Unrealistic current estimates of climate change mitigation?

Current energy and climate policies around the world aim to deliver climate change mitigation in order to limit global warming to 2 degrees above pre-industrial levels. The backbone of this policy is that this mitigation will be delivered by increased energy efficiency and ‘clean’ energy technology. The underlying force of increased energy consumption is being driven by larger populations with more resource intensive lifestyles.


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Arvesen, Bright and Hertwich (2011) argue that the current policies are based on simplified models of complex social and physical systems that don’t include links between climate and other environmental pressures or the indirect effects of the mitigation measures themselves. Using a narrow view of systems and mitigation effects means environmental impacts can be underestimated and mitigation success can be overestimated.

The Copenhagen Accord national emissions-reduction pledges are not sufficient for global warming to be limited to 2 degrees, especially in the face of lopsided CO2 emissions for 2000-2009 (321 Gt emitted out of 1000 Gt goal for 2000-2049). Of great concern is the speed of climate change and combined with the disregard of long term feedbacks the modelled amount of climate change mitigation may be grossly overestimated. In addition there are many other environmental factors, such as habitat change and loss of biodiversity, which could impact on the rate of climate change.

The authors examine six areas they believe are not sufficiently considered in the development of energy and climate policy:

1. Transitioning to ‘clean’ energy supply will reduce climate impacts

Even though there is no fossil fuel combustion in the operation of energy converters (e.g. photovoltaic solar cells converting solar energy into electricity) emissions still occur in processes that support these ‘clean’ technologies, such as the manufacturing of solar cells.

2. Realised net climate change mitigation from energy efficiency is unlikely to live up to its expectations

Negative costs – modelling often shows that negative costs are associated with reducing emissions, but individual end consumers can often be faced with real costs even if the modelling shows this is not the case in aggregate.

Rebound effects – the reduction in the price of energy from increased efficiency may not reduce the amount of energy consumed as the lower price may result in increased demand and/or the income available for consumption may increase.


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3. Developing fossil energy with carbon capture and storage (CCS) and renewable energy in parallel may lower system-wide performance

Technological, institutional or social factors can hinder the implementation of greenhouse gas saving mechanisms, leading to the continuation of fossil fuel dependence.

4. The notion of absolute decoupling is not supported by historical records (absolute decrease in environmental impact as income grows).

5. Linkages between environmental pressures are likely to complicate mitigation

Biophysical and social systems are highly complex (so much so that a large portion of the complexity is not understood) so models of their function don’t encompass all of the complexity. A risk of this reduction in complexity is that interactions that aren’t modelled could lead to unforseen impacts. This could lead to problem shifting (generating a problem while solving another) and/or the hindering of solutions to overcome a biophysical limit by other physical constraints.

6. Future demands for energy services may be underestimated

Current energy models account for upscaling demand in existing categories of energy consumption, but not new categories of demand that may arise. There may also be unexpected growth in existing areas of energy demand (e.g. energy for pumping, treatment and desalination of water).

In this paper Arvesen, Bright and Hertwich dispute the idea that energy efficiency and ‘clean’ energy technologies (without social and economic structural changes) can produce the amount of climate change mitigation necessary to limit global warming to 2 degrees. The complexity of environmental and social systems doesn’t seem to be taken into account in the principles underlying energy and climate policy. Combining this complexity and other impacts on climate change could lead to unforeseen consequences for energy consumption and global warming in the future.

Read more:
Arvesen A, Bright RM, Hertwich EG (2011) Considering only first-order effects? How simplifications lead to unrealistic technology optimism in climate change mitigation. Energy Policy, 39, 7448-7454.

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