Note: this article appeared in the Association of Massachusetts Wetland Scientists Newsletter July, 2009
The Role of Uncertainty in Climate Change Decisions.
GORDON PEABODY
Introduction
Uncertainty is a significant issue in climate change scenarios. We will be challenged to make room for uncertainty in our thought process, teachings and recommendations to policy makers.
Three years ago, I was given a mystery to solve. While I was purchasing lobsters on Cape Cod, a lobsterman’s son casually mentioned that they had been “seeing some unusual things” in their traps. I was curious and asked, “What were they?” His dad had been fishing the ocean side of Cape Cod all his life. “Some kind of crab; Dad said he’d never seen them before,” the son answered. A second lobsterman, who had also never seen these crabs, chimed in that he’d been by-catching “thousands of them a week.” With a warming trend in water temperatures, invasive species from the south have been drifting into Cape Cod Bay; perhaps we had another southern invader?
When we identified a crab specimen from the lobsterman’s trap at Cape Cod National Seashore’s Marine Lab, it unexpectedly turned out to be a “toad crab,” with a habitat range north of Cape Cod. I realized my simple and erroneous presumption that the crab was a southern invasive came from my classically educated perspective where A leads to B and B to C. That is to say, I was thinking linearly, not laterally. I was wrong in my presumption that, since previous invasive marine species migrated from the south, any invasive would be from the south. I was also wrong in my presumption that I could find out why these crabs were turning up.
The Age of Uncertainty
“Uncertainty” seems to have become the new catch-all for the future of our planet. The ability of the scientific community to successfully communicate climate change information incorporating uncertainty is often inversely proportional with the public’s expectations. People expect scientists to be able to provide clarity in complex, uncertain scenarios and answer specific questions with certainty. But understanding climate change requires us to put classical, linear models aside and use new models that are capable of incorporating non-linear events as well as varying degrees of uncertainty.
In April 2009 for instance, we saw all-time monthly maximum temperature records for New York State and Maine.[1] Locally significant events such as this would have been easier to explain 100 years ago when we access to far less information. Today’s climate scientist has the responsibility of sifting through satellite data,, world wide weather stations and a new awareness of coupled models and teleconnections. This new information cascade contributes to more complicated explanations, and less certainty.  are easy to explain with classical linear models such as, “The past few years have been warmer so Maine is in a warming trend.” Today’s climate scientist, however, incorporates cascades of data: coupled models, atmospheric teleconnections, satellite information, and the scientist’s favorite term “uncertainty.” As NOAA put it understatededly, “Science for climate scientists is challenging.”[2]
Uncertainty has been a focus of the International Panel on Climate Change (the “IPCC”) and is especially germane in discussions of presumption, thresholds, tipping points and the transition of more predictable, linear systems to less predictable, non-linear systems. Declaring uncertainty as a critical component necessary to understand climate change, however, has received an unwelcome public reception. “You’ve been studying this for three years; why can’t you give us an answer?” Science has become more successful teaching people to view the world as a closed system. Now we need to find a way to incorporate and accept the significant role of climate change uncertainty in our planning and policy-making decisions.
Uncertainty and the NADC
Established models may also be subject to uncertainty. One familiar model is the North Atlantic Drift Current (“NADC”). A component of global thermohaline circulation (“THC”), this NADC current contributes heat to Northern and Western Europe. [3] In fact, the NADC constitutes the main moderating force over Scandinavia, the United Kingdom, and Western Europe.[4] Multiple models recently incorporated data reflecting a reduction in flow of the NADC.[5] These alterations may cause significant latitudinal climate changes in Western Europe.[4] Uncertainty over this type of possible change in Western Europe’s heat budget has generated concern in the scientific community. At Stanford University last January, I met with Leif Thomas, an Assistant Professor in the Department of Environmental Earth System Sciences. Dr. Thomas is a physical oceanographer working on models of the Gulf Stream’s north wall. I asked him to confirm my concerns about NADC flow reductions. He replied, “Those thermohaline circulation models that you looked at don’t incorporate the wind-driven Gulf Stream Current.” The Gulf Stream is a significant heat delivery system. I was totally unprepared for his answer because I had, once again, trapped myself into thinking there were only two answers: “yes” or “no.” I had forgotten to incorporate both lateral thinking and uncertainty.
Below, thermal image of the wind driven Gulf Stream Current
Uncertainty and Teleconnections
Teleconnections offer a window of understanding into global climate relationships. Teleconnections encompass uncertainty by correlating anomalies. Teleconnections describe patterns of significant, simultaneous correlations, between weather and climate anomalies at widely separated centers of action. The stage was set for the study of teleconnections as early as 1932, when links between sea level pressures and sea air temperatures were studied.[6] More recently, positive connections between the NADC and the North Atlantic Oscillation (“NAO”), an atmospheric dynamic subject to decadal and multidecadal oscillations, have been discussed.[7] Teleconnections were referred to as “atmospheric bridges” in reference to the influence of El Nino Southern Oscillation (“ENSO”) on air sea interactions over the global oceans.[8] ENSO has three phases: positive El Nino; negative La Nina; and neutral. Changes associated with ENSO influence global atmospheric circulation.[9]
The correlation of anomalies has continued into present research. In Shaw’s “Exercise in Correlation, East/West Teleconnections,” teleconnections are used to link meteorology and physical oceanography.[10] Teleconnections are often counterintuitive. For example, the timing of the cycles in the North Pacific Residual agrees with those of the North Atlantic Sub-polar Gyre SST anomalies.[11] Teleconnections can also be useful in the study of larval fish distribution. During the 1995 Canadian conference on Climate Change and Northern Fish Populations, S.N. Rodionov of the National Center for Atmospheric Research used the term “biological teleconnections” to describe the linkage between ocean-atmospheric processes and fish population dynamics. Such linkages may be applicable to understanding population fluctuations in economically important fish species, such as the North Atlantic Cod.
The Atlantic hurricane season may be influenced by three important teleconnections, which contribute to predictions of Atlantic hurricanes: (1) There are correlations between hurricanes and ENSO; a strong El Nino phase may act to reduce hurricanes; (2) Changes in the strength of the THC may influence hurricanes. Stronger THC has been correlated with stronger hurricanes.[12]; and (3) There are also correlations with the West African Monsoon and Atlantic hurricanes. A recent study was conducted of storm-induced deposits in Caribbean coastal lagoons. Results of the study indicated that, “variability in Western North Atlantic intense hurricanes was probably modulated by atmospheric dynamics associated with El Nino and West African monsoon.”[13]
Below, thermal image of sea surface temperatures (SST) and Hurricane Katrina.
NOAA is now monitoring Teleconnections between Tropical Atlantic and Tropical Eastern Pacific in real time.[14] El Nino prediction models for the 2009 Atlantic hurricane season vary in uncertainty. Most are predicting neutral conditions. According to a NOAA synopsis, “Conditions are favorable for transition from ENSO neutral to El Nino conditions between June and August.” Further on some qualifying details are included indicating that “current conditions reflect the evolution towards potential El Nino.” We can’t select specific models because they agree with a preferred outcome but Columbia University’s International Institute for Climate Research and Society predicts a “30% chance of El Nino during hurricane season.” NOAA has predicted “a 50% chance of a normal hurricane season, a 25% chance of an above normal season and a 25% chance of a below normal season.”[15]. As noted previously, NOAA commented, “Science for climate scientists is challenging.”[2]
Conclusion
As scientists we are going to be challenged to make informed decisions that may re-prioritize social, economic, and natural resources. We have new tools for understanding but we also have the responsibility to consider uncertainty as a critical tool that will contribute to making better decisions that will help to define our future.
The author would like to acknowledge Karen Stamieszkin, Associate Scientist, Provincetown Center for Coastal Studies, B.A., M.S.C., Yale University and Austin Becker, Ph.D. student, Stanford University, Department of Environmental Earth System Sciences, for their assistance in the preparation of this article.
Citations
1.   ”Selected U.S City and State Extremes”. NOAA/NWS Forecast Offices compiled by NCDC April 2009.
2.   NOAA press release, May 24, 2009.
3.   The North Atlantic Current. Rowe, E., A. Mariano, E.H. Ryan. The Cooperative Institute for Marine and Atmospheric Studies, 2001-2008 web site.
4.   Bigg, G.R. 1996: The Oceans and Climate, Cambridge University Press, UK, 266p.
5.   Climate Change 2001, The Scientific Basics, IPCC Report, Modeling an Abrupt Climate Change, Chap. 9, p. 105.
6.   Walker, G.T. and E.W. Bliss. 1932. World Weather. V. Mem. Roy. Meteor. Soc., 4. No. 36, pgs 53-84.
7.   Blindheim, J., V. Borokov, B. Hansen, S.A. Malmberg, W.R. Turrell, and S. Osterhus. 2000. Deep Sea Research I, 47, pgs 655-80.
8.   Lee, S.-K., D. B. Enfield, and C. Wang. 2008. Geophysical Research Letters, 35, L16705.
9.   Alexander et al., “NOAA CIRES Climate Diagnostic Center.” Journal of Climate Science August 2002 (pgs 2205-31).
10.   Shaw “ENSO Teleconnections and the North Atlantic Ocean: An Exercise in Correlation” MPO 671, 2008.
11.   Tisdale “An Interesting Correlation with the North Atlantic Sub Polar Gyre SST.” Climate Observations: Notes from Bob Tisdale on Climate Change and Global Warming (November 25, 2008).
12.   Gray. “Hurricanes and Hot Air.” Wall Street Journal July 26, 2007.
13.   Donnelly and Woodruff. “Intense Hurricane Activity Over the Past 5,000 Years Controlled by El Nino and the West African Monsoon” Nature May 2007, p 465-8.
14.   ”Atlantic Hurricane Season Outlook” NOAA Press Release, May 21, 2009.
15.   NOAA ENSO Prediction Synopsis, June 4, 2009.
Gordon Peabody
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