e-book

Abrupt Impacts of Climate Change: Anticipating Surprises

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Climate is changing, forced out of the range of the last million years by levels of carbon dioxide and other greenhouse gases not seen in Earth’s atmosphere for a very long time. Lacking action by the world’s nations, it is clear that the planet will be warmer, sea level will rise, and patterns of rainfall will change. But the future is also partly uncertain—there is considerable uncertainty about how we will arrive at that different climate. Will the changes be gradual, allowing natural systems and societal infrastructure to adjust in a timely fashion? Or will some of the changes be more abrupt, crossing some threshold or “tipping point” to change so fast that the time between when a problem is recognized and when action is required shrinks to the point where orderly adaptation is not possible?

A study of Earth’s climate history suggests the inevitability of “tipping points”—thresholds beyond which major and rapid changes occur when crossed—that lead to abrupt changes in the climate system. The history of climate on the planet—as read in archives such as tree rings, ocean sediments, and ice cores—is punctuated with large changes that occurred rapidly, over the course of decades to as little as a few years. There are many potential tipping points in nature, as described in this report, and many more that we humans create in our own systems. The current rate of carbon emissions is changing the climate system at an accelerating pace, making the chances of crossing tipping points all the more likely. The seminal 2002 National Academy Report,
Abrupt Climate Changes: Inevitable Surprises (still required reading for anyone with a serious interest in our future climate) was aptly named: surprises are indeed inevitable.

The question is now whether the surprises can be anticipated, and the element of surprise reduced. That issue is addressed in this report. Scientific research has already helped us reduce this uncertainty in two important cases; potential abrupt changes in ocean deep water formation and the release of carbon from frozen soils and ices in the polar regions were once of serious near-term concern are now understood to be less imminent, although still worrisome as slow changes over longer time horizons. In contrast, the potential for abrupt changes in ecosystems, weather and climate extremes, and groundwater supplies critical for agriculture
now seem more likely, severe, and imminent. And the recognition that a gradually changing climate can push both natural systems, as well as human systems, across tipping points has grown over the past decade. This report addresses both abrupt climate changes in the physical climate system, and abrupt climate impacts that occur in human and natural systems from a steadily changing climate.

In addition to a changing climate, multiple other stressors are pushing natural and human systems toward their limits, and thus become more sensitive to small perturbations that can trigger large responses. Groundwater aquifers, for example, are being depleted in many parts of the world, including the southeast of the United States. Groundwater is critical for farmers to ride out droughts, and if that safety net reaches
an abrupt end, the impact of droughts on the food supply will be even larger. Must abrupt changes always be surprises? Certainly not. As knowledge of the tipping points in natural and human systems improves, an early warning system can be developed.
Careful and vigilant monitoring, combined with a constantly improving scientific understanding of the climate system, can help society to anticipate major changes before they occur. But it is also important to carefully and vigilantly catalog the assets at risk—societies cannot protect everything and will need to prioritize, and without an understanding of what could be lost, such as coastal infrastructure to rising seas, for
example, intelligent decisions about what to protect first cannot be made. Can all tipping points be foreseen? Probably not. Some will have no precursors, or may be triggered by naturally occurring variability in the climate system. Some will be difficult to detect, clearly visible only after they have been crossed and an abrupt change becomes inevitable. Imagine an early European explorer in North America, paddling
a canoe on the swift river. This river happens to be named Niagara, but the paddler does not know that. As the paddler approaches the Falls, the roar of the water goes from faint to alarming, and the paddler desperately tries to make for shore. But the water is too swift, the tipping point has already been crossed, and the canoe—with the paddler—goes over the Falls. This tipping point is certainly hard to anticipate, but
is it inevitable? No. The tipping point in this case could have been detected by an early warning system (listening for the roar of a waterfall), but importantly, prudence was required.

Sticking closer to shore, in other words taking some prudent precautions, could have saved the paddler. Precaution will help us today as well, as we face a changing climate, if we are prudent enough to exercise it. Key to this is the need to be watching and listening for the early warning signals.

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Informasi Detail

Judul Seri

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No. Panggil

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Penerbit

New York : National Academy of Sciences., 2013

Deskripsi Fisik

250 pages, 7 x 10, PAPERBACK (2013)

Bahasa

English

ISBN/ISSN

978-0-309-28773-9

Klasifikasi

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Tipe Isi

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Tipe Media

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Tipe Pembawa

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Edisi

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Subjek

LINGKUNGAN HIDUP

Info Detail Spesifik

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Pernyataan Tanggungjawab

agus

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