Synthesis Report - Question 1

1.6

With regard to strategies for addressing climate change, the TAR provides an assessment of the potential for achieving different levels of concentrations through mitigation and information about how adaptation can reduce vulnerability. The causality works in both directions. Different stabilization levels result from different emission scenarios, which are connected to underlying development paths. In turn, these development paths strongly affect adaptive capacity in any region. In this way adaptation and mitigation strategies are dynamically connected with changes in the climate system and the prospects for ecosystem adaptation, food production, and sustainable economic development.

WGII TAR Chapter 18 & WGIII TAR Chapter 2

1.7

An integrated view of climate change considers the dynamics of the complete cycle of interlinked causes and effects across all sectors concerned. Figure 1-1 shows the cycle, from the underlying driving forces of population, economy, technology, and governance, through greenhouse gas and other emissions, changes in the physical climate system, biophysical and human impacts, to adaptation and mitigation, and back to the driving forces. The figure presents a schematic view of an ideal "integrated assessment" framework, in which all the parts of the climate change problem interact mutually. Changes in one part of the cycle influence other components in a dynamic manner, through multiple paths. The TAR assesses new policy-relevant information and evidence with regard to all quadrants of Figure 1-1. In particular, a new contribution has been to fill in the bottom righthand quadrant of the figure by exploring alternative development paths and their relationship to greenhouse gas emissions, and by undertaking preliminary work on the linkage between adaptation, mitigation, and development paths. However, the TAR does not achieve a fully integrated assessment of climate change, because of the incomplete state of knowledge.

WGII TAR Chapters 1 & 19, WGIII TAR Chapter 1, & SRES

1.8

Climate change decision making is essentially a sequential process under general uncertainties. Decision making has to deal with uncertainties including the risk of non-linear and/or irreversible changes and entails balancing the risk of eitherinsufficient or excessive action, and involves careful consideration of the consequences (both environmental and economic), their likelihood, and society's attitude towards risk. The latter is likely to vary from country to country and from generation to generation. The relevant question is "what is the best course for the near term given the expected long-term climate change and accompanying uncertainties."

WGI TAR, WGII TAR, & WGIII TAR Section 10.1.4

1.9

Climate change impacts are part of the larger question of how complex social, economic, and environmental subsystems interact and shape prospects for sustainable development. There are multiple links. Economic development affectsecosystem balance and, in turn, is affected by the state of the ecosystem; poverty can be both a result and a cause of environmental degradation; material- and energy-intensive life styles and continued high levels of consumption supported by non-renewable resources and rapid population growth are not likely to be consistent with sustainable developmentpaths; and extreme socio-economic inequality within communities and between nations may undermine the social cohesion that would promote sustainability and make policy responses more effective. At the same time, socio-economic and technology policy decisions made for non-climate-related reasons have significant implications for climate policy andclimate change impacts, as well as for other environmental issues (see Question 8). In addition, critical impact thresholds and vulnerability to climate change impacts are directly connected to environmental, social, and economic conditions and institutional capacity.

WGII TAR

1.10

As a result, the effectiveness of climate policies can be enhanced when they are integrated with broader strategies designed to make national and regional development paths more sustainable. This occurs because of the impacts of natural climate variation and changes, climate policy responses, and associated socio-economic development will affect the ability of countries to achieve sustainable development goals, while the pursuit of those goals will in turn affect the opportunities for, and success of, climate policies. In particular, the socio-economic and technological characteristics of different development paths will strongly affect emissions, the rate and magnitude of climate change, climate change impacts, the capability to adapt, and the capacity to mitigate climate. The Special Report on Emissions Scenarios (SRES, see Box 3-1) outlined multiple plausible future worlds with different characteristics, each having very different implications for the future climate and for climate policy.

WGIII TAR Section 10.3.2

1.11

The TAR assesses available information on the timing, opportunities, costs, benefits, and impacts of various mitigation and adaptation options. It indicates that there are opportunities for countries acting individually, or in cooperation with others, to reduce costs of mitigation and adaptation and realize benefits associated with achieving sustainable development.

WGII TAR Chapter 18, WGIII TAR Chapters 8, 9, & 10, & SRES

Figure 1-1: Climate change- an integrated framework. Schematic and simplified representation of an integrated assessment framework for considering anthropogenic climate change. The yellow arrows show a full clockwise cycle of cause and effect among the four quadrants shown in the figure, while the blue arrow indicates the societal response to climate change impacts. For both developed and developing countries, each socio-economic development path explored in the Special Report on Emissions Scenarios has driving forces which give rise to emissions of greenhouse gases, aerosols, and precursors -- with carbon dioxide (CO₂ ) being the most important. The greenhouse gas emissions accumulate in the atmosphere, changing concentrations and disturbing the natural balances, depending on physical processes such as solar radiation, cloud formation, and rainfall. The aerosols also give rise to air pollution (e.g., acid rain) that damage human and the natural systems (not shown). The enhanced greenhouse effect will initiate climate changes well into the future with associated impacts on the natural and human systems. There is a possibility of some feedback between the changes in these systems and the climate (not shown), such as albedo effects from changing land use, and other, perhaps larger, interactions between the systems and atmospheric emissions (e.g., effects of changes in land use (again not shown)). These changes will ultimately have effects on socio-economic development paths. The development paths also have direct effects on the natural systems (shown by the anti-clockwise arrow from the development box) such as changes in land use leading to deforestation. This figure illustrates that the various dimensions of the climate change issue exist in a dynamic cycle, characterized by significant time delays. Both emissions and impacts, for example, are linked in complex ways to underlying socio-economic and technological development paths. A major contribution of the TAR has been to explicitly consider the bottom righthand domain (shown as a rectangle) by examining the relationships between greenhouse gas emissions and development paths (in SRES), and by assessing preliminary work on the linkage between adaptation, mitigation, and development paths (WGII and WGIII). However, the TAR does not achieve a fully integrated assessment of climate change, since not all components of the cycle were able to be linked dynamically. Adaptation and mitigation are shown as modifying the effects shown in the figure.

Other reports in this collection