JP

Climatology and Trends in the Forcing of the Stratospheric Zonal-Mean Flow

The momentum budget of the Transformed Eulerian-Mean (TEM) equation is calculated using the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis (ERA-40) and the National Centers for Environmental Prediction (NCEP) Reanalysis 2 (R-2). This study outlines the considerable contribution of unresolved waves, deduced to be gravity waves, to the forcing of the zonal-mean flow. A trend analysis, from 1980 to 2001, shows that the onset and break down of the Northern Hemisphere (NH) stratospheric polar night jet has a tendency to occur later in the season in the more recent years. This temporal shift follows long-term changes in planetary wave activity that are mainly due to synoptic waves, with a lag of one month. In the Southern Hemisphere (SH), the polar vortex shows a tendency to persist further into the SH summertime. This also follows a statistically significant decrease in the intensity of the stationary EP flux divergence over the 1980–2001 period. Ozone depletion is well known for strengthening the polar vortex through the thermal wind balance. However, the results of this work show that the SH polar vortex does not experience any significant long-term changes until the month of December, even though the intensification of the ozone hole occurs mainly between September and November. This study suggests that the decrease in planetary wave activity in November provides an important feedback to the zonal wind as it delays the breakdown of the polar vortex. In addition, the absence of strong eddy feedback before November explains the lack of significant trends in the polar vortex in the SH early spring. A long-term weakening in the Brewer-Dobson (B-D) circulation in the polar region is identified in the NH winter and early spring and during the SH late spring and is likely driven by the decrease in planetary wave activity previously mentioned. During the rest of the year, there are large discrepancies in the representation of the B-D circulation and the unresolved waves between the two reanalyses, making trend analyses unreliable.

Climatology and Trends in the Forcing of the Stratospheric Zonal-Mean Flow

The momentum budget of the Transformed Eulerian-Mean (TEM) equation is calculated using the European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-40). This study outlines the considerable contribution of the dissipative forcing, identified as a gravity wave drag, to the forcing of the zonal-mean flow. A trend analysis shows that, in recent times, the onset and break down of the Northern Hemisphere (NH) stratospheric polar night jet occur later. This temporal shift is associated with long-term changes in the planetary wave activity that are mainly due to synoptic waves. In the Southern Hemisphere (SH), the polar vortex shows a tendency to persist further into the SH summertime. This is explained by a statistically significant decrease in the intensity of the stationary EP flux divergence over the 1980-2001 period. The prevailing theory explaining the long-term changes in the stratospheric polar vortex postulates that ozone depletion leads to a strengthening of westerly winds which in turn causes the reduction in wave activity in high latitudes. We show that the strongest component in the dynamical response to stratospheric ozone changes is in fact the feedback of planetary wave activity on the zonal wind. Finally, we identify long-term changes in the Brewer-Dobson circulation that are mainly caused by trends in the planetary wave activity during winter and by trends in the gravity wave body force otherwise.

CO2 Abatement by Multi-fueled Electric Utilities: An Analysis Based on Japanese Data

Multi-fueled electric utilities are commonly seen as offering relatively greater opportunities for reasonably priced carbon abatement through changes in the dispatch of generating units from capacity using high emission fuels, coal or oil, to capacity using lower emitting fuels, natural gas (LNG) or nuclear. This paper examines the potential for such abatement using Japanese electric utilities as an example. We show that the potential for abatement through re-dispatch is determined chiefly by the amount of unused capacity combining low emissions and low operating cost, which is typically not great. Considerably more abatement potential lies in changing planned, base load, fossil-fuel fired capacity additions to nuclear capacity. Our results are at odds with the common view that the demand for natural gas or LNG would increase, or at least not fall, as the result of a carbon constraint; and our analysis suggests that this result may not be limited to Japan.

CO2 emissions from world passenger transport: Reduction options

Today, passenger transport worldwide is responsible for almost 15% of anthropogenic energy-related emissions of carbon dioxide (CO2), the most abundant greenhouse gas. If the strong forces that generate travel demand and concomitant greenhouse gas emissions continue, world passenger traffic volume may rise more than fourfold over the 1990 level by 2050. During the same period, carbon dioxide emissions due to passenger transport are expected to multiply by a factor of more than 3, ultimately accounting for 2.7 billion tons of carbon in 2050. Based on these projections, the present study evaluates a range of emission-reduction options. Among these, technological measures offer the greatest potential and are key to drastically reducing carbon dioxide emissions. Radical fuel efficiency improvements in the world's automobile fleet--along with continuations of past trends in the energy intensity of other passenger transport modes--could curtail the projected 2050 baseline emissions level by about 40%. Simultaneous substitution of oil products by natural gas could reduce CO2 emissions by another 25% and ultimately lead to emission stabilization at 1.2 billion tons of carbon in 2050; any further significant reduction in CO2 emissions would require the large-scale introduction of zero-carbon fuels. Although the CO2-reduction potential of transportation systems management measures is comparatively limited, such measures are needed to abate other transport sector externalities such as accidents, noise, and traffic congestion.

Copyright © 2008. National Academy of Sciences

CO2 emissions limits: Economic adjustments and the distribution of burdens

Policies under consideration within the Climate Convention would impose CO2 controls on only a subset of nations. A model of economic growth and emissions, coupled to an analysis of the climate system, is used to explore the consequences of a sample proposal of this type. The results show how economic burdens are likely to be distributed among nations, how carbon "leakage" may counteract the reductions attained, and how policy costs may be influenced by emissions trading. We explore the sensitivity of results to uncertainty in key underlying assumptions, including the influence on economic impacts and on the policy contribution to long-term climate goals. © IAEE, 1997

CO2 Emissions Limits: Economic Adjustments and the Distribution of Burdens

Policies under consideration within the Climate Convention would impose CO2 controls on only a subset of nations. A model of economic growth and emissions, coupled to an analysis of the climate system, is used to explore the consequences of a sample proposal of this type. The results show how economic burdens are likely to be distributed among nations, how carbon "leakage" may counteract the reductions attained, and how policy costs may be influenced by emissions trading. We explore the sensitivity of results to uncertainty in key underlying assumptions, including the influence on economic impacts and on the policy contribution to long-term climate goals.

CO2 Mitigation Costs for Canada and the Alberta Oil Sands

The threat of climate change proposes difficult problems for regulators and decision-makers in terms of uncertainties, varying exposures to risks and different attitudes towards risk among nations. Impact and cost assessments aim to alleviate some of these difficulties by attempting to treat the costs of inaction, regulation and adaptation. For such assessments to be relevant, they must deal with regions individually to estimate costs associated with different regulations since across regions the impacts from climate change and climate change regulation are heterogeneous. Canada, and her oil sands industry, is the focus of this CO2 mitigation cost and climate change impacts study. Two Canadian policies, in line with the stated goals of the two largest Canadian political parties, have been modeled using MIT’s Emission Prediction and Policy Analysis tool to better understand the costs of the policies and the emission reductions that they will achieve. Welfare losses reaching 3.3% (in 2050) for the goals outlined in the Canadian government’s “Climate Action Plan” and 8.3% (in 2050) for the goal to meet Kyoto and post-Kyoto targets put forward by the opposition are predicted by the model. Oil sands upgrading/refining experiences severe carbon leakage while Oil Sands production is more resilient and may present less regulatory risk for investment. Gasification to produce natural gas substitutes could potentially be undermined by strict CO2 policy unless optimistic carbon capture technology emerges. The results are highly dependent on whether an international carbon trading regime exists and whether bio-fuels emerge as a large scale, affordable, alternative to fossil fuels. The results are also dependent, to a lesser extent, on international CO2 policy.

Coastal Communities and Climate Change: A Dynamic Model of Risk Perception, Storms, and Adaptation

Climate change impacts, including sea-level rise and changes in tropical storm frequency and intensity, will pose significant challenges to city planners and coastal zone managers trying to make wise investment and protection decisions. Meanwhile, policymakers are working to mitigate impacts by regulating greenhouse gas emissions. To design effective policies, policymakers need more accurate information than is currently available to understand how coastal communities will be affected by climate change.

My research aims to improve coastal impact and adaptation assessments, which inform climate and adaptation policies. I relax previous assumptions of probabilistic annual storm damage and rational economic expectations—variables in previous studies that are suspect, given the stochastic nature of storm events and the real-world behavior of people. I develop a dynamic stochastic adaptation model that includes explicit storm events and boundedly rational storm perception. I also include endogenous economic growth, population growth, public adaptation measures, and relative sea-level rise.

The frequency and intensity of stochastic storm events can change a region’s long-term economic growth pattern and introduce the possibility of community decline. Previous studies using likely annual storm damage are unable to show this result.

Additionally, I consider three decision makers (coastal managers, infrastructure investors, and residents) who differ regarding their perception of storm risk. The decision makers' perception of risk varies depending on their rationality assumptions. Boundedly rational investors and residents perceive storm risk to be higher immediately after a storm event, which can drive down investment, decrease economic growth, and increase economic recovery time, proving that previous studies provide overly optimistic economic predictions. Rationality assumptions are shown to change economic growth and recovery time estimates.

Including stochastic storms and variable rationality assumptions will improve adaptation research and, therefore, coastal adaptation and climate change policies.

Combined Effects of Anthropogenic Emissions and Resultant Climatic Changes on Atmospheric OH

Using a coupled global atmospheric chemistry and climate model we have predicted the evolution of tropospheric concentrations of chemical species along with climate parameters, based on a set of economic model predictions for anthropogenic emissions of chemically and radiatively important trace gases in the next 120 years. In particular, our predictions for tropospheric hydroxyl radical (OH) concentrations indicate the potential for substantial future changes affecting both atmospheric chemistry and climate. OH is arguably the most important free radical in the troposphere because it is the primary removal mechanism for most gases entering the atmosphere, and therefore, determines the lifetimes of these species. Our research indicates that if CH4 and CO emissions continually increase as expected through the next century, the tropospheric concentration of OH could decrease by as much as 29% from its current value. As a result, the lifetime of CO in the year 2100 is predicted to lengthen by 0.6 months beyond its current value of 2 months, and the CH4 lifetime in 2100 would exceed its current value (9 years) by 2.5 years in our reference case.

Combining a Renewable Portfolio Standard with a Cap-and-Trade Policy: A General Equilibrium Analysis

Many efforts to address greenhouse gas emissions combine a cap-and-trade system with other measures such as a renewable portfolio standard. In this paper we use a computable general equilibrium (CGE) model, the MIT Emissions Prediction and Policy Analysis (EPPA) model, to investigate the effects of combining these policies. We find that adding an RPS requiring 20 percent renewables by 2020 to a cap that reduces emissions by 80% below 1990 levels by 2050 increases the net present value welfare cost of meeting such a cap by 25 percent over the life of the policy, while reducing the CO2-equivalent price by about 20 percent each year.

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