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Abrupt, near-term impacts to rival dinosaur extinction seen in climate study

The report references two rapid and sweeping changes that are already apparent, and a third that is invisible to a worrisome degree.

Arctic sea ice extent from Sept. 16, 2012, compared to the average minimum extent over the past 30 years (in yellow). Some scientists predict the disappearance of late-summer sea ice in the Arctic within decades.
NASA/Goddard Scientific Visualization Studio

Not to seize on the sensational, but when a report from the National Research Council suggests that a wave of extinctions rivaling the dinosaurs’ demise might well be coming within the century — and that the time has come to set up early warning systems to detect this and other imminent climate catastrophes — it tends to capture one’s attention.

The report, “Abrupt Impacts of Climate Change: Anticipating Surprises,” came out on Tuesday to remarkably little press attention, for reasons I can’t explain, except maybe it’s just too god-awful grim for the holiday season.

But it’s important work, the kind of enterprise that might actually be able to change some conversations about climate change, and it deserves a higher profile.

You can think of the NRC as the applied-science and policymaker-advising arm of the National Academies of Science and the National Academy of Engineering, which should be credentials enough for any doubters and deniers who have read this far before preparing a flaming riposte.

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In this case, the report was also sponsored by the National Science Foundation, the National Oceanic and Atmospheric Administration and unspecified agencies in “the U.S. intelligence community.”

Tuesday’s report is an update, in some ways, of the council’s 2002 report that termed some abrupt consequences of climate change as “inevitable” — chiefly because the earth’s climate record showed signs of sudden upheavals, or tipping points, at which the pacing of gradual processes shifted from centuries or even millennia to just a few years.

First, the good news

But the arrival times and even overall probabilities of future surprises were highly indistinct back then. A little over a decade later, the report says, scientific advances have now somewhat clarified the likely time scales for certain sweeping changes. Taking the better news first:

…[P]otential abrupt changes in ocean deep water formation and the release of carbon from frozen soils and ices in the polar regions [that] were once of serious near-term concern are now understood to be less imminent, although still worrisome as slow changes over longer time horizons.

By longer time horizons, the authors mean beyond this century. On the other hand:

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. …

In addition to a changing climate, multiple other stressors are pushing natural and human systems towards 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.

These are the kinds of impacts that are commonly included in discussions of climate change, usually on the supposition that the really bad stuff is at least a few generations off in the future.  But in a particularly poignant comment to the phys.org Website, one of the report’s authors, Anthony Barnosky, distinguished the new report in this way:

Tipping points within this lifetime

“Our report focuses on abrupt change, that is, things that happen within a few years to decades: basically, over short enough time scales that young people living today would see the societal impacts brought on by faster-than-normal planetary changes.” (emphasis added)

The report references two rapid and sweeping changes that are already apparent, and a third that is invisible to a worrisome degree:

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  • The disappearance of late-summer sea ice in the Arctic, with predictions that it may be gone entirely within decades, which “would have potentially large and irreversible effects of various components of the Arctic East Coast system including disruptions in the marine food web, shifts and habitats of summary mammals, and erosion of vulnerable coastlines.”

Because the Arctic region interacts with a large-scale circulation systems of the ocean and atmosphere, changes in the extent of sea ice could cause shifts in climate and weather around the northern hemisphere. The Arctic is also region of increasing economic importance for diverse range of stakeholders, and reductions in Arctic sea ice will bring new legal and political challenges this navigation routes for commercial shipping open and marine access to the region increases for offshore oil and gas development, tourism, fishing and other activities.

  • Rapidly increasing extinction of plant and animal species at a rate already “probably as fast as any warming event in the past 65 million years, and it is projected that its pace over the next 30 to 80 years will continue to be faster and more intense.” Speaking of the forces driving these extinctions, it says:

If unchecked, habitat destruction, fragmentation, and over-exploitation, even without climate change, could result in a mass extinction within the next few centuries equivalent in magnitude to the one that wiped out the dinosaurs. With the ongoing pressures of climate change, comparable levels of extinction conceivably could occur before the year 2100; indeed, some models show a crash of coral reefs from climate change alone as early as 2060 under certain scenarios.

  • Destabilization of the west Antarctic ice sheet, an “abrupt change of unknown probability,” carries the threat of sea-level rise “at a rate several times faster than those observed today. “

Because the probability of reaching this tipping point within the century is “plausible” though “probably low,”  its impact on coastal populations across the globe would be so enormous that the report gives it special focus as a doomsday risk that is not yet well understood.

In the face of these threats, the report urges development of an Abrupt Change Early Warning System (ACEWS) to closely monitor signals of tipping points drawing near, digest the data and feed it into the best predictive models that can be developed.

This may seem a no-brainer, or something that’s already been done, but in fact the amount of instrumentation devoted to measuring and recording climate data on this planet remains embarrassingly small.

“We watch our streets, we watch our banks,” the report’s chief author, climatologist James White of the University of Colorado at Boulder, told the Los Angeles Times. “But we do not watch our environment with the same amount of care and zeal.”

And in a bit of notable understatement, White told the Boulder Daily Camera that “the planet is arguably our most valuable asset. We need it for clean water, clean air, energy, food. We don’t monitor that with the same kind of zeal as we do other places that we think are precious.”

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The full 201-page text of “Abrupt Impacts of Climate Change: Anticipating Surprises” can be downloaded here at no charge.