Abrupt climate change evokes among many the fanciful image of New York
City instantly frozen solid. This
from the Day After Tomorrow was inspired by the real and sudden Younger Dryas
event that plunged the North Atlantic into a millennium-long deep freeze 12,000
years ago. Although scientists have recently downgraded fears that this kind of event might happen today,
abrupt climate changes are a more immediate threat than anyone knew.
It turns out that
climate change isn't just applicable to massive events like the Young Dryas
cooling but to regional or local abrupt changes too. Think drought. A recent
study authored by
and colleagues at the Center for Sustainability and the Global Environment (full
disclosure: we are employed here but did not take part in this study) discovered
about thirty abrupt changes in precipitation around the world over the last
hundred years. Everybody has heard of the U.S. dust bowl in the 1930's and many
know the catastrophic
in the Sahel during the 1960's and 70's. But what about the droughts in the
Former Soviet Union in the 1930's or those in Southern Africa in the 1980's that
also claimed millions of victims?
These droughts aren't simply a random string of years that happened to have
little rain. They are a persistent situation where the climate regime jumped
from a normal or wet-stable state to a dry one. The abrupt droughts identified
by Narisma et al. lasted for at least 10 years and majority had a 10% decrease
from 20th century average rainfall. Most of the droughts occurred in arid or
semi-arid areas already perched precariously on the edge of livable climates,
where slight deviations from normal can have devastating consequences on the
ecology and people that live there. A 10% decrease in rainfall might not sound
like much, but it's enough to devastate crops, livestock, and livelihoods. In
the Sahel, over one million people died, and 50 million people were affected by
the change in rainfall, which according to the study decreased by 12% and lasted
Abrupt climate change is inherently unpredictable. Although we'll never have
perfect knowledge on who will be hit, we can at least learn who is most
vulnerable and what we might do about it:
By identifying diverse regions around the globe where rapid
climatic shifts have taken place, the study opens up new opportunities for
understanding why these changes happen and what makes areas susceptible to them,
says Narisma. A range of factors is likely involved, including human activities,
such as deforestation and land degradation, and natural phenomena, like sea
surface temperatures. The work might also lead to interventions that would make
systems less vulnerable to sudden climate change, Narisma adds.
This new bit of knowledge reinforces three increasingly recognized
First, we need to give more attention to climate change, especially abrupt
change, on the scale of human lives. Too much talk about global average
temperature detracts attention from the ways climate change manifests in
particular places. Studies like this one help us understand how small
perturbations can cause the climate system to cross the thresholds that bring on
abrupt changes. Narisma et al.'s study, for instance, lends support to dynamic
climate-vegetation models that include feedbacks between the land surface and
the atmosphere. Under certain circumstances, a little more grazing or a bit more
deforestation can induce large shifts in the regional climate. Regardless of the
mechanism for the change, reducing vulnerability while increasing the capacity
for adaptation and mitigation are key to persevering through change.
Studies of the magnitude of Narisma and colleagues', however, would be
impossible without an extensive network of climate monitoring stations. The
second point is to therefore give 'mundane' monitoring the attention it
deserves. Unfortunately, the number of climate monitoring stations around the
world increased throughout the 20th century until around 1980, when the number
of stations began their
decline and now there are about as many stations as there were in 1900.
Without these local measurements, it becomes much more difficult to produce the
kind of place-based information that can help decisions on the ground. While
satellite monitoring has picked up part of the slack, some types of climate data
are impossible to sense remotely. As we become more vulnerable to abrupt
changes, now is the time to bolster our monitoring network. And we
From ice cores that are used to reconstruct climate from long ago, to
distributed networked devices that monitor local conditions, to autonomous
of the future, collecting and analyzing environmental data across the globe is
crucial to seeing the big picture.
No amount of monitoring, however, will change the fact that abrupt climate
change is inherently unpredictable, which brings us to the third point: we must
get over the idea that
adaptation plays second string to climate mitigation of greenhouse gases.
Climate skeptics are right when they say the climate has always been changing.
But they are completely wrong in their conclusions that we need neither mitigate
nor adapt. We need to flip this dubious card on its head. Knowledge that abrupt
climate change, and natural disasters in general, have wrenched past societies into
disarray makes the climate question more, not less urgent. Global climate change
only compounds an already painful history and strengthens the case to build resilient societies.
Climate changes implies complex studies, beginning with natural factors such as volcanoes, ocean currents, air currents, plate tectonics, and solar activity as major factors all over geological time and secondary to cloud formation and algaes implication into cloud formation, magnetic field fluctuations, cosmic radiations interactions, earth inner core modifications and then human interactions which means industry, deforestation and land use. Beyond all these, the research must also cover the way the society react to information and to real changes, because in the media there are more info then in reality it happens. Also there must be a study whereby the people might become aware of the implications of climate changes and many more. I can provide you a full list of detailed research issues which might be discussed, if you provide me an e-mail address capable of accepting a small pdf file.
Posted by: Cristian Muresanu on 10 Aug 07
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