Saturday, November 29, 2014

Antarctica’s Point of No Return

POTSDAM – Recent satellite observations have confirmed the accuracy of two independent computer simulations that show that the West Antarctic ice sheet has now entered a state of unstoppable collapse. The planet has entered a new era of irreversible consequences from climate change. The only question now is whether we will do enough to prevent similar developments elsewhere.

What the latest findings demonstrate is that crucial parts of the world’s climate system, though massive in size, are so fragile that they can be irremediably disrupted by human activity. It is inevitable that the warmer the world gets, the greater the risk that other parts of the Antarctic will reach a similar tipping point; in fact, we now know that the Wilkes Basin in East Antarctica, as big or even bigger than the ice sheet in the West, could be similarly vulnerable.

There are not many human activities whose impact can reasonably be predicted decades, centuries, or even millennia in advance. The fallout from nuclear waste is one; humans’ contribution to global warming through greenhouse-gas emissions from burning fossil fuels, and its impact on rising sea levels, is another.

Indeed, the latest Intergovernmental Panel on Climate Change (IPCC) report stated, in uncharacteristically strong terms, that the sea level is “virtually certain” to continue to rise in the coming centuries or millennia. Moreover, the greater our emissions, the higher the seas will rise.

But the recent revelations about Antarctica are different. Rather than reacting to global warming with gradual and predictable patterns of change, the West Antarctic ice sheet has suddenly “tipped” into a new state. A relatively small amount of melting beneath the Amundsen Sea’s ice shelf has pushed its grounding line to the top of a sub-glacial hill, from which it is now “rolling down.” Simply put, one thermal kick was enough to initiate an internal dynamic that will now continue under its own momentum, regardless of any action that humans might take to prevent it.

It is not completely clear whether humans have caused this tipping – though nothing like it has ever occurred during the 11,500-year Holocene period before humans started interfering with the planet’s energy balance. But that is not the point. What is important is that we recognize the existence of gigantic parts of the earth’s climate system – such as West Antarctica’s three-quadrillion-ton ice sheet – that can be tipped when a fractional temperature rise occurs in key locations.

This risk is no longer merely theoretical. For the first time, findings based on observations and computer simulations all point to the same conclusion: the huge Amundsen Sea sector of West Antarctica has begun an irreversible ice discharge, and nothing can now halt the subsequent drainage of the entire basin. It has passed the point of no return.

That is why we must now focus on similar topographic conditions elsewhere. If an “ice plug” near the coast of Wilkes Basin melts or breaks off into icebergs, the basin’s huge quantities of water will drain into the ocean. Although no one knows precisely what might destabilize the Wilkes Basin, we can be fairly certain that further global warming, caused by greenhouse-gas emissions, will increase the risk.

The fact that sea levels will continue to rise is now clear. But we can still determine how high and how fast levels rise by controlling the degree of global warming that we cause. Climate change is caused by mankind, so the good news is that mankind can stop it by cutting greenhouse-gas emissions.

Although West Antarctica’s fate is sealed, we may still be able to prevent the collapse of East Antarctica’s marine ice sheet. That means deciding – sooner rather than later – which path to follow. The current path risks further destabilization in Antarctica; choosing the alternative path of a new energy system for the planet is our last best hope.

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    1. CommentedJames Greyson

      Agree on a new energy system. Yet this has been proposed for many decades without really taking the new path. What if the economic and political obstacles to the new path are just a way of saying we must fix the whole system not just the energy system. Again, perhaps it helps to say how - since regular policy entirely misses this path?

    2. CommentedJames Greyson

      Climate policy is founded on cutting emissions but is this enough? Does the ambition of policy need to cut not just emissions but also concentrations - before climate change could be stopped? Isn't this the actual climate dynamics? This scale of ambition seems to lie beyond the imagination of policy - perhaps it helps to say how it could be done?

    3. CommentedNichol Brummer

      I'm curious about this Wilkes basin, and those 'huge quantities of water'. Or is that ice that could flow into the sea and melt? Are there any reasonable estimates of sea level rise beyond 2100, or is the biggest uncertainty really related to how much greenhouse gasses we continue to emit?

    4. CommentedGilles St-Pierre

      However, the Antartic ice sheet is growing!

      "The Antarctic surge is so big that overall, although Arctic ice has decreased, the frozen area around both poles is one million square kilometres more than the long-term average."

    5. CommentedShoshon Tama-Sweet

      "Climate change is caused by mankind, so the good news is that mankind can stop it by cutting greenhouse-gas emissions."

      This comment is factually false. Climate change has been going on for many many millions of years. During the period of Human evolution average mean global temperature has fluctuated over 15 degrees. Human beings are responsible for a small share of temperature change on top of significant background warming (or cooling) Humans have not caused global warming, except possibly in the last 20-30 years, nor can we contain it. At no point in the last 400,000 years has temperature ever been stable and flat, it has always been rising or falling at significant rates. Most climate change is not caused by humans, and most will be climate change will not respond to our efforts to 'stabilize' it.

        CommentedZsolt Hermann

        I agree what you and Marc Sargen said about adaptation and managing.
        Indeed the vast natural system we exist in is infinitely greater and more powerful we are or could be, thus we cannot change anything but we need to learn how to adapt to it.

        But in order to adapt and manage the changes we need to fulfill some conditions:

        1. We have to accept and understand that we are not above the system, but we are part of it, bound by all of its natural laws.

        2. Adaptation, managing, partnering the system is only possible by "equivalence of form", in other words human society, human behavior, lifestyle adapting to the general laws and principles nature is based on.

        3. The vast natural system is based on integrality, mutually complementing collaboration, and existing within natural necessities and available means.

        The present human society, the artificial bubble we created, that is built on ruthless, exploitative competition, succeeding at the expense of others, excessively producing and consuming artificial, harmful goods in order to generate excessive profit, is unsustainable, has become self-destructive as cancer.

        4. In order to create the necessary shift, building a new human society that accepts and lives by the natural principles safeguarding homeostasis,a humanity that dynamically adapts to the natural system we need to implement a global, integral education program, and change the main values of society.

        CommentedShoshon Tama-Sweet

        Thanks Marc- I agree. Adaptation and mitigation are going to both be necessary, with some pretty smart cost-benefit analysis, and a trade off between economic and humanitarian goals. But right now the conversation is driven by a lot of fanaticism that has grown pretty divorced from the science. In the long run, that will prove unhelpful.

        CommentedMarc Sargen

        There has been a number of factors that caused the change but I do think the human actions amplified the change & part of the effects is due to the last 200 to 300 years were our affects on the world became dramatically increased.
        Whatever is happening, is happening & human won't be able to substantial reverse it effects. Our effort would be much better at managing & adapting. It is our greatest strength as a race.

    6. CommentedAlamanach .

      "Climate change is caused by mankind..."

      Climate change was happening long before humans ever appeared. Antarctica itself used to be verdant. Shifts in ocean currents a hundred million years ago covered it in a mile of ice, and that had nothing to do with us. Now some of that ice-- huge, on any human scale, but still small when compared to the entire continent-- is falling into the ocean. Maybe it's supposed to. These things happen. Let's keep it in perspective.