Climate hotspots: key vulnerable regions, climate change and limits to warming

Abstract

Defining and operationalizing Article 2 of the UNFCCC remains a challenge. The question of what is dangerous climate change is not a purely scientific one, as danger necessarily has a subjective dimension and its definition requires judgment and precaution. The papers in this special issue of Regional Environmental Change attempt to navigate this problem, by offering an overview of the latest scientific findings in the context of risks and uncertainties, and assess some key vulnerabilities that might lead to dangerous climate change. This synthesis provides an overview of the papers in this issue and looks at four areas of possible dangerous climate changeadverse declines in regional food and water security, loss of arctic sea ice with projected extinction of species, largescale sea-level rise and loss of coral reef systems. These issues affect a number of different regions including Africa, South Asia, and Small Island Developing States. Significant risks to vulnerable regions and systems at warming levels of 1.5-2°C above pre-industrial are identified. The direct effects of CO 2 concentration increases in terms of ocean acidification are identified as relevant to Article 2 because of the risks posed to coral reefs. Ultimate CO 2 stabilization levels that allow for the long-term viability of coral reefs likely are below 350 ppm. The paper concludes by arguing that the emission reduction pledges made by countries under the Copenhagen Accord will not suffice to prevent dangerous climate change.

Perceptions of Australian marine protected area managers regarding the role, importance, and achievability of adaptation for managing the risks of climate change

“…These findings may also suggest that MPA managers in Australia may be unaware of recent research highlighting the predicted and potential risk of ecosystem collapse associated with climate change (e.g., Smith et al 2009, Hare et al 2011. Given the potential importance of ecosystem collapse to society, it is important that the likelihood and consequences of future ecosystem collapses as a result of climate change are demonstrated in the scientific literature and then communicated as a priority to raise awareness among Australian MPA managers.…”

Science and policy characteristics of the Paris Agreement temperature goal

“…Eventually, this 'not exceed' limit was taken up by the G8 in 2009 4 . The gradual adoption of specific warming limits by political bodies can be linked to the evolution of the underlying scientific basis.…”

“…Informed by the conclusions of the IPCC AR4 8 , approximately 100 countries at the UNFCCC Copenhagen Conference (COP15) in 2009 were calling for warming to be limited to below 1.5 °C relative to pre-industrial levels 4,9 . Although COP15 itself was widely regarded as a failure, two politically durable outcomes from the Copenhagen Accord 10 have ultimately translated into the Paris Agreement: first was the emergence of a long-term goal agreed at head-of-government level, expressed then as an aim to hold the increase in warming below 2 °C, combined with a recognition that deep cuts in global emissions are required 'according to science' .…”

The role of negative CO2 emissions for reaching 2 °C—insights from integrated assessment modelling

“…associated with 'business-as-usual' scenarios could very well lead to considerable impacts, such as reduction of agricultural production, biodiversity loss, sea level rise and extreme weather events (Hansen et al 2008;Hare et al 2011;Parry et al 2007). Based on the available scientific evidence, policy makers have proposed to use the so-called 2°C target (a maximum increase of global mean temperature above pre-industrial levels) as an important objective for international climate policy (UNFCCC 2010).…”