CHAPTER 3 VARIABLE WEATHER AND CHANGING CLIMATE A Continuing Challenge?

CHAPTER 3 VARIABLE WEATHER AND CHANGING CLIMATE A Continuing Challenge?

CHECK-IN: Hurricane Katrina August 2005 Costliest disaster: USD $81 billion One of the deadliest: 1,836 people died 6th strongest in Atlantic history

CHAPTER 3 VARIABLE WEATHER AND CHANGING CLIMATEA Continuing Challenge? In this chapter you will explore three key questions: • Why do different places experience different weather and climate? • What is happening to the Earth’s climate? • Is the weather becoming more extreme?

CHAPTER 3 VARIABLE WEATHER AND CHANGING CLIMATE Gateway 3: Is the weather becoming more extreme? a. What are the characteristics of tropical cyclones? b. Where are tropical cyclones found? c. What are the hazards associated with tropical cyclones? d. What are the impacts of tropical cyclones? e. How do people respond to tropical cyclones?

a. What are the characteristics of tropical cyclones? Tropical Cyclone Weather system created over warm oceans in the tropics. Size ranges from 150 km to 1,000 km in diameter. Hurricane Catarina over Brazil in 2004 as seen from space

a. What are the characteristics of tropical cyclones? • Tropical Cyclones have two key characteristics: • Strong winds • Low central pressure causes winds to spiral inwards and upwards at high speeds of 119 km/h. The huge difference in pressures creates strong winds. • Low central pressure • An area of low central pressure is formed in the middle of the tropical cyclone (eye). The eye is characterised by calm conditions and the absence of clouds.

a. What are the characteristics of tropical cyclones?

CHAPTER 3 VARIABLE WEATHER AND CHANGING CLIMATE KQ3: Is the weather becoming more extreme? a. What are the characteristics of tropical cyclones? b. Where are tropical cyclones found? c. What are the hazards associated with tropical cyclones? d. What are the impacts of tropical cyclones? e. How do people respond to tropical cyclones? f. Example: Tropical Cyclone Yasi

b. Where are tropical cyclones found?

b. Where are tropical cyclones found? • Latitude 8° and 15° N and S of Equator. • Conditions needed: • High ocean surface temperatures of above 26.5°C. • Coriolis effect (deflection of winds, creating spiraling motion) • In northern hemisphere, tropical cyclones move in anti- clockwise direction • In southern hemisphere, tropical cyclones move in clockwise direction • Tropical cyclones are also known as hurricanes and typhoons.

c. What are the hazards associated with tropical cyclones? • Storm surges • Wind damage • Torrential rain Damage from Cyclone Sidr which hit Bangladesh in 2007

Storm surge • How is it formed? Low eye pressure causes sea Level to rise; strong winds push water towards the coast and create huge waves. • What is a storm surge? Sudden rise of sea level in which water is piled up against a coastline beyond normal conditions at high tide.

Storm surge • Greatest destruction to coastal areas. • Loss in property and lives • Vessels swept and stranged inland • Eg. Hurricane Ike (2008) • Storm surge was 4–6 metresabove normal tide level • Property damage: US$ 24.9b Damage from Hurricane Ike

Wind damage • Hurricane Camille recorded the highest wind speed at 305km/hour! • Causes huge damage: • Destroy infrastructure and buildings • Injure people • Causes loose debris to fly and hit people/buildings

Torrential rain • Flooding • Large amount of rainfall causes flooding inland and also cause rivers to overflow. • Eg. Hurricane Isabel in 2003 flooded areas 120 times the size of Singapore in USA causing damages of more than US$2.23billion. • Landslide • Excess water in soil will destabilise slopes. • Eg. Typhoon Megi created landslides in Taiwan, destroying buildings and roads.

d. What are the impacts of tropical cyclones? • Physical • Economic • Social Damage from Cyclone Sidr

Physical impacts • Damage to infrastructure • Houses and buildings • Unable to live in them • Roads and bridges • Unable to transport emergency supplies such as food, medicine, water. Road networks and houses destroyed by hurricane Katrina

Economic impacts • Cost of repairs • Fixing or renovating buildings • Cost of damage • Damage to crops and buildings/ infrastructure • Loss of income • Income lost due to inability to work during period of tropical cyclone or damaged crops

Economic impacts • US$4 billion needed to repair infrastructure and provide humanitarian aid (eg medicine, water filter, tents etc) after Typhoon Nargis in Myanmar in 2008 . • Economic losses for countries affected by typhoons amount to US$26 billion annually, projected to increase to US$55 billion by 2100.

Social impacts • Disrupt water supply • Burst sewage pipes will contaminate water. • Damage to infrastructure disrupts supply of fresh water to people. • Spreading of diseases • Stagnant water allows mosquitoes to breed, aiding the spread of malaria and dengue. • Dirty water also results in water-borne diseases such as cholera and typhoid fever. • Displacement of people from homes • People lose their homes due to rising flood waters.

e. How do people respond to tropical cyclones? • Emergency action • Evacuation of people • Provision of emergency aid • Mitigation measures: strategies to reduce or avoid the impact of a hazard • Prediction and warning • Land use Control • Floodplain management • Reducing vulnerability of Infrastructure

Emergency action • Immediate action in response to a situation that poses an immediate risk to health, life, property or environment. • Evacuation of people: Community cyclone shelters are built near homes of people to protect them from tropical cyclones and provide them a place to live temporarily. People injured from Hurricane Katrina being evacuated

Emergency action Tents set up by the Federal Emergency Management Agency after Hurricane Andrew in 1992 • Provision of emergency aid by the government, neighbouring countries and non-governmental organisations • Provision of clothes, shelter, food, medicine • Repair damage to infrastructure

Mitigation measures: Prediction and warning • Prediction: • Analyse long-term climate records • Establish pattern and severity of past cyclones to predict future cyclones. • Analyse path of current cyclone through computer modelling • Establish the likely path the cyclone will take based on weather information • However these methods are limited • Warning • Allows people to evacuate in time • Japan and America has advanced prediction and warning systems, which allows people to evacuate way before tropical cyclones arrive

Mitigation measures: Land use control • Regulates the use of land by placing restrictions on how the land can be used • Developers pay higher taxes for use of land • Land which is vulnerable to tropical cyclones only used for recreation • Land converted into protected areas.

Mitigation measures: Land use Control • Limitations to land use control • Authorities need to be able to enforce the ruleswhich requires time and manpower • Residents along coastlines often reluctant to move out; government needs to buy back the land to turn the land into recreational areas, which is costly

Mitigation measures: Floodplain management • Floodplain management: masterplan to reduce the flood damage potential • Mapping risk levels of areas allows planners to: • Ensure new developments on floodplains are not prone to flooding • Reduce flood damage potential in already developed floodplains • Ensure people are able to evacuated quickly during floods.

Mitigation measures: Reducing vulnerability of infrastructure • Infrastructure needs to be able to withstand the impacts of tropical cyclones • Wind and water resistant buildings • Inspect river embankments and coastal dikes for wear and tear • Locate utility lines underground

Mitigation measures: Reducing vulnerability of infrastructure • Wind and water resistant buildings • Galvanised steel hurricane ties • Nailed to roof to secure it prevent it from being blown off during typhoons. • Secondary water resistant layer • Added to roof to prevent leaking should roofs be blown off • Effectiveness seen in when houses with these improvements in Florida, USA, survived Hurricane Wilma with little damage in 2005.

Mitigation measures: Reducing vulnerability of infrastructure • Protective barriers: river embankments and coastal dykes. • Prevent water from overflowing river banks and also prevent surging waves from moving inland • However, regular inspection and expensive maintenance are needed for these measures to be effective

f. Example: Tropical Cyclone Yasi When and where did Tropical Cyclone Yasi occur? • One of most significant tropical cyclones in the Pacific Ocean

f. Example: Tropical Cyclone Yasi What were the weather conditions and the damages inflicted by Tropical Cyclone Yasi? • Category 5 tropical cyclone on Saffir-Simpson Hurricane Scale • Meaning wind speeds of > 200km/h • Yasi hit 290km/h • Caused serious damage to the country (cost of damages up to US$3.5 billion)

f. Example: Tropical Cyclone Yasi What were the weather conditions and the damages inflicted by Tropical Cyclone Yasi? • Heavy rainfall • 200–300 mm in 24 hours (similar to what Singapore receives in its rainiest month, December!) • Widespread flooding from storm surges • Significant storm surge of 5.5 m in Cardwell • Power supply cut • Took 1 month to restore all power due to the sheer number affected (170,000 homes) • Crops destroyed • Banana and cane fields, wiped out 75% of Australia’s crop production.

f. Example: Tropical Cyclone Yasi How effective were the measures adopted to mitigate the impact of Tropical Cyclone Yasi? • Despite being a category 5 storm, death toll was low due to high level of disaster risk awareness and preparedness.

f. Example: Tropical Cyclone Yasi

f. Example: Tropical Cyclone Yasi • Increasing number of tropical cyclones and increasing number with category 4 or 5 intensity storms. • Linked to rise in global sea surface temperatures which is a condition needed for cyclone formation • Despite improvements in prediction, tracking and preparation for cyclones, damage is always unavoidable. • As favourable conditions for tropical cyclones will always exist, they are a challenge we always need to be prepared for.

CHAPTER 3 VARIABLE WEATHER AND CHANGING CLIMATE A Continuing Challenge?