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4 The Way Forward
Pages 147-170

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From page 147...
... In looking back at the previous studies of abrupt climate change in the Introduction to this report, the committee notes that even when dragons, i.e., possible threats, are identified and clearly pointed out, they may then be ignored and their presence not acted upon. This is not an unusual situation, and ignoring early warnings is a welldocumented phenomenon in environmental research (e.g., EEA, 2001)
From page 148...
... Often, as humans have explored more of the world, threats have become less -- in this case, the "dragons" may have referred to Komodo dragons, rather than dragons of fairy tales. ice coverage in the North Atlantic, that they had a near-global footprint but regionally distinct impacts, and that even slow changes in freshwater flux to the North Atlantic could cross a threshold and trigger a sudden event (e.g., Alley, 2007)
From page 149...
... Fast changes in atmospheric methane concentration in ice cores from glacial time correlated with abrupt climate changes (e.g., Chappellaz et al., 1993)
From page 150...
... Other unknowns include the rapid loss of Arctic sea ice and the potential impacts on Northern Hemisphere weather and climate that could potentially come from that shift in the global balance of energy, the widespread extinction of species in marine and terrestrial systems, and the increase in the frequency and intensity of extreme precipitation events and heat waves. The committee reviews the various abrupt changes described in Chapter 2 in Table 4.1.
From page 151...
... There is still much to learn about the potential for and possible prediction of these kinds of abrupt changes, but a sound body of theory and empirical data (Barnosky et al., 2012; Carpenter et al., 2011; Hastings and Wysham, 2010; Mumby et al., 2007; Scheffer, 2010; Scheffer et al., 2001, 2009, 2012b) confirm that there are real "dragons" out there to be discovered.
From page 152...
... Using network modeling techniques to identify the nodes and connections that construct social systems at a variety of spatial scales, and how projected climate changes would be expected to propagate through the system, may well lead to better predictive ability. A more empirical ap 152
From page 153...
... . ANTICIPATING SURPRISES The recognition of the importance of tipping-point behavior in physical, biological, and social systems has prompted a growing body of research to provide as much early warning as possible of incipient or ongoing abrupt changes (Box 4.2)
From page 154...
... Finally, there is some evidence that previous abrupt changes in Earth's history have been noise-induced transitions (see Box 1.4) ; such events will have very limited predictability (Ditlevsen and Johnsen, 2010)
From page 155...
... would be part of such an overall risk management strategy, providing required information for hazard identification and risk assessment (adapted from NRC, 2012c)
From page 156...
... It is noted that communication is a crucial component of any early warning system to ensure the timely delivery of information on impending events, and prepare potential risk scenarios and preparedness strategies. Special considerations need to be given to the importance of accuracy, lead time, warning message content, warning transmission, and the appropriate social response to minimize negative consequences from the hazard (Kasperson et al., 1988; Mileti, 1999)
From page 157...
... An excellent summary of lessons learned from early warnings in past environmental issues can be found in a 2001 report by the European Environment Agency, and are shown in Box 4.3. In this section, the Committee provides further thoughts on selected aspects of an ACEWS: the monitoring, modeling, and synthesis aspects, as well as some special considerations for designing and implementing an ACEWS.
From page 158...
... , have provided unique insights into the mechanisms and likelihood for abrupt climate change (Hodell et al., 1995; Alley and Joughin, 2012)
From page 159...
... In addition, large ensemble simulations are important for adequately characterizing the probability of extreme events in the past, present, and future, as well as to support developments of scenarios for societal stress tests and plans for observing systems. To date, modeling studies have had less focus on how gradual changes in climate could induce abrupt changes in other aspects of the system.
From page 160...
... A security camera that does not work, or does not watch all entrances and exits, is not very useful. Current resources to provide high-quality and continuous monitoring are at risk, and there are notable examples including critical time series that have been compromised due to reductions of in-situ and remotely sensed observational networks (e.g., the NOAA Cooperative Air Sampling Network)
From page 161...
... The science of abrupt climate change is not settled; monitoring needs will evolve over time and an iterative mechanism would allow ongoing assessment and evaluation. There needs to be some mechanism to allow for evolution of the ACEWS.
From page 162...
... A few examples of current monitoring programs that integrate monitoring with active interpretation of the data include the Long Term Ecological Programs of the National Science Foundation, NOAA's atmospheric gas monitoring program, NASA's Stratospheric Observatory 5  The initial failure of satellite monitoring to identify the ozone hole over Antarctica because an automatic routine flagged anomalous data as potential errors shows what can happen without sufficiently integrated interpretation (see Grundmann, 2002 for a more complete historical account)
From page 163...
... This step is important for an ACEWS as in some cases we know what to watch for, such as changes in AMOC, and in some cases we are less sure, such as changes in Northern Hemisphere weather patterns that may accompany the large energy changes in the Arctic as sea ice melts, trading white sea ice that reflects solar energy for blue ocean that absorbs solar energy. Also, the system should be nimble enough to change focus if necessary as knowledge about abrupt change improves.
From page 164...
... The committee views this call as being particularly salient in light of its analysis of the previous reports on abrupt climate change, where a common theme emerged. Beginning with the 2002 NAS study (NRC, 2002)
From page 165...
... The Way Forward "No matter how clear our foresight, no matter how accurate our computer models, a belief about the future should never be mistaken for the truth. The future, as such, never occurs.
From page 166...
... • Southward shift of tropical • Monitoring of overturning at rain belts other latitudes • Large disruptions to local • Enhanced understanding of marine ecosystems drivers of AMOC variability • Ocean and atmospheric temperature and circulation changes • Changes in ocean's ability to store heat and carbon Sea level rise (SLR) from Moderate Low2 High High • Maintenance and expansion Abrupt Changes in the Ocean ocean thermal expansion increase in of monitoring of sea level • Coastal inundation sea level rise (tide gauges and satellite • Storm surges more likely to data)
From page 167...
... ) detected oxygen content, pH, and • Threats to aerobic marine life temperature • Release of nitrous oxide • Improved understanding gas -- a potent greenhouse and modeling of ocean gas -- to the atmosphere mixing • Improved understanding of microbial processes in OMZs Changes to patterns Trends not Low Moderate Low to • Maintaining continuous of climate variability detectable for Moderate records of atmospheric most patterns pressure and temperatures • Substantial surface weather of climate from both in-situ and changes throughout variability remotely sensed sources much of extratropics if the Exception • Assessing robustness extratropical jetstreams were is southern of circulation shifts in to shift abruptly annular individual ensemble mode -- members in climate change detectable simulations Abrupt Changes in the Atmosphere poleward shift • Developing theory on of middle circulation response to latitude anthropogenic forcing jetstream Increase in intensity, Detectable Moderate High High • Continued progress on frequency, and duration of increasing (Regionally understanding climate heat waves trends variable, dynamics • Increased mortality dependent • Increased focus on risk • Decreased labor capacity on soil assessment and resilience • Threats to food and water moisture)
From page 168...
... Understanding Monitoring, etc.) Increasing release of Neutral trend Low High Moderate4 • Improved models of carbon stored in soils and to small trend hydrology/cryosphere permafrost in increasing interaction and ecosystem • of human- soil carbon response induced climate change3 release • Greater study of role of in rapid carbon release • Expanded borehole temperature monitoring networks • Enhanced satellite and ground-based monitoring of atmospheric methane concentrations at high latitudes Increasing release of Trend not Low5 Moderate Moderate6 • Field and model based methane from ocean clearly characterization of the Abrupt Changes at High Latitudes methane hydrates detected sediment column • of human- • Enhanced satellite and induced climate change ground-based monitoring of atmospheric methane concentrations at high latitudes Late-summer Arctic sea ice Strong trend High Very high High • Enhanced Arctic disappearance in decreasing observations, including • Large and irreversible effects sea ice cover atmosphere, sea ice, and on various components of ocean characteristics the Arctic ecosystem • Better monitoring and • Impacts on human society census studies of marine and economic development ecosystems in coastal polar regions • Improved large-scale • Implications for Arctic models that incorporate the shipping and resource evolving state of knowledge extraction • Potential to alter large-scale atmospheric circulation and its variability Winter Arctic sea ice Small trend Low Moderate High • Same as late summer disappearance (Decreasing Arctic sea ice • Same as late summer Arctic but not disappearance above sea ice disappearance disappearing)
From page 169...
... Understanding Monitoring, etc.) Rapid state changes in Species Moderate High Moderate • Long term remote sensing ecosystems, species range shifts and in-situ studies of key range shifts, and species systems boundary changes others not • Improved hydrological and • Extensive habitat loss clearly ecological models • Loss of ecosystem services detected Abrupt Changes in Ecosystems • Threats to food and water supplies Increases in extinctions Species and High Very high Moderate • Better understanding of of marine and terrestrial population how species interactions species losses and ecological cascades • Loss of high percentage accelerating might magnify extinctions of coral reef ecosystems (Portion intensity (already underway)


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