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Dec 21, 2012

From giant sunshades to 'sodium trees': this is a climate crisis

Current efforts to restrain emissions are nowhere near the scale required to address climate change. Scientist Andrew Glikson calls for a planetary defence effort -- on the scale spent on the military.

Short-term solar radiation shields such as sulphur aerosols. Space sunshade technology. Dissemination of ocean iron filings aimed at increasing fertilisation by plankton and algal blooms. Temperature exchange through vertical ocean pipe systems. “Sodium trees.”

These are some of the options being seriously considered in efforts to restrain human-induced climate change.

An understanding of the scientific knowledge indicates that attempts at returning the climate to anywhere near its original condition will require an effective planetary defence effort on the scale spent on the military — which has totalled more than $20 trillion since World War II.

This kind of action is not presently occurring. Atmospheric carbon dioxide is triggering amplifying feedbacks, and therefore efforts at reduction in atmospheric CO2 emissions are no longer sufficient to prevent further global warming. Efforts need to be undertaken in an attempt to reduce atmospheric CO2 levels from their current level of near 400 parts per million (ppm) to well below 350 ppm.

The scale and rate of modern climate change have been greatly underestimated. The release of a total of over 560 billion tonnes of carbon through emissions from  industrial and transport sources, land clearing and fires, has raised CO2 levels from about 280 ppm in pre-industrial periods to 397-400 ppm, reaching a current CO2 growth rate of about 2 ppm per year.

These developments are shifting the Earth’s climate toward Pliocene-like (5.2-2.6 million years ago; mean global temperatures of 2-3 degrees above pre-industrial temperatures) and possibly toward mid-Miocene-like (approximately 16 million years ago; mean global temperatures 4 degrees above pre-industrial temperatures) conditions within a few centuries. That’s a geological blink of an eye.

The current CO2 level generates amplifying feedbacks, including the reduced capacity of warming water to absorb CO2 from the atmosphere, released from fires, droughts, loss of vegetation cover, disintegration of methane released from bogs, permafrost and methane-bearing ice particles and methane-water molecules.

With CO2 atmospheric residence times in the order of hundreds to tens of thousands of years, protracted reduction in emissions, either flowing from human decision or due to reduced economic activity in an environmentally stressed world, may no longer be sufficient to arrest the feedbacks.

Four of the large mass extinction of species events in the history of Earth have been associated with rapid perturbations of the carbon, oxygen and sulphur cycles, on which the biosphere depends, at rates to which species could not adapt.

Since the 18th century, and in particular since about 1975, the Earth system has been shifting away from Holocene (from approximately 10,000 years ago) conditions, which allowed agriculture, previously hindered by instabilities in the climate and by extreme weather events. The shift is most clearly manifested by the loss of polar ice. Sea level rises have been accelerating, with a total of more than 20cm since 1880 and about 6cm since 1990.

For temperature rise of 2.3 degrees, to which the climate is committed if sulphur aerosol emission discontinues, sea levels would reach Pliocene-like levels of 25 metres plus or minus 12 metres, with lag effects due to ice sheet inertia.

With global atmospheric CO2 equivalent (a value which includes the effect of methane) above 470 ppm, just under the upper stability limit of the Antarctic ice sheet, with current rate of CO2 emissions from fossil fuel combustion, cement production, land clearing and fires of about 9.7 billion tonnes of carbon in 2010, global civilisation faces the following alternatives:

  • With carbon reserves sufficient to raise atmospheric CO2 levels to above 1000 ppm, continuing business-as-usual emissions can only result in advanced melting of the polar ice sheets, a corresponding rise of sea levels on the scale of meters to tens of meters, on a time scale of decades to centuries, and high to extreme continental temperatures rendering agriculture and human habitat over large regions unlikely.
  • With atmospheric CO2 at about 400 ppm, abrupt decrease in carbon emissions may no longer be sufficient to prevent current feedbacks (melting of ice, methane release from permafrost, fires). Attempts to stabilise the climate require global efforts using a range of methods, including global reforestation, extensive biochar application, chemical CO2 sequestration (using sodium hydroxide, serpentine and new innovations) as well as burial of CO2.

As indicated in Table 1, the use of short-term solar radiation shields such as sulphur aerosols cannot be regarded as more than a band aid, with severe deleterious consequences in terms of ocean acidification and retardation of the monsoon and of precipitation over large parts of the Earth. By contrast, retardation of solar radiation through space sunshade technology, may allow time for CO2 draw-down. Unlike sulphur dioxide injections this will not have ocean acidification effects — an effort requiring a planetary defence project by NASA.

Dissemination of ocean iron filings aimed at increasing fertilisation by plankton and algal blooms, or temperature exchange through vertical ocean pipe systems, are unlikely to constitute effective means of transporting CO2 to storage at relatively safe water depths.

By contrast to these methods, CO2 sequestration through fast track reforestation, soil carbon, biochar and possible chemical methods such as “sodium trees” may be effective, provided these are applied on a global scale.

It is likely that a species which decoded the basic laws of nature, split the atom, placed a man on the moon and ventured into outer space should also be able to develop the methodology for fast sequestration of atmospheric CO2. The alternative, in terms of global heating, sea level rise, extreme weather events, and the destruction of the world’s food sources is unthinkable.

*Andrew Glikson is honorary professor in earth and paleoclimate science at the University of Queensland, and visiting fellow at the Australian National University

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47 comments

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47 thoughts on “From giant sunshades to ‘sodium trees’: this is a climate crisis

  1. khtagh

    You forgot the most effective measure of all, KILL Rupert Murdoch & limited news.

  2. Roger Clifton

    It is nonsense to dream of extracting waste carbon out of the atmosphere, when our clear responsibility is not to have emitted it in the first place.

  3. Hugh (Charlie) McColl

    Roger, who washes the dishes at your place?

  4. hern andog

    i can’t believe people are thinking of pumping sulphur into the atmosphere. “severe deleterious consequences” – um yeah, ya think? that’s how acid rain is born.

    and these sun shades reminds me of mr burns trying to block out the sun over springfield. at least that one’s comical.

    hey here’s an idea, how ’bout stopping burning fossil fuels and pumping co2 into the atmosphere? oh apparently that’s in the too hard basket, so lets just pump the atmosphere full of sulphur dioxide instead. yeah sounds smart.

  5. Roger Clifton

    Hugh McColl, are you saying that we must dirty our dishes in order to eat and thus must clean up after ourselves?

    One difference to your metaphor is that we don’t need to emit carbon to get energy. To be sure, we need a emergency-type effort to create massive energy storage technology. Already, we should be mass producing (N-word) power stations, for the entire world.

    The other difference is that the means to clean away our waste gases are hopelessly inadequate. Consider that every year, 40 gigatons, that’s twenty thousand cubic kilometres, of CO2 should be permanently buried in some place where carbon would not otherwise appear. It can’t be done. Toying with these silly schemes offers us an illusion of innocence, but will not fool any jury of survivors.

  6. Andybob

    Bacterial formation of carbonates is interesting.

  7. michael r james

    One might quibble with some of the statements here. For example “sodium trees” seem a highly unlikely solution for at least two reasons which are the same as for Carbon Capture and Sequestration for coal-fired power stations (essential identical technology): 1. energy cost and 2. sequestration of CO2. The iron-seeding of oceans is, IMO, much more promising than almost any other technology, as Crikey readers should know from my article:

    [(crikey.com.au/2010/06/11/geoengineering-does-not-remove-the-need-to-decarbonise/)
    Friday, 11 June 2010 /
    Geoengineering does not remove the need to decarbonise
    by Michael R James

    Bio-sequestration has enormous potential in the form of iron seeding of oceans and charcoal in soils. But again a lot of research is required as no one really understands the processes or long-term effects. There is some optimism for ocean seeding because it is potentially easy, cheap and scalable — and innocuous. There are vast segments of the Pacific ocean that are dead zones with very little life — because they are a long way from coasts and do not have currents to bring nutrients, one of which, iron is limiting to the growth of blue-green algae and phytoplankton, the very bottom of the whole ocean food chain.
    .
    This is kind of equivalent to carbon capture and storage (CCS) except it is done naturally by organisms and the carbon is sequestered as stable calcium carbonate skeletons that fall to the ocean floor at the end of the animals’ life. In fact it is a kind of solar power as the energy that drives the process is free from the sun coupled to a billion years of biological evolution. It is why it is economically feasible and clean coal is not. This process is the origin of the massive limestone deposits throughout the world, such as those exposed in the White Cliffs of Dover. Staggering amounts of carbon are embedded in these deposits and in principle, creating some more in some unoccupied part of the Pacific may well be ecologically innocuous and very affordable.]

    But one cannot quibble with the need for serious research on any or all of these potential methods. Some may play a short-term role, eg. increasing the upper atmosphere’s albedo via various methods including sulphur, reflective microparticles (that stay aloft a lot longer) and water vapour. Others such as ocean seeding may be a longer term method of permanently sequestering carbon; any pessimism needs to acknowledge that it has happened–those white cliffs of Dover and all limestone and marble deposits etc. The research needs to be done to find optimal conditions, and yes, if the sequestration can be made permanent (the acidification of oceans is what can cause calcium carbonate to re-dissolve but deep ocean–especially in the precise areas of the Pacific likely to be used for any ocean seeding–is surely the last to be acidified (it requiring exchange with surface water which by definition is what doesn’t happen in these areas).

    Even Clive Hamilton has changed his mind on the importance of this research as he revealed on a recent ABC Lateline; see my earlier article which was in part a response to Hamilton’s antipathy to any kind of geo-engineering at that time.

  8. michael r james

    Roger Clifton at 4:01 pm

    I too have always thought using sulphur injection into the upper atmosphere to be an odd approach, however the amount needed is presumably a lot less than the amounts our old dirty coal-burning put into the air that caused acid-rain.

    In any case as a biochemist, naturally I prefer the bio-sequestration approach discussed in my post above. As to Dr Glikson’s closing words: “By contrast to these methods, CO2 sequestration through fast track reforestation, soil carbon, biochar and possible chemical methods such as “sodium trees” may be effective, provided these are applied on a global scale.” I cannot imagine the land-based methods having the chance of a snowflake in hell as they are in such conflict with developmental aims of the parts of the planet where they would have to happen. Worse, at any time and in short time frames, all the good work could be undone by political action/inaction. if it works, ocean-seeding sequestration would not be subject to such political problems.

  9. michael r james

    Roger Clifton at 4:01 pm

    I too have always thought using sulphur injection into the upper atmosphere to be an odd approach, however the amount needed is presumably a lot less than the amounts our old dirty coal-burning put into the air that caused acid-rain.

    In any case as a biochemist, naturally I prefer the bio-sequestration approach discussed in my post above. As to Dr Glikson’s closing words:

    “By contrast to these methods, CO2 sequestration through fast track reforestation, soil carbon, biochar and possible chemical methods such as “sodium trees” may be effective, provided these are applied on a global scale.”

    I cannot imagine the land-based methods having the chance of a snowflake in h*ll as they are in such conflict with developmental aims of the parts of the planet where they would have to happen. Worse, at any time and in short time frames, all the good work could be undone by political action/inaction. if it works, ocean-seeding sequestration would not be subject to such political problems.

  10. zut alors

    Just for the record – is the Amazon still being cleared and is Indonesia persisting with major forest burn-offs to create palm oil crops?

    Instead of skipping directly to scientific solutions first we should cease behaving like vandals.

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