Increasing levels of Extreme Weather

Extreme weather events classified as hydro-meteorological hazards by the Emergency Events Database.

Increase in reported extreme weather

• Frequency (how often)
• Magnitude (size)
• Impact (amount of damage)

Flood events

• Coastal river and flash flooding
• 10% of land surface is very flood prone
• Flood prone land contains 40% of the world's people.
• Areas include Midwest USA, coastal South America, Bangladesh and Northern England.

Storms

• Mainly tropical cyclones (hurricanes, typhoons)
• Can include tornadoes and temperate storms
• Concentrated in tropical belts, especially coastal areas covering 7% of the world's area but 24% of the world's population.

Droughts

• A drought is when there is less than 50% median rainfall over 3 or more months
• Often includes extreme,heat,wildfires and the secondary hazard of famine
• Affects 40% of the world's land surface containing 70% of the population and 70% of agricultural production

Slides

• Can be a secondary hazard resulting from extreme weather (e.g. heavy rain or snowfall. Includes avalanches)
• Affects 5% of the world's population

What are the reasons for the increasing level of extreme weather?

• More reporting because of improved communication
• Different methods of recording events
• Population growth leads top densely populated hazard prone areas
• Deforestation and land degradation, increasing magnitude of floods and droughts
• Climate Change has an impact on extreme weather but there are other contributing factors

Risky Sea Levels

The IPCC (Intergovernment Panel for Climate Change) predicted the sea level rise for 2080

• Low Emission Scenario-9.48cm
• High Emission Scenario-16.69cm

Whatever happens sea levels will rise.

Causes (Key factors associated with climate change):

• Warming ocean-water expands and more precipitation (Thermal expansion).
• Exchange of water stored on land as glaciers and ice caps with ocean water.
• Sea levels could rise up by 7 metres if Greenland melted entirely.
• Glacial retreat

Impacts:

• The weight of ice cover caused crust to sink-creating a see-saw effect
• Out of the 15 largest cities-13 of them will be affected by sea level rise as they are on the coast
• Sea level rise in the UK will affect the South and East of the UK which would cause flooding and coastal erosion
• Small islands in the Pacific and Indian Oceans will be affected the most

Geometry of the Oceans

The oceans influence climate over long and short time scales. The oceans and the atmosphere are tightly linked together to form the most dynamic component of the climate system. The oceans play a critical role in storing heat and carbon. The ocean's waters are being constantly moved by powerful currents which are mainly wind-driven. These currents influence the climate by transporting heat. Currents involved in 'deep-water formation' are particularly important for climate. Apparently a small change in just one aspect of the ocean's behaviour can produce major climate variations over large areas of the Earth.

Thermohaline Circulation

What is it?

Thermohaline circulation is a part of the large-scale ocean circulation that is driven by global density gradients created by heat and fresh water fluxes. It is also known as the ocean conveyor belt, great ocean conveyor or the global conveyor belt. It supplies heat to the polar regions and regulates the amount of ice in those regions.

In 2005, the net flow of the Northern Gulf Stream had decreased by 30% since 1957.

Thermo-Heat
Haline-Salt Content