Key climate indicators such as global mean surface temperature, sea-level rise and extreme climatic events are already moving beyond the patterns of natural variability within which contemporary society and economy have developed. This is one of the key messages of a report presented by leading scientists in Brussels June 18 in preparation for the United Nations Climate Change Conference in Copenhagen in December.
“We have covered new findings on climate science, climate impacts on society and the environment, and effective tools and approaches to deal with these challenges,” says Hans Joachim Schellnhuber, director of the Potsdam Institute for Climate Impact Research (PIK) and member of the writing team. “The scientific findings presented in this update create by themselves a sense of urgency that we hope will lead the Copenhagen conference to success,” says Schellnhuber, who advises the German government on global change issues. In Copenhagen a follow-up to the Kyoto protocol will be debated.
The Synthesis Report summarises new knowledge that was presented at the congress “Climate Change: Global Risks, Challenges & Decisions” at the University of Copenhagen in March this year. Approximately 2500 people from nearly 80 countries attended the congress with over 1400 scientific presentations. “The bottom line is that limiting global warming to a manageable extent will require all our ingenuity for the climate-smart evolution of existing structures,” says Schellnhuber. Yet large-scale transformational measures would also be needed.
For example, the current planetary land-use pattern is the result of erratic historical processes. These were blind to global sustainability considerations, Schellnhuber and Veronika Huber from PIK point out in the report. Future land-use must accommodate the demands of some nine billion people for food and fibre, energy, infrastructures and conservation – on a non-expandable global surface.
Analyses led by PIK indicate that twelve billion people could be nourished on less than one third of the present agricultural area, if the best sites were used for the most appropriate crops and if world food trade would operate undistorted by protectionism. This bold approach would only become feasible, however, if the prime locations (as shown in the figure) were reserved for agriculture as part of a long-term global deal – in the same way as the tropical rainforests hopefully will be earmarked for conservation as part of the global commons.
“If humanity is to learn from history and to limit these threats [of anthropogenic climate change], the time has come for stronger control of the human activities that are changing the fundamental conditions for life on Earth,” the writing team states in the Synthesis Report. To decide on effective control measures, an understanding of how human activities are changing the climate, and of the implications of unchecked climate change, needs to be widespread among world and national leaders, as well as among the public. The report communicates this understanding through six key messages:
Key Message 1: Climatic Trends
Recent observations show that greenhouse gas emissions and many aspects of the climate are changing near the upper boundary of the IPCC range of projections. Many key climate indicators are already moving beyond the patterns of natural variability within which contemporary society and economy have developed and thrived. These indicators include global mean surface temperature, sea-level rise, global ocean temperature, Arctic sea ice extent, ocean acidification, and extreme climatic events. With unabated emissions, many trends in climate will likely accelerate, leading to an increasing risk of abrupt or irreversible climatic shifts.
Key Message 2: Social and environmental disruption
The research community provides much information to support discussions on “dangerous climate change”. Recent observations show that societies and ecosystems are highly vulnerable to even modest levels of climate change, with poor nations and communities, ecosystem services and biodiversity particularly at risk. Temperature rises above 2°C will be difficult for contemporary societies to cope with, and are likely to cause major societal and environmental disruptions through the rest of the century and beyond.
Key Message 3: Long-term strategy – Global Targets and Timetables
Rapid, sustained, and effective mitigation based on coordinated global and regional action is required to avoid “dangerous climate change” regardless of how it is defined. Weaker targets for 2020 increase the risk of serious impacts, including the crossing of tipping points, and make the task of meeting 2050 targets more difficult and costly. Setting a credible long-term price for carbon and the adoption of policies that promote energy efficiency and low-carbon technologies are central to effective mitigation.
Key Message 4: Equity Dimensions
Climate change is having, and will have, strongly differential effects on people within and between countries and regions, on this generation and future generations, and on human societies and the natural world. An effective, well-funded adaptation safety net is required for those people least capable of coping with climate change impacts, and equitable mitigation strategies are needed to protect the poor and most vulnerable. Tackling climate change should be seen as integral to the broader goals of enhancing socioeconomic development and equity throughout the world.
Key Message 5: Inaction is inexcusable
Society already has many tools and approaches – economic, technological, behavioural, and managerial – to deal effectively with the climate change challenge. If these tools are not vigorously and widely implemented, adaptation to the unavoidable climate change and the societal transformation required to decarbonise economies will not be achieved. A wide range of benefits will flow from a concerted effort to achieve effective and rapid adaptation and mitigation. These include job growth in the sustainable energy sector; reductions in the health, social, economic and environmental costs of climate change; and the repair of ecosystems and revitalisation of ecosystem services.
Key Message 6: Meeting the Challenge
If the societal transformation required to meet the climate change challenge is to be achieved, then a number of significant constraints must be overcome and critical opportunities seized. These include reducing inertia in social and economic systems; building on a growing public desire for governments to act on climate change; reducing activities that increase greenhouse gas emissions and reduce resilience (e.g. subsidies); and enabling the shifts from ineffective governance and weak institutions to innovative leadership in government, the private sector and civil society. Linking climate change with broader sustainable consumption and production concerns, human rights issues and democratic values is crucial for shifting societies towards more sustainable development pathways.
The up-to-date overview of research relevant to climate change was handed over to the Danish Prime Minister Lars Løkke Rasmussen, the host of the conference.
Abstracts for the scientific presentations at the congress “Climate Change: Global Risks, Challenges & Decisions”
Materials provided by Potsdam Institute for Climate Impact Research (PIK). Note: Content may be edited for style and length.
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