Sextant to Satellite
161
of El Ni˜ no to have rigorous tests for models that attempt predictions. Given that
El Ni˜ no occurs every few years, enough data to test models and to settle debates about
the predictability of El Ni˜ no should be available a few decades hence.
Recently the change in the properties of El Ni˜ no that occurred in the late 1970s
has generated much interest in climate variability on time scales of decades and longer.
This topic is related to the impact of future global warming on El Ni˜ no. Tentative
results are available from climate models, but what are the tests for the models that
will bolster confidence in their results? If the acquisition of data to test models that
predict interannual El Ni˜ no episodes will take a few decades, how long before we can
test theories for decadal variability?
NEXT
In science, measurements are essential for the testing of theories and models. The
past few decades permitted the acquisition of extensive data sets only for phenomena
with time scales shorter than a decade. That is why the biggest advances have concerned relatively brief phenomena that range from surface gravity waves to seasonal
and interannual fluctuations such as El Ni˜ no. Now that our attention is shifting to
phenomena with time scales much longer than a decade, we are obliged to take an
interest in paleoclimates.
The remarkable achievements of paleoclimatologists, which include detailed
descriptions of the astonishingly different climates our planet has experienced in the
past, are not widely known among physical oceanographers. For example, everybody
knows that dinosaurs were dominant during the extremely hot Cretaceous period,
but few are aware of the strange journey that took our planet from that period to the
present. The Earth experienced gradual global cooling during those 60 million years.
The superimposed Milankovitch cycles were relatively modest at first but, around
3 million years ago, started to amplify, culminating in wild oscillations between
prolonged Ice Ages and brief, warm interglacial periods such as the present one. At
the moment, explanations for those phenomena have a decidedly “dreamlike” quality,
thus presenting oceanographers with wonderful, new opportunities to explore strange
worlds. To do so will require the cooperation of paleoclimatologists. As mentioned
earlier, this is proving a challenge because of the different cultures of the two groups.
Thus far, most attempts to overcome this problem have been “top-down” rather than
“bottom-up.” Important generals recruit officers who serve for a limited period of a
few years on organizing committees that draft grand plans for large armies; the troops
are expected to perform the same exercises. This approach is understandable, given
that both paleoclimatology and oceanography are “big” sciences with huge communities and budgets. The results are impressively voluminous, filling many books and
journals, but unfortunately those results continue to have a “dreamlike” quality.
Many of the problems we face today because of the rapid growth of science
have been faced by our predecessors. Newton’s contemporaries complained about
161
of El Ni˜ no to have rigorous tests for models that attempt predictions. Given that
El Ni˜ no occurs every few years, enough data to test models and to settle debates about
the predictability of El Ni˜ no should be available a few decades hence.
Recently the change in the properties of El Ni˜ no that occurred in the late 1970s
has generated much interest in climate variability on time scales of decades and longer.
This topic is related to the impact of future global warming on El Ni˜ no. Tentative
results are available from climate models, but what are the tests for the models that
will bolster confidence in their results? If the acquisition of data to test models that
predict interannual El Ni˜ no episodes will take a few decades, how long before we can
test theories for decadal variability?
NEXT
In science, measurements are essential for the testing of theories and models. The
past few decades permitted the acquisition of extensive data sets only for phenomena
with time scales shorter than a decade. That is why the biggest advances have concerned relatively brief phenomena that range from surface gravity waves to seasonal
and interannual fluctuations such as El Ni˜ no. Now that our attention is shifting to
phenomena with time scales much longer than a decade, we are obliged to take an
interest in paleoclimates.
The remarkable achievements of paleoclimatologists, which include detailed
descriptions of the astonishingly different climates our planet has experienced in the
past, are not widely known among physical oceanographers. For example, everybody
knows that dinosaurs were dominant during the extremely hot Cretaceous period,
but few are aware of the strange journey that took our planet from that period to the
present. The Earth experienced gradual global cooling during those 60 million years.
The superimposed Milankovitch cycles were relatively modest at first but, around
3 million years ago, started to amplify, culminating in wild oscillations between
prolonged Ice Ages and brief, warm interglacial periods such as the present one. At
the moment, explanations for those phenomena have a decidedly “dreamlike” quality,
thus presenting oceanographers with wonderful, new opportunities to explore strange
worlds. To do so will require the cooperation of paleoclimatologists. As mentioned
earlier, this is proving a challenge because of the different cultures of the two groups.
Thus far, most attempts to overcome this problem have been “top-down” rather than
“bottom-up.” Important generals recruit officers who serve for a limited period of a
few years on organizing committees that draft grand plans for large armies; the troops
are expected to perform the same exercises. This approach is understandable, given
that both paleoclimatology and oceanography are “big” sciences with huge communities and budgets. The results are impressively voluminous, filling many books and
journals, but unfortunately those results continue to have a “dreamlike” quality.
Many of the problems we face today because of the rapid growth of science
have been faced by our predecessors. Newton’s contemporaries complained about