Climate extremes in a warming world : historical trends, physical causes, and response to increasing anthropogenic emissions
Abstract/Contents
- Abstract
- Climate and weather extremes cause considerable humanitarian and socio-economic impacts across the globe. Global economic losses from extreme events in recent years are estimated to come close to $200 billion dollars annually. The impact of extremes varies depending upon the exposure and vulnerability of affected natural and human systems. Minimizing the risk of disasters from the physical climate to these systems through suitable adaptation planning and management requires an accurate quantification of the characteristics of extreme events including their timing and severity. My dissertation aims to characterize the response of daily-scale extreme events to external climate forcings in two regions -- North America and India, with very different exposure and vulnerability profiles. I use statistical tools to quantify the magnitude and significance of changes in several characteristics of extremes that have occurred and that are likely to occur in a future climate with increasing anthropogenic emissions. Combined with this statistical analysis, I use a process-oriented approach to understanding the physical causes of these changes. Together, these approaches provide a found for investigating the influence of anthropogenic factors on extreme events. In Chapter 2, I quantify transient changes in wet and dry precipitation extremes over the continental U.S. in the 21st century climate under a high-emissions scenario using a multi-member, high-resolution climate modeling experiment. The results from this analysis suggest simultaneous increases in both extremes across most regions within the near-term that have implications for future water availability. Increase in moisture availability and daily-scale precipitation variability consistent with increasing greenhouse gas concentrations, and atmospheric circulation changes contribute to the spatial heterogeneity in the changes. In Chapter 3, I analyze historical changes in the temporal characteristics of rainfall extremes associated with the variability of the Indian Summer Monsoon on intraseasonal timescales. The summer monsoon supports agricultural activities and provides water for the large population living in the region. Intraseasonal variability in the monsoon impacts agricultural activities and can result in socio-economic losses associated with heavy precipitation events. Here, I show that the intensity of wet spells and the frequency of dry spells has increased significantly in the historical record associated with increasing moisture availability, atmospheric warming, and changes in the atmospheric patterns associated with these events. Chapter 4 presents a framework for attributing the contribution of historical anthropogenic emissions to specific extreme events using statistical tools and identifying the proximal causes of the event. Such information is critical for planning for the impacts of climate change and has important consequences for climate policy. This methodology is applied to a severe precipitation event that caused catastrophic flooding in Northern India in mid-June 2013. In Chapter 5, I investigate historical trends and causes of the warm-west/cool-east temperature pattern that has persisted in recent winter seasons (2013-2014 and 2014-2015) over North America. I present evidence to show that there is an increasing trend in the occurrence and severity of these events since 1980 that are related to surface warming over western North America and more frequent occurrence of the related mid-atmospheric pattern. Though the increasing trend in occurrence is more likely in a warmer climate relative to the pre-industrial climate, natural variability has a strong influence on the observed trend. Overall, I show that changes have occurred in several characteristics of high impact extremes in both these regions and relate these historical changes to atmospheric processes that have contributed to the occurrence and severity of extremes. This combined approach of statistical methods to find trends and the dynamics-approach to identify causes, provides a more robust method of identifying the effects of external climate factors such as greenhouse gas warming on extremes. Increasing occurrence of extremes as shown in this dissertation is likely to pose increasing risks to communities in these regions. Effective climate risk management requires an understanding of how these characteristics. This integrated approach can further provide insights into reducing uncertainties in the response of climate extremes to increasing emissions, providing information to minimize future losses from similar disasters.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2015 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Singh, Deepti |
|---|---|
| Associated with | Stanford University, Department of Environmental Earth System Science. |
| Primary advisor | Diffenbaugh, Noah S |
| Thesis advisor | Diffenbaugh, Noah S |
| Thesis advisor | Caldeira, K. (Ken) |
| Thesis advisor | Field, Christopher B |
| Thesis advisor | Rajaratnam, Balakanapathy |
| Thesis advisor | Thomas, Leif N |
| Advisor | Caldeira, K. (Ken) |
| Advisor | Field, Christopher B |
| Advisor | Rajaratnam, Balakanapathy |
| Advisor | Thomas, Leif N |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Deepti Singh. |
|---|---|
| Note | Submitted to the Department of Environmental Earth System Science. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2015. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2015 by Deepti Singh
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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