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Lesson 5 Extreme events, Exposure and Vulnerability
The document discusses extreme weather events and their relationship with climate change, emphasizing increased severity and frequency in phenomena like heatwaves, droughts, and bushfires. It highlights the impact of climate change on water resources and presents the concept of vulnerability, defined as the susceptibility to adverse effects from such events due to social and environmental factors. Additionally, it addresses the importance of measuring vulnerability to inform decisions on climate change adaptation and disaster risk reduction.
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Overview of extreme events in relation to climate change and introduction to the course.
Explanation of extreme weather, including definitions and examples like heat waves, droughts, storms.
Discussion on effects of extreme events on health, economy, and ecosystems due to climate change.
Highlight statistics on increasing extremes in weather patterns due to climate change from IPCC data.
Historical context on bushfires in Australia and significant events that impacted communities.
Connection between climate change and increased bushfire occurrences, with statistical data.
Assessment of water resource risks, trends in rainfall, and drought patterns exacerbated by climate change.
Analysis of temperature extremes over decades and their increased frequency globally.
Discussion on the relationship between climate change and alterations in precipitation and moisture.
Insights into public attitudes towards climate change and weather, highlighting skepticism during cold weather.
Integration of climate events, disaster risk management, and development towards resilience.
Definition of exposure related to climate change and its impact on communities and assets.
Framework for assessing vulnerability to climate change, including exposure, sensitivity, and adaptation.
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Lesson 5 Extreme events, Exposure and Vulnerability
- 1. Climate Change &Global Environment Department of Environmental Management Rajarata University of Sri Lanka BA (Special) in Environmental Management EMGT 4234 Lesson 5 - Extreme events, exposure and vulnerability P.B. Dharmasena 0777 613234, 0717 613234 [email protected] , [email protected] https://independent.academia.edu/PunchiBandageDharmasena https://www.researchgate.net/profile/Punchi_Bandage_Dharmasena/contributions http://www.slideshare.net/DharmasenaPb
- 2. Extreme Events • Anextreme weather event is the occurrence of a value of a weather variable above (or below) a threshold value near the upper (or lower) ends of the range of observed values of the variable. These events are not a sign of climate change by itself, as they always existed but the occurrence and severity of at least some of these events have increased.
- 3. Extreme Weather Events •Heat and cold waves • Drought • Tropical storms • Heavy rains
- 4. Impacts on humanhealth and mortality, economic impacts, ecosystem and wildlife impacts
- 5. Changes in extremesmatter most for society and the environment With a warming climate: More high temperatures, heat waves Wild fires and other consequences Fewer cold extremes. More extremes in hydrological cycle: Drought, heavy rains, floods Intense storms
- 6. Bigger percentage changesin extremes Increase in Mean
- 7. Much bigger percentagechanges in extremes
- 8. Source: IPCC AR4 Evena small increase in average temperature can cause a big change in hot weather.
- 9.
- 10. The Consequences ofBushfires • Australia has a long history of bushfires – Black Friday 1939; Ash Wednesday 1983 • In 2003 large and uncontrollable bushfires devastated several suburbs in Canberra • In 2009 the Black Saturday fires took 173 lives and destroyed over 2,000 houses in Victoria • In 2013 large bushfires in Tasmania swept into the town of Denalley, destroying nearly 200 properties and forcing the evacuation of hundreds of people from the Tasman Peninsula.
- 11. Bushfires and ClimateChange • Climate change exacerbates bushfire conditions by increasing the frequency of very hot days. • Between 1973 and 2010 the Forest Fire Danger Index increased significantly at 16 of 38 weather stations across Australia, mostly in the southeast. None of the stations showed a significant decrease. • Projected increases in hot days across Australia, and in dry conditions in the southwest and southeast, will very likely lead to more days with extreme fire danger in those regions.
- 12. Impact on WaterResources
- 13. Risks: Water Resources Source:Bureau of Meteorology Trends in annual rainfall (mm/10 years) across Australia for the periods 1900-2011 and 1970-2011
- 14. Drought and ClimateChange
- 15. 15 Droughts and ClimateChange • Climate change is likely influencing the drying trend in southwest and southeast Australia via a southwards shift of the rain-bearing fronts from the Southern Ocean in the cooler months. • These regions are likely to experience more droughts in the future. • The increasing trend in extreme hot weather due to climate change exacerbates the impacts of drought, intensifying the drought-related heat arising from clear skies and a lack of evaporative cooling.
- 16. 16 Day and NightTemperature
- 17. • From 1951to 1961, only 1% of the land area in the Northern Hemisphere was exposed to temperatures higher than 3 standard deviations (SD) from the mean for 1951– 1980. • But from 2001-2011, 11% of land area was exposed to temperatures higher than 3 SD away from the average. • About 1% of land area, an area twice the size of France, experienced heat extremes of 5 SD from the mean. • The same trend is seen in the Southern Hemisphere.
- 18. Extreme high temperaturesbecome more frequent • The annual frequency of warm nights (90th percentile) and warm days (90th percentile) for the period 1950-2010 is increasing, relative to the period 1961 to 1990, in many regions of the World. The same trend is seen in decadal values (right panel). Occurrence of warm nights is more widespread than that of warm days.
- 19. In contrast, theincidence of cold days and nights (10th percentile of temperatures) have decreased.
- 20. 10th (left) and90th (right) percentiles Frequency of occurrence of cold or warm temperatures for 202 global stations with at least 80% complete data between 1901 and 2003 for 3 time periods: 1901 to 1950 (black), 1951 to 1978 (blue) and 1979 to 2003 (orange). 1979-2003 1951-1978 1901-1950 Warm nights are increasing; cold nights decreasing fewer more fewer more IPCC
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- 22. Air holds morewater vapour at higher temperatures Total water vapour Observations show that this is happening at the surface and in lower atmosphere: 0.55C since 1970 over global oceans and 4% more water vapor. This means more moisture available for storms and an enhanced greenhouse effect.
- 23. How should precipitationP change as the climate changes? With increased GHGs: increased surface heating evaporation E and P With increased aerosols, E and P Net global effect is small and complex Warming and T means water vapour as observed Because precipitation comes from storms gathering up available moisture, rain and snow intensity : widely observed But this must reduce lifetime and frequency of storms Longer dry spells
- 24. More watervapor plus moisture transports from divergence regions (subtropics) to convergence zones. Result: wet areas get wetter, dry areas drier The moisture and energy transport is a physical constraint, and with increased moisture, the winds can be less to achieve the same transport. Hence the divergent circulation weakens. Precipitation decreases on edges of convergence zones as it takes more instability to trigger convection: more intense rains and upward motion but broader downward motion. How should precipitation P change as the climate changes?
- 25. Public perceptions ofextreme weather events and climate change 26
- 26. Public perceptions ofhot weather 27 • Hot weather is one of the most commonly expected outcomes of climate change • Climate change concerns vary with recent local temperatures • Most of these studies focused on the US
- 27. Public skepticism (suspicion)in cold weather 28 • When the weather is cold, beliefs in climate change may be less strong • People who live in areas without hot summers may look forward to ‘global warming’ • Even if it is cold, might other local weather inform beliefs about climate change?
- 28. Weather & Climate Events Disaster Risk Climate Natural variability Anthropogenic Climate Change Development Disaster Risk Reduction Climate Change Adaptation GreenHouse Gas emission Disaster Risk reduction Model
- 29. Exposure to ClimateChange Events • Exposure refers to the presence (location) of people, livelihoods, environmental services and resources, infrastructure, or economic, social, or cultural assets in places that could be adversely affected by physical events and which, thereby, are subject to potential future harm, loss, or damage. • Under exposed conditions, the levels and types of adverse impacts will be the result of a physical event (or events) interacting with socially constructed conditions denoted as vulnerability.
- 30. Vulnerability to ClimateChange Events • Vulnerability is defined as the propensity (susceptibility) or predisposition to be adversely affected. Such predisposition constitutes an internal characteristic of the affected element. In the field of disaster risk, this includes the characteristics of a person or group and their situation that influences their capacity to anticipate, cope with, resist, and recover from the adverse effects of physical events. • Vulnerability is a result of diverse historical, social, economic, political, cultural, institutional, natural resource, and environmental conditions and processes. • In brief it is the degree to which a system is susceptible to or unable to cope with adverse effects of climate change including climate variability and extremes.
- 31. Vulnerability to ClimateChange Events • Vulnerability is a function of the character, magnitude, and rate of climate variation to which a system is exposed, its sensitivity, and its adaptive capacity. • The vulnerability can be reduced by introducing adaptation measures like protecting the area by means of sea wall or by retreating from the flood prone area, etc.
- 32. Importance of measuringvulnerability 1. Identify magnitude of threats, such as climate change. 2. Guide decision-making on international aid and investment. 3. Prioritize aid for climate change adaptation. 4. Identify measures to reduce vulnerability.
- 33. Methodological framework forvulnerability and adaptation assessment V = f (E, S, AC) E = Exposure, S = Sensitivity, AC = Adaptive Capacity Exposure: The degree of climate stress upon a particular unit of analysis long-term climate conditions climate variability, magnitude and frequency of extreme events. Sensitivity: The degree to which a system will respond, either positively or negatively, to a change in climate. Adaptive capacity: The degree to which adjustments in practices, processes, or structures can moderate or offset the potential for damage or take advantage of opportunities created by a given change in climate.
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