Dangerous Anthropogenic Climate Change from the Perspective of Adaptation

The stated “ultimate objective” of the United Nations Framework Convention on Climate Change is “stabilisation of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system”. In the more than 20 years since the Convention was negotiated, understanding has increased of the risks posed to human and natural systems by climate change. The social construction underlying the negotiations is that greenhouse gases (GHGs) are pollutants whose control could prevent serious (and future) impacts. However, research on climate change impacts has led to an enlarged framework: the magnitude and extent of possible risks of climate change depend not only on changes in global average temperature (e.g. global warming), but also the human and natural systems exposed to those changes and their underlying vulnerability. Climate change interacts with other drivers to increase (or decrease) risks, and affects risk through multiple pathways. Adaptation then focuses not just on climate change, but also on addressing underlying exposure and vulnerability. The determination of what atmospheric concentration of GHGs constitutes dangerous anthropogenic interference with the climate system is a value judgment, which means that science alone cannot provide an answer. To help inform the policy process, the Intergovernmental Panel on Climate Change issued reports in 2001 and 2007, synthesising the literature on climate change impacts and identified reasons of concern to enable readers to evaluate the relationships between increases in global mean temperature and associated impacts. Each concern is consistent with a paradigm that could be used independently or in combination with other reasons to help determine dangerous atmospheric concentrations. The reasons for concern are the relationship between global mean temperature increase and damage to or irreparable loss of unique and threatened systems; distribution of impacts 713 https://doi.org/10.5771/9783845242774_713, am 06.11. 2019, 08:25:44 Open Access https://www.nomos-elibrary.de/agb among people and across regions; global aggregate damages; and probability of extreme weather events and of large-scale singular events. Assessments in 2001 and 2007 showed increasing risk with increasing temperatures, with the temperature at which risks become apparent varying across the reasons for concern, and with greater risks in 2007 than in 2001. The assessments addressed only how risks change as global mean temperature increases, and not how risks might change at different levels of warming. The assessments also identified impacts, vulnerabilities, and risks that would merit policymakers’ attention, including food supply, infrastructure, health, water resources, coastal systems, ecosystems, global biogeochemical cycles, ice sheets, and modes of oceanic and atmospheric circulation. Reasons for concern about the ability to adapt to projected impacts and the likelihood of sustainable adaptation include contractions and uncertainties in the window of opportunity for adaptation; the difference between adaptive capacity and adaptive action; the risk of maladaptation; and the misguided measures of loss. Effective and efficient adaptation will be critical to increase the resilience of human and natural systems over the next few decades, although it will not be possible to prevent all impacts. Over the longer term, the magnitude and extent of climate change impacts will depend on the mix of adaptation and mitigation, with rapid and successful reductions in GHG emissions reducing how much adaptation will be needed later this century. Slower and less comprehensive mitigation will increase the likelihood of crossing thresholds that will result in dangerous impacts to human and natural systems.