assessment of the uncertainties

Abstract. A selection of the potential impacts of climate change – on agriculture, forestry, unmanaged ecosystems, sea level rise, human mortality, energy consumption, and water resources – are estimated and valued in monetary terms. Estimates are derived from globally comprehensive, internally consistent studies using GCM based scenarios. An underestimate of the uncertainty is given. New impact studies can be included following the meta-analytical methods described here. A 1 ◦C increase in the global mean surface air temperature would have, on balance, a positive effect on the OECD, China, and the Middle East, and a negative effect on other countries. Confidence intervals of regionally aggregated impacts, however, include both positive and negative impacts for all regions. Global estimates depend on the aggregation rule. Using a simple sum, world impact of a 1 ◦C warming would be a positive 2 % of GDP, with a standard deviation of 1%. Using globally averaged values, world impact would be a negative 3 % (standard deviation: 1%). Using equity weighting, world impact would amount to 0 % (standard deviation: 1%). Key words: adaptation, climate change, impacts

* We thank the late David Bradford for initiating a conversation that motivated this project. Our admiration for David’s brilliance as an economist was only exceeded by our admiration for him as a human being. We are grateful for especially valuable criticisms from Maximillian Auffhammer, David

Abstract. Cost-benefit analysis is only applicable if the variances of both costs and benefits are finite. In the case of climate change, the variances of the net present marginal costs and benefits of greenhouse gas emission reduction need to be finite. Finiteness is hard, if not impossible to prove. The opposite is easier to establish as one only needs to show that there is one, not impossible representation of the climate change with infinite variance. The paper shows that all relevant current variables of the FUND model have finite variances. However, there is a small chance that climate change reverses economic growth in some regions. In that case, the discount rate becomes negative and the net present marginal benefits of greenhouse gas emission reduction becomes very large. So large, that its variance is unbounded. One could interpret this as an indication that cost-benefit analysis is invalid. Alternatively, one could argue that the infinity is present in both the base case and the policy scenario, and therefore irrelevant; in that interpretation, cost-benefit analysis is a valid tool. 1.

Poorer countries are generally believed to be more vulnerable to climate change than richer countries because poorer countries are more exposed and have less adaptive capacity. This suggests that, in principle, there are two ways of reducing vulnerability to climate change: economic growth and greenhouse gas emission reduction. Using a complex climate change impact model, in which development is an important determinant of vulnerability, the hypothesis is tested whether development aid is more effective in reducing impacts than is emission abatement. The hypothesis is barely rejected for Asia but strongly accepted for Latin America and, particularly, Africa. The explanation for the difference is that development (aid) reduces vulnerabilities in some sectors (infectious diseases, water resources, agriculture) but increases vulnerabilities in others (cardiovascular diseases, energy consumption). However, climate change impacts are much higher in Latin America and Africa than in Asia, so that money spent on emission reduction for the sake of avoiding impacts in developing countries is better spent on vulnerability reduction in those countries. Key words climate change, climate change impacts, vulnerability, adaptive capacity, developmentEMISSION ABATEMENT VERSUS DEVELOPMENT AS STRATEGIES TO

This paper uses historical fluctuations in temperature within countries to identify its effects on aggregate economic outcomes. We find three primary results. First, higher temperatures substantially reduce economic growth in poor countries. Second, higher temperatures appear to reduce growth rates, not just the level of output. Third, higher temperatures have wide-ranging effects, reducing agricultural output, industrial output, and political stability. These findings inform debates over climate’s role in economic development and suggest the possibility of substantial negative impacts of higher temperatures on poor countries.

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Why economic dynamics matter in assessing climate change damages: illustration on extreme events Stephane Hallegatte a;b, Jean-Charles Hourcade c,

The user of the Vocational Interest Survey (VIS) has available a number of interpretative approaches at various descriptive and qualitative levels. This report provides a brief outline of the various approaches. Whenever all six scales of the VIS are administered, the client's total score on all six scales should be within the average range. The average total score is 54. Fifty percent of all clients range from 26 to 72. The clients ' highest scores determine their resemblance to one of the six vocational types. People who resemble many vocational types are labeled as undifferentiated or poorly defined; the average level of differentiation in a sample of 206 high school students was 58. The level of consistency refers to the compatibility between a person's highest interests. Compatibility is measured by the distance between the vocational types of interest on a hexagonal typology of interests

A technology protocol to govern long-term international greenhouse gas emission reduction is proposed. The protocol consists of three parameters: a graduation income, below which countries have no emission reduction obligations; a convergence rate, at which emission intensities should approach that of the most carbon-extensive countries; and an acceleration rate, at the which the most carbon-extensive countries should improve its technology over and above the business as usual scenario. Depending on the parameter values, emission reduction ranges from draconian to almost nil. The graduation income and acceleration rate have the expected effects. The effect of the convergence rate is strongly scenario-dependent; some scenarios, perhaps unrealistically assume strong technological convergence in the no policy case; in other scenarios, adopting best commercial technology in the whole world would lead to substantial emission reduction. Not surprisingly, regions prefer different parameters in the technology protocol. Adopting the opinion of the median voter, atmospheric concentrations of carbon dioxide in the year 2200 would be reduced from 1650 ppm to 950 ppm. This reduction is relatively robust to changes in crucial model parameters. The costs of complying to the technology protocol can be reduced substantially through international trade in emission permits and, particularly, banking and borrowing. Key Words climate change, international climate policy, technology, integrated assessment JEL Classification