Abstract

The Copenhagen Accord reiterates the international community’s commitment to “hold the increase in global temperature below 2 degrees Celsius”. Similarly, the EU maintains it ‘must ensure global average temperature increases do not exceed 2°C’ and the UK’s 2009 Low Carbon Transition Plan, states that “to avoid the most dangerous impacts of climate change, average global temperatures must rise no more than 2°C”. Despite such unequivocal statements the accompanying policies or absence of policies demonstrate a pivotal disjuncture between high-level aspirations with regards to 2°C and the policy reality. In part this reflects the continued dominance of ‘end point’ targets rather than scientifically-credible emission budgets and pathways, but even within the UK, where the policy-community and legislation aligns more closely with the science of climate change, the disjuncture nevertheless remains. In recent years increasing numbers of national and global emissions scenarios have been developed, each with differing carbon budgets and hence with different temperature impacts. Coordinating national with global analyses is evidently a prerequisite of understanding the scale and rate of mitigation and adaptation accompanying differing levels of climate change. However, as it stands, such coordination is rare with little more than perfunctory correlation between national emission pathways and the quantitative scale of the challenge at a global level. By disaggregating selected global emission pathways into Annex 1 and non-Annex 1 nations, this presentation outlines a much improved understanding of the extent of the mitigation challenge specifically and the adaptation challenge more generally. The analysis offers a stark and unremitting assessment of climate change. There is now little to no chance of maintaining the global mean surface temperature at or below 2°C, despite both repeated high-level statements to the contrary and the conclusions of more orthodox analysis (Committee on Climate Change, Stern, ADAM , AVOID, etc). Moreover, the impacts associated with 2°C have been revised upwards, sufficiently so that 2°C now more appropriately represents the threshold between ‘dangerous and extremely dangerous climate change’. Consequently and with tentative signs of global emissions returning to their earlier levels of growth, 2010 represents a political tipping point. The science of climate change allied with emission scenarios for Annex1 and non-Annex 1 nations suggests a very different mitigation and adaption challenge from that we are collectively prepared to countenance. The implications of this are profound for policy. In terms of adaptation, the scale of change and timeframe within which such changes need to be implemented are much more demanding than previously thought. Current commitments to reduce emissions suggest a global temperature rise of 4°C by 2060-70 is increasingly likely; with the rise being greater at more northerly and southerly latitudes, and greater still for the land areas once the relative thermal inertia of the oceans is accounted for. Turning to mitigation, urgent and radical reductions in emissions are essential even if a 4°C rise is to be avoided. Focussing on the emissions and science with regards to climate change is an increasingly melancholy affair. However, whilst there is now little chance of avoiding significant climate change, early harnessing of human will and ingenuity may still offer opportunities to develop relatively low-carbon and climate-resilient communities.