22 November 2012

Serious talk about geo-engineering better than pious hand-wringing about 2 degrees

Cambridge Professor and Arctic expert Peter Wadhams
ABC TV's Lateline programme is schedule to discuss climate geo-engineering tonight, a debate that is long overdue.
     Suggesting that climate geo-engineering – such as top-of-atmosphere sulfate injections to reduce incoming solar radiation as a temporary measure until the world gets its act together to avoid the big global warming tipping points – might be necessary is as popular in the environment and climate movements as farting in the middle of a slow movement at a concert.
Almost everybody is keen to rail against it, such as Climate Authority member Clive Hamilton in The Philosophy of Geoengineering. I have yet to hear a climate or environment advocacy group in Australia even say that we should at least consider the issues on their merits.
      There's lots of reasons to be worried about the ideas – and reasons why we need to consider them – as has been canvassed recently in Nature, on the BBC, on NPR, in the Guardian, and in many scientific papers including herehere, here and here, for example.
     Yet some of those most willing to consider it are those scientists who seem most aware and forthright about where global warming is heading and why, when all things are considered, geo-engineering appears to be the least-worst option.
    For example, Chuck Greene, Bruce Monger, Mark Huntley find in Geoengineering: The Inescapable Truth of Getting to 350 that: "After evaluating the challenge of stabilizing CO2 concentration at 350 ppm, we conclude that society will only be successful in meeting this goal by supplementing aggressive reductions in greenhouse gas emissions with geoengineering." So what's the choice?
    Ken Caldeira of the Caldeira Lab at Stanford says  we need to look closely at geo-engineering and pioneered research in the area. Discussion of his work may be found here, here, here and here, just for starters.
    Geo-engineering is no substitute for zero emissions and carbon drawdown, it has as yet not-fully-known side effects, there are huge political and governance issues, and some in the fossil fuel industry have shown an interest. All true. And it won't deal with ocean acidification even if it can slow global warming by reducing incoming solar radiation.
     But without it, we are screwed. Take professor Peter Wadhams of Cambridge University, who is a world-leading authority on the Arctic and is scheduled to appear in tonight's Lateline. We told his story in Big call: Cambridge prof. predicts Arctic summer sea ice “all gone by 2015” on 30 August this year as the Arctic melted dramatically.
     Wadhams, who heads the Arctic Methane Emergency Group, recently gave an off-the-cuff description of what is going to happen in the Arctic, as nations and political leaders fiddle and the planet burns:
  • Summer sea ice disappears, except perhaps for small multiyear remnant north of Greenland and Ellesmere Island, by 2015-16.
  • By 2020 the ice free season lasts at least a month and by 2030 has extended to 3 months.
  • September sea surface temperatures are already elevated by 6-7°C over continental shelves of Arctic. As shrink back continues, the newly exposed surface water over abyssal depths warms up less in a single summer (say 2-3°C) because of deeper surface water layer (150 m) than over a shelf (50 m).
  • The 6-7°C warming over the shelves causes offshore permafrost to shrink back and vanish over about 10 years. During this time there is elevated methane emission from offshore and from onshore warming, and global warming rates increase by about 50%.
  • Result is that bad effects forecast for end of century (4°C warming worldwide, 10°C in Arctic) actually occur by about 2060. Speed of change is catastrophic for agriculture; warfare and population crashes ensue.
The current level of greenhouses gases is just over 450 parts per million carbon dioxide equivalent, enough for two degrees of warming. Losing the Arctic sea-ice in summer will add another half a degree, as I discussed recently in After the Arctic big melt: A hotter planet.
     And that's without any more greenhouse gas emissions, which are now churning into the atmosphere at a record rate.  Two degrees is not a safe target, but without regional geo-engineering over the Arctic it now seems out of reach. So what's the choice?
     As NASA climate science chief Jim Hansen keeps on telling us, it is hard to argue that anything above the Holocene maximum (of around 0.5 degrees above the pre-industrial temperature) can preserve a safe climate, and that we have already gone too far.  The notion that 1.5C is a safe target is out the window, and even 1 degree looks like an unacceptably high risk.
    In recent rivetting and disturbing presentations here and here, Professor Kevin Anderson has shown that the 2 degrees target now requires advanced-economy, high-polluting nations like Australia to reduce emissions by 10-20% per year if there is to be an equitable global effort to get there. [This concurs with Copenhagen reality check: 25% by 2020 isn't in the ball park.] And that's assuming the Arctic warming does not feed back into the system.
    None of this, of course, is mentioned in polite company when people tut-tut about the latest report from the World Bank, or whomever, showing we are heading for 4 degrees, accompanied by vague exhortations to hold to 2 degrees, without ever honestly talking about what that means.
     As Anderson points out, even holding warming to 4 degrees requires emissions peaking by 2020 a 3.5% p.a. reduction in CO2 from energy from then on.  Meanwhile Australia's emissions will be greater in 2020 than now due to dodgy carbon permit imports, as the prime minister and the climate minister oversee the massive expansion of coal exports and LNG, all the while mouthing platitudes about a 2-degree target.
     Their policies are not consistent with two degrees, but with four.
     In his presentations, Anderson has pointed out that
For 4°C global mean surface temperature (that means)
      5°C - 6°C global land mean
            … and increase °C on the hottest days of:
                6°C - 8°C in China
                     8°C - 10°C in Central Europe
                          10°C -12°C in New York
 He says that "In low latitudes 4°C gives up to 40% reduction in maize and rice as population heads towards 9 billion by 2050" and concludes that:
There is a widespread view that a 4°C future is incompatible with an organised global community, is likely to be beyond ‘adaptation’, is devastating to the majority of eco-systems & has a high probability of not being stable (i.e. 4C would be an interim temperature on the way to a much higher equilibrium level).
If the Arctic sea-ice goes in a few years and events unfurl as Wadhams and the peer-reviewed science suggests, 4 degrees will  be difficult to avoid, to put it politely.
     Then it will be too late to talk about geo-engineering, and the billion or so people left on a hot planet will be wishing like crazy we had taken the idea more seriously. Not because it's win-win, but because our collective stupidity over the last two decades now makes it the least-worst option.

David Spratt