Scientists see natural causes for greater hurricane activity
17 Gennaio 2008
The recent rise in hurricane activity in the Caribbean and neighbouring regions in recent years is likely to be a natural phenomenon and not caused by human activity, this is the conclusion
that researchers at the Leibniz Institute for Marine Sciences (IFM-GEOMAR) at the University of Kiel, Germany, have drawn from the analysis of coral data, direct measurements and simulations.
Their study was published in the January issue of international journal Geology.
The scientists analysed a coral drilling core, which had been extracted off the coast of Venezuela. It gave them information about long-term fluctuations in sea surface temperature (SST) and
rainfall above the tropical Atlantic from the corals’ chalk skeleton.
‘Corals grow in a way similar to trees: Every year a new layer of chalk is added,’ explains Professor Wolf-Christian Dullo of IFM-GEOMAR, co-author of the study. ‘The composition of the chalk
allows us to draw conclusions on water temperature and precipitation,’ which are closely linked to hurricane activity.
‘With the help of our colleagues from climate modelling, we were then able to show that data from the corals, which goes back as far as the year 1918, coincide very well with ‘real’ temperature
measurements as well as with the parameters relevant to hurricane activity,’ Professor Dullo adds.
‘In the long-term average, there is indeed a slight upward trend of theses parameters, but this is superposed by long-periodic natural changes, which we call Atlantic Multidecadal Oscillation
(AMO),’ says Professor Mojib Latif of IFM-GEOMAR. ‘This oscillation has shown a considerable maximum in recent years, so that the increase in hurricane activity that we have witnessed lately is
likely to have natural causes.’
The record number of hurricanes over the past decade has frequently been assigned to global warming and is thus said to be anthropogenic, in part at least. Determining the actual cause,
however, has been difficult until now, as reliable records do not go back far enough to detect possible long-term changes. The analysis of the coral samples has thus provided some new insights,
the scientists claim.
The research was conducted jointly by scientists from the IFM-GEOMAR in Germany and Dutch colleagues from the University of Amsterdam.
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