No 1204 Posted by fw, December 7, 2014
“Our cumulative emissions – and our carbon budget — are pivotal to understanding temperature and climate change. This insight is fundamentally important; it exposes how inadequate it is to aim for long-term, gradual reductions to be delivered by future technology while highlighting the need for urgent and radical reductions that we need to bring about now. That is obviously much less attractive.” —Kevin Anderson, Deputy Director of the Tyndall Centre for Climate Change Research
With the above words, Anderson captures the essence of this post, Part 2 in a multipart series extracted from his 2012, 24-page article. In Part 1 he explained the significance of 2°C as the target limit for a rise in average global warming, expressing alarm that policy-makers are now proposing policies that imply a very high chance of exceeding 2°C. He carries forward this discussion in Part 2, concluding that leaders are not ready to hear what science is telling them – that drastic lifestyle changes are needed in order to urgently and radically reduce CO2 emissions.
To read Anderson’s original 24-page paper, click on the following linked title. Alternatively, below is a reposting of the excerpted passages with some added subheadings inserted as hanging indents in bold italics.
The framing of 2°C refers to the global mean surface temperature rise compared to the pre-industrial period. Since then, and due to the burning of fossil fuels, greenhouse gas concentrations in the atmosphere have continued to increase and temperatures have gradually risen.
A 2°C average rise may not sound too bad if you live in the UK, for example. However, the regional repercussions vary considerably. An average warming of 2°C might mean that temperatures at the poles rise by up to 6°C and parts of Africa experience considerably higher warming than many other regions (May, 2006). Furthermore, most of the planetary surface consists of oceans, and water has a high capacity for absorbing heat, so an average global rise of 2°C may correspond to an average land-based temperature rise of 3°C – triggering marked changes in temperature and precipitation patterns. The repercussions of an average 2°C warming reach deeper than we tend to imagine.
Why has a 2°C rise become the focal point of climate change discourse?
Over the past decades, many scientists have explored the various impacts associated with changes in global and regional temperatures. More recently these have been summarized and brought together to provide a succinct management and policy tool to help guide decision-making. The impacts have been summarized according to five different categories* with each category coloured along a continuum from white (acceptable) to red (dangerous) (Figure 1). Through a slow process of engagement between scientists, policy-makers, companies and civil society, 2°C has become established as a ‘guard-rail’ between acceptable and dangerous levels of climate change. While impacts resulting from temperature rises below 2 are not, on average, considered desirable either, it is widely, and often tacitly, assumed that they are somehow manageable and tolerable. (*The 5 risk categories are: risks to unique and threatened systems; risks of extreme weather events; distribution of impacts; aggregate impacts; and risks of large-scale discontinuities (i.e. ‘tipping points’)).
Figure 1 — Comparison of climate change risks 2001 & 2008
The first assessment of these impacts was made in the late 1990s and early 2000s (the left-hand graph). When the impacts were revisited in time for the Copenhagen climate summit in 2009, the scientific understanding of global warming impacts had advanced, with all of the bars demonstrating greater impacts for any given increase in temperature. Not only do the impacts occur earlier than had been thought, but the set of impacts considered to be just about acceptable corresponds with much lower temperatures. The conclusion is clear. The impacts of 2°C are more serious than previously thought, and consequently the 2°C guard-rail lies in far more dangerous territory. If the logic of defining 2°C impacts as dangerous is to hold, the more recent impact analysis suggests 2°C represents the threshold between dangerous and extremely dangerous, rather than between acceptable and dangerous climate change. Certainly, it could reasonably be argued that 1°C rather than 2°C should become the de facto appropriate target.
If one accepts the rationale of safeguarding against dangerous climate change it is difficult to argue against a 1°C goal from a scientific point of view. However, from a practical, political point of view, it is almost impossible to imagine us now stabilizing at 1°C, given what we have emitted into the atmosphere already. Even if all emissions were immediately stopped, 1°C would likely be exceeded. In other words, 2°C, perhaps 1.5°C, poses a limit of what we could plausibly aim for. At the same time, we should bear in mind that we have consistently and abjectly failed to set a course that would ensure remaining below even 2°C.
What degree of mitigation – what level of carbon reduction – is necessary to stay at or below a temperature rise of 2°C?
Since the temperature goal of 2°C has significant political momentum behind it, let us turn to the question of what this entails, politically and socially. What degree of mitigation – what level of carbon reduction – is necessary to stay at or below a temperature rise of 2°C? Asking this question raises an associated question. How should a global carbon budget be distributed between Annex I (broadly OECD countries) and non-Annex I (broadly non-OECD) countries, between industrialised parts and the industrialising and less wealthy parts of the world?
The problem with 2050 emission reduction targets is that they may prove to be meaningless
With respect to the first question, there are many long-term targets that sound ambitious. For example, the UK has committed to reductions of 80 percent CO2 equivalent by 2050. The EU has adopted a similar goal, while the 2007 UN climate negotiations in Bali concluded that cuts of 50 per cent in global emissions by 2050 are necessary. The problem with 2050 targets is that they conveniently give the illusion that we can carry on with what we are doing and pass the problem on to future generations.
A 2050 goal is convenient for policy-makers, companies and the public alike – it does not interfere with decision-making, immediate business issues or how we live our lives. Indeed, the lure of long-term targets is considerable. Unfortunately, there is no basis in science for banking on the problem being solved through technology, by someone else, in the future; disturbingly, many scientists have used this inappropriate shorthand and continue to do so.
The CO2 that we release into the atmosphere today will remain there for well over 100 years. Therefore, a target of cutting 2050 emissions by a given percentage does not directly correspond to how much the temperature will rise and whether we will avoid dangerous climate change or not. (Imagine, for example, continuously high emissions for decades followed by a sharp drop just in time to meet the 2050 target.) For long-lived gases such as CO2 and many other greenhouse gases, cumulative emissions, the stock that builds up in the atmosphere, is the quantity that matters. Every day we turn the lights on, every time we drive a car we add to the accumulating stock of atmospheric CO2. Our cumulative emissions – and our carbon budget — are pivotal to understanding temperature and climate change. This insight is fundamentally important; it exposes how inadequate it is to aim for long-term, gradual reductions to be delivered by future technology while highlighting the need for urgent and radical reductions that we need to bring about now. That is obviously much less attractive.
Science reveals what policy makers don’t want to hear – We must begin today to make lifestyle changes
Hence we shy away from addressing cumulative emissions. We much prefer to stick to long-term targets. They may prove meaningless with respect to global warming but they are tailored to cater for our cognitive dissonance. Bringing in the science reveals what we are not prepared to countenance – that we have to make changes to our lifestyles today.
End of Part 2
(NOTE: Anderson’s original article is based on a transcript of a public presentation at the UK’s Department for International Development (DFID) in July 2011, available at http://www.slideshare.net/DFID/professor-kevin-anderson-climate-change-going-beyond-dangerous.)
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