Lecture 8 - Weather Extremes Notes PDF

Lecture 8 - weather extremes 18 November 2024 16:37 Climate Change: A change in the state of the climate that can be identified by changes in the mean and/or the variability of its properties and that persists for an extended period, typically decades or longer. Climate Extreme: The occurrenc...

Lecture 8 - weather extremes 18 November 2024 16:37 Climate Change: A change in the state of the climate that can be identified by changes in the mean and/or the variability of its properties and that persists for an extended period, typically decades or longer. Climate Extreme: The occurrence of a value of a weather or climate variable above (or below) a threshold value near the upper (or lower) ends of the range of observed values of the variable. For simplicity, both extreme weather events and extreme climate events are referred to collectively as 'climate extremes'. Social Vulnerability - Wisner (2004) defines vulnerability as the characteristics of a person or group and their situation that influence their capacity to cope with, resist and recover from the impact of a natural hazard. - 'Vulnerability populations are those at risk, not simply because they are exposed to hazard, but as a result of a marginality that makes their life a 'permanent emergency' (Bankoff, 2007) - 'In assessing societal impacts, the vulnerability of individuals and communities is as important as the relative magnitude of the hazard' (McEwen and Werritty, 2007) - '…the concept of vulnerability still encourages as sense of societies and peoples as weak, passive and pathetic' (Bankoff, 2007) - '…People who live with the daily threat of disaster have frequently evolved certain strategies or coping practices for dealing with effects that are quite successful' (Bankoff, 2007 Heat index - August 2003, Europe: Around 35,000 people died from heat-related causes as a record heatwave swept France and other countries - August 2009, Argentina: Record temperatures reach more than 40C in many areas of the South American country in a winter heatwave. - August 2010, Russia: Wildfires around Moscow and drought brought on by extreme heatwave Extreme cold weather events - With extreme cold conditions, freak weather events can happen very quickly and become disasters, affecting thousands of home/life. - Most common: ○ Snow storms ○ Blizzards ○ Avalanches ○ Snow accumulation ○ Black ice - UK, 7th January 2007 ○ Most of the UK blanketed under few cm of snow ○ More than 10% workforce unable to commute ○ Schools shut ○ Delayed trains and planes - Ice storm or frozen rain ○ When falling rain comes into contact with a freezing cold surface, rain turns into ice on contact ○ Covers everything with a smooth surface ○ Weight of ice can collapse structures - North American ice storm 4-10th Jan 1998 ○ Left nearly 3 million people in Ontario and Quebec freezing in the dark ○ New Brunswick, Ontario and Quebec requested aid from the Canadian forces on 7th January. Operation Recuperation began on 8th January Over 15,000 troops deployed Notes Page 1  ○ Over 15,000 troops deployed ○ Largest deployment of troops on Canadian soil in response to a natural disaster since the Manitoba floods in 1997. Largest operational deployment of Canadian military personnel since the Korean war ○ Between 28 to 40 fatalities ○ 120mm of ice deposited 16,000 military personal deployed ○ Some homes didn't have power for 6 weeks ○ Damages estimated between 5 and 7 billion USD - 2007 again - Spectacular extreme cold weather events ○ Ice storm or Frozen rain ○ Ice tsunami ▪ Also called an Ice Shove: pill up of ice on the oceans or lakes being pushed by winds, currents or temperature differences Are these events becoming more frequent and extreme? - North Atlantic Oscillation - Pacific Decadal Oscillation - Atlantic Oscillation - Although some indications that extra-tropical storms may gain in strength, it is still not proven as we do not have a long record (millennia vs decades) - Do we see an increase of snow storms in the UK? ○ Thames froze but product of hydraulics not climate Cold vs Heat events 'Vulnerable populations are those at risk, not simply because they are exposed to hazard, but as a result of a marginality that makes their life a 'permanent emergency' (Bankoff, 2007) Extreme weather on the edge of the world: School log books and Hebridean life - 3.5 year (2013-2017) £1.2m AHRC research project Notes Page 2 - 3.5 year (2013-2017) £1.2m AHRC research project - Social vulnerability to the weather - A social history of the Outer Hebrides - Weather, school and island life ○ Mobility and attendance ○ Storm damage ○ Health and wellbeing ○ Occupations and traditions ○ Weather memory - 'Story of human vulnerability to climate, told along a chain of causation running from natural forcing to economics and to the level of political and social decision making, requires a change from the macroscale of generalization to the micro-scale of case-studies' (Pfister and Brazdil, 2006) - 'More comparative studies of socio-environmental interactions should be encouraged, albeit not in view of arriving at a universalized picture of social vulnerability to climate impacts, as was repeatedly attempted for global climate change studies in the last millennium. Quite the contrary: It would be worthwhile to illustrate the plurality of human responses and solutions in mitigating the social vulnerability to climate variability' (Pfister and Brazdil, 2006) - 'the capitalist system that gained a grip on island lives in the late 18th century… ultimately led to the disruption of settlements and customary farming practices, and the dispersal of whole communities. The pursuit of profit by a small number of individuals, galvanised by the ideologies of individualism and improvement, can be seen to have created conditions of extreme poverty' (Symonds, 2011) - Weather and mobility ○ Very bad attendance at school ○ Weather events making children go home early - Damage to infrastructure ○ Flooding ○ Wind damage - Weather memory ○ Little evidence of forward thinking re weather, some limited evidence of attempts to gauge the significance of weather events in a longer community history, whether in terms of memory of teacher/recorder, or in terms of community memory ○ Why is there a lack of evidence? ▪ Dealing with an essentially oral culture, the majority of the population was illiterate ▪ Headmasters and teachers changed regularly, usually once they got a job on the main land, little opportunity for them to get a sense of the significance of weather events over time ▪ Extreme weather was so frequent, to some extent the norm between October and March - Key events ○ Late 1860s represented the start of a 30-year period when Scotland was to be struck by successions of severe winter storms. From the 1870s onwards, winters were wither extremely cold, with snow lying for weeks on the ground, or they were incredibly stormy. By and large summers and autumns were wet. (Alastair Dawson, 2009) ○ 1881 - extensive sea ice in north Atlantic: 'With the southern extension of sea ice came with the southward movement of cold polar waters and, with this, a steeper thermal gradient across the North Atlantic and many more storms' (Dawson, 2009) Poor harvest and social unrest, rent strikes - Cultural memory ○ The impact of extreme weather may even vary between individuals, depending on a multitude of factors, which are in turn informed by cultural and historical experiences. ○ The way in which an extreme event is experienced and perceived determines whether it becomes inscribed into the memory of a community or an individual in the form of oral history, ideology, custom, narrative, artefact, technological and physical adaption, including adaptions to the working landscape and built environment (Hassan, 2000) Notes Page 3  including adaptions to the working landscape and built environment (Hassan, 2000) ○ These different forms remembering and recording the past represent the central media through which info on past events is curated recycled and transmitted across generations and into the future (Naylor et al, 2022) ○ Experience or awareness of unusual or extreme events can effectively condition how people comprehend and respond to the problems of risk and uncertainty with respect to timing and impact of extreme events in the future (Macdonald et al., 2022) ○ Notes Page 4 Lecture 9 - Earthquakes and Tsunamis 19 November 2024 16:22 1. Earthquakes Global distribution of Earthquakes The history of Earthquakes - Early ideas on the origin of Earthquakes ○ Japanese Folklore says earthquakes were caused by a giant catfish beneath the ground. When the catfish flailed about, the ground shook. Causes of earthquakes - Plate boundaries ○ Divergent, convergent and transform - Types of Faults ○ Normal ▪ Fault than forms due to strengthening or lengthening of the Earth's crust ○ Reversed ▪ Fault where the block above the fault plane moves up relative to the block below ○ Strike-slip Notes Page 5 Lecture 10 - Tropical Storms 25 November 2024 13:04 Different names for the same thing: - Hurricane: US & Caribbean - Typhoons: E. Asia - Cyclones: S. Asia More economic damage with hurricanes but more deaths with typhoons and cyclones. 100m people exposed annually (Pelling, 2004) Formation TS created from difference in pressure - Low pressure surrounded by high - Giant engine and warm moist air as fuel - Coriolis force causes moving objects to be deflected to the right in the N. Hemisphere and left in the S. Hemisphere Beaufort - Royal Navy Officer - Developed 14 point scale for measurement of wind force Saffir-Simpson scale - Developed in 1971 - Scale separates hurricanes into five different categories based on sustained wind speed; with category 3 and above classed as major hurricanes Notes Page 6 Process: 1. Warm ocean waters throughout a significant depth. 2. Coriolis force -> min. distance of at least 500km from the equator. For tropical cyclongenesis to occur, there is a requirement for non-negligible amounts of the Coriolis force to provide for near gradient wind balance to occur. Without, the low pressure disturbance cannot be maintained. 3. An atmosphere which cools fast enough with height such that it is potentially unstable to moist convection. 4. Relatively moist layers near the troposphere. Dry mid-levels are not conducive for allowing the continuing development of widespread thunderstorm activity 5. Pre-existing near-surface disturbance with sufficient vorticity and convergence. Cyclones can't be generated spontaneously. Require weakly organised system and sizable spin and low level inflow. 6. Low values of vertical wind shear between surface and troposphere. Tropical storms driven by global atmospheric circulation and steered by global winds Tropical storm dissipation - After making landfall, may burn out within couple days - Even as storm weakens it can still bring huge amounts of water vapour and rainfall hundred km inland - Winds and surges most intense in right front quadrant where wind speeds combine with storm movements. Storm surges - Abnormal rise of water - Water pushed towards the shore by the force of the winds, moving cyclonically around the storm (horizontal action) - Low pressure = higher water level (vertical action) Notes Page 7  - Low pressure = higher water level (vertical action) - Types: ○ Tropical storms ▪ Small, very intense gyres ▪ Generated at sea ▪ Unpredictable track ▪ Very high surges ▪ Wind stress >> pressure ○ Extratropical storms ▪ Large and slow ▪ Surround a depression ▪ Considerable duration ▪ Pressure = wind effect - Galveston Bay (Texas), Hurricane Ike 2006 - Total water level = tide + storm surge + wave setup Pressure setup (inverted barometric effect) = Adjustment of sea level to changes in barometric pressure; an increase in barometric pressure of 1 mb corresponds to a fall in sea level of 0.01 m (1cm). Tropical storm trends - Increasing temperature trends would suggest an increase in TSs. - Low confidence that long terms changes in tropical cyclone activity are robust, and there is low confidence in the attribution of global changes to any particular cause. - Virtually certain that tropical cyclones in the N. Atlantic have increased since 1970. Tropical Storm management - Monitoring using satellite, observational stations and deployable instruments, such as dropsondes from aircraft - Early warning systems need to communicate info to dispersed communities in areas with poor infrastructure - Challenges of communicating over wide areas, with diverse needs - Challenges of communicating risk Tropical storm impacts - storm surges - Importance of past experiences, cultural and social knowledge and role of communities key - Embedded and local knowledge can facilitate and improve risk reduction and post event recovery, particularly important in communities globally Notes Page 8 Lecture 11 - Overview 30 December 2024 15:49 Key Terms: - Natural hazards include geophysical and biological events that may cause large impacts on society. - Human vulnerability determines the extent to which a natural hazard results in a disaster - Vulnerability reflects the level of physical exposure of people and assets to damaging natural events and their susceptibility to loss - Vulnerability can be reduced by improvements to environmental security - The relationship between the probability of a natural process occurring, the elements at risk and the level of vulnerability determine the degree of risk Drought Kills the most people (11.7 Million from 1900-2004) Degree of loss can be used to determine the cost associated with the occurrence of a hazard with a given magnitude. Examples of risk assessment: 1. Strategic flood risk assessment (SFRA) - Modelling possible future flood magnitudes and probability of flooding - Identifying assets at risk for a given flood height - Assessing vulnerability of assets at risk - Combining assets and vulnerability to estimate probability of losses - Use vulnerability to determine the potential financial loss and insurance costs 2. Wildfire risk planning - Community wildfire protection plans (US) - Combining mapping of fuel hazard, ignition risk and assets at risk to give an overall risk rating Management responses - Significance since the 90s on 'disasters' rather than 'hazards' - Convergence of hazard domains and human vulnerability has become central component of research - Tendency to focus on the emergency phase of management responses to disasters caused by natural hazards - Capacity to respond is highly dependent on other societal factors, particularly levels of development - Perceptions of natural hazards has greatly influenced past management approaches Reducing Impacts of NH 1. Protection: aim to reduce hazards impacts by seeking to control hazardous processes (flood defences) 2. Mitigation: aim to reduce losses (emergency aid, insurance) 3. Adaption: aim to reduce vulnerability (land use planning, relocation, forecasting) Frameworks for DRR - Landmark policy developments led by the United Nations in DRR: - … Protection - Macro protection: - Large scale structures to control and direct flows (lava/rivers/debris) - Function as either storages (flood plain/control reservoirs) or diverting flows (levees/embankments) - Micro protection: - Individual building scale measures (earthquake proof houses/flood defences/stilt houses) Notes Page 9  houses) - Retrofitting can reduce losses (hurricane proof houses; concrete) Mitigation - Disaster aid: - Rapid responses to reduce further loss of life and limit the spread of disease - Key phases: Emergency period (24hr - 3weeks), Relief period (2weeks - 6months), Recovery period (5weeks - 10years or more) - Government (internal) aid: requires declaration of a disaster to release government funding - International aid: developing countries depend heavily on this in response to disasters - International responses dependent on media coverage, political interest and agency presence - Insurance: - Transfer risk to insurer for a premium to compensate for losses - Can be used to reduce vulnerability: high premiums act as financial disincentive to locate in high risk areas - Reduction in premiums may be offered for actions that reduce vulnerability - Some Challenges - Insurance may not be obtained by high risk areas without government support (UK flood insurance) - Also issue of low uptake of insurance with implications for government disaster relief: Govt to fund rebuilding houses?? But then why take out insurance if government will pay? - Issue of under-insurance by individuals and governments (Neumayer et al, 2014) - Flat rate premiums: these do not differentiate between low and high risk areas, leading to cross-subsidisation by those insured for less hazardous areas. Adaption - Preparedness - Agencies to coordinate responses to disasters (FEMA) - Emergency services - Stockpiling of emergency supplies - Community training - Forecast and warning systems - Of most value for hurricanes, floods, extreme temperatures, and wildfires - Stages 1. Establish FWS 2. Hazard evaluation 3. Warning dissemination 4. Public response (evacuation planning) - Land use planning - Identify spatial variation in risk and limit development of areas based on this risk classification - Zonation may apply to volcanic and seismic hazards, coastal and river flooding, debris flow hazard on alluvial fans and wildfires ▪ Land use and wildfire hazard (Buxton et al 2011) Notes Page 10 Vulnerability and resilience - Human vulnerability to natural hazards arises from both physical and socioeconomic factors - Extend beyond the physical exposure definition to include underlying factors that enhance vulnerability, such as: - Poverty (affects recovery) - Economy (diversity of national economy) - Age/Gender/Disability - Health and sanitation (impact on recovery) - Political system (corruption, exclusion from decision making) - Education (access to disaster planning info) - Five major vulnerability types: 1. Physical (exposure to risks; settlement in hazard prone areas; poor quality housing and inadequate physical protection) 2. Economic (Loss of livelihoods and income opportunities; economic status; loss of assets and savings and need for recurrent aid 3. Social (Disintegration of social organisations; incidence of female headed households and health status) 4. Educational/informational (Forecasting; early warning and evacuation systems and training for emergency responses) 5. Environmental (land use and environmental degradation and increasing risks of hazards) - Disaster Risk Index ○ Example of a metric for quantifying human vulnerability for natural hazards (Peduzzi et al, 2009) ○ DRI outputs only for floods, droughts, earthquakes and cyclones ○ DRI combines spatial datasets in GIS for hazard occurrence and population distribution to determine human exposure ○ DRI uses statistical analyses to determine to what extent past losses of life are related to population exposure and vulnerability ○ It uses deaths per year and deaths as percentage of country population in multiple regressions with human exposure and vulnerability indices ○ Strong relationship between higher levels of development and lower disaster deaths - Resilience refers to the ability of a community to resist, absorb, accommodate and recover from the effects of a natural hazard (UN/ISDR, 2009) - The concept of resilience in disaster planning focuses on community strengths rather than weaknesses. It focuses on assets such as: ○ Natural Capital (land, water, forests) Financial Capital (savings, taxes, credit, pensions) Notes Page 11  ○ Financial Capital (savings, taxes, credit, pensions) ○ Human Capital (knowledge, skills) ○ Social Capital (family relations, networks) ○ Physical Capital (infrastructure, roads, sanitation) - Resilience focuses more on local capacities and resourcing, and self sufficiency - Disaster resilience of place (DROP) model links vulnerability and resilience (Cutter et al, 2008) Environmental change includes: - Natural processes - Human-modified natural processes - Socio-economic processes Two broad categories of change have been identified (Turner et al, 1990) - Systematic change: direct impact on global systems (greenhouse gas emissions) - Cumulative change: impact results from smaller scale but widespread effects (water pollution, deforestation) Pathways for global environmental change: Geo-physical path Socio-economic path Drivers of change - Variations in hydro-climatic processes - Globalisation and economic - Anthropogenic climate change development - Population growth - Urbanisation Examples of - Changes to the magnitude and frequency of - Land degradation hazard-related floods, droughts and wildfire - Soil erosion effects - Disease outbreaks and expanded range - Landslide risk - Sea-level rise and coastal flooding - Water and air pollution - Desertification What affect may climate change have on the frequency and magnitude of natural hazards? - Limited data available on the magnitude and frequency of occurrence of NH since infrequent and extreme events - More data available for some hazardous processes than others - Makes it difficult to quantify the possible future change in frequency of these extreme events relative to historic data - Care needed when interpreting historic datasets where there have been improvements in data quality and increased monitoring - Occurrence of extreme event does not equate to a disaster, which is dependent on societal vulnerability and disaster reduction measures - Evidence suggests that anthropogenic climate change has not yet had a significant impact on normalised economic losses from NH (Bouwer, 2011) Generalised changes to selected NHs based on observations since 1950 and projected to 2100 (Smith, 2013) Notes Page 12 Notes Page 13