Extreme Weather W hat is happening to the world’s weather From all parts of the globe reports are coming in of strange weather events that have never happened before On August 16 2004 the villages of Boscastle and Crackington Haven in Cornwall in England experienced flash floods Torrential rainfall 1 inch 24 mm in just 15 minutes led to a 6-foot 2-m rise in river levels in an hour A 10-foot 3-m wave traveling almost 10 mph 16 km h surged down the main road wrecking stores and houses uprooting trees and carrying cars out to sea A heap of cars in the village of Boscastle in Cornwall after the flood in August 2004 4
Hurricane Katrina was one of the five deadliest hurricanes in the history of the United States The hurricane formed over the Bahamas crossed Florida and then strengthened rapidly over the Gulf of Mexico On the morning of August 29 2005 Katrina hit New Orleans flooding more than 80 percent of the city Its wind speeds reached 175 mph 280 km h and at least 1,830 people lost their lives In February 2009 wildfires swept through the state of Victoria in southern Australia destroying entire towns More than 1,800 houses were burned down leaving 7,000 people homeless The fires caused such extensive damage because the land was very dry following a week of unusual extremely hot weather Daily temperatures had been almost 115 F 45 C every day of the preceding week and even the nighttime temperatures never dropped below 86 F 30 C Hurricane Katrina swirls over the Gulf of Mexico shortly before hitting the southern coast of the U S on August 29 2005 Extreme weather events like these have always occurred from time to time But many places now seem to be experiencing them on a more regular basis some areas are hotter some are drier the storms are much stronger the rain more torrential Is the world’s climate actually changing Why is it happening and what can we do about it Firefighters battle with bushfires in southern Victoria in Australia in February 2009
What Is Climate C limate is the average weather in a place over a long period of time Many things combine to create the climate of a place how much sunshine it gets how close to the equator it is how high it is and how close to the sea Air ice water and even living things all play a part The Climate System The movement of heat and water around the air water and land is called the climate system It starts with the Sun warming the Earth which then warms the atmosphere The atmosphere keeps the Earth from becoming too hot or too cold Water is constantly moving between the land and the atmosphere It evaporates from the oceans lakes and rivers and forms clouds and returns to the ground as rain snow or hail 6
Climate Zones The surface of the Earth can be divided into different zones or biomes depending on what climate it has Between the Tropic of Cancer and the Tropic of Capricorn is an area known as the tropics Climates here can be hot and wet as in tropical rain forests or hot and dry as in the Sahara Desert As you go farther away from the Equator the climate gets cooler These areas have temperate climates characterized by grasslands and forests For example the taiga biome stretches across a large part of Canada Europe and Asia It consists of mainly coniferous forests In this biome summers are short and mild and the winters are long cold and dry The areas around the North and South Poles have frozen polar climates Although they can be very sunny in summer the temperature never rises above freezing The Human Effect Many factors can cause the Earth’s climate to change Usually these changes take place over thousands of years Today scientists believe that the actions of humans are causing our climate to alter in a much faster way Before we can consider if this is true we need to look at how the Earth’s climate has changed in the past and the natural causes of climate change Tropic of Cancer Equator Tropic of Capricorn The savannah biome covers much of central Africa It consists of grasslands with bushes and low trees
