An open letter to Professor Ross Garnaut

September 27, 2008

Dear Professor Garnaut,

In your recent letter to scientists and environmental groups, you asked for further input into your final report on the question of the 450ppm target and "overshoot", and Australia's position given the uncertainties about the outcome of future global negotiations.

As community-based climate action and environment advocacy groups across Australia, we wish to make two points.

1. 450ppm is not a reasonable target for a safe-climate future, nor is planning to overshoot 450ppm.

A 450ppm target may not be sufficient to avoid dangerous climate change. With the added risk of a sustained overshoot causing threshold effects and triggering tipping points, this target holds a very real possibility of climate change running away from the human capacity to stabilise it.

There is now a growing recognition, led by the USA's most prominent climate scientist, NASA Goddard Institute for Space Studies chief Dr James Hansen, for a target in the range of 300–325ppm CO2. This is necessary, says Hansen, in order to restore the Arctic sea-ice and avoid the collapse of the Greenland and Himalayan ice-sheets, catastrophic sea-level rises and dangerous levels of ocean acidification. Hansen has noted that:

Recent greenhouse gas emissions place the Earth perilously close to dramatic climate change that could run out of our control, with great dangers for humans and other creatures. There is already enough carbon in the Earth's atmosphere for massive ice sheets such as West Antarctica to eventually melt away, and ensure that sea levels will rise metres in coming decades. Climate zones such as the tropics and temperate regions will continue to shift, and the oceans will become more acidic, endangering much marine life. We must begin to move rapidly to the post-fossil fuel clean energy system. Moreover, we must remove some carbon that has collected in the atmosphere since the Industrial Revolution. (1)

A temperature cap of 2–2.4°C, as proposed at Bali and now the subject of international negotiations, would take the planet beyond the temperature range of the last million years and into extreme danger.

(2) The tipping points for large ice-sheet and species loss have already been crossed, as we are witnessing in the Arctic. It is no longer a case of how much more we can safely emit, but whether we can quickly stop emissions and produce a cooling before we hit tipping points and amplifying feedbacks — such as large-scale release of greenhouse gases from melting permafrost — that will take the trajectory of the Earth's climate system beyond any hope of human restoration.

Some of the scientific input to the Review may have been reticent in giving insufficient emphasis to what you have termed the scientific "bad possibilities" with "immense impacts" and "highly adverse outcomes". These are much more than "10% likely", the risk you suggested at your Sydney public meeting. As just one example, there is a substantial body of evidence that indicates long-term climate sensitivity (the temperature rise for a doubling of CO2) is closer to 6°C than 3°C as widely assumed in climate models, including those that underlie the Review's modelling. (3)

For example, CO2 levels have approximately doubled from 190 ppm at the depth of the last ice age 20,000 years ago to
380 ppm today, whilst the temperature has increased around 5°C, with more to come for the present level of CO2, due to thermal inertia. Matching greenhouse gas levels with the Earth's temperature over the last 450,000 years has established climate sensitivity with slow feedbacks to be 6°C. (4)

This would mean that 450ppm may produce a rise of around 4°C, not the 2°C on which the Review's modelling is predicated.

Given this understanding, overshooting of any magnitude and duration is flirting with disaster.

Overshooting assumes that there is a robust mechanism operating to remove the carbon dioxide "overshoot" from the air to lower the level of greenhouse gases from the peak, before the full force is felt. But if the weakening of the carbon sinks, as predicted and observed (5) — including the permafrost time-bomb — is sufficiently large, this drawdown effect will not be strong enough. In this case, unless the natural carbon sinks are supplemented by humanity deliberately drawing down atmospheric carbon on a huge scale, "overshooting" will be a failed strategy, and atmospheric greenhouse gases will be stranded at a far higher level than planned.

We are already near or past thresholds for profound climate change impacts, including loss of the Arctic sea-ice and the Arctic ecosystem, significant ice sheet loss and multi-metre sea-level rises, and loss of significant carbon sinks. In these circumstances, the notion of having "room to move" through "overshooting" is fanciful.

We could also point to new research which has doubled the previous estimate of the carbon content of permafrost (to be more that the total atmospheric carbon equivalent); has estimated that the unstoppable loss of permafrost carbon will trigger around 9–10°C regional warming; and has shown that sea-ice loss can boost Arctic warming to 3.5 times the global average. (6) A tipping point of a regional 9–10°C rise could be reached in Siberia as early as mid-century and now seems very likely by century's end if a global target in the range of 450–550 ppm is adopted. The consequences are

We are confident that many in the climate science community would support modelling of the 300–325ppm target. We urge you to recommend in your final report that this be undertaken as a matter of urgency, in conjunction with an up-to-date review of the scientific "bad possibilities" that are becoming more evident. "Middle of the road" outcomes on which the modelling was based are unlikely to eventuate; much worse outcomes are likely and must be considered if policy making is to be robust enough to remain credible.

2. Australia should not wait for an international agreement before acting.

In Asia, more than a billion people populate river basins that draw melt-water from the Himalayan-Hindu Kush ice sheet during the dry season, yet it is expected that the ice sheet could be effectively gone by mid-century. (7) What are our values here? Should we "wait and see" if the whole world will act, before we do? Or should we take the only possible moral course and do what we need to do now, without waiting, because if other nations were to act similarly it may be possible to stop those billion people facing a catastrophe beyond words?

We cannot wait, as one of the world's highest per capita emitters (even excluding the impact of our coal and gas exports). We have a greater responsibility to lead, in proportion to our responsibility for the problem. Your interim target of 550 ppm is at least a 3-degree target, likely much more with higher climate sensitivity. Playing a game of "blink" with the international community when the stakes are the survival of most people and species is clearly indefensible.

If all nations know that we all have to take drastic action, then the first and best choice for all nations is to act unilaterally, because we can and must. We do not have to wait for an international agreement. To decide not to act with urgency now is to choose failure.

There is a suggestion that we should not act decisively now because it would involve too great a cost. That is a political judgement, not a scientific one. Yet it may not be valid.

Recent McKinsey & Company research (8) found that a significant portion of emissions reduction measures are cash-positive, so there can be no reason to wait. Consultants are now reporting to government that within two decades the cost of stationary energy from solar-thermal and geo-thermal sources will likely be lower than from coal because of the rate of innovation and economies of scale attached to the former, and the burden of rising global coal and gas prices attached to the latter. If we decide to plan and oversee a rapid transition of Australia's stationary energy system to renewable sources, we could halve Australian emissions within a decade or two. Why wait for an international agreement when it is in our own national interest to act now on stationary energy?

This was at the core of the challenge to America Al Gore issued in July: Today I challenge our nation to commit to producing 100% of our electricity from renewable energy and truly clean carbon-free sources within 10 years … This goal is achievable, affordable and transformative. To those who argue that we do not yet have the technology … I've seen what they [entrepreneurs who will drive this revolution] are doing and I have no doubt that we can meet this challenge. (9)

We urge you in your final report to advocate this inspiring and transformative challenge for Australia.

We believe that if Australians "have a go", we can lead the world by example, instead of playing this dangerous international gamble with the planet's future.


Damien Lawson, Friends of the Earth (Australia)
Catherine Potter, Conservation Council of the South East Region and Canberra
Julie Pettett, Conservation Council of South Australia
Ian Herbert, Capricorn Conservation Council
Erland Howden, Nature Conservation Council of NSW
Warrick Jordan, Environment Tasmania
Robin Knox, COOLmob (a project of the Environment Centre NT)
Carol Ride, Darebin Climate Action Now
Steve Meacher, C4 Healesville
David Spratt, Carbon Equity
Deborah Hart, Locals into Victoria's Environment
Lizette Salmon, Wodonga and Albury Towards Climate Health
Jonathan Doig, Sutherland Climate Action Network
Adrian Whitehead, Target 300
Richard Laverack, Frankston Climate Change Action Group
Lee Fuller, Emerald for Sustainability
Catherine Manning, Southern Victoria Community Action Group Inc.
Shakti Burke, Kyogle Climate Action Network
Jenny Curtis, Climate Change Balmain-Rozelle
Wendy French, Tarrangower Branch, Mount Alexander Sustainability Group
Nick Lanyon, Ballarat Renewable Energy And Zero Emissions
Alex Schlotzer, Brimbank Climate Action Network
Sandi Keane, Mansfield Environment and Climate Action
Sue Pratt, Families Facing Climate Change
Tony Doherty, Climate Change Australia Inc. (Manning Branch)
Tim Luckett, Newtown Climate Action Group
Vicki Brooke, Climate Action Newcastle
Phil Cocks, Climate Action Denmark
Janice Marshall, Denmark Environment Centre Inc
Lyn Hovey, Riddells Creek Sustainability
Cameron Tampion, Bayside Climate Change Action Group
Russell Pearse, Ararat Greenhouse Action Group
Peter Cook, Dandenong Ranges Renewable Energy Association
Genevieve Barlow, Newstead 2021 Community Group
Dr Gideon Polya, Yarra Valley Climate Action Group
Paul Hanly, Drummoyne/Lowe/Canada Bay Climate Action Group
Linda Haefeli, Pittwater Climate Action Group
Tracey Tipping, Pittwater Committee to Implement Plan for Carbon Neutrality by 2020
Steve Phillips, Rising Tide, Newcastle
Brynnie Goodwill, Al Gore Climate Project Ambassador
Duncan Jinks, Transition Towns Newcastle
Jenny Francis, Hughes Creek Group, Inc
Barbara Jackson, Nillumbik Climate Action Now
Sandra Menteith, Climate Action Now Wingecarribe
Mary Hall, Murrindindi Climate Network
Julie James, A Grand Stand for the Environment
Laura Dean, Earth Hour Avalon
Kirsten Kennedy, Pine Rivers Climate Action Network
Erland Howden, Hills Against Global Warming
William Blunt, Association for Berowra Creek

cc Prime Minister, Minister for Climate Change and Water, Minister for the Environment, Heritage and the Arts

Correspondence: Damien Lawson, Friends of the Earth, Box 222, Fitzroy, 3065. . Phone 0419 253 342.

(1) J. Hansen, frontispiece, Climate Code Red, D. Spratt and P. Sutton (Scribe 2008).
(2) J. Hansen, M. Sato et al. (2006), "Global temperature change", Proceedings National. Academy of Sciences 103: 14288-14293.
(3) N. Bellouin, O. Boucher et al. (2005) "Global estimate of aerosol direct radiative forcing from satellite measurements", Nature 438: 1138–41; M. O. Andreae, C. D. Jones et al. (2005) "Strong present-day aerosol cooling implies a hot future", Nature 435: 1187–90; J. Hansen, M. Sato, et al. (2007) "Dangerous human-made interference with climate: a GISS model E study", Atmospheric Chemistry and Physics 7: 2287–312.
(4) J. Hansen, M. Sato et al., "Target atmosphere CO2: where should humanity aim", submitted to Science, 7 April 2008,
(5) C. D. Jones, P. M. Cox et al. (2003) "Strong carbon cycle feedbacks in a climate model with interactive CO2 and sulphate aerosols", Geophysical Research Letters 30: 1479; T. H. Lenton, H. Held et al. (2008)
"Tipping elements in the Earth's climate system", Proceedings National Academy Sciences 105: 1786–93; D. Solovyov and A. Doyle, "Siberian thaw could speed up global warming", Sydney Morning Herald, 26 September 2007; J. Randerson, "Forests battle to soak up carbon", The Age, 4 January 2008; J. B. Miller
(2008) "Carbon cycle: Sources, sinks and seasons", Nature 451: 26–27; C. LeQuere, C. Rodenbeck, et al.
(2007) "Saturation of the southern Ocean CO2 sink due to recent climate change", Science 316: 1735–38; A.
Woodcock, "Scientists fear climate change speed-up as oceans fail to hold greenhouse gases", The Scotsman,
21 October 2007.
(6) E. A. G. Schuur, James Bockheim et al. (2008) "Vulnerability of permafrost carbon to climate change: Implications for the global carbon cycle", BioScience 58: 701–714; D. V. Khvorostyanov, P. Ciais, et al.
(2008) "Vulnerability of east Siberia's frozen carbon stores to future warming", Geophysical Research Letters
35: 10703; D. M. Lawrence, A. G. Slater et al. (2008) "Accelerated Arctic land warming and permafrost degradation during rapid sea ice loss during rapid sea ice loss", Geophysical Research Letters 35: 11506.
(7) Reuters, "Vanishing Himalayan Glaciers Threaten a Billion", 5 June 2007; IPCC (2007), Working Group II Report: "Impacts, Adaptation and Vulnerability" Summary for Policymakers", chapter 10; WWF Nepal Programme (2005) An overview of glaciers, glacier retreat, and subsequent impacts in Nepal, India and China.
(8) A. Lewis, S. Gorner et al., An Australian Cost Curve for Greenhouse Gas Reduction (McKinsey, 2008).
(9) <>

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