Catastrophic ice shelf collapse would see oceans rise for millennia, say experts

With the 2015 United Nations Climate Change Conference set to commence next month with the objective of securing a binding, universal agreement to limit global temperature increase, there’s never been a more dramatically opportune moment for world leaders to take a meaningful stand against rising sea levels.

And we don’t have any time to lose. New research published this week suggests that if temperatures rise just 1.5°C to 2°C above present levels it will result in a catastrophic collapse in Antarctic ice sheets, ensuring sea levels will rise for not hundreds of years – but potentially thousands.

“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,” said Nicholas Golledge, a senior research fellow from the Antarctic Research Centre at the Victoria University of Wellington in New Zealand.

Together with researchers from the University of New South Wales (UNSW) in Australia, Golledge used computer modelling to simulate ice sheet responses to a warming climate based on a number of different emissions scenarios.

In all but one of the projections – which would require significantly reduced emissions to begin as soon as 2020 – the collapse of the major Antarctic ice shelves triggers what the researchers call “a centennial- to millennial-scale response” in the Antarctic ice sheet, with enhanced viscous flow producing an effectively unstoppable contribution to rising seas.

The findings contradict a 2013 projection on rising sea levels issued by the Intergovernmental Panel on Climate Change (IPCC) that suggested rising seas would peak at 5 centimetres this century. But the researchers, one of whom was involved with the previous estimation, acknowledge that we now know significantly more about the science of ice sheet melting – and the new insights afford a drastic view.

“Our new models include processes that take place when ice sheets come into contact with the ocean,” said Golledge. “Around 93 percent of the heat from anthropogenic [pollutant-based] 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.”

It’s not the first time scientists have warned that previous estimates of the impact of global warming were too modest. A report issued earlier in the year by former NASA physicist James Hansen said revised modelling of glacier melting indicated that coastal cities could be uninhabitable within 50 years.

In light of these new estimations, the researchers emphasise that humanity has the power to control this situation – or at least to temper it on behalf of future societies.

“It becomes an issue of whether we choose to mitigate now for the benefit of future generations or adapt to a world in which shorelines are significantly re-drawn,” said Golledge. “In all likelihood we’re going to have to do both, because we are already committed to 25 centimetres by 2050, and at least 50 centimetres of sea-level rise by 2100.”

source: The findings are published in Nature.

Advertisements
Catastrophic ice shelf collapse would see oceans rise for millennia, say experts

Why we live on Earth and not Venus

Compared to its celestial neighbours Venus and Mars, Earth is a pretty habitable place. So how did we get so lucky? A new study sheds light on the improbable evolutionary path that enabled Earth to sustain life.

The research, published this week in Nature Geoscience, suggests that Earth’s first crust, which was rich in radioactive heat-producing elements such as uranium and potassium, was torn from the planet and lost to space when asteroids bombarded the planet early in its history. This phenomenon, known as impact erosion, helps explain a landmark discovery made over a decade ago about the Earth’s composition.

Researchers with the University of British Columbia and University of California, Santa Barbara say that the early loss of these two elements ultimately determined the evolution of Earth’s plate tectonics, magnetic field and climate.

“The events that define the early formation and bulk composition of Earth govern, in part, the subsequent tectonic, magnetic and climatic histories of our planet, all of which have to work together to create the Earth in which we live,” said Mark Jellinek, a professor in the Department of Earth, Ocean & Atmospheric Sciences at UBC. “It’s these events that potentially differentiate Earth from other planets.”

On Earth, shifting tectonic plates cause regular overturning of Earth’s surface, which steadily cools the underlying mantle, maintains the planet’s strong magnetic field and stimulates volcanic activity. Erupting volcanoes release greenhouse gases from deep inside the planet and regular eruptions help to maintain the habitable climate that distinguishes Earth from all other rocky planets.

Venus is the most similar planet to Earth in terms of size, mass, density, gravity and composition. While Earth has had a stable and habitable climate over geological time, Venus is in a climate catastrophe with a thick carbon dioxide atmosphere and surface temperatures reaching about 470 C. In this study, Jellinek and Matt Jackson, an associate professor at the University of California, explain why the two planets could have evolved so differently.

“Earth could have easily ended up like present day Venus,” said Jellinek. “A key difference that can tip the balance, however, may be differing extents of impact erosion.”

With less impact erosion, Venus would cool episodically with catastrophic swings in the intensity of volcanic activity driving dramatic and billion-year-long swings in climate.

“We played out this impact erosion story forward in time and we were able to show that the effect of the conditions governing the initial composition of a planet can have profound consequences for its evolution. It’s a very special set of circumstances that make Earth.”

Story Source:

The above post is reprinted from materials provided by University of British ColumbiaNote: Materials may be edited for content and length.


Journal Reference:

  1. A. M. Jellinek, M. G. Jackson. Connections between the bulk composition, geodynamics and habitability of EarthNature Geoscience, 2015; DOI: 10.1038/ngeo2488
Why we live on Earth and not Venus

Polar bears threatened: Experience limited energy savings in summer

A young polar bear stands on pack ice over deep waters in the Arctic Ocean in October 2009, during a major research project headed by the University of Wyoming.
Credit: Shawn Harper

Polar bears are unlikely to physiologically compensate for extended food deprivation associated with the ongoing loss of sea ice, according to one-of-its-kind research conducted by University of Wyoming scientists and others, and published today in the journal Science.

“We found that polar bears appear unable to meaningfully prolong their reliance on stored energy, confirming their vulnerability to lost hunting opportunities on the sea ice — even as they surprised us by also exhibiting an unusual ability to minimize heat loss while swimming in Arctic waters,” says John Whiteman, the UW doctoral student who led the project.

The loss of sea ice in the Arctic, which is outpacing predictions, has raised concern about the future of polar bears, leading to their listing as a globally threatened species under the U.S. Endangered Species Act in 2008. The bears depend on hunting seals on the surface of the sea ice over the continental shelf, most successfully from April to July. In parts of the polar bears’ range, the lengthening period of sea ice retreat from shelf waters — caused by increasing temperatures — can reduce their opportunities to hunt seals, leading to declines in bear nutritional condition.

Some earlier research suggested that polar bears could, at least partially, compensate for longer summer food deprivation by entering a state of lowered activity and reduced metabolic rate similar to winter hibernation — a so-called “walking hibernation.” But the new research shows that the summer activity and body temperature of bears on shore and on ice were typical of fasting, non-hibernating mammals, with little indication of “walking hibernation.”

Whiteman and his colleagues concluded in theSciencepublication: “This suggests that bears are unlikely to avoid deleterious declines in body condition, and ultimately survival, that are expected with continued ice loss and lengthening of the ice-melt period.”

The researchers reached that conclusion by capturing more than two dozen polar bears, implanting temperature loggers and tracking their subsequent movements on shore and on ice in the Arctic Ocean’s Beaufort Sea, north of Alaska and Canada, during 2008-2010. The unprecedented effort, logistically supported by the U.S. Geological Survey (USGS) and funded by the National Science Foundation, USGS, U.S. Fish and Wildlife Service (USFWS), as well as the Environmental Protection Agency, required the assistance of numerous personnel, multiple helicopters and deployment of the U.S. Coast Guard ice-breaker, the Polar Sea.

“Many colleagues — even some on our research team — doubted whether the study was possible, until we actually did it,” says Merav Ben-David, the UW professor who developed the research plan along with Professor Hank Harlow, an eco-physiologist and colleague in the Department of Zoology and Physiology, and Steve Amstrup, previously with the USGS and currently the chief scientist at Polar Bears International. “This project was logistically so intense that it may never be replicated.”

At the same time, the scientists found that polar bears use an unusual physiological response to avoid unsustainable heat loss while swimming in the cold Arctic waters. To maintain an interior body temperature that allows them to survive longer and nowadays more frequent swims, the bears temporarily cool the outermost tissues of their core to form an insulating shell — a phenomenon called regional heterothermy.

“This regional heterothermy may represent an adaption to long-distance swims, although its limits remain unknown,” wrote the scientists, who in an earlier publication — in the journalPolar Biology— noted that one of the bears in the study survived a nine-day, 400-mile swim from shore to ice. When recaptured seven weeks later, the bear had lost 22 percent of her body mass, as well as her cub.

By shedding light on potential mechanisms that facilitated that bear’s survival during her long swim, as well as the overall metabolism and activity of bears, the current study “profoundly contributes to understanding the value of summer habitats used by polar bears in terms of their energetics,” Harlow says. Amstrup adds, “It fills a gap in our otherwise extensive knowledge of polar bear ecology and corroborates previous findings that the key to polar bear conservation is arresting the decline of their sea ice habitat.”

In addition to Whiteman, Ben-David, Harlow and Amstrup, co-authors of theSciencepaper are Research Zoologist George Durner of the USGS Alaska Science Center and Wildlife Biologist Eric Regehr of the USFWS Marine Mammals Management in Alaska, both previously Ph.D. students at UW, who also participated in project development and execution; and Professor Richard Anderson-Sprecher of UW’s Department of Statistics and Research Scientist Shannon Albeke of UW’s Wyoming Geographic Information Science Center, who contributed to data analyses.

Additional support for the project was provided by the UW Program in Ecology and Wyoming NASA Space Grant Consortium. Consultation with key Inuit communities in Alaska and Canada ensured the successful completion of the study.

Source: University of Wyoming. “Polar bears threatened: Experience limited energy savings in summer.” ScienceDaily. ScienceDaily, 16 July 2015

Polar bears threatened: Experience limited energy savings in summer

Bolivia passes “Law of Mother Earth” which gives rights to our planet as a living system

The Law of Mother Earth (“Ley de Derechos de La Madre Tierra”) holds the land as sacred and holds it as a living system with rights to be protected from exploitation, and creates 11 distinguished rights for the environment. It was passed by Bolivia’s Plurinational Legislative Assembly. This 10 article law is derived from the first part of a longer draft bill, drafted and released by the Pact of Unity by November 2010. Can we please spread this law? There has to be a way for the free market to interoperate with reverence for this planet. Period.

In accordance with the philosophy of Pachamama, it states, “She is sacred, fertile and the source of life that feeds and cares for all living beings in her womb. She is in permanent balance, harmony and communication with the cosmos. She is comprised of all ecosystems and living beings, and their self-organisation.”

“It makes world history. Earth is the mother of all,” said Vice-President Alvaro García Linera. “It establishes a new relationship between man and nature, the harmony of which must be preserved as a guarantee of its regeneration.”

The law enumerates seven specific rights to which Mother Earth and her constituent life systems, including human communities, are entitled to:

  • To life It is the right to the maintenance of the integrity of life systems and natural processes which sustain them, as well as the capacities and conditions for their renewal
  • To the Diversity of Life: It is the right to the preservation of the differentiation and variety of the beings that comprise Mother Earth, without being genetecally altered, nor artificially modified in their structure, in such a manner that threatens their existence, functioning and future potential
  • To water: It is the right of the preservation of the quality and composition of water to sustain life systems and their protection with regards to contamination, for renewal of the life of Mother Earth and all its components
  • To clean air: It is the right of the preservation of the quality and composition of air to sustain life systems and their protection with regards to contamination, for renewal of the life of Mother Earth and all its components
  • To equilibrium: It is the right to maintenance or restoration of the inter-relation, interdependence, ability to complement and functionality of the components of Mother Earth, in a balanced manner for the continuation of its cycles and the renewal of its vital processes
  • To restoration: It is the right to the effective and opportune restoration of life systems affected by direct or indirect human activities
  • To live free of contamination: It is the right for preservation of Mother Earth and any of its components with regards to toxic and radioactive waste generated by human activities

Sources:

http://en.wikipedia.org/wiki/Law_of_the_Rights_of_Mother_Earth

http://www.theguardian.com/environment/2011/apr/10/bolivia-enshrines-natural-worlds-rights

http://www.huffingtonpost.com/2011/04/13/bolivias-law-of-mother-earth_n_848966.html

http://www.nytimes.com/2009/12/14/science/earth/14bolivia.html

http://www.newser.com/story/116229/bolivia-to-give-nature-same-rights-as-humans.html

Bolivia passes “Law of Mother Earth” which gives rights to our planet as a living system

Arctic sea ice rebound shows resilience

North pole unlikely to be ice-free this summer, say UK scientists, but long-term decline continues

Icebergs in eastern Greenland (Flickr/ Mariusz Kluzniak)

By Megan Darby

Arctic sea ice extent has shrunk 40% since the 1970s, prompting speculation as to when it might disappear altogether.

At a scientific gathering last September, Cambridge University’s Peter Wadhams said it could be as soon as summer 2015.

That’s unlikely, according to UK scientists, after the latest data showed sea ice volume had rebounded from low points in 2010 and 2012.

A study published in Nature Geoscience on Monday found an unusually cool summer in 2013 drove a 41% increase in sea ice volume that year.

Models show Arctic sea ice melting over the long term, UCL scientist and lead author Rachel Tilling said. The latest data shows “it can recover by a significant amount if the melting season is cut short”.

It means the Arctic might be more resilient than previously thought, added Andy Shepherd, professor at UCL and at the University of Leeds.

“Understanding what controls the amount of Arctic sea ice takes us one step closer to making reliable predictions of how long it will last, which is important because it is a key component of Earth’s climate system.

“Although the jump in volume means that the region is unlikely to be ice free this summer, we still expect temperatures to rise in the future, and so the events of 2013 will have simply wound the clock back a few years on the long-term pattern of decline.”

The melting icecap has seen the region opened up to shipping and oil exploration in the summer.

Shell’s controversial drilling plans in the region were put on holdlast week after an icebreaker ship got a gash in the hull.

Source: Arctic sea ice rebound shows resilience  – study

Arctic sea ice rebound shows resilience