Bibliography - Michael Oppenheimer

1. Little, C. M., Michael Oppenheimer, and Nathan M. Urban, March 2013: Upper bounds on twenty-first-century Antarctic ice loss assessed using a probabilistic framework. Nature Climate Change, Macmillan Publishers Limited, doi:10.1038/NCLIMATE1845
   [ Abstract ]

   Climate adaptation and flood risk assessments have incorporated sea-level rise (SLR) projections developed using semi-empirical methods (SEMs) and expert-informed mass-balance scenarios. These techniques, which do not explicitly model ice dynamics, generate upper bounds on twenty-first century SLR that are up to three times higher than Intergovernmental Panel on Climate Change estimates. However, the physical basis underlying these projections, and their likelihood of occurrence, remain unclear. Here, we develop mass-balance projections for the Antarctic ice sheet within a Bayesian probabilistic framework, integrating numerical model output and updating projections with an observational synthesis.Without abrupt, sustained, changes in ice discharge (collapse), we project a 95th percentile mass loss equivalent to ~13 cm SLR by 2100, lower than previous upper-bound projections. Substantially higher mass loss requires regional collapse, invoking dynamics that are likely to be inconsistent with the underlying assumptions of SEMs. In this probabilistic framework, the pronounced sensitivity of upper-bound SLR projections to the poorly known likelihood of collapse is lessened with constraints on the persistence and magnitude of subsequent discharge. More realistic, fully probabilistic, estimates of the ice-sheet contribution to SLR may thus be obtained by assimilating additional observations and numerical models.

2. Little, C. M., Daniel Goldberg, A. Gnanadesikan, and Michael Oppenheimer, 2012: On the coupled response to ice-shelf basal melting. Journal of Glaciology, 58(208), doi:10.3189/2012JoG11J037 203-215
   [ Abstract ]

   Ice-shelf basal melting is tightly coupled to ice-shelf morphology. Ice shelves, in turn, are coupled to grounded ice via their influence on compressive stress at the grounding line ('ice-shelf buttressing'). Here, we examine this interaction using a local parameterization that relates the basal melt rate to the ice-shelf thickness gradient. This formulation permits a closed-form solution for a steady-state ice tongue. Time-dependent numerical simulations reveal the spatial and temporal evolution of ice-shelf/ice-stream systems in response to changes in ocean temperature, and the influence of morphology-dependent melting on grounding-line retreat.We find that a rapid (<1 year) re-equilibration in upstream regions of ice shelves establishes a spatial pattern of basal melt rates (relative to the grounding line) that persists over centuries. Coupling melting to ice-shelf shape generally, but not always, increases grounding-line retreat rates relative to a uniform distribution with the same areaaverage melt rate. Because upstream ice-shelf thickness gradients and retreat rates increase nonlinearly with thermal forcing, morphology-dependent melting is more important to the response of weakly buttressed, strongly forced ice streams grounded on beds that slope upwards towards the ocean (e.g. those in the Amundsen Sea).

3. O'Reilly, Jessica, Keynyn Brysse, Michael Oppenheimer, and Naomi Oreskes, 2011: Characterizing uncertainty in expert assessments: ozone depletion and the West Antarctic ice sheet. WIREs Climate Change, John Wiley & Sons, Ltd., doi:10.1002/wcc.135
   [ Abstract ]

   Large-scale assessments have become an important vehicle for organizing, interpreting, and presenting scientific information relevant to environmental policy. At the same time, identifying and evaluating scientific uncertainty with respect to the very questions these assessments were designed to address has become more difficult, as ever more complex problems involving greater portions of the Earth system and longer timescales have emerged at the science-policy interface. In this article, we explore expert judgments about uncertainty in two recent cases: the assessment of stratospheric ozone depletion, and the assessment of the response of the West Antarctic ice sheet (WAIS) to global warming. These assessments were fairly adept at characterizing one type of uncertainty in models (parameter uncertainty), but faced much greater difficulty in dealing with structural model uncertainty, sometimes entirely avoiding grappling with it. In the absence of viable models, innovative approaches were developed in the ozone case for consolidating information about highly uncertain future outcomes, whereas little such progress has been made thus far in the case of WAIS. Both cases illustrate the problem of expert disagreement, suggesting that future assessments need to develop improved approaches to representing internal conflicts of judgment, in order to produce amore complete evaluation of uncertainty.

4. Turner, Will R., B. A. Bradley, Lyndon D. Estes, Michael Oppenheimer, and David S. Wilcove, August 2010: Climate Change: Helping Nature Survive the Human Response. Conservation International, doi:10.1111/j.1755-263X.2010.00128.x
   [ Abstract ]

   Climate change poses profound, direct, and well-documented threats to biodiversity. A significant fraction of Earth’s species is at risk of extinction due to changing precipitation and temperature regimes, rising and acidifying oceans, and other factors. There is also growing awareness of the diversity and magnitude of responses, both proactive and reactive, that people will undertake as lives and livelihoods are affected by climate change. Yet to date few studies have examined the relationship between these two powerful forces. The natural systems upon which people depend, already under direct assault from climate change, are further threatened by how we respond to climate change. Human history and recent studies suggest that our actions to cope with climate change (adaptation) or lessen its rate and magnitude (mitigation) could have impacts that match—and even exceed—the direct effects of climate change on ecosystems. If we are to successfully conserve biodiversity and maintain ecosystem services in a warming world, considerable effort is needed to predict and reduce the indirect risks created by climate change.

5. Bradley, B. A., Michael Oppenheimer, and David S. Wilcove, 2009: Climate Change and Plant Invasions: Restoration Opportunities Ahead. Global Change Biology, 15(6), doi:10.1111/j.1365-2486.2008.01824.x 1511-1521
   [ Abstract ]

   Rather than simply enhancing invasion risk, climate change may also reduce invasive plant competitiveness if conditions become climatically unsuitable. Using bioclimatic envelope modeling, we show that climate change could result in both range expansion and contraction for five widespread and dominant invasive plants in the western United States. Yellow starthistle (Centaurea solstitialis) and tamarisk (Tamarix spp.) are likely to expand with climate change. Cheatgrass (Bromus tectorum) and spotted knapweed (Centaurea biebersteinii) are likely to shift in range, leading to both expansion and contraction. Leafy spurge (Euphorbia esula) is likely to contract. The retreat of onceintractable invasive species could create restoration opportunities across millions of hectares. Identifying and establishing native or novel species in places where invasive species contract will pose a considerable challenge for ecologists and land managers. This challenge must be addressed before other undesirable species invade and eliminate restoration opportunities.

6. Gerber, S., L.O. Hedin, Michael Oppenheimer, Stephen W. Pacala, and E. Shevliakova, 2009: Nitrogen Cycling and Feedbacks in a Global Dynamic Land Model. Global Biogeochemical Cycles, http://www.agu.org/journals/pip/gb/2008GB003336-pip.pdf, doi:10.1029/2008GB003336
   [ Abstract ]

   Global anthropogenic changes in carbon (C) and nitrogen (N) cycles call for modeling tools that are able to address and quantify essential interactions between N, C, and climate in terrestrial ecosystems. Here, we introduce a prognostic N cycle within the Princeton-GFDL LM3V land model. The model captures mechanisms essential for N cycling and their feedbacks on C cycling: N limitation of plant productivity, the N dependence of C decomposition and stabilization in soils, removal of available N by competing sinks, ecosystem losses that include dissolved organic and volatile N, and ecosystem inputs through biological N fixation.
   Our model captures many essential characteristics of C-N interactions, and is capable of broadly recreating spatial and temporal variations in N and C dynamics. The introduced N dynamics improves the model’s short term NPP response to step changes in CO₂. Consistent with theories of successional dynamics, we find that physical disturbance induces strong C-N feedbacks, caused by intermittent N loss and subsequent N limitation. In contrast, C-N interactions are weak when the coupled model system approaches equilibrium. Thus, at steady state many simulated features of the carbon cycle, such as primary productivity and carbon inventories are similar to simulations that do not include C-N feedbacks.

7. Kopp, Robert E., Frederick J. Simons, Jerry X. Mitrovica, Adam C. Maloof, and Michael Oppenheimer, December 2009: Probabilistic assessment of sea level during the last interglacial stage. Nature, New York, NY, Macmillan, 462, 863-867(17 December 2009), doi:10.1038/nature08686
   [ Abstract ]

   With polar temperatures ~ 3-5° warmer than today, the last interglacial stage (~125 kyr ago) serves as a partial analogue for 1-2° global warming scenarios. Geological records from several sites indicate that local sea levels during the last interglacial were higher than today, but because local sea levels differ from global sea level, accurately reconstructing past global sea level requires an integrated analysis of globally distributed data sets. Here we present an extensive compilation of local sea level indicators and a statistical approach for estimating global sea level, local sea levels, ice sheet volumes and their associated uncertainties. We find a 95% probability that global sea level peaked at least 6.6m higher than today during the last interglacial; it is likely (67% probability) to have exceeded 8.0m but is unlikely (33% probability) to have exceeded 9.4 m. When global sea level was close to its current level (>10m), the millennial average rate of global sea level rise is very likely to have exceeded 5.6mkyr^-1 but is unlikely to have exceeded 9.2mkyr^-1. Our analysis extends previous last interglacial sea level studies by integrating literature observations within a probabilistic framework that accounts for the physics of sea level change. The results highlight the long-term vulnerability of ice sheets to even relatively low levels of sustained global warming.

8. Searchinger, Timothy, Steven P. Hamburg, J. M. Melillo, W. Chameides, Petr Havlik, Daniel M. Kammen, Gene E. Likens, Ruben N. Lubowski, M. Obersteiner, Michael Oppenheimer, G. Philip Robertson, William H. Schlesinger, and G. David Tilman, October 2009: Fixing a Critical Climate Accounting Error. Science, Washington, D.C., American Association for the Advancement of Science, 326(5952), doi:10.1126/science.1178797 527-528
   [ Abstract ]

   The accounting now used for assessing compliance with carbon limits in the Kyoto Protocol and in climate legislation contains a far-reaching but fixable flaw that will severely undermine greenhouse gas reduction goals (1). It does not count CO₂ emitted from tailpipes and smokestacks when bioenergy is being used, but it also does not count changes in emissions from land use when biomass for energy is harvested or grown. This accounting erroneously treats all bioenergy as carbon neutral regardless of the source of the biomass, which may cause large differences in net emissions. For example, the clearing of long-established forests to burn wood or to grow energy crops is counted as a 100% reduction in energy emissions despite causing large releases of carbon.

9. Crutzen, P., and Michael Oppenheimer, 2008: Learning about ozone depletion. Climatic Change, 89(1-2), doi:10.1007/S10584-008-9400-6 143-154
   [ Abstract ]

   Stratospheric ozone depletion has been much studied as a case history in the interaction between environmental science and environmental policy. The positive influence of science on policy is often underscored, but here we review the photochemistry of ozone in order to illustrate how scientific learning has the potential to mislead policy makers. The latter may occur particularly in circumstances where limited observations are combined with simplified models of a complex system, such as may generally occur in the global change arena. Even for the well-studied case of ozone depletion, further research is needed on the dynamics of scientific learning, particularly the scientific assessment process, and how assessments influence the development of public policy.

10. Mignone, B. K., Robert H. Socolow, Jorge Sarmiento, and Michael Oppenheimer, 2008: Atmospheric Stabilization and the Timing of Carbon Mitigation. Climatic Change, 88(3-4), doi:10.1007/S10584-007-9391-8 251-265
    [ Abstract ]

    Stabilization of atmospheric CO₂ concentrations below a pre-industrial doubling (~550 ppm) is a commonly cited target in climate policy assessment. When the rate at which future emissions can fall is assumed to be fixed, the peak atmospheric concentration – or the stabilization “frontier” – is an increasing and convex function of the length of postponement. Here we find that a decline in emissions of 1% year⁻¹ beginning today would place the frontier near 475 ppm and that when mitigation is postponed, options disappear (on average) at the rate of ~9 ppm year⁻¹, meaning that delays of more than a decade will likely preclude stabilization below a doubling. When constraints on the future decline rate of emissions are relaxed, a particular atmospheric target can be realized in many ways, with scenarios that allow longer postponement of emissions reductions requiring greater increases in the intensity of future mitigation. However, the marginal rate of substitution between future mitigation and present delay becomes prohibitively large when the balance is shifted too far toward the future, meaning that some amount of postponement cannot be fully offset by simply increasing the intensity of future mitigation. Consequently, these results suggest that a practical transition path to a given stabilization target in the most commonly cited range can allow, at most, one or two decades of delay.

11. Oppenheimer, Michael, B. O'Neill, and M. Webster, 2008: Negative Learning. Climatic Change, 89(1-2), doi:10.1007/S10584-008-9405-1 155-172
    [ Abstract ]

    New technical information may lead to scientific beliefs that diverge over time from the a posteriori right answer. We call this phenomenon, which is particularly problematic in the global change arena, negative learning. Negative learning may have affected policy in important cases, including stratospheric ozone depletion, dynamics of the West Antarctic ice sheet, and population and energy projections. We simulate negative learning in the context of climate change with a formal model that embeds the concept within the Bayesian framework, illustrating that it may lead to errant decisions and large welfare losses to society. Based on these cases, we suggest approaches to scientific assessment and decision making that could mitigate the problem. Application of the tools of science history to the study of learning in global change, including critical examination of the assessment process to understand how judgments are made, could provide important insights on how to improve the flow of information to policy makers.

12. Donner, S. D., T. R. Knutson, and Michael Oppenheimer, 2007: Model-based assessment of the role of human-induced climate change in the 2005 Caribbean coral bleaching event. Proceedings of the National Academy of Sciences of the United States of America, 104(13), doi:10.1073/pnas.0610122104 5483-5488
    [ Abstract ]

    Episodes of mass coral bleaching around the world in recent decades have been attributed to periods of anomalously warm ocean temperatures. In 2005, the sea surface temperature (SST) anomaly in the tropical North Atlantic that may have contributed to the strong hurricane season caused widespread coral bleaching in the Eastern Caribbean. Here, we use two global climate models to evaluate the contribution of natural climate variability and anthropogenic forcing to the thermal stress that caused the 2005 coral bleaching event. Historical temperature data and simulations for the 1870–2000 period show that the observed warming in the region is unlikely to be due to unforced climate variability alone. Simulation of background climate variability suggests that anthropogenic warming may have increased the probability of occurrence of significant thermal stress events for corals in this region by an order of magnitude. Under scenarios of future greenhouse gas emissions, mass coral bleaching in the Eastern Caribbean may become a biannual event in 20–30 years. However, if corals and their symbionts can adapt by 1– 1.5°C, such mass bleaching events may not begin to recur at potentially harmful intervals until the latter half of the century. The delay could enable more time to alter the path of greenhouse gas emissions, although long-term ‘‘committed warming’’ even after stabilization of atmospheric CO₂ levels may still represent an additional long-term threat to corals.

13. Keller, Klaus, S.-R. Kim, J. Baehr, David F. Bradford, and Michael Oppenheimer, 2007: What is the economic value of information about climate thresholds? Human-Induced Climate Change: An Interdisciplinary Assessment, Cambridge University Press, Cambridge, MA, http://www.geosc.psu.edu/~kkeller/Keller_snowmass_pp_07.pdf, (Chapter 28), 343-354
    [ Abstract ]

    The field of integrated assessment of climate change is undergoing a paradigm shift towards the analysis of potentially abrupt and irreversible climate changes (Alley et al., 2003; Keller et al., 2006b). Early integrated studies broke important new ground in exploring the relationship between the costs and benefits of reducing carbon dioxide (CO₂) emissions (e.g., Nordhaus, 1991; Manne and Richels, 1991; or Tol, 1997). These studies project the climate response to anthropogenic CO₂ emissions to be relatively smooth and trypically conclude that the projected benefits of reducing CO₂ emissions would justify only small reductions in CO₂ emissions in a cost-benefit framework. The validity of the often-assumed smooth climate response is, however, questionable, given how that climate system has responded to forcing in the geological past. Before the Anthropocene, the geological time period where humans have started to influence the global biogeochemical cycles considerably (Crutzen, 2002) , the predominant responses of the climate system were forced by small changes in solar insolation occurring on timescales of thousands of years (Berger and Loutre, 1991). Yet this slow and smooth forcing apparently triggered abrupt climate changes - a threshold response where the climate system moved between different basins of attraction (Berger, 1990; Clement et al., 2001). Anthropogenic forcing may trigger climate threshold responses in the future (Alley et al., 2003; Keller et al., 2006b). Examples of such threshold responses include (i) a collapse of the North Atlantic meridional overturning circulation (Rahmstorf, 2000; Stommel, 1961), (ii) a disintegration of the West Antarctic Ice Sheet (Mercer, 1978; Oppenheimer, 1998), (iii) abrupt vegetation changes (Claussen et al., 1999; Scheffer et al., 2001), or (iv) changes in properties of the El Nino Southern Oscillation, ENSO (Fedorov and Philander, 2000; Timmermann, 201). Here we focus on the first two examples: a possible collapse of the North Atlantic meridional overturning circulation and a possible disintegration of the West Antarctic Ice Sheet. Our analysis address three main questions. (i) What underlying mechanisms define a climate threshold? (ii) What are the key scientific uncertainties in predicting whether these thresholds may be crossed in the future? (iii) What might be reasonable order-of-magnitude estimates of the expected economic value of reducing these uncertainties? Our analysis suggests that climate strategies designed to reduce the risk of crossing climate thresholds have to be designed in the face of large uncertainties. Some of the key uncertainties (e.g., the sensitivity of the meridional overturning circulation to anthropogenic greenhouse gas emissions) can be reduced by observation systems. We conclude by identifying future research needs.

14. Keller, Klaus, A. Robinson, David F. Bradford, and Michael Oppenheimer, 2007: The regrets of procrastination in climate policy. Environmental Research Letters, (Lett 2, No. 2), doi:10.1088/1748-9326/2/2/024004
    [ Abstract ]

    Anthropogenic carbon dioxide (CO₂) emissions are projected to impose economic costs due to the associated climate change impacts. Climate change impacts can be reduced by abating CO₂ emissions. What would be an economically optimal investment in abating CO₂ emissions? Economic models typically suggest that reducing CO₂ emissions by roughly ten to twenty per cent relative to business-as-usual would be an economically optimal strategy. The currently implemented CO₂ abatement of a few per cent falls short of this benchmark. Hence, the global community may be procrastinating in implementing an economically optimal strategy. Here we use a simple economic model to estimate the regrets of this procrastination—the economic costs due to the suboptimal strategy choice. The regrets of procrastination can range from billions to trillions of US dollars. The regrets increase with increasing procrastination period and with decreasing limits on global mean temperature increase. Extended procrastination may close the window of opportunity to avoid crossing temperature limits interpreted by some as ‘dangerous anthropogenic interference with the climate system’ in the sense of Article 2 of the United Nations Framework Convention on Global Climate Change.

15. Naik, V., D. L. Mauzerall, L. W. Horowitz, M. D. Schwarzkopf, V. Ramaswamy, and Michael Oppenheimer, 2007: On the sensitivity of radiative forcing from biomass burning aerosols and ozone to emission location. Geophysical Research Letters, 34(L03818), doi:10.1029/2006GL028149
    [ Abstract ]

    Biomass burning is a major source of air pollutants, some of which are also climate forcing agents. We investigate the sensitivity of direct radiative forcing due to tropospheric ozone and aerosols (carbonaceous and sulfate) to a marginal reduction in their (or their precursor) emissions from major biomass burning regions. We find that the largest negative global forcing is for 10% emission reductions in tropical regions, including Africa (-4.1 mWm-2 from gas and -4.1 mWm-2 from aerosols), and South America (-3.0 mWmfrom gas and -2.8 mWmfrom aerosols). We estimate that a unit reduction in the amount of biomass burned in India produces the largest negative ozone and aerosol forcing. Our analysis indicates that reducing biomass burning emissions causes negative global radiative forcing due to ozone and aerosols; however, regional differences need to be considered when evaluating controls on biomass burning to mitigate global climate change.

16. Nævdal, E., and Michael Oppenheimer, 2007: The Economics of the Thermohaline Circulation – A Problem with Multiple Thresholds of Unknown Locations. Resource and Energy Economics, 27(4), doi:10.1016/j.reseneeco.2007.01.003 262-283
    [ Abstract ]

    A potentially serious environmental threat facing humanity is the possibility of a collapse of the thermohaline circulation. Resulting climate changes, including absolute cooling near Greenland and northwest Europe, could be abrupt. Collapse of the thermohaline circulation may be triggered if the temperature or the rate of temperature change exceeds certain thresholds. The locations of these thresholds are unknown. Economic regulation of this problem requires solution methods for a class of dynamic optimization problems with multiple thresholds located in n-dimensional space. This class of problems has hitherto not been discussed in the literature. We present a model for the economic regulation of CO₂ emissions in the presence of threshold-triggered risk of a collapsing thermohaline circulation and derive optimality conditions for regulation.

17. Oppenheimer, Michael, B. O'Neill, M. Webster, and S. Agrawala, 2007: Climate Change: The Limits of Consensus. Science, 317, doi:10.1126/science.1144831 1505-1506
    [ Abstract ]

    The Intergovernmental Panel on Climate Change (IPCC) has just delivered its Fourth Assessment Report (AR4) since 1990. The IPCC was a bold innovation when it was established, and its accomplishments are singular (1, 2). It was the conclusion in the IPCC First Assessment Report that the world is likely to see “a rate of increase of global mean temperature during the next century … that is greater than seen over the past 10,000 years” (3) that proved influential in catalyzing the negotiation of the United Nations Framework Convention on Climate Change. The conclusions of the Second Assessment with regard to the human influence on climate (4) marked a paradigm shift in the policy debate that contributed to the negotiation of the Kyoto Protocol. IPCC conclusions from the Third, and now the Fourth, assessments have further solidified consensus behind the role of humans in changing the earth’s climate.

18. Schneider, S. H., S. Semenov, A. Patwardhan, I. Burton, C.H.D. Magadza, Michael Oppenheimer, A. B. Pittock, A. Rahman, J. B. Smith, A. Suarez, and F. Yamin, 2007: Assessing Key Vulnerabilities and the Risk from Climate Change. Intergovernmental Panel on Climate Change, http://www.ipcc.ch/pdf/assessment-report/ar4/wg2/ar4-wg2-chapter19.pdf, 19(Working Group II), 781-810
    [ Abstract ]

    Climate change will lead to changes in geophysical, biological and socio-economic systems.An impact describes a specific change in a system caused by its exposure to climate change. Impacts may be judged to be harmful or beneficial.Vulnerability to climate change is the degree to which these systems are susceptible to, and unable to cope with, adverse impacts. The concept of risk,which combines the magnitude of the impact with the probability of its occurrence, captures uncertainty in the underlying processes of climate change, exposure, impacts and adaptation. Many of these impacts, vulnerabilities and risks merit particular attention by policy-makers due to characteristics that might make them ‘key’. The identification of potential key vulnerabilities is intended to provide guidance to decision-makers for identifying levels and rates of climate change that may be associated with ‘dangerous anthropogenic interference’ (DAI) with the climate system, in the terminology of United Nations Framework Convention on Climate Change (UNFCCC) Article 2. Ultimately, the definition of DAI cannot be based on scientific arguments alone, but involves other judgements informed by the state of scientific knowledge. No single metric can adequately describe the diversity of key vulnerabilities, nor determine their ranking.

19. Yang, C.-J., and Michael Oppenheimer, 2007: A “Manhattan Project” for Climate Change? Climatic Change, 80(3-4), doi:10.1007/S10584-006-9202-7 199-204
    [ Abstract ]

    Climate change is a chronic yet unprecedented threat to civilization. Large scale abatement of greenhouse-gas emissions would require not only replacing carbon-intensive fuels (like coal and oil) with low-emission or carbon-free energy alternatives, but also replacing much of the infrastructure that uses primary and secondary energy. As a political issue, the scale of the problem makes carbon mitigation unique and difficult to resolve. Its chronic nature is another obstacle to implementation of policy in the near term. It would take decades to displace fossil fuels even if the technologies to do so were available. Furthermore, disagreement has arisen on whether currently available technologies are sufficient to significantly reduce emissions over the next several decades (Pacala and Socolow 2004; Hoffert et al. 2002). The notion of developing new technologies before mandating emissions reductions has gained currency in response to these complexities. The Bush Administration climate policy favors this line of thinking, rejecting any Kyoto-style arrangement involving mandatory targets and proposing the development of new technologies as an alternative (Bush 2005). Here we argue that such approaches are based on the misconception that innovations needed for carbon mitigation can be effectively and efficiently developed without carbon regulations.

20. Kunkel, C., R. Hallberg, and Michael Oppenheimer, 2006: Coral Reefs Reduce Tsunami Impact in Model Simulations. Geophysical Research Letters, 33(L23612), doi:10.1029/2006GL027892
    [ Abstract ]

    Significant buffering of the impact of tsunamis by coral reefs is suggested by limited observations and some anecdotal reports, particularly following the 2004 Indian Ocean tsunami. Here we simulate tsunami run-up on idealized topographies in one and two dimensions using a nonlinear shallow water model and show that a sufficiently wide barrier reef within a meter or two of the surface reduces run-up on land on the order of 50%. We studied topographies representative of volcanic islands (islands with no continental shelf) but our conclusions may pertain to other topographies. Effectiveness depends on the amplitude and wavelength of the incident tsunami, as well as the geometry and health of the reef and the offshore distance of the reef. Reducing the threat to reefs from anthropogenic nutrients, sedimentation, fishing practices, channelbuilding, and global warming would help to protect some islands against tsunamis.

21. Naik, V., D. L. Mauzerall, L. W. Horowitz, M. D. Schwarzkopf, V. Ramaswamy, and Michael Oppenheimer, 2006: Net radiative forcing due to changes in regional emissions of tropospheric ozone precursors. Journal of Geophysical Research, 110(D24306), doi:10.1029/2005JD005908
    [ Abstract ]

    The global distribution of tropospheric ozone (O₃) depends on the emission of precursors, chemistry, and transport. For small perturbations to emissions, the global radiative forcing resulting from changes in O₃ can be expressed as a sum of forcings from emission changes in different regions. Tropospheric O₃ is considered in present climate policies only through the inclusion of indirect effect of CH₄ on radiative forcing through its impact on O₃ concentrations. The short-lived O₃ precursors (NO_x, CO, and NMHCs) are not directly included in the Kyoto Protocol or any similar climate mitigation agreement. In this study, we quantify the global radiative forcing resulting from a marginal reduction (10%) in anthropogenic emissions of NO_x alone from nine geographic regions and a combined marginal reduction in NO_x, CO, and NMHCs emissions from three regions. We simulate, using the global chemistry transport model MOZART-2, the change in the distribution of global O₃ resulting from these emission reductions. In addition to the short-term reduction in O₃, these emission reductions also increase CH₄ concentrations (by decreasing OH); this increase in CH₄ in turn counteracts part of the initial reduction in O₃ concentrations. We calculate the global radiative forcing resulting from the regional emission reductions, accounting for changes in both O₃ and CH₄. Our results show that changes in O₃ production and resulting distribution depend strongly on the geographical location of the reduction in precursor emissions. We find that the global O₃ distribution and radiative forcing are most sensitive to changes in precursor emissions from tropical regions and least sensitive to changes from midlatitude and high-latitude regions. Changes in CH₄ and O₃ concentrations resulting from NO_x emission reductions alone produce offsetting changes in radiative forcing, leaving a small positive residual forcing (warming) for all regions. In contrast, for combined reductions of anthropogenic emissions of NO_x, CO, and NMHCs, changes in O₃ and CH₄ concentrations result in a net negative radiative forcing (cooling). Thus we conclude that simultaneous reductions of CO, NMHCs, and NO_x lead to a net reduction in radiative forcing due to resulting changes in tropospheric O₃ and CH₄ while reductions in NO_x emissions alone do not.

22. O'Neill, B., P. Crutzen, A. Grübler, M. H. Duong, Klaus Keller, C. Kolstad, A. Lange, M. Obersteiner, Michael Oppenheimer, W. Pepper, W. Sanderson, and M. Schlesinger, et al., 2006: Learning and Climate Change. Climate Policy, http://www.geosc.psu.edu/~kkeller/O%27Neill_cp_07.pdf, 6,
    [ Abstract ]

    Learning – i.e. the acquisition of new information that leads to changes in our assessment of uncertainty – plays a prominent role in the international climate policy debate. For example, the view that we should postpone actions until we know more continues to be influential. The latest work on learning and climate change includes new theoretical models, better informed simulations of how learning affects the optimal timing of emissions reductions, analyses of how new information could affect the prospects for reaching and maintaining political agreements and for adapting to climate change, and explorations of how learning could lead us astray rather than closer to the truth. Despite the diversity of this new work, a clear consensus on a central point is that the prospect of learning does not support the postponement of emissions reductions today.

23. Oppenheimer, Michael, 2006: Science and Environmental Policy: The Role of Nongovernmental Organizations. Social Research, http://findarticles.com/p/articles/mi_m2267/is_3_73/ai_n27052540/,
    [ Abstract ]

    THIS PAPER ADDRESSES THE ROLE OF NONGOVERNMENTAL ORGANIZATIONS, or NGOs, in the science-policy nexus. I shall draw on my 21 years of experience working for a nongovernmental organization, Environmental Defense, my earlier experience as a research scientist, and my recent experience as a professor, the latter two positions at large universities. I hope this quasi-anecdotal approach is informative, but in addition, it is a necessity because there have been relatively few academic studies of nongovernmental advocacy organizations.

24. Donner, S. D., W. J. Skirving, C. M. Little, Michael Oppenheimer, and O. Hoegh-Guldberg, 2005: Global assessment of coral bleaching and required rates of adaptation under climate change. Global Change Biology, 11(12), doi:10.1111/j.1365-2486.2005.01073.x 2251-2265
    [ Abstract ]

    Elevated ocean temperatures can cause coral bleaching, the loss of colour from reefbuilding corals because of a breakdown of the symbiosis with the dinoflagellate Symbiodinium. Recent studies have warned that global climate change could increase the frequency of coral bleaching and threaten the long-term viability of coral reefs. These assertions are based on projecting the coarse output from atmosphere–ocean general circulation models (GCMs) to the local conditions around representative coral reefs. Here, we conduct the first comprehensive global assessment of coral bleaching under climate change by adapting the NOAA Coral ReefWatch bleaching prediction method to the output of a low- and high-climate sensitivity GCM. First, we develop and test algorithms for predicting mass coral bleaching with GCM-resolution sea surface temperatures for thousands of coral reefs, using a global coral reef map and 1985–2002 bleaching prediction data. We then use the algorithms to determine the frequency of coral bleaching and required thermal adaptation by corals and their endosymbionts under two different emissions scenarios. The results indicate that bleaching could become an annual or biannual event for the vast majority of the world’s coral reefs in the next 30–50 years without an increase in thermal tolerance of 0.2 – 1.0°C per decade. The geographic variability in required thermal adaptation found in each model and emissions scenario suggests that coral reefs in some regions, like Micronesia and western Polynesia, may be particularly vulnerable to climate change. Advances in modelling and monitoring will refine the forecast for individual reefs, but this assessment concludes that the global prognosis is unlikely to change without an accelerated effort to stabilize atmospheric greenhouse gas concentrations.

25. Keller, Klaus, M. G. Hall, S.-R. Kim, David F. Bradford, and Michael Oppenheimer, 2005: Avoiding dangerous anthropogenic interference with the climate system. Climatic Change, 73(3), doi:10.1007/s10584-005-0426-8 227-238
    [ Abstract ]

    The UN Framework Convention on Climate Change calls for the avoidance of “dangerous anthropogenic interference with the climate system”. Among the many plausible choices, dangerous interference with the climate system may be interpreted as anthropogenic radiative forcing causing distinct and widespread climate change impacts such as a widespread demise of coral reefs or a disintegration of the West Antarctic ice sheet. The geological record and numerical models suggest that limiting global warming below critical temperature thresholds significantly reduces the likelihood of these eventualities. Here we analyze economically optimal policies that may ensure this risk-reduction. Reducing the risk of a widespread coral reef demise implies drastic reductions in greenhouse gas emissions within decades. Virtually unchecked greenhouse gas emissions to date (combined with the inertia of the coupled natural and human systems) may have already committed future societies to a widespread demise of coral reefs. Policies to reduce the risk of a West Antarctic ice sheet disintegration allow for a smoother decarbonization of the economy within a century and may well increase consumption in the long run.

26. Oppenheimer, Michael, and A. Petsonk, 2005: Article 2 of the UNFCCC: Historical Origins, Recent Interpretations. Climatic Change, 73(3), doi:10.1007/s10584-005-0434-8 195-226
    [ Abstract ]

    Article 2 of the UN Framework Convention on Climate Change (UNFCCC), which states the treaty’s long-term objective, is the subject of a growing literature that examines means to interpret and implement this provision. Here we provide context for these studies by exploring the intertwined scientific, legal, economic, and political history of Article 2. We review proposed definitions for “dangerous anthropogenic interference” and frameworks that have been proposed for implementing these definitions. Specific examples of dangerous climate changes suggest limits on global warming ranging from 1 to 4°C and on concentrations ranging from 450 to 700 ppm CO₂ equivalents. The implications of Article 2 for near term restrictions on greenhouse-gas emissions, e.g., the Kyoto Protocol, are also discussed.

27. Oppenheimer, Michael, and R. B. Alley, 2005: Ice Sheets, Global Warming, and Article 2 of the UNFCCC. Climatic Change, 68(3), doi:10.1007/s10584-005-5372-y 257-267
    [ Abstract ]

    Rapid disintegration of the West Antarctic ice sheet (WAIS) was cited decades ago as a potentially severe consequence of global warming (Mercer, 1968, 1978; Revelle, 1983) and climate scientists have cast a wary eye toward the cryosphere ever since. Total loss of the West Antarctic or Greenland ice sheet (GIS) would cause eustatic sea level rise of 4–6 m and 7 m, respectively. The stability of the much larger East Antarctic ice sheet (EAIS) is sometimes questioned but it is likely that the two other ice sheets would disintegrate with less warming. Initially, WAIS was the main focus of concern because as a marine ice sheet, it was thought by many to be inherently unstable (Oppenheimer, 1998). That WAIS has undergone a large reduction in area and perhaps in mass since the Last Glacial Maximum (Bindschadler, 1998; Huybrechts, 2002) provides evidence of its vulnerability to global temperature and sea level variations. In contrast, GIS is estimated to have shrunken by about 30% from its LGM volume (Fleming and Lambeck, 2004). Disintegration ofWAIS may provide a plausible example of “dangerous anthropogenic interference with the climate system” under Article 2 of theUNFramework Convention on Climate Change. In this context, two recent studies proposed specific temperatures and greenhouse gas concentrations (O’Neill and Oppenheimer, 2002, Oppenheimer and Alley, 2004) to be avoided. A key issue is the degree to which warming can affect the rate of ice loss by altering the mass balance between precipitation rates on the one hand, and melting and ice discharge to the ocean through ice streams on the other.

28. Oppenheimer, Michael, 2005: Defining Dangerous Anthropogenic Interference: The Role of Science, the Limits of Science. Workshop Perspectives on Dangerous Climate Change, Tyndall Centre, Norwich, UK, 25(6), doi:10.1111/j.1539-6924.2005.00687.x 1399-1407
    [ Abstract ]

    Defining "dangerous anthropogenic interference" with the climate system in the context of Article 2 of the UN Framework Convention on Climate Change (UNFCCC) presents a complex challenge for those developing long-term climate policy. Natural science has a key role to play in quantifying vulnerabilities of elements of the Earth system and estimating the risks from a changing climate. But attempts to interpret Article 2 will inevitably draw on understanding from social science, psychology, law, and ethics. Here I consider the limits of science in defining climate "danger" by focusing on the potential disintegration of the major ice sheets as an example of an extreme impact. I show that considerations of timescale, uncertainty, and learning preclude a definition of danger drawn purely from natural science. Decision makers will be particularly challenged by one characteristic of global problems: answers to some scientific questions become less accurate over decadal timescales, meandering toward the wrong answer, a feature I call negative learning. I argue for a precautionary approach to Article 2 that would be based initially on current, limited scientific understanding of the future of the ice sheets.

29. Doney, S. C., C. J. Kucharik, and Michael Oppenheimer, 2004: The Influence of Climate on In-stream Removal of Nitrogen. Geophysical Research Letters, 31(L20509), doi:10.1029/2004GL020477
    [ Abstract ]

    Nitrogen (N) removal via benthic denitrification in large river systems can be a significant sink of terrestrial N and a source of nitrous oxide (N₂O) to the atmosphere. Recent studies have demonstrated the fraction of in-stream N removed from a river reach is related to the water residence time. We used the HYDRA aquatic transport model to examine the sensitivity of in-stream N removal and the associated N₂O emissions in the Mississippi River system to the interannual variability in climate. The results suggested an almost two-fold range in the percent of N removed in the Mississippi River system and a three-fold range in the associated N₂O emissions, with the lowest percent removed (10–33%) and the highest N₂O emissions (15.5–26.0 106 kg N) occurring in the wettest years. The results demonstrate the importance of considering climate variability and change in the management of nutrient export by large rivers.

30. O'Neill, B., and Michael Oppenheimer, 2004: Climate Change Impacts Sensitive to Path to Stabilization. Proceedings of the National Academy of Sciences of the United States of America, 101, doi:10.1073/pnas.0405522101 16411-16416
    [ Abstract ]

    Analysis of policies to achieve the long-term objective of the United Nations Framework Convention on Climate Change, stabilizing concentrations of greenhouse gases at levels that avoid ‘‘dangerous’’ climate changes, must discriminate among the infinite number of emission and concentration trajectories that yield the same final concentration. Considerable attention has been devoted to path-dependent mitigation costs, generally for CO₂ alone, but not to the differential climate change impacts implied by alternative trajectories. Here, we derive pathways leading to stabilization of equivalent CO₂ concentration (including radiative forcing effects of all significant trace gases and aerosols) with a range of transient behavior before stabilization, including temporary overshoot of the final value. We compare resulting climate changes to the sensitivity of representative geophysical and ecological systems. Based on the limited available information, some physical and ecological systems appear to be quite sensitive to the details of the approach to stabilization. The likelihood of occurrence of impacts that might be considered dangerous increases under trajectories that delay emissions reduction or overshoot the final concentration.

31. Oppenheimer, Michael, and R. B. Alley, 2004: The West Antarctic Ice Sheet and Long Term Climate Policy. Climatic Change, 64(1-2), doi:10.1023/B:CLIM.0000024792.06802.31 1-10
    [ Abstract ]

    Disintegration of the West Antarctic ice sheet (WAIS) has long served as a benchmark of dangerous climate change (Mercer, 1968, 1978; Revelle, 1983; Smith et al., 2001). Recent findings with implications for the future of the West Antarctic ice sheet in a warming world (Rott et al., 2002; De Angelis and Skvarca, 2003) may be of importance to policy makers and others (Berk et al., 2002) grappling with the meaning of Article 2 of the U.N. Framework Convention on Climate Change and its injunction to avoid ‘dangerous anthropogenic interference with the climate system.’ These observations show acceleration of glaciers coupled to abrupt ice-shelf disintegration along the Antarctic Peninsula (Doake et al., 1998). The key issue is whether the main body of the ice sheet would behave similarly if its ice shelves were thinned or removed by a warming climate. The accompanying editorial essay by Dessai et al. (2004) argues ‘internal definitions of dangerous climate change –“danger as experienced” – warrants at least as much attention as external definitions – “danger as defined” ’. We agree that the interpretation of Article 2 ought to expand beyond traditional approaches grounded in climatology, biology, economics and engineering. The editorial further states ‘it is not possible to make progress on defining dangerous climate change, or in developing sustainable responses to this global problem, without recognising the central role played by social or individual perceptions of danger.’ There is a substantial risk in adopting the latter view. Addressing the psychological and much of the social dimension of dangerous climate change is in its infancy in comparison to the decades-old process of physical assessment. An equally prolonged discussion of the social and psychological dimension is in the offing. The continuing increase in greenhouse gas concentrations could make certain dangers unavoidable unless a preliminary interpretation of Article 2, based largely on the ‘external’ framework, is implemented (O’Neill and Oppenheimer, 2002). In practice, such an approach already may be feasible for a handful of climate changes, such as the ‘large-scale discontinuities’ (e.g. disintegration of WAIS, shutdown of the thermohaline circulation) noted in the Third Assessment Report of the Intergovernmental Panel on Climate Change (Smith et al., 2001). The recent glaciological findings provide an opportunity to consider how a long-term objective consistent with Article 2 might be selected, because they shed new light on the range of climate change that may trigger disintegration of WAIS. Here we explore the key scientific issues and consider a long-term approach to limiting greenhouse gas concentrations based upon these observations, tied to the viability of the major West Antarctic ice shelves.We believe the consequences of a WAIS collapse would be so large that despite uncertainties, external considerations supplemented by a precautionary interpretation of the recent observations may be sufficient to define dangerous levels of climate change, and the corresponding greenhouse gas (ghg) concentrations.

32. Oppenheimer, Michael, 2004: Book Review: The Discovery of Global Warming. Journal of Environmental History, 9, 327-328
    [ Abstract ]

    As a scientific problem, global warming has a history dating back at least to Fourier in 1827. Its origins as a political issue are much more recent, with serious discussions of limiting greenhouse gas emissions beginning among scientists and economists only in the middle of the 1970s when the prospect of warming vied on an equal footing with the possibility of future cooling of the planet. Policy makers came to the table a decade later. The evolution of the climate question from science to politics and back and forth has been the subject of surprisingly few in-depth treatments. This void leads to a damaging lack of perspective in the public debate. Without the context of history, assertions like "not long ago, the same scientists who now warn us of warming were alarmists over global cooling" or "global warming is a left wing plot hatched by anti-capitalist environmentalists" too often go unchallenged. Spencer Weart's The Discovery of Global Warming goes a long way toward rectifying this situation. Weart, director of the Center for the History of Physics at the American Institute of Physics, is most effective at laying out the early scientific developments, and discussing how scientists moved the issue onto governmental research agendas. He is somewhat less effective in describing political developments once the issue veered squarely into the policy arena. Weart highlights the importance of the actions of networks of scientists in constructing a bridge from science to policy on an arcane issue of no apparent urgency to the general public. He correctly points to the key leadership role of Swedish climatologist Bert Bolin in shepherding his colleagues toward consensus, beginning in the late 1960s. Weart's exploration of the science-policy interaction in the 1970s, which focused largely on increasing support for research, is thorough. His discussion of scientists' activity after the mid-1980s, which helped build the road to the U.N. Framework Convention on Climate Change and the Kyoto Protocol, is more superficial. One of the most useful features of this book is the timeline of events following the last chapter. Oddly, it ends at 1988 because "the period since 1988 is too recent to identify historical milestones." Perhaps this is a valid assertion from a historian's professional viewpoint. But the importance of some events, like the signing of the Framework Convention in 1992, is likely to endure. In contrast, the author is quite willing to highlight scientific questions, like the potential importance of warming-induced shifts in the major ocean circulation, whose significance also may not become clear for decades. But never mind these shortcomings. The clear value of this book to scholars, reporters, and the interested public will hopefully spawn additional efforts that will fill these gaps, and lead to a greater understanding of scientists as political actors. The Discovery of Global Warming has done us all a great favor by pointing the way.

33. Oppenheimer, Michael, September 2004: Reinvigorating the Kyoto System and Beyond: Maintaining the Fundamental Architecture, Meeting Long-Term Goals. Leaders’ Summit on Post-Kyoto Architecture: Toward an L20, http://www.princeton.edu/step/people/faculty/michael-oppenheimer/recent-publications/,
    [ Abstract ]

    While it is increasingly clear that anthropogenic emissions of greenhouse gases (GHGs) are causing potentially irreversible shifts in Earth's climate, efforts to craft a durable and effective architecture for addressing the problem remain stymied by deep divisions between north and south, between major emitting nations and those that will be most affected by global warming, between some nations that are heavily export-dependent on fossil fuels and the rest of the world. Even within governments, disagreements among different ministries with different mandates have stalled action. This delay is not without cost: every year that nations postpone action to reverse GHG emissions growth and bring forward a robust response, the time window for averting dangerous levels of climate change narrows. The L20 provides a potentially important forum that could offer much needed global leadership on innovative approaches for overcoming international divisions on this crucial challenge. In particular, L20 leaders' experience in strengthening the world's international financial architecture provides an important lens through which to view new approaches for the international market-based architecture to reduce GHG emissions. The following paper proposes, for L20 consideration, three approaches to rejuvenating the United Nations Framework Convention on Climate Change (UNFCCC) and its Kyoto process. We ground our argument in these integrated assumptions: The incentive-based architecture that was incorporated, if imperfectly, in the Kyoto Protocol provides an optimal basis to broaden participation and develop a viable long term approach to address climate change. Further, we assert that the Kyoto formulation of successive near-term (decade-scale) targets for limiting total emissions of greenhouse gases (GHGs) provides a necessary element for achieving the long-term goal of the UNFCCC (stated in its Article 2). Our analysis is motivated by three main objectives: 1) US participation, 2) developing country/non-Annex I participation,1 and 3) coupling near-term obligations of the Parties to an effective long-term strategy for limiting climate change.

34. Mann, M. E., C. M. Ammann, R. S. Bradley, K. R. Briffa, T. J. Crowley, M. K. Hughes, P. D. Jones, Michael Oppenheimer, T. J. Osborn, J. T. Overpeck, S. Rutherford, K. E. Trenberth, and T.M.L. Wigley, 2003: On past temperatures and anomalous late-20th century warmth. EOS Trans. AGU, 84, doi:10.1029/2003EO270003 256
    [ Abstract ]

    Evidence from paleoclimatic sources and modeling studies support AGU's official position statement on "Climate Change and Greenhouse Gases," that there is a compelling basis for concern over future climate changes, including increases in global-mean surface temperatures, due to increased concentrations of greenhouse gases, primarily from fossil-fuel burning. More specifically, a number of reconstructions of large-scale temperature changes over the past millennium support the conclusion that late-20th century warmth was unprecedented over at least the past millennium. Modeling and statistical studies indicate that such anomalous warmth cannot be fully explained by natural factors but, instead, require a significant anthropogenic forcing of climate that emerged during the 19th and 20th centuries.
    Two (nearly identical) recent papers [Soon and Baliunas, 2003 and Soon et al., 2003--henceforth both referred to as 'SB03'] challenge this view, and have been used to support the claim that recent hemispheric-scale warmth is not unprecedented in the context of the past millennium (see e.g. "20th Century Climate Not So Hot", press-release, Harvard-Smithsonian Center for Astrophysics, March 31, 2003: http://cfa-www.harvard.edu/press/pr0310.html). Such claims are inconsistent with the preponderance of scientific evidence. We therefore review these claims in the light of the fact that they have found their way into the media and have been read into the U.S. Senate record.

35. Oppenheimer, Michael, 2003: Atmospheric Pollution: History, Science, and Regulation. Physics Today, http://scitation.aip.org/getpdf/servlet/GetPDFServlet?filetype=p, 56, 65-66
    [ Abstract ]

    Scientific and political interest in atmospheric pollution, as well as attempts to regulate it, have expanded from local to regional to global scales over the three decades since the passage of the US Clean Air Act of 1970. Acid deposition, ozone depletion, regional-scale smog, and global warming – unknown or little understood before 1970 – are at the center of atmospheric research, domestic regulation, and international affairs. With regard to international affairs, witness the broad effect on US-European relations of the Bush administration’s rejection of the Kyoto Protocol on climate change.

36. Oppenheimer, Michael, and A. Petsonk, 2003: Global Warming: Formulating Long Term Goals. Climate Policy Beyond Kyoto: Meeting the Long Term Challenge of Global Warming, http://www.princeton.edu/~cmi/research/Policy/Papers/oppenheimer.pdf,
    [ Abstract ]

    In this paper we explore the origins and potential implementation of long term climate objectives and the particular concept of “dangerous anthropogenic interference with the climate system,” outlined in Article 2 of the Framework Convention. We show that the need for a long term perspective and also its specific framing in the form of Article 2 reflects views held on both sides of the Atlantic from the earliest days of the climate issue. We review the evolution of the concept of “dangerous” and the various proposals for implementing Article 2 as a regulatory regime. It is here that we find the greatest potential for transatlantic differences, arising from differing governmental views on risk and uncertainty. We argue that these potential differences need to be addressed quickly so that current conceptions of what constitutes “dangerous” can play a significant role in determining near term, as well as long-term, climate policy. That is, policy approaches that address “stabilization of concentrations” and those that address near term emissions limitations should be considered together.

37. O'Neill, B., and Michael Oppenheimer, 2002: Climate change - Dangerous climate impacts and the Kyoto protocol. Science, 296, doi:10.1126/science.1071238 1971-1972
    [ Abstract ]

    Defining a long-term goal for climate change policy remains a critical international challenge. Article 2 of the UN Framework Convention on Climate Change defines the long-term objective of that agreement as stabilization of greenhouse gas concentrations at a level that avoids “dangerous anthropogenic interference” with the climate system. “Dangerous interference” can be viewed from a variety of perspectives, and the choice will ultimately involve a mixture of scientific, economic, political, ethical, and cultural considerations, among others (1). In addition, the links among emissions, greenhouse gas concentrations, climate change, and impacts are uncertain. Furthermore, what might be considered dangerous could change over time. However, both proponents and detractors of the Kyoto Protocol, which was designed as an initial step to implement the Framework Convention, have begun to demand a definition of long-term objectives. For example, on 11 June 2001, U.S. President George W. Bush stated that the emissions targets embodied in the Kyoto Protocol “were arbitrary and not based upon science” and “no one can say with any certainty what constitutes a dangerous level of warming, and therefore what level must be avoided.” Here, we propose several plausible interpretations of dangerous interference in terms of particular environmental outcomes (2) and examine the consistency between the Kyoto Protocol and emissions changes over time that would avoid these outcomes. Although the emissions limits required by the Kyoto Protocol would reduce warming only marginally (3), we show that the accord provides a first step that may be necessary for avoiding dangerous interference.

38. Oppenheimer, Michael, 2002: Book Review - Jeremy Leffett, The Carbon War: Global Warming and the End of the Oil Era. Climatic Change, 54(4), doi:10.1023/A:1016135402292 497-505
    [ Abstract ]

    Jeremy Leggett: 2000, The Carbon War: Global Warming and the End of the Oil Era, Penguin Books, 342 pp., ISBN 0-14-028494-X
    With the U.S. government rejecting further consideration of the Kyoto Protocol and the EU and other countries moving toward its ratification, it is far too early to write the definitive political history of the global warming problem. The public policy issue named Global Warming or Climate Change has many moving parts, with each at a different stage of development. Much is known about the geophysical and technological aspects of the issue and rather less about its biological and economic implications. Tomes have been written on each aspect, most notably the reports of the Intergovernmental Panel on Climate Change (IPCC).
    However, on the political and diplomatic aspects of the issue, the literature, as voluminous as it is, leaves much to be desired. There are lots of questions and not enough credible answers. Is the UN Framework Convention on Climate Change a noble but ultimately toothless statement of purpose or a set of visionary principles? Is the Kyoto Protocol the first step on a long road or a time-consuming detour? Are the European countries heroes or hypocrites for savaging the U.S.’s demurral on Kyoto? What about the myriad technologies, policies, and mechanisms for abating greenhouse gases and their consequences, including emission taxes, emission trading, solar energy, nuclear energy, energy efficiency, sinks, geo-engineering, natural gas, and so on? What will work outside the think tanks in the real world of politics and people? Most important of all, when, if ever, will the developing countries agree to emissions limitation?
    Have you been hammering your head against the wall on one side of this issue or another for longer than you care to remember? Have you had enough of the details? Do you want to relax with a good book? Allow me to recommend The Carbon War by Jeremy Leggett. Dr. Leggett, former oil geologist and former Greenpeace campaigner, is currently a solar energy entrepreneur. Leggett had a bright idea. By proselytizing insurance companies and other firms in the financial sector about the damage to insured property in a progressively less-predictable and potentially more-violent climate, he would try to convince them to lobby in favor of greenhouse gas reductions while altering their investment portfolios to favor solar energy. The Carbon War is a diary of those efforts. As in most interesting stories, there

39. Oppenheimer, Michael, et al., 2001: Technical Summary and Summary for Policy Makers. Climate Change 2001: The Science of Climate Change. 3rd Assessment Report of the IPCC, Cambridge University Press,
    [ Abstract ]

    Climate Change 2001: The Scientific Basis is the most comprehensive and up-to-date scientific assessment of past, present and future climate change. The report:
    • Analyses an enormous body of observations of all parts of the climate system. • Catalogues increasing concentrations of atmospheric greenhouse gases. • Assesses our understanding of the processes and feedbacks which govern the climate system. • Projects scenarios of future climate change using a wide range of models of future emissions of greenhouse gases and aerosols. • Makes a detailed study of whether a human influence on climate can be identified. • Suggests gaps in information and understanding that remain in our knowledge of climate change and how these might be addressed. Simply put, this latest assessment of the IPCC will again form the standard scientific reference for all those concerned with climate change and its consequences, including students and researchers in environmental science, meteorology, climatology, biology, ecology and atmospheric chemistry, and policymakers in governments and industry worldwide. J.T.

Direct link to page: http://cmi.princeton.edu/bibliography/results.php?author=3474