9.35 |
Studies examined in the TAR suggest substantial technological and other opportunities for lowering mitigation costs. National mitigation responses to climate change can be more effective if deployed as a portfolio of policy instruments to limit or reduce net greenhouse gas emissions. The costs of mitigation are strongly affected by development paths, with those paths involving substantial increases in greenhouse gas emissions requiring more mitigation to reach a stabilization target, and hence higher costs. These costs can be substantially reduced or even turned into net benefits with a portfolio of policy instruments (including those that help to overcome barriers) to the extent that policies can exploit "no-regrets" opportunities in the following areas:
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Q7.6-7, Q7.14-15, Q7.20, & Q7.23, & Q7 Box 7-1 |
9.36 | Modeling studies show that emissions trading reduces costs of mitigation for those participating in the trading. Global modeling studies, with results depending strongly upon assumptions, project that costs of mitigation based on Kyoto targets are likely to be reduced by full carbon-permit trading within the Annex B27 group of countries. Annex I OECD28 countries may expect aggregate costs to be reduced by about half through full permit trading. Annex I economies in transition are projected to be unaffected or to gain several percent increase in GDP. Oil-exporting, non-Annex I countries may also expect similar reductions in costs under such trading. The aggregate effects of trading are expected to be positive for other non-Annex I countries. Those countries that may expect a loss or gain without Annex I trading may expect a smaller change with trading. A key uncertainty is the extent of the underlying costs, which vary widely across countries, and how these cost estimates will be changed (a) when methods are improved and (b) when some of the assumptions of the models are relaxed. Such assumptions are concerned with:
|
Q7.18-19 |
9.37 | Although model projections indicate that
long-term global growth paths of GDP are not significantly affected by mitigation
actions towards stabilization, these do not show the larger variations that
occur over some shorter time periods, sectors, or regions. |
Q7.25 |
9.38 | Unexpected public policies ("quick
fixes") with sudden short-term effects may cost economies much more
than expected policies with gradual effects. A key uncertainty
in the magnitude of the costs lies in the existence of well-designed contingency
plans in the event of policy shifts (e.g., as a result of a sudden shift
in public perception of the climate change). Other key uncertainties for
costs lie in the possibilities of the rapid short-term effects including,
or leading to, abrupt reductions in costs of low-carbon processes and products,
shifts towards low-emission technologies, and/or changes towards more sustainable
lifestyles. |
Q7.24 & Q7.31 |
9.39 | Near-term action in mitigation and adaptation
would reduce risks. Because of the long time lags associated both
with the climate system (e.g., ~100 years for atmospheric CO2)
and with human response, near-term action in mitigation and adaptation would
reduce risks. Inertia in the interacting climate, ecological, and socio-economic
systems is a major reason why anticipatory adaptation and mitigation actions
are beneficial. |
Q5.19 & Q5.24 |
9.40 | Adaptation can complement mitigation in
a cost-effective strategy to reduce climate change risks; together they
can contribute to sustainable development objectives. Some future
paths that focus on the social, economic, and environmental elements of
sustainable development may result in lower greenhouse gas emissions than
other paths, so that the level of additional policies and measures required
for a particular level of stabilization and any associated costs can also
be lower. A key uncertainty is the lack of appropriate
knowledge on the interactions between climate change and other environmental
issues and the related socio-economic implications. A related issue is the
pace of change in integrating the main global conventions and protocols
associated with climate change (e.g., those involving world trade, transboundary
pollution, biodiversity, desertification, stratospheric ozone depletion,
health, and food security). It is also uncertain at which rate individual
countries will integrate sustainable development concepts into policy-making
processes. |
Q1.9 & Q8.21-28 |
9.41 | Development paths that meet sustainable
development objectives may result in lower levels of greenhouse gas emissions.
Key choices about future development paths and the future of the climate
are being made now in both developed and developing countries. Information
is available to help decision makers evaluate benefits and costs from adaptation
and mitigation over a range of options and sustainable development pathways.
Anticipated adaptation could be much less costly than reactive adaptation.
Mitigation of climate change can reduce and postpone the impacts, lowering
the damages and giving human societies as well as animals and plants more
time to adapt. |
Q5.22, Q7.25, & Q8.26 |
Further
Work |
||
9.42 |
Significant progress has been made in the TAR in many aspects of the knowledge required to understand climate change and the human response to it. However, there remain important areas where further work is required, in particular:
|
WGI TAR SPM, WGII TAR SPM, & WGIII TAR SPM |
Other reports in this collection |