this year, the ocean around Greenland has been unusually cold, perhaps due to the melting of the ice sheet into the ocean
While many parts of the world experienced an unusually warm winter and spring this year, the ocean around Greenland has been unusually cold, perhaps due to the melting of the ice sheet into the ocean
At the time sea levels rose by between 16-30 feet (5-9 metres) due to ice loss from Antarctica and Greenland. It is thought that global temperatures were around 1 degree C warmer than today.
According to the Washington Post, Paul Hearty, a geologist at the University of North Carolina, Wilmington, who co-authored the study, said: 'During this last warm interglacial, not much warmer than the present, [the world saw] not only a higher than present average sea level, but ultimately a significantly higher sea level that required the melting and or collapse of probably both Greenland and West Antarctica, along with basically this great oceanic disturbance.
'There were storms, and a lot of more catastrophic type events associated with this big climate shift.'
However, some scientists have reacted sceptically to the findings in the paper.
Dr Ruth Mottram, a glaciologist at the Danish Meteorological Institute, said she did not think such large rises in sea level were possible and doubted the rate reported in the article.
Dr Michael Mann, a climate researcher at Penn State University, told the Washington Post that he felt the shut down of heat transport in the oceans 'seems rather far fetched'.
However, he said their arguments for the collapse of the West Antarctic ice sheet and substantial sea level rise that would result was 'compelling'.
Climate change targets could still lead to 'highly dangerous' global warming | Daily Mail Online
Former Top NASA Scientist Predicts Catastrophic Rise In Sea Levels
Climate Change Guru's Warning Of 10-Foot Sea Level Rise: Realistic Or Too Much? : SCIENCE : Tech Times 

This is from Slate magazine - plus a video:


Earth’s Most Famous Climate Scientist Issues Bombshell Sea Level Warning

By Eric Holthaus

Monday's new study greatly increases the potential for catastrophic near-term sea level rise. Here, Miami Beach, among the most vulnerable cities to sea level rise in the world.

Photo by Joe Raedle/Getty Images

In what may prove to be a turning point for political action on climate change, a breathtaking new study casts extreme doubt about the near-term stability of global sea levels.

The study—written by James Hansen, NASA’s former lead climate scientist, and 16 co-authors, many of whom are considered among the top in their fields—concludes that glaciers in Greenland and Antarctica will melt 10 times faster than previous consensus estimates, resulting in sea level rise of at least 10 feet in as little as 50 years. The study, which has not yet been peer-reviewed, brings new importance to a feedback loop in the ocean near Antarctica that results in cooler freshwater from melting glaciers forcing warmer, saltier water underneath the ice sheets, speeding up the melting rate. Hansen, who is known for being alarmist and also right, acknowledges that his study implies change far beyond previous consensus estimates. In a conference call with reporters, he said he hoped the new findings would be “substantially more persuasive than anything previously published.” I certainly find them to be.

To come to their findings, the authors used a mixture of paleoclimate records, computer models, and observations of current rates of sea level rise, but “the real world is moving somewhat faster than the model,” Hansen says.

Hansen’s study does not attempt to predict the precise timing of the feedback loop, only that it is “likely” to occur this century. The implications are mindboggling: In the study’s likely scenario, New York City—and every other coastal city on the planet—may only have a few more decades of habitability left. That dire prediction, in Hansen’s view, requires “emergency cooperation among nations.”

We conclude that continued high emissions will make multi-meter sea level rise practically unavoidable and likely to occur this century. Social disruption and economic consequences of such large sea level rise could be devastating. It is not difficult to imagine that conflicts arising from forced migrations and economic collapse might make the planet ungovernable, threatening the fabric of civilization.

The science of ice melt rates is advancing so fast, scientists have generally been reluctant to put a number to what is essentially an unpredictable, nonlinear response of ice sheets to a steadily warming ocean. With Hansen’s new study, that changes in a dramatic way. One of the study’s co-authors is Eric Rignot, whose own study last year found that glacial melt from West Antarctica now appears to be “unstoppable.” Chris Mooney, writing for Mother Jones, called that study a “holy shit” moment for the climate.

One necessary note of caution: Hansen’s study comes via a nontraditional publishing decision by its authors. The study will be published in Atmospheric Chemistry and Physics, an open-access “discussion” journal, and will not have formal peer review prior to its appearance online later this week. [Update, July 23: The paper is now available.] The complete discussion draft circulated to journalists was 66 pages long, and included more than 300 references. The peer review will take place in real time, with responses to the work by other scientists also published online. Hansen said this publishing timeline was necessary to make the work public as soon as possible before global negotiators meet in Paris later this year. Still, the lack of traditional peer review and the fact that this study’s results go far beyond what’s been previously published will likely bring increased scrutiny. On Twitter, Ruth Mottram, a climate scientist whose work focuses on Greenland and the Arctic, was skeptical of such enormous rates of near-term sea level rise, though she defended Hansen’s decision to publish in a nontraditional way.

In 2013, Hansen left his post at NASA to become a climate activist because, in his words, “as a government employee, you can’t testify against the government.” In a wide-ranging December 2013 study, conducted to support Our Children’s Trust, a group advancing legal challenges to lax greenhouse gas emissions policies on behalf of minors, Hansen called for a “human tipping point”—essentially, a social revolution—as one of the most effective ways of combating climate change, though he still favors a bilateral carbon tax agreed upon by the United States and China as the best near-term climate policy. In the new study, Hansen writes, "there is no morally defensible excuse to delay phase-out of fossil fuel emissions as rapidly as possible."

Asked whether Hansen has plans to personally present the new research to world leaders, he said: “Yes, but I can’t talk about that today.” What’s still uncertain is whether, like with so many previous dire warnings, world leaders will be willing to listen.






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Infographic: Sea Level Rise and Global Warming | Union of Concerned Scientists

Meanwhile, back in the UK:
Growing climate change threat to Britain's historic coastline - Telegraph
Hull could be wiped off the map in 100 years if sea levels continue to rise at current rate, warns expert - Home News - UK - The Independent
From floating cities to high rise farms: Experts outline the future of Britain's architecture - Home News - UK - The Independent

And back in the South-West... and Sidmouth:
Futures Forum: Climate change: from the Somerset Levels to London >>> "We have to speak out to take action."
Futures Forum: Sidmouth Beach Management Plan >>> Pennington Point and the importance of the shingle bank
Futures Forum: A flood plan for Sidmouth
Futures Forum: Making communities resilient to flooding: >>> "Learning to listen: a community approach to understanding localised flood events"
Futures Forum: Climate change: and coastal communities >>> "We need to make sure businesses and communities are more resilient."
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