NRC: “Abrupt Change Early Warning System” Needed
Prepared by Michael Marien
Climate change is almost surely the major issue of the 21st century. It is a complex and evolving concern, and scientific understanding is constantly improving, albeit still far from certain. This report provides the latest overview of the state of knowledge and uncertainty on trends, surprises, and potential impacts.
The commendable foresight employed by these leading climate scientists on the NRC "Committee on Understanding and Monitoring Abrupt Climate Change and its Impacts" deserves attention by others. Any planner, policy-maker, or futurist should be paying close attention to the distinction between widely-assumed steady change and abrupt change, as well as to the worsening climate change issue itself. To this end, an Appendix is provided here, with abstracts of five recent and related reports: America's Climate Choices from the NRC (2011), Bankrupting Nature: Denying Our Planetary Boundaries by Anders Wijkman and Johan Rockström (2012), The Projected Timing of Climate Departure from Recent Variables by Camilo Mora et al. (2013), an outline of the IPCC Fifth Assessment Report (2014), and The Climate Casino: Risk, Uncertainty, and Economics for a Warming World by William Nordhaus (2013).
"Levels of CO2 and other greenhouse gases in Earth's atmosphere are exceeding levels recorded in the past millions of years, and thus climate is being forced beyond the range of the recent geological era. Lacking concerted action by the world's nations, it is clear that the future climate will be warmer, sea levels will rise, global rainfall pattern will change, and ecosystems will be altered." (NRC, p.1)
But there is still uncertainty about how we will arrive at this future state. Many projections of future conditions predict steadily changing conditions, suggesting that communities have time to gradually adapt. However, scientists have been paying increasing attention to the possibility that at least some changes will be abrupt, perhaps crossing a threshold or "tipping point" to change so quickly that there will be little time to react. Earth's history—gathered from sources such as fossils, sediment cores, and ice cores—contains ample evidence of abrupt changes in the past. In addition to abrupt changes within the climate system, gradual climate changes can cross thresholds in both natural systems and human systems (e.g., rising sea levels surpassing sea walls, or thawing permafrost destabilizing pipelines, buildings, and roads).
"Understanding the potential risks posed by both abrupt climate changes and the abrupt impacts resulting from gradual climate change is a crucial piece in advancing the ability of society to cope with changes in the Earth system." (p.2) This report, sponsored by the US intelligence communities, the National Oceanic and Atmospheric Administration, the National Science Foundation, and the National Academies, examines current knowledge about the likelihood and timing of 14 potential abrupt changes. It also calls for an Abrupt Change Early Warning System, and identifies gaps in scientific understanding and monitoring capabilities. "The primary timescale of concern is years to decades. A key characteristic of these changes is that they can come faster than expected, planned, or budgeted for, forcing more reactive, rather than proactive, modes of behavior." (p2)
ABRUPT CHANGES ALREADY UNDERWAY
Two changes are of immediate concern: the disappearance of late-summer Arctic sea ice and increases in species extinctions.
Rapid reduction in Arctic sea ice already qualifies as an abrupt change, due to substantial decreases in ice extent in the past several decades. "Projections from climate models suggest that ice loss will continue in the future, with the full disappearance of late-summer Arctic sea ice possible in the coming decades." (p.3) The impacts are likely to be considerable, including disruptions in the marine food web, shifts in the habits of some marine mammals, and erosion of vulnerable coastlines. "Changes in the extent of sea ice could cause shifts in climate and weather around the northern hemisphere." They will bring new legal and political challenges as navigation routes for commercial shipping open, and access to fishing, tourism, and offshore oil and gas is enabled.
"The rate of climate change now underway is 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. These rapidly changing conditions make survival difficult for many species." (p.5) The distinct risks of climate change exacerbate other widely recognized and severe extinction pressures, especially habitat destruction, competition from invasive species, and unsustainable exploitation of species for economic gain, which have already elevated extinction rates. Loss of a species has economic impacts from loss of ecosystem services, revenue, and jobs in fishing, forestry, and ecotourism. It also has ethical implications, as the current generation's legacy to future generations. [ALSO SEE The Sixth Extinction: An Unnatural History by New Yorker staff writer Elizabeth Kolbert (NY: Henry Holt, Feb 2014, 319p), the latest global summation of this worrisome megatrend.]
ABRUPT CHANGES OF UNKNOWN PROBABILITY OR UNLIKELY IN THE 21C
Foremost is destabilization of the West Antarctic Ice Sheet, a large part of it capable of flowing rapidly into deep ocean basins, representing 3-4 meters of potential sea-level rise. "It remains possible that future rates of sea-level rise from the WAIS are underestimated, perhaps substantially." An abrupt change of the WAIS in the twenty-first century is plausible, with an unknown although probably low probability. The Greenland ice sheet is not expected to destabilize rapidly within this century.
Recent research shows that some abrupt changes previously considered as potential threats may be less likely to occur in this century than previously considered possible. These include disruption to the Atlantic Meridional Overturning Circulation and potential abrupt changes of high-latitude methane sources (permafrost soil carbon and ocean methane hydrates). But if they occur in the next century or beyond, "there would likely be severe impacts." Arctic carbon stores (e.g. permafrost soils and methane-containing ices) "are poised to play a significant amplifying role in the century-scale buildup of carbon dioxide and methane in the atmosphere, but are unlikely to do so abruptly, i.e., on a timescale of one or a few decades." (p.10)
14 POTENTIAL PROCESSES THAT MAY CHANGE
A 4-page chart (pp. 14-17) summarizes a wide range of potential changes and their consequences, the current trend, the outlook before 2100 and after 2100, level of scientific understanding, and critical needs for research.
Abrupt Changes in the Ocean
a) Disruption to Atlantic Meridional Overturning Circulation (low probability before 2100, high probability after 2100, moderate level of understanding)
b) Sea Level Rise from Ocean Thermal Expansion, with storm surges more likely and severe (low probability by 2100, high probability after 2100, high level of understanding)
c) Sea Level Rise from West Antarctic Ice Sheet (probably low likelihood by 2100, unknown likelihood after 2100, low level of understanding)
d) Sea Level Rise from Greenland and Other Ice Sheets (low probability by 2100, high probability after 2100, high understanding for some aspects but low for others)
e) Decrease in Ocean Oxygen with threats to marine life and release of nitrous oxide GHG (moderate probability to 2100, high probability after 2100, low to moderate understanding)
Abrupt Changes in the Atmosphere
a) Changes to Patterns of Climate Variability (moderate probability by 2100, high probability after 2100, low to moderate understanding)
b) Heat Waves Increasing in Intensity, Frequency, and Duration (moderate probability by 2100, high probability after 2100, high level of understanding)
c) Extreme Precipitation Events Increase in Frequency and Intensity, with threats to food and water (moderate probability to 2100, moderate to high probability after 2100, low to moderate level of understanding)
Abrupt Changes at High Latitudes
a) Increased Release of Carbon Stored in Soils and Permafrost (low probability to 2100, high probability after 2100, moderate level of understanding)
b) Increased Release of Methane from Ocean Methane Hydrates (low probability to 2100, moderate probability after 2100, moderate level of understanding)
c) Late-Summer Arctic Sea Ice Disappears (high probability by 2100, very high probability after 2100, high level of understanding)
d) Winter Arctic Sea Ice Disappearance (low probability by 2100, moderate probability after 2100, high level of understanding)
Abrupt Changes in Ecosystems
a) Rapid State Changes in Ecosystems, Species Range Shifts, and Species Boundary Changes (moderate probability by 2100, high probability after 2100, moderate level of understanding)
b) Increased Extinctions of Marine and Terrestrial Species (high probability by 2100, very high probability after 2100, moderate level of understanding)
THE NRC SUMMARY
"In light of the importance of actionable information about the occurrence and impacts of abrupt changes, it is the [NRC] Committee's judgment that action is urgently needed to improve society's ability to anticipate climate change and impacts." (p.11) Surprises in the climate system are inevitable, and development of an Abrupt Change Early Warning System is recommended, part of an overall risk management strategy. The ACEWS would monitor key variables of abrupt change, engage in modeling to project future abrupt changes, and synthesize knowledge "to avoid the trap of data collection without continuing and evolving data analysis and model integration. This will require dedicated teams of researchers, improved collaborative networks, enhanced educational activities, and innovative tools for data analysis and modeling techniques." (p.12)
Although there is still much to learn, 'to willfully ignore the threat of abrupt change could lead to more costs, loss of life, suffering, and environmental degradation. The time is here to be serious about the threat of tipping points so as to better anticipate and prepare ourselves for the inevitable surprises." (p.13)
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APPENDIX: FIVE RELATED REPORTS
Five recent reports serve to complement and expand the NRC concern about climate change and potential abrupt changes.
1) America's Climate Choices by the National Research Council (National Academies Press, May 2011, 118p; GFB Book of the Month, Oct 2011) warns that climate change "poses significant risks for a broad range of human and natural systems," and that "substantial action" is needed to limit the magnitude of climate change and to prepare to adapt to its impacts. Given the complexities of the climate system, "we can expect always to be learning more and to be facing uncertainties regarding future risks." Of particular note is the discussion of the unique challenges of climate change (e.g. significant time lags in the climate system and in human response), and the sensible and distinctive call for "iterative risk management" as a process of ongoing assessment, action, reassessment, and response.
2) Bankrupting Nature: Denying Our Planetary Boundaries by Anders Wijkman (Co-President, Club of Rome) and Johan Rockström of the Stockholm Resilience Centre (Earthscan/Routledge, Nov 2012, 206p.; GFB Book of the Month, Jan 2013) also focuses on the "need to acknowledge the risk of surprises, tipping points, or threshold events." But it does so with the broader concept of "planetary boundaries" involving nine biophysical processes: climate stability, ozone depletion, ocean acidification, biogeochemical loading (nitrogen and phosphorus cycles), biodiversity loss, degradation of land resources, over-exploitation of freshwater, pollution from toxic chemicals, and atmospheric aerosol loading (nitrates, sulphates, and soot particles). Humanity has already exceeded three of these boundary limits, as concerns climate, biodiversity, and excess nitrogen. Based on two scientific papers published in 2009 by Rockström and 28 others, the "planetary boundaries" concept is also described by Carl Folke of the Stockholm Resilience Centre in State of the World 2013: Is Sustainability Still Possible? (Island Press/Worldwatch Institute, April 2013, 441p; GFB Book of the Month, Oct 2013).
3) The Prospective Timing of Climate Departure from Recent Variability by Camilo Mora of the U of Hawaii and 13 others (Nature, 10 Oct 2013, 183-187; reported by Justin Gillis in The New York Times, 10 Oct 2013, A10), arguing that "if greenhouse emissions continue their steady escalation, temperatures across most of the earth will rise to levels with no recorded precedent by the middle of this century." (NYT) Thus the coldest year in the future will be warmer than the hottest year in the past, based on temperatures recorded between 1860 and 2005. Unprecedented climates will arrive even sooner in the tropics, where climate variability is much smaller than in high latitudes, and plants and animals are accustomed to a narrow temperature range. Under continuing high emissions (the business-as-usual scenario), climate departure dates will be 2029 for Jakarta and Lagos and 2031 for Mexico City, contrasted to 2047 for New York City and 2071 in Anchorage, plus or minus a five-year margin of error. "The models show that unprecedented temperatures could be delayed by 20 to 25 years if there is a vigorous global effort to bring emissions under control."
4) Fifth Assessment Report: Climate Change 2013, from the Intergovernmental Panel on Climate Change, is delivered in three parts and a synthesis, as in previous years. Working Group 1: The Physical Science Basis (Jan 2014, c.1500p) states that warming is unequivocal and that there is a 95% chance that most of it is human-caused (up from 90% in the previous report). Contents include projected climate change over the 21st century and beyond, an atlas of climate projections for 35 world regions, and potentially abrupt or irreversible changes. The report from WG II, Impacts, Adaptation, and Vulnerability, is due in March 2014. The WG III report, Mitigation of Climate Change, is due in April 2014. A Dec 2013 draft was leaked, and reported in the New York Times by Justin Gillis (17 Jan 2014, A8), who writes that "Nations have so dragged their feet in battling climate change that the situation has grown critical and the risk of severe economic disruption is rising...another 15 years of failure to limit carbon emissions could make the problem virtually impossible to solve with current technologies." While the spread of technologies like solar power and wind farms might give the impression of progress, such developments are being overtaken by rising emissions, especially in China. While emissions appear to have fallen in recent years in some rich countries, that is somewhat of an illusion because many of the goods consumed in wealthy countries are now made abroad; thus the wealthy countries have outsourced their emissions. A delay in curbing emissions would likely force future generations to suck greenhouse gases out of the atmosphere—an approach that "would probably be wildly expensive compared with taking steps now to slow emissions." The IPCC Synthesis Report will be published in Oct 2014.
5) The Climate Casino: Risk, Uncertainty, and Economics for a Warming World, by Yale economist William Nordhaus (Yale U Press, 2013, 378p), explains in a non-technical manner how we are entering the Climate Casino, where "economic growth is producing unintended but perilous changes in the climate and earth systems. These changes will lead to unforeseeable and probably dangerous consequences. We're rolling the climatic dice, the outcome will produce surprises, and some of them are likely to be perilous." (p.3) Chapters discuss the science of global warming, projections of future climate change from the IPCC Fourth Assessment, dangerous tipping points in the climate casino (collapse of large ice sheets, feedback that triggers more warming), the fate of farming, the potential for major impacts on health, perils for the oceans (sea level rise, ocean acidification and carbonization), intensification of hurricanes, impacts on wildlife and ecosystems, adding up the damages (showing vulnerability by economic sector), adaptation and geoengineering, the costs of reducing emissions, the discounting issue of comparing present and future costs and benefits (costs are paid largely in the near term, while benefits come far in the future), balancing costs and benefits, the central role of carbon prices, national climate change policies, new technologies for a low-carbon economy, climate science and its critics, public opinion and climate change, why carbon taxes are an ideal policy for true conservatives (they can be imposed without burdensome regulations and without betting on technology winners), and overcoming obstacles to climate change policies (prisoners of nationalism, of the present, of partisanship, of economic self-interest). Concludes that clear and persistent explanations of the science must continue; the evidence will become increasingly clear as it did with smoking, and "the political winds will eventually shift."
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