State-of-the-art global models underestimate impacts from climate extremes (original) (raw)
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Estimating global impacts from climate change
Global Environmental Change-human and Policy Dimensions, 2004
We surveyed the literature to assess the state of knowledge with regard to the (presumed) benefits or avoided damages of reducing atmospheric concentrations of greenhouse gases to progressively lower levels. The survey included only published studies addressing global impacts of climate change; studies that only addressed regional impacts were not included. The metric we used for change in climate is increase in global mean temperature (GMT). The focus of the analysis centred on determining the general shape of the damage curve, expressed as a function of GMT. Studies in sea level rise, agriculture, water resources, human health, energy, terrestrial ecosystems productivity, forestry, biodiversity, and marine ecosystems productivity were examined. In addition, we analysed several studies that aggregate results across sectors. Results are presented using metrics as reported in the surveyed studies and thus are not aggregated.
2015
Numerous studies have highlighted that water resources and hydrologic extremes are sensitive to climate change. An interesting research question is what the role of climate change is in occurrence of extreme events. More importantly, how climate extremes may change under future climate conditions and emission scenarios. Therefore, there exists a strong need to study water resources and hydrologic cycle under different climate change scenarios at the global scale.In the past decades, numerous methods and models have been developed for assessing climate change impacts on water resources. However, there are still major research gaps from uncertainties in climate model simulations to limitations in the current large scale water cycle (or global hydrologic) models. Some of the current research gaps include: (I) high uncertainty of climate model simulations; (II) limitations and high uncertainties of the global hydrologic model simulations because of calibration challenges at the global s...
Moving Forward with Incorporating “Catastrophic” Climate Change into Policy Analysis
RePEc: Research Papers in Economics, 2013
It has often been stated that current studies aimed at understanding the magnitude of optimal climate policy fail to adequately capture the potential for "catastrophic" impacts of climate change. While economic modeling exercises to date do provide evidence that potential climate catastrophes might significantly influence the optimal path of abatement, there is a need to move beyond experiments which are abstracted from important details of the climate problem in order to substantively inform the policy debate. This paper provides a foundation for improving the economic modeling of potential large scale impacts of climate change in order to understand their influence on estimates of socially efficient climate policy. We begin by considering how the term "catastrophic impacts" has been used in the scientific literature to describe changes in the climate system and carefully review the characteristics of the events that have been discussed in this context. We contrast those findings with a review of the way in which the economic literature has modeled the potential economic and human welfare impacts of events of this nature. We find that the uniform way in which the economic literature has typically modeled such impacts along with the failure to understand differences in the end points and timescales examined by the natural science literature has resulted in the modeling of events that do not resemble those of concern. Based on this finding and our review of the scientific literature we provide a path forward for better incorporating these events into integrated assessment modeling, identifying areas where modeling could be improved even within current modeling frameworks and others where additional work is needed.
Leaving the world as we know it: Hotspots of global climate change impacts
2014
The impacts of global climate change on different aspects of humanity's diverse life-support systems are complex and often difficult to predict. To facilitate policy decisions on mitigation and adaptation strategies, it is necessary to understand, quantify, and synthesize these climate-change impacts, taking into account their uncertainties. Crucial to these decisions is an understanding of how impacts in different sectors overlap, as overlapping impacts increase exposure, lead to interactions of impacts, and are likely to raise adaptation pressure. As a first step we develop herein a framework to study coinciding impacts and identify regional exposure hotspots. This framework can then be used as a starting point for regional case studies on vulnerability and multifaceted adaptation strategies. We consider impacts related to water, agriculture, ecosystems, and malaria at different levels of global warming. Multisectoral overlap starts to be seen robustly at a mean global warming of 3°C above the 1980-2010 mean, with 11% of the world population subject to severe impacts in at least two of the four impact sectors at 4°C. Despite these general conclusions, we find that uncertainty arising from the impact models is considerable, and larger than that from the climate models. In a low probability-high impact worst-case assessment, almost the whole inhabited world is at risk for multisectoral pressures. Hence, there is a pressing need for an increased research effort to develop a more comprehensive understanding of impacts, as well as for the development of policy measures under existing uncertainty. coinciding pressures | differential climate impacts | ISI-MIP
Climate Change Impacts at the National Level: Known Trends, Unknown Tails, and Unknowables
Springer Climate, 2014
Economists attempting to evaluate the impacts of climate change are often caught between hard theory and exceedingly rocky empirics. Impact assessment models are necessarily based on highly aggregated-and sometimes highly simplified-damage functions. This study takes an alternative approach: a bottom-up, physical impact assessment and respective monetization, attempting to cover a much broader set of impact fields, feeding directly into a macroeconomic and welfare analysis at the national level. To ensure consistency, our approach applies impact assessment at the sectoral impact chain level using shared socioeconomic pathways, consistent climate scenarios, computable general equilibrium evaluation, and non-market impact evaluation. The approach is applied to assess a broad scope of climate impacts in Austria. Results indicate significant impacts around 'known knowns' (such as changes in agricultural yield from climatic shifts), with uncertainty increased by 'known unknowns' (e.g. changes in water availability for irrigation, changes in pest and diseases) but also raises the question of unknowns and unknowables, which may possibly dominate future impacts (such as exceedance of critical ecosystem function
Bounding the future: The use of scenarios in assessing climate change impacts
Futures, 2011
Assessments about the nature, rate, impacts of and responses to climate change deal with change in coupled environmental-human systems. In making future projections of climate variability and change, mitigation and adaptation, assessments are therefore faced with making assumptions about future social and economic changes, often over the longterm [1]. These assumptions will have an important influence on results of assessments, either because they are inputs for emissions scenarios that drive climate models (e.g. [2]), or because they portray the context in which climate change impacts, exposure, vulnerability and adaptation are analysed [3]. Climate models generate scenarios that provide information about e.g. the temperature and precipitation at a certain location in a specific timeframe. But the impacts of climate change can only be assessed if one has knowledge about the vulnerability and coping capacity of future societies. In climate assessments, socioeconomic scenarios are likely to be as important as climate scenarios. For instance, a recent study of flood risk in The Netherlands showed that the main contributor to growing losses in the coming four decades was not due to climate change (due to a growing risk of riverine flooding), but due to socioeconomic changes leading to greater exposure and vulnerability of populations and capital stocks [4]. Scenario planning can be applied to take possible future developments into account in investments, policy and planning. However, it is essential that organizations involved in such policies not only apply scenarios, but also engage in the process of Futures 43 (2011) 488-496
Uncertainties and risks – Key Drivers and Economic Consequences of High End Climate Scenarios
The consequences of high end climate scenarios and the risks of extreme events involve a number of critical assumptions and methodological challenges related to key uncertainties in climate scenarios and modelling, impact analysis, and economics. A methodological framework for integrated analysis of extreme events and damage costs is developed and applied to a case study of urban flooding for the Danish medium size city of Odense. Moving from our current climate to higher atmospheric greenhouse gas (GHG) concentrations including a 2 degree C scenario, a 4 degree C scenario, and a high end 6 degree C scenario implies that the frequency of extreme events increase beyond scaling, and in combination with economic assumptions we find a very wide range of risk estimates for urban precipitation events. A sensitivity analysis addresses 32 combinations of climate scenarios, damage cost curve approaches, and economic assumptions, including risk aversion and equity represented by discount rates. Major impacts of alternative assumptions are investigated. Based on this, the paper demonstrates that in terms of decision making the actual expectations concerning future climate scenarios and the economic assumptions applied are very important in determining the risks of extreme climate events, and thereby for the level of cost-effective adaptation seen from society's point of view.
Toward a consistent modeling framework to assess multi-sectoral climate impacts
Nature communications, 2018
Efforts to estimate the physical and economic impacts of future climate change face substantial challenges. To enrich the currently popular approaches to impact analysis-which involve evaluation of a damage function or multi-model comparisons based on a limited number of standardized scenarios-we propose integrating a geospatially resolved physical representation of impacts into a coupled human-Earth system modeling framework. Large internationally coordinated exercises cannot easily respond to new policy targets and the implementation of standard scenarios across models, institutions and research communities can yield inconsistent estimates. Here, we argue for a shift toward the use of a self-consistent integrated modeling framework to assess climate impacts, and discuss ways the integrated assessment modeling community can move in this direction. We then demonstrate the capabilities of such a modeling framework by conducting a multi-sectoral assessment of climate impacts under a r...
Changes in Impacts of Climate Extremes: Human Systems and Ecosystems
Chapter 4 Changes in Impacts of Climate Extremes: Human Systems and Ecosystems Chapter 4 Changes in Impacts of Climate Extremes: Human Systems and Ecosystems analysis of potential and projected damages are limited to a few countries, infrastructure types, and sectors. [4.3.2, 4.3.5.2] Estimates of adaptation costs to climate change exhibit a large range and relate to different assessment periods. For 2030, the estimated global cost ranges from US$ 48 to 171 billion per year (in 2005 US$) with recent estimates for developing countries broadly amounting to the average of this range with annual costs of up to US$ 100 billion. Confidence in individual estimates is low because the estimates are derived from only three relatively independent studies. These studies have not explicitly separated costs of adapting to changes in climate extremes from other climate change impacts, do not include costs incurred by all sectors, and are based on extrapolations of bottom-up assessments and on top-down analysis lacking site-specificity. [4.5.3, 4.5.5, 4.5.6] Chapter 4 Changes in Impacts of Climate Extremes: Human Systems and Ecosystems Chapter 4 Changes in Impacts of Climate Extremes: Human Systems and Ecosystems Chapter 4 Changes in Impacts of Climate Extremes: Human Systems and Ecosystems