The Hot Zone

Speed of Change

Posted by Alison Hawkes on February 26, 2010
Category : Climate Science and Scientists, Climates of the Past

By Alison Hawkes

There’s been a lot of speculation about how fast climate change can happen. Are we talking a Day After Tomorrow scenario or something that slowly builds over time? Can you predict the warning signs of a tipping point?

A couple of papers caught my interest recently from leading science journals that show just how dramatically change can occur – and within a human lifetime – surprising since many natural processes seem to pass at, well, geologic time.

One study published Feb. 12 in the journal Science tackled the magnitude of sea level rise in previous interglacial periods. The University of Iowa study looked at a type of mineral deposit on stalactites and stalagmites in coastal caves on the Mediterranean island of Mallorca, which turn out to be a good record-keeper of changes in sea levels. It found that some 81,000 years ago, the seas rose and later dropped again (presumably from the onset of another ice age) on the order of one meter in a 50-year period. One meter sea level rise in today’s terms would wipe out much of the world’s coastlines, where over one-third of the world’s population lives.

This graph shows sea level rise in mm from 1994-2004

This graph shows sea level rise in mm from 1994-2004

“Our findings demonstrate that changes of this magnitude can happen naturally on the timescale of a human lifetime. Sea level change is a very big deal,” says Jeffrey Dorale, a lead researcher in the study.

Meltwater from the Greenland Ice Sheet

Meltwater from the Greenland Ice Sheet

Another study, put out by the University of California at Davis and published on Feb. 8 in the journal Ecology Letters, examined ecological systems. Current research has focused on finding the leading indicators, or warning signs of impending collapse. But the theoretical ecologists at Davis modeled the population dynamics of a single species and a food chain to determine that large shifts can occur rapidly and without any leading indicators, especially in systems that have complicated dynamics (like inter-species interactions) and multiple outcomes.

“This means that some effects of global climate change on ecosystems can be seen only once the effects are dramatic. By that point returning the system to a desirable state will be difficult, if not impossible,” says UC Davis ecologist Alan Hastings.

So what to do? In the case of ecological systems, Hastings says to closely watch what’s changing and act fast.

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