Few would disagree that the world should avoid "dangerous" (or unsafe) climate warming, but what does that term mean? What does climate safety mean? Is climate change already dangerous? Are greenhouse gas levels already too high? This report surveys some recent developments in climate science knowledge as a way of discerning the gaps between myth and reality in climate policy-making.
Scientific and political reticence
Amongst advocates for substantial action on climate warming, there is a presumption of agreement on the core climate science knowledge that underlies policy-making, even though differences exist in campaign strategy.
But the boundaries between science and politics have become blurred in framing both the problem and the solutions. Amongst advocates, advisors and policy-makers there are very different levels of understandings of the core climate science knowledge, how it is changing, what constitutes "danger", what needs to be done, and at what pace.
Myth 1: Climate change is not yet dangerous
In 2008 John Holdren, who was then senior advisor to President Barack Obama on science and technology issues, told the Eighth Annual John H. Chafee Memorial Lecture on Science and the Environment: "… the (climate) disruption and its impacts are now growing much more rapidly than almost anybody expected even a few years ago. The result of that, in my view, is that the world is already experiencing ‘dangerous anthropogenic interference in the climate system’ " (emphasis added) (Holdren, 2008).
“Dangerous” climate changed is broadly characterised by the Intergovernmental Panel on Climate Change (IPCC) in the “burning embers” diagram as including five “reasons for concern”: risk to unique and threatened systems; risk of extreme weather events; distribution of impacts; aggregate (total economic and ecological) impacts; and risk of large-scale discontinuities (that is, abrupt transitions or “tipping points”). See Figure 1.
From this perspective, tipping points have already been passed, at less than 1°C of warming, for:
The loss of the Amundsen Sea West Antarctic glaciers, and 1–4 metres of sea level rise (Rignot, Mouginot et al., 2014; Joughin, Smith et al., 2014). Dr Malte Meinshausen, advisor to the German government and one of the architects of the IPCC's Representative Concentration Pathways, calls the evidence published this year of "unstoppable" (Rignot, 2014) deglaciation in West Antarctica "a game changer", and a "tipping point that none of us thought would pass so quickly", noting now we are "committed already to a change in coastlines that is unprecedented for us humans" (Breakthrough, 2014).
The loss of Arctic sea-ice in summer (Duarte, Lenton et al., 2012; Maslowski, Kinney et al., 2012), which will hasten regional warming, the mobilization of frozen carbon stores, and the deglaciation of Greenland.
Numerous ecosystems, which are already severely degraded or in the process of being lost, including the Arctic (Wolf, 2010). In the Arctic, the rate of climate change is now faster than ecosystems can adapt to naturally, and the fate of many Arctic marine ecosystems is clearly connected to that of the sea ice (Duarte, Lenton et al., 2012). In May 2008, Dr Neil Hamilton, who was then director of Arctic programmes for WWF, told a stunned audience (of which I was a member) at the Academy of Science in Canberra that WWF was not trying to preserve the Arctic ecosystem because “it was no longer possible to do so”.
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