Chilling warning on warming’s future legacy

The sea sweeps across a road after Hurricane Sandy hit Assateague Island off the east coast of the US in 2012. Image: NPS Climate Change Response via Wikimedia Commons

Scientists stress the need for climate policy to focus not on this century but on the inescapable impacts of greenhouse gas emissions over the next 10,000 years.

LONDON, 11 February, 2016 – Humanity is taking a huge risk of causing irreversible damage for untold millions of people in future generations by treating climate change as simply a short-term problem, according to an international team of scientists..

They warn that the window of opportunity for reducing emissions is now small, and that the speed at which we are currently emitting carbon into the atmosphere could result in the Earth suffering damage lasting for tens of thousands of years.

Writing in Nature Climate Change journal, they say too much of the climate policy debate has focused on the past 150 years and their impact on global warming and sea level rise by the end of this century.

Peter Clark, professor of geology and geophysics at Oregon State University in the US, and the study’s lead author, says: “Much of the carbon we are putting in the air from burning fossil fuels will stay there for thousands of years – and some of it will be there for more than 100,000 years.”

Long-term view

Co-author Thomas Stocker, professor of climate and environmental physics at the University of Berne, Switzerland, and former co-chair of Working Group I of the Intergovernmental Panel on Climate Change (IPCC), warns of “the essential irreversibility” of greenhouse gas emissions.

He writes: “The long-term view sends the chilling message of what the real risks and consequences are of the fossil fuel era. It will commit us to massive adaptation efforts so that, for many, dislocation and migration becomes the only option.”

The authors say sea level rise is one of the most graphic impacts of global warming, yet its effects are only just starting to be felt. The latest IPCC report, for example, expects that likely sea level rise by the year 2100 will be no more than one metre.

They examined four scenarios based on different rates of warming, from a low end attainable only with massive effort to eliminate fossil fuel use over the next few decades, to a higher rate based on consumption of half the remaining fossil fuels over the next few centuries.

“We are making choices that will affect our
grandchildren’s grandchildren – and beyond”

The Paris Agreement reached at the UN climate change summit in December last year aims to keep temperatures “well below” the 2°C previously accepted internationally as the safe level of increase

But with just 2°C of warming in the low scenario examined in the study, sea levels are predicted eventually to rise by about 25 metres. And with 7°C expected in the high scenario, the rise is estimated at 50 metres, over several centuries to millennia.

“It takes sea level rise a very long time to react – on the order of centuries,” Professor Clark says. “It’s like heating a pot of water on the stove; it doesn’t boil for quite a while after the heat is turned on – but then it will continue to boil as long as the heat persists. Once carbon is in the atmosphere, it will stay there for tens or hundreds of thousands of years.”

An estimated 122 countries have at least 10% of their population in areas that will be directly affected by rising sea levels in the low scenario. About 1.3 billion people – 20% of the Earth’s population – may be directly affected.

“We can’t keep building seawalls that are 25 metres high,” Clark says. “Entire populations of cities will eventually have to move.”

Moral questions

Another of the study’s co-authors, Daniel Schrag, director of Harvard University’s Centre for the Environment, is concerned about the moral questions involved in the kind of environment this generation is handing on.

“Sea level rise may not seem like such a big deal today, but we are making choices that will affect our grandchildren’s grandchildren – and beyond,” he says.

The analysis says the long timescales involved mean that reducing emissions slightly or even significantly is not sufficient. Clark says: “To spare future generations from the worst impacts of climate change, the target must be zero or even negative carbon emissions – as soon as possible.”

Geologists say that in the last 50 years humans have changed the climate and introduced the Anthropocene, a new geological era with fundamentally altered living conditions for thousands of years ahead.

“Because we do not know to what extent adaptation will be possible for humans and ecosystems, all our efforts must focus on a rapid and complete decarbonisation – the only option to limit climate change,” Stocker concludes. – Climate News Network

One thought on “Chilling warning on warming’s future legacy”

  1. Lewis Cleverdon

    Alex – I’m surprised that the quite senior scientists quoted above adopt so defeatist and even contradictory positions on the climate predicament.
    In stating that carbon dioxide released today will be there for thousands of years it is assumed that we will not adopt the absolutely necessary and urgently needed Carbon Recovery mode of Geo-engineering – yet Clark is quoted as calling for “zero or even negative carbon emissions – as soon as possible” (and so fudges the issue).

    Stocker’s conclusion that “Because we do not know to what extent adaptation will be possible for humans and ecosystems, all our efforts must focus on a rapid and complete decarbonisation – the only option to limit climate change,” is thus evidently fundamentally wrong. It is neither the only option to do so nor is it a sufficient option to do so.

    However – the scientists are not quoted as warning either of AGW’s self-reinforcing capacity – via the 8 Major Interactive Feedbacks that are now reported in the literature to be accelerating, nor do they address the main proximate threat of Climate Destabilization – which is the rising frequency, duration and severity of droughts putting us on a path to serial global crop failures – potentially as early as next decade.

    In this regard an Oct 2012 a study led by Prof. Peirs Forster (an IPCC lead author) is worth considering: “Food Security: Near future projections of the impact of drought in Asia”

    From the press release:
    “Research released today shows that within the next 10 years [by 2022] large parts of Asia can expect increased risk of more severe droughts, which will impact regional and possibly even global food security. On average, across Asia, droughts lasting longer than three months will be more than twice as severe in terms of their soil moisture deficit compared to the 1990-2005 period. This is cause for concern as China and India have the world’s largest populations and are Asia’s largest food producers.

    Dr Lawrence Jackson, a co-author of the report, said: “Our work surprised us when we saw that the threat to food security was so imminent; the increased risk of severe droughts is only 10 years away for China and India. These are the world’s largest populations and food producers; and, as such, this poses a real threat to food security.”

    I think you know at least as well as I the burgeoning impacts of droughts worldwide, which in light of the study imply that by the 2020s we are liable to see crop failures coinciding across two or more major food producing regions, thus forming the onset of serial global crop failures. The resulting geopolitical destabilization would, undoubtedly, have dire and wholly unpredictable consequences.

    Under these circs for senior scientists to worry publicly about sea level rise in 200 years or more seems at best misguided – in inadvertently boosting the widespread government-backed “Denial of Urgency” –

    Given the declaratory Paris Outcome, plus the warming from the timelag, from the loss of the sulphate parasol, and from the feedbacks’ rising outputs,
    it seems rather obvious that our best efforts at Emissions Control would not be sufficient to constrain Climate Destabilization,
    and given that even additional Carbon Recovery on a huge and rapid global scale – using the most efficient coppice sylviculture and charcoal sequestration – would not significantly dent airborne CO2 before at best 2060,
    it is surely increasingly obvious that the Albedo Restoration mode of Geo-E is going to form the necessary and sufficient complement to Carbon Recovery and rapid Emissions Control ?
    The fact that stringent UN supervision of the R&D of both modes of Geo-E is needed to accredit demonstrably benign technologies before there can be any question of the UN member states discussing their deployment,
    and that for the Albedo Restoration mode that means at least 10 years of careful limited trials,
    – implies that the really urgent call is for the establishment of the Scientific Supervision Agency to oversee a global program of research.

    Thus far Forster is one of very few scientists who is publicly taking the predicament as seriously as the science plainly justifies. Should you consider an article one day on just what is the necessary strategic response to AGW, he’d be well worth contacting (via Leeds Uni).

    All the best,

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