Can natural disasters have positive consequences? Investigating the role of embodied technical change

It has been suggested that disasters might have positive economic consequences, through the accelerated replacement of capital. This possibility is referred to as the productivity effect. This effect is investigated using a model with embodied technical change. In this framework, disasters can influence the production level but cannot influence the growth rate, in the same way than the saving ratio in a Solow-like model. Depending on reconstruction quality, indeed, accounting for embodied technical change can either decrease or increase disaster costs, but is never able to turn disasters into positive events. Moreover, a better but slower reconstruction amplifies the short-term consequences of disasters, but pays off over the long-term. Regardless, the productivity effect cannot prevent the existence of a bifurcation when disaster damages exceed the reconstruction capacity, potentially leading to poverty traps.     

GHG Targets as Insurance Against Catastrophic Climate Damages

The climate system is an angry beast and we are poking it with sticks 1 . A critical issue in climate change economics is the specification of the so‐called “damages function” and its interaction with the unknown uncertainty of catastrophic outcomes. This paper asks how much we might be misled by our economic assessment of climate change when we employ a conventional quadratic damages function and/or a thin‐tailed probability distribution for extreme temperatures. The paper gives some numerical examples of the indirect value of various greenhouse gas (GHG) concentration targets as insurance against catastrophic climate change temperatures and damages. These numerical exercises suggest that we might be underestimating considerably the welfare losses from uncertainty by using a quadratic damages function and/or a thin‐tailed temperature distribution. In these examples, the primary reason for keeping GHG levels down is to insure against high‐temperature catastrophic climate risks.     

Climate change and economic growth: An intertemporal general equilibrium analysis for Egypt

This study advances the state of the art in country-level computable general equilibrium analysis for climate change impact and adaptation analysis by incorporating forward-looking expectations. The analytic framework is used to explore the long-run growth prospects for Egypt in a changing climate. Based on a review of existing estimates of climate change impacts on agricultural productivity, labour productivity and the potential losses due to sea-level rise for the country, the model is used to simulate the effects of climate change on aggregate consumption, investment and income up to 2050. Available cost estimates for adaptation investments are employed to explore adaptation strategies.The simulation analysis suggests that in the absence of policy-led adaptation investments, real GDP towards the middle of the century will be 6.5% lower than in a hypothetical baseline without climate change. A combination of adaptation measures, that include coastal protection investments for vulnerable sections along the low-lying Nile delta, support for changes in crop management practices and investments to raise irrigation efficiency, could reduce the GDP loss in 2050 to around 2.6%.Further work along these lines for developing countries in climate change hotspot regions deserves a high priority on the research agenda in economic modelling.     

中国技术贸易与经济增长关系研究

第二次世界大战后,国际技术贸易开始形成规模并迅速扩大,已经成为推动各国乃至世界经济发展的助推器。本文从中国技术贸易与经济发展的现状出发,运用协整与误差修正模型对1985～2020年中国技术贸易与经济增长的长期均衡与短期调整关系进行了实证分析。研究认为,技术贸易收支比对GDP增速在短期和长期均有负向影响,但长期影响比短期影响大；技术贸易收支比对GDP增速之间具有短期反向调整机制,但调整力度较小。     

Economic Policy in the Face of Severe Tail Events

From time to time, something occurs which is outside the range of normal expectations. We will call these “tail events” in the sense that they are way out of the tail of a probability distribution. I consider the question of the implications of tail events for economic policy and climate‐change economics. This issue has been analyzed by Martin Weitzman who proposed a Dismal Theorem. The general idea is that, under limited conditions concerning the structure of uncertainty and risk aversion, society has an indefinitely large expected loss from high‐consequence, low‐probability events. Under such conditions, standard economic tools such as cost‐benefit analysis cannot be applied. The present study is intended to put the Dismal Theorem in context and examine the range of its relevance, with an application to catastrophic climate change. I conclude that tail events are sometimes of extreme importance, and we must be extremely careful to include them in situations of deep uncertainty. However, we conclude that no loaded gun of strong tail dominance has been uncovered to date.     

Climate Policy Under Uncertain and Heterogeneous Climate Damages

We highlight that uncertainty about climate damages and the fact that damages will be distributed heterogeneously across the global population can jointly be an argument for substantially stricter climate policy even if uncertainty and heterogeneity in isolation are not. The reason is that a given climate risk borne by fewer people implies greater welfare losses. However, these losses turn out to be significant only if society is both risk and inequality averse and if climate damages are highly heterogeneous. We discuss how insurance and self-insurance of climate risk could theoretically mitigate this joint effect of uncertainty and heterogeneity and thus admit weaker climate policy. Insurance provides more efficient risk sharing and self-insurance allows strongly impacted individuals to compensate damages by increasing savings. We first use a simple analytical model to introduce the different concepts and then provide more realistic results from the integrated assessment model DICE.     

A two-dimensional non-equilibrium dynamic model

This paper develops a non-equilibrium dynamic model (NEDyM) with Keynesian features (it allows for a disequilibrium between output and demand and it considers a constant marginal propensity to consume), but where production is undertaken under plain neoclassical conditions (a constant returns to scale production function, with the stocks of capital and labor fully employed, is assumed). The model involves only two endogenous/prognostic variables: the stock of physical capital per unit of labor and a measure of market disequilibrium (MMD). The two-dimensional system allows for a careful analysis of local and global dynamics. Points of bifurcation and long-term cyclical motion are identified. The main conclusion is that the disequilibrium hypothesis leads to persistent fluctuations generated by intrinsic deterministic factors. These fluctuations may reflect some of the features frequently encountered in observed business cycles, once the model is conveniently adapted to this purpose.     

Dynamic modelling of water demand, water availability and adaptation strategies for power plants to global change

According to the latest IPCC reports, the frequency of hot and dry periods will increase in many regions of the world in the future. For power plant operators, the increasing possibility of water shortages is an important challenge that they have to face. Shortages of electricity due to water shortages could have an influence on industries as well as on private households. Climate change impact analyses must analyse the climate effects on power plants and possible adaptation strategies for the power generation sector. Power plants have lifetimes of several decades. Their water demand changes with climate parameters in the short- and medium-term. In the long-term, the water demand will change as old units are phased out and new generating units appear in their place.In this paper, we describe the integration of functions for the calculation of the water demand of power plants into a water resources management model. Also included are both short-term reactive and long-term planned adaptation. This integration allows us to simulate the interconnection between the water demand of power plants and water resources management, i.e. water availability. Economic evaluation functions for water shortages are also integrated into the water resources management model. This coupled model enables us to analyse scenarios of socio-economic and climate change, as well as the effects of water management actions.     

A stable climate or economic growth?

The 2015 UN Paris Agreement reinforced and declared compatible the two goals of avoiding dire climate change and maintaining global economic growth, and it specified that technological innovation is ‘critical’ to this joint achievement. Unfortunately, any confidence that near-term global economic growth is consistent with a stabilized climate is severely undermined by empirical evidence. Despite the rapid increase of alternative energies in recent decades, global GDP growth continues to require burning greater quantities of climate-destabilizing fossil fuels. The dim outlook for sufficiently reducing CO₂ while maintaining economic growth is underscored by global data and Germany specific data on the decoupling of GDP from CO₂. This paper summarizes pertinent climate science, substantiates the dependence of economic growth on fossil fuels, and uses the Kaya identity to demonstrate the unfavorable prospects for reducing CO₂ while maintaining GDP growth.     

Climate and happiness

Climate is an important input to many human activities. Climate affects heating and cooling requirements, health, clothing and nutritional needs as well as recreational activities. As such, it is to be expected that individuals will have a preference for particular types of climate. This paper analyses a panel of 67 countries attempting to explain differences in self-reported levels of happiness by reference to, amongst other things, temperature and precipitation. Various indices are used for each of these variables, including means, extremes and the number of hot, cold, wet and dry months. Using a panel-corrected least squares approach, the paper demonstrates that, even when controlling for a range of other factors, climate variables have a highly significant effect on country-wide self-reported levels of happiness. On the basis of these results, it is determined that differential patterns of anthropogenically induced climate change might alter dramatically the distribution of happiness between nations, with some countries moving towards a preferred climate and others moving further away. We find that high-latitude countries included in our dataset might benefit from temperature changes. Countries already characterized by very high summer temperatures would most likely suffer losses from climate change.     

Making sense of Brexit losses: An in-depth review of macroeconomic studies

Almost all economic assessments of Brexit conclude that there would be significant losses for both the UK and the EU. This paper examines the driving forces behind these results. We consider the strong economic relationships between the UK and EU both at the sectoral and macroeconomic levels that are at risk from Brexit. We review fifteen studies that explore various Brexit scenarios (hard and soft) and explain why their different methodologies and assumptions yield different degrees of economic damage. Our review concludes that GDP losses for the UK from a hard Brexit range from 1.6% to 7.8%, while a soft Brexit would moderate the losses by roughly half. We also find that potential UK trade agreements with third countries could partially compensate for significant Brexit losses.     

The Fatter the Tail, the Fatter the Climate Agreement

International climate negotiations take place in a setting where uncertainties regarding the impacts of climate change are very large. In this paper, we examine the influence of increasing the probability and impact of large climate change damages, also known as the ‘fat tail’, on the formation of an international mitigation agreement. We systematically vary the shape and location of the distribution of climate change damages using the stochastic version of the applied game-theoretical STACO model. Our aim is to identify how changes to the distributional form affect the stability of coalitions and their performance. We find that fatter upper tails increase the likelihood that more ambitious coalitions are stable as well as the performance of these stable coalitions. Fatter tails thus imply more successful, or ‘fatter’, international climate agreements.     

Optimal climate and fiscal policy in an OLG economy

This paper develops a climate–economy model to study the joint design of optimal climate and fiscal policies in economies with overlapping generations (OLGs). I demonstrate how capital taxation, if optimal, drives a wedge between the market costs of carbon (the net present value of marginal damages using the market interest rate) and the Pigouvian tax (the net present value of marginal damages using the consumption discount rate of successive OLGs). In contrast to deterministic infinitely lived representative agent models, at the optimum, the capital income tax is positive, the carbon price equals the market costs of carbon but it falls short of the Pigouvian tax when (i) preferences are not separable over consumption and leisure; and (ii) labor income taxes cannot be age-dependent. I also show that restrictions on climate change policy provide a novel rationale for positive capital income taxes.     

The economic costs to fisheries because of marine sand mining in Ongjin Korea: Concepts, methods, and illustrative results

We illustrate a methodology for estimating the damages to commercial fisheries from entrainment and from temporary loss of seafloor habitat productivity because of marine sand mining. A Beverton-Holt, year-class model is used to estimate illustrative short-term, long-term, and indirect (food web) effects from the inception of mining through the time to recovery of the injured resource stocks. A Base Case analysis evaluates hypothetical mining for a 4 km² mining site with biological recovery of the mined area beginning seven months after mining ceases and the bottom excavation fills in. Sensitivity analyses also are used to illustrate damages for alternative recovery paths and for 20 hypothetical mining sites for one year of mining and for recurring mining for 5 and for 10 years. Important qualifications and directions for further research are outlined.     

Climate Change and Adaptation: The Case of Nigerian Agriculture

The present research offers an economic assessment of climate change impacts on the four major crop families characterizing Nigerian agriculture. The evaluation is performed by shocking land productivity in a computable general equilibrium model tailored to replicate Nigerian economic development up to 2050. The detail of land uses in the model has been increased by differentiating land types per agro-ecological zones. Uncertainty about future climate is captured, using, as inputs, yield changes computed by a crop model under ten general circulation models runs. Climate change turns out to be negative for Nigeria in the medium term, with production losses and increase in crop prices, higher food dependency on foreign imports, and GDP losses in all the simulations after 2025. In a second part of the paper, a cost effectiveness analysis of adaptation in Nigerian agriculture is conducted. The adaptation practices considered are a mix of cheaper “soft measures” and more costly “hard” irrigation expansion. The main result is that the cost effectiveness of the whole package depends crucially on the possibility of implementing adaptation by exploiting low-cost opportunities which show a benefit-cost ratio larger than one in all the climate regimes.     

Exchanging Goods and Damages: The Role of Trade on the Distribution of Climate Change Costs

The impacts of climate change vary significantly across world regions. Whereas tropical and subtropical regions are expected to suffer severely from the effects of climate change, the impacts in northern latitudes should remain relatively moderate. However, regions are not self-sufficient, and the costs of climate change can spread across regions through international trade. I study the international spillover of climate impacts within a regionalised, climate-sensitive, dynamic computable general equilibrium model of the world economy. Using data from a global climate model shows that the world regions face welfare losses between 0.6 and 2.1 % due to climate change. I also show that climate change affects terms of trade and sectoral competitiveness. By means of a decomposition method, the extent of spillover impacts through international trade can be identified. Spillover impacts significantly affect, either positively or negatively, the total costs of climate change for a region. For regions with low exposure to climate change and high adaptive capacities, spillover effects are responsible for a 1/6 of the total cost of climate change.     

Beyond the Stern Review: Lessons from a risky venture at the limits of the cost-benefit analysis

This paper argues that debates amongst economists triggered by the Stern Review are partly relevant, focusing on key parameters translating real ethical issues, and partly misplaced in that they do not consider enough other determinants of climate change damages: i) the specifications of the utility function used for the assessments (preference for the environment, preference for smooth growth paths), ii) the interplay between uncertainty and the sequentiality of the decision, and iii) whether the growth engines behind the integrated assessment models can account for transient disequilibrium and sub-optimality. We derive some suggestions for any future research agenda in integrated assessment modelling, whatever the position of the analysts about the relevance of the intertemporal optimisation framework and the Bayesian approach to uncertainty in the climate affair.     

Global warming and livestock husbandry in Kenya: Impacts and adaptations

This paper examines the economic impact of climate change on livestock production in Kenya. We estimate a Ricardian model of net livestock incomes and further estimate the marginal impacts of climate change. We also simulate the impact of different climate scenarios on livestock incomes. The Ricardian results show that livestock production in Kenya is highly sensitive to climate change and that there is a non-linear relationship between climate change and livestock productivity. The estimated marginal impacts suggest modest gains from rising temperatures and losses from increased precipitation. The predictions from atmospheric ocean general circulation models suggest that livestock farmers in Kenya are likely to incur heavy losses from global warming. The highest and lowest losses are predicted from the Hadley Centre Coupled model (HADCM) and Parallel Climate Model (PCM) respectively, based on the Intergovernmental Panel on Climate Change A2 Special Report on Emissions Scenarios. The paper concludes that in the long term, climate change is likely to lead to increased poverty, vulnerability and loss of livelihoods. Several policy interventions are recommended to counter this impact.     

What if people value nature? Climate change and welfare costs

We introduce temperature shocks and preferences for environmental quality in a real business cycle model with natural resources. Temperature anomalies are transmitted to the business cycles via their negative effects on output and agents’ utility. Our findings suggest that permanent and temporary weather shocks propagation and their welfare implications depend crucially on whether agents value environmental quality. A permanent increase in temperature reduces output with damages reaching up to 1.61% of GDP. Agents who value environmental quality experience a higher temporary welfare gain when facing a negative weather shock, but welfare drops faster as the economy returns to equilibrium. Temperature anomalies amplify the (negative) effect of climate change on natural resources use and welfare.     

我国GDP形成中供给和需求因素作用的比较分析

实际GDP的形成是社会累积供给和累积累求平衡后实现的，是累积供给因素和累积需求因素短边效果的体现。我们选取工业生产增加值代表经济的供给成分，选取社会消费品零售总额代表经济的消费需求成分，比较它们同实际GDP之间的长期均衡关系和短期波动模式。通过使用协整检验和误差修正模型，我们发现，从供给和需求角度量实际GDP，它们具有类似的长期趋势，但它们在短期波动模式上却存在显著差别，这表明我国当前经济运行当中消费需求驱动成分更为显著，体现了买方市场的基本特征和一定程度的需求不足。