Reduced sea-ice extent and thickness would increase the seasonal duration of
polar navigation on rivers and in coastal areas that are presently affected
by seasonal ice cover (IPCC 1996, WG II, Section 7.5). Improved opportunities
for water transport, tourism, and trade at high latitudes are expected as a
result. These activities will have important implications for the people, economies,
and navies of nations along the Arctic rim (IPCC 1996, WG II, Chapter 7 Executive
Summary). Reduced sea ice will provide safer approaches for tourist ships and
new opportunities for sightseeing around Antarctica and the Arctic (IPCC 1996,
WG II, Section 7.5.5). Increased calving of icebergs from the Antarctic Peninsula
may, however, affect navigation and shipping lanes north of the Antarctic Convergence.
Decreased sea-ice extent around Antarctica could make it easier for tourist
vessels with less preparedness for sea-ice travel to visit the continent and
surrounding islands. Some may be ill-prepared to navigate and respond to the
extreme and highly variable environmental conditions in the Southern Ocean.
There is no clear consensus, however, about whether the frequency of icebergs,
and their danger to shipping, will change with global warming (IPCC 1996, WG
II, Section 7.4). Increased precipitation may reduce the enthusiasm for tourism
in some areas.
Projected reductions in the extent and thickness of the sea-ice cover in the
Arctic Ocean and its peripheral seas could substantially benefit shipping, perhaps
opening the Arctic Ocean as a major trade route (IPCC 1996, WG II, Technical
Summary, Section 3.2.4). This projection would include the opening of both the
NorthWest Passage and the Russian Northern Sea Route for up to 100 days a year.
One French experiment indicated that the use of the Northeast Passage in ice-free
seasons shortened by about 3 weeks the shipping duration between Europe and
Far East Asia compared with the present route (i.e., via the Suez Canal). Although
a reduction of sea ice may be a boon to international shipping and consumers
in East Asia, North America, and Western Europe, policies designed to limit
the total burden of pollutants entering the Arctic environment from ports, ship
operations, and accidents may have to be developed (IPCC 1996, WG II, Chapter
8 Executive Summary).
Less river ice and a shorter ice season in northward flowing rivers of Canada
and Russia should enhance north-south river transport. Combined with less sea
ice in the Arctic, this development would provide new opportunities for reorganization
of transport networks and trade links. Ultimately, those changes could affect
Northern Hemisphere trading patterns (IPCC 1996, WG II, Section 7.5.1).
A survey of the potential impacts on Canadian shipping suggested net benefits
to Arctic and ocean shipping due to deeper drafts in ports and longer navigational
seasons, with mixed results for lake and river shipping due to the opposing
effects of a longer shipping season but lower drafts. Demands to maintain Arctic
shipping may increase. In Siberia and Canada, many rivers are used as solid
roads during winter. Warmer winters would require a shift to water transport
or the construction of more all-weather roads. Other impacts on means of transport
could arise from changes in snowfall or melting of the permafrost (IPCC 1996,
WG II, Section 18.104.22.168).
Currently, ice-breaking efforts are an expensive aspect of navigation in the
Arctic. Interannual variability prevents the elimination of these programs unless
extreme changes in sea ice should occur. Some ice-breaking programs in some
areas may be cut back with moderate warming of the Arctic. In other areas, costs
may rise to keep newly available routes open longer. A disappearance of sea
ice south of Labrador would eliminate Canadian Coast Guard ice-breaking requirements.
This would mean an annual saving of CDN$15-20 million. Even larger savings also
can be expected in the former Soviet Union if ice retreats from the shores of
the Kara, Laptev, and Chukchi Seas. Similar savings would accrue along the Gulf
of Bothnia with the absence of ice. The effect of annual warming on ice calving
(simulated using a simple degree-day model) shows that for every 1°C of warming
there would be a 1° latitude retreat of iceberg occurrence in the Atlantic Ocean.
In the Southern Ocean, any effects of reduced sea ice will be economically less
pronounced (IPCC 1996, WG II, Section 7.5.3).
Offshore oil and gas exploration and production conducted at high latitudes
may be assisted by a longer ice-free season. A possible beneficial effect would
be shorter winters to disrupt construction, exploration, and drilling programs.
A decrease in thickness and extent of sea ice in the Arctic will extend the
drilling seasons for floating vessels considerably. A reduction in sea ice and
icebergs also will reduce "downtime" on offshore oil and gas drilling explorations.
Currently such interruptions cost Canadian explorations more than CDN$40 million
annually. The most critical factor could be ice movement during winter. If there
were increased numbers and severity of storm surges and wave activity, design
requirements for offshore structures and associated coastal facilities would
increase, and oil spill clean-up could become more difficult (IPCC 1996, WG
II, Section 7.5.4).
3.3.8. Sub-Antarctic Islands
The sub-Antarctic islands are small land areas surrounded by vast areas of
the Southern Ocean. Some of these islands are sufficiently high to possess glaciers
and small ice caps. Their climate is characterized by strong and persistent
winds, little sunshine, many rain days, and cool temperatures. They are generally
uninhabited, though they contain highly specialized flora and important marine
mammal and bird populations.
Many of these islands have shown a tendency for warming over the last half
of this century. Their future climate will be controlled by changes in the surface
temperature of the Southern Ocean and the strength of Southern Hemisphere westerlies.
The sub-Antarctic islands are expected to continue to warm. The impacts of climate
change are unlikely to be important for most animal and bird species, but there
could be changes in the species composition of plant communities. Glaciers will