Sea Ice

Climate

With regards to the exploration and exploitation of resources in the Arctic, as
well as shipping routes through the Arctic, the main concern in terms of climate
are the ice conditions in the Arctic Ocean and the Arctic and sub-Arctic marginal
seas. Hence, although there is much more to the global climate we will reduce this
KF to the ice conditions in the Arctic. The climate models employed by AMSA
are building on models developed for the ACIA, which are the most advanced and
capable GCMs for the Arctic domain. These models are equivalent to the models
employed in the fourth IPCC assessment. Nearly all of them show a continuing
trend of declining summer ice cover, however in an envelope that includes hardly
any changes in summer ice extend to the disappearance of the perennial ice cover
by 2050 (e.g. [on Climate Change , IPCC]). The break-down of the thermohaline
circulation in the Atlantic Ocean and a subsequent cooling period is a scenario
which reappears on the scientific agenda every once in a while (e.g. ,[Schiermeier,
2006]) and should not be excluded, although unlikely.

1.1 Extremely warm climate in the Arctic

Plausibility: 0.05

Although very unlikely for the next 100 years, it should not be neglected that the
Arctic once was a very warm place. As there is little knowledge as to how fast a
climate system can tip this a very uncertain future projection.
The Cretaceous Period (145.5 Ma – 65.5 Ma ago) is believed to have been
the warmest period on Earth. The climate is believed to have been mild, with
tropical ocean’s temperatures up to 42 ºC [Bice et al., 2006]. It is believed that the
Cretaceous’ poles were ice free while vast parts of the continental land masses were
covered by shallow seas. This is the most extreme global warming development
that can be envisaged. The Arctic Ocean is completely ice free all year round.
The weather is relatively mild as the temperature gradient between equator and
poles is rather low as a fact of the large oceans being interconnected.
Even less extreme climate change scenarios suggest that a largely ice-free Arctic
Ocean during summertime is within the realm of possibility in the late 21st century.
It is projected that both the North-West Passage (NWP) and the Northern Sea
Route (NSR) will be ice free by 2070-2090 [Hassol, 2004]. Hence, under a extremely
accelerated climate change ice free shipping routes might be the norm by 2030.
The current wind and wave conditions are manageable for large vessels (CITATION
NEEDED) and are not expected to change severely for this future projection.

1.2 Ice Free Arctic Ocean – Severe Weather

Plausibility: 0.15

As for the FP 1.1 the ice conditions are in favor of an open North West Passage
and Northern Sea Route. However, the weather is much more severe than it
is nowadays. Using the Northern routes is very risky as weather conditions are
unpredictable and can change very rapidly.

1.3 Seasonal Ice Cover – Shippable

Plausibility: 0.35 0.4

Due to ice-cover the NWP and the NSR are impassable in the winter months due
to pack ice, but are shippable in the summer months. The weather during the
shipping season is moderate and the risk of operation is low.
This FP is likely for the time-frame 2030-2040 if the projections in [Hassol, 2004]
are accurate. However, weather conditions in a changing climate are inherently
difficult to extrapolate.

1.4 Seasonal Ice Cover – Hazardous shipping

Plausibility: 0.35 0.4

As in FP 1.3 the ice conditions are favorable in the summer months. However,
the weather conditions are unpredictable and there is a high risk of ships getting
trapped in dangerous floating ice conditions due to unfavorable ice and current
regimes.

1.5 Break-down of Atlantic’s Thermohaline Circulation – New Ice Age in the North

Plausibility: 0.1

Due to the massive intake of fresh water the thermohaline circulation in the Atlantic
Ocean slows down and then stops. This leads to regional cooling as the heat
transfer to the Arctic from lower latitudes is greatly reduced. This regional ice age
could last for several decades while the rest of the globe is warming much more
rapidly [Hassol, 2004].