What is climate change?
– Climate is the average weather in an area over
time. Climate change is a change in these aver-
ages, higher or lower temperatures, more or less
precipitation. The averages in an area have to
change for a certain amount of time before you
can say that the climate is changing, so when we
started to notice warming in the early 1980s, it
was argued that time series of just 4 or 5 years
just weren’t enough, statistically speaking. You
need to see things from a 30-year perspective,
which is what we can do now. With such a long
time span, we can see a change.
It is said that the past is the key to the
future, but we don’t have very exten-
sive temperature records from the
past. How do we know what the climate
was like before?
– The thermometer has only been around for
150 years, so if you want to know something
about climate change before then, you have
to use other ways of measuring. My focus as a
geologist has been to study layers inmarine sedi
ments to see how the climate has changed. We
can make certain measurements in sediment
cores that can give us information on actual sea
temperatures at the time. Looking at this data,
we can see that the sea has gottenwarmer.We’ve
looked at sediment cores from the continental
shelf off the coast of Svalbard dating back 2,000
years, studying small animal fossils and the geo-
chemical elements they contain, tracing them
back in time. By creating an equation where
we link the temperatures we have measured to
the environment in which animals live today,
we end up with a temperature curve that shows
that water temperatures in the seas around
Svalbard averaged 3.4 degrees until about 100
years ago, when temperatures began to rise.
The seas around Svalbard are warmer now than
they’ve ever been in the past 2,000 years. We’ve
also taken core samples fromMalangs fjord that
show that the bottom of Malangen is warmer
now than it’s ever been on record. The accu-
racy of these measurements may be somewhat
questionable, but the overall trends that they
show are still convincing.
Is climate change man-made, or might
we be seeing natural fluctuations in
climate?
Will climate change be
greatest in the North?
The Earth’s temperature is rising and the climate is
changing.
Professor Morten Hald
has no doubt that
climate change is man-made.
Text: Per Nordgård Næss
42
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labyrint
•
research magazine
from
u
i
t
the
arctic
university
of
norway
QUESTIONS
|
ANSWERS
Morten Hald
Professor and Dean of the Faculty of Science
and Technology at UiT
His main areas of interest are marine geo
logy and palaeoceanography. This involves
studying sediment cores, fossils and sedi-
ments from the continental shelf and fjord,
which can provide important information
about climate change in prehistoric times.
Photo: Torbein Kvil Gamst
