3.4. Integrated Analysis of Potential Vulnerabilities and Impacts and Future
Individual sectors and resources will not be affected in isolation but in interaction
with one another. The direct effects of climate change include shifts in geographic
distribution of ecosystems, changes in sea and river ice, thaw of permafrost,
and changes in coastal areas. Indirect effects include feedbacks to the climate
system through less ice and snow reflectivity, changes in sea ice and ocean
circulation, and ecological sources and sinks of CO2 and CH4. Improvements are
needed in modeling of future sea-ice distribution and thickness because of their
importance as drivers for other physical and ecological systems, economics,
and transportation. There is uncertainty about whether changes in tundra will
cause it to act as a source or a sink for CO2. This issue needs to be resolved.
There is a variety of positive and negative shifts in opportunities for shipping,
the oil industry, fishing, mining, and tourism, as well as coastal infrastructure
and the movement of populations. These impacts will lead to further interactions
and potential changes in trade and strategic balance. The health consequences
of these shifts will depend on human capacity to adapt.
The Arctic is more vulnerable than the Antarctic because of its sensitive and
fragile ecosystems and the impacts on traditional lifestyles of indigenous peoples
and because climate changes are expected to be greater. An integrated impact
assessment using multiple stress models is required for the Arctic. When associated
with baseline monitoring, it should be possible to distinguish natural variability
from human impacts.
Further analysis should focus on particularly sensitive zones and activities,
vulnerable species, marginal communities, and estimates of economic impacts.
To improve biological components of regional and global models, it is important
to understand how, when, and where productivity in the Southern Ocean will change
with global warming (IPCC 1996, WG II, Section 8.3.2). More certainty is required
regarding the future behavior of the marine-based West Antarctic Ice Sheet and
ice balance of the continent. Changes have the potential to substantially alter
sea level and southern hemispheric climate, but the time frame needs to be defined.
Most human and natural systems in the Arctic and the Antarctic Peninsula are
extremely sensitive to temperature. Future global warming is expected to be
greatest in these areas. Large reductions in sea ice, permafrost, and tundra
will disrupt many natural systems and change species composition over land and
in the polar oceans. These areas appear to be vulnerable to climate change,
although the number of people directly affected would be relatively small. However,
most are indigenous people, who lead traditional lifestyles and have few adaptive
strategies that can be implemented. Antarctica is less vulnerable because the
temperature changes envisioned over the next century are likely to have little
impact, and few people are involved.