– Most people agree that human activity is an
important contributor to the high temperatures
we’ve been observing. Both meteorological
measurements and reconstructions that we’ve
done show this. If we look at the changes in
amounts of carbon dioxide in the atmosphere,
we can see that levels are higher now than
before. If you believe in the greenhouse effect,
which has been physically proven, then there’s
no reason to doubt that global warming is
much stronger now than it was 100 years ago.
That alone contributes significantly to increas-
ing temperatures. Natural causes for climate
change over 100- to 200-year periods include
solar activity, how much solar radiation reaches
the Earth, and volcanic activity. If we only
include natural causes, we simply can’t account
for the temperature increases we’re observing.
Climate change can only be explained by con-
sidering both natural and man-made causes.
Most climate researchers agree on this. We’ve
made detailed models of temperature changes
taking only into account natural causes, then
made similar models with both natural and
man-made causes. The model that incorporates
both natural and man-made climate change
matches our actual temperature measurements
very well, while the model that only takes into
account natural changes deviated significantly
from real observations.
Is it getting hotter in Norway as a result
of climate change?
–Yes, it’s gettingwarmer inNorway.We’ve seen
that the effect of global warming is much greater
at high latitudes. It’s most intense in the Arctic
and Antarctic, and decreases as it reaches the
Tropics. You may wonder if this is good news
for Norway. Some certainly appreciate that it
gets green earlier – spring reaches Tromsø by
May almost every year now, while it hardly ever
did 40 years ago. Although climate change may
be seen as OK for some of Norway’s popula-
tion, we’re a small country of only five million
inhabitants. Globally speaking, climate change
certainly isn’t a good thing.
Will a warmer climate cause major
changes to the weather as we know it?
– We may not necessarily get less snow, but
spring will come sooner. Generally speaking, it
will be more humid, which means an increased
danger of landslides. This certainly isn’t a good
thing for Norway. We’ll also experience more
extreme weather events, and sea level will rise.
The rise in sea level isn’t that significant right
now, but if the Greenland ice cap were to melt
and drain into the sea, the volume of the ocean
would increase significantly. Another factor to
consider when it comes to a rise in sea level is
that warmer water is less dense, so as global
ocean temperatures increase, so does the vol-
ume of the ocean. Rising sea levels pose major
problems for nations such as Bangladesh and
the Netherlands, but they aren’t Norway’s big-
gest concern.
Is that why it is important to monitor
the climate in the Arctic? Will climate
change be most drastic in the North?
– Yes, it is important to monitor climate change
in the Arctic, because changes are very evident
in the far north. Climate change in the Arctic
is amplified because the Arctic Ocean, which is
covered by ice for most of the year, reflects a
lot of solar radiation back into the atmosphere.
As sea ice disappears, less solar radiation will
be reflected, and will instead be absorbed by
the ocean. This will warm up the seawater and
strengthen the effects of solar radiation.
If the ice melts, will ocean currents
change?
– Ice ages come in cycles of about 100,000
years. The reason for this is the variation in the
amounts of solar energy received by the earth
due to the Earth’s orbit around the sun, and the
tilt and orientation of the Earth’s axis. Warm
periods, when there is little ice on the Earth,
called interglacial periods, are relatively short,
about 10,000 years. Many think that we may
be headed toward a new ice age, but it may be
thousands of years before this happens. Our
industrial activity has also had an impact on
these cycles, although we’re not sure exactly
how it will affect natural glacial activity. When
the fresh water currently found in ice caps and
glaciers melts and flows into the ocean, ocean
currents will certainly be affected. We have
many examples of the Gulf Stream being dis-
rupted by large amounts of fresh water. As the
Gulf Stream flows north, the water cools, its
density increases, and it drops to the sea floor.
We’ve made several models showing how this
circulation can stop or slow, or how it in some
cases could be stronger than it is today. We’ve
shown that at the end of the last ice age, the
circulation of the Gulf Stream almost stopped
completely, and then started again suddenly.
There are large amounts of CO
2
and
methane stored in the ice and tundra.
What will happen if these gases are
released?
– It may further enhance the greenhouse effect.
Methane is a disaster waiting to happen in the
North – there’s so much frozen in the ground,
either on land or in the seabed. A Centre of
Excellence has been established in the Depart-
ment of Geology to study gas hydrates in the
seabed. These are deposits of frozen methane
that may melt as the oceans warm up. We see
that with global warming, more and more of
these frozen methane gas deposits will melt and
rise to the surface, which will allow the methane
42
labyrint
•
research magazine
from
u
i
t
the
arctic
university
of
norway
QUESTIONS
|
ANSWERS
The Arctic is strongly
affected by climate
change.
– Climate is the average
weather pattern in an area
over time.
– Climatic models
have been modest,
rather than exaggerated, when it comes
to global warming forecasts.
