CHAPTER ONE EARTH’S CHANGING CLIMATE Climate is the normal weather in a city or region over a long period of time The climate in Phoenix Arizona is hot and dry while the climate in Antarctica is dry and very cold Earth’s climate is the average of all the regional climates around the world Arizona has a hot climate year-round while Antarctica’s climate is very cold 4
Climate can change over time The average summer temperature for a city could rise for example Or the average annual snowfall for a region could fall The climate of the planet can change too An area of cold air meeting an area of warm air brings in a storm CLIMATE VS WEATHER Weather refers to short-term conditions such as if it is rainy or sunny outside Weather can change quickly The morning weather may be dry while the afternoon can bring a thunderstorm Climate can change too but it doesn’t change quickly the way weather does 5
Hemispheric Temperature Change Northern Hemisphere 5 Yr Mean Southern Hemisphere 5 Yr Mean Temperature Anomaly °C 1880 1900 1920 1940 1960 1980 2000 Most climate scientists agree that Earth's climate is growing warmer They tell us that Earth's average temperature has risen by about 1 4 degrees Fahrenheit 0 8 degree Celsius since 1880 6
Cordilleran Ice Sheet Laurentide Ice Sheet FROZEN PLANET Earth’s climate has changed many times in the past Over the last two million years huge ice sheets have spread over the Earth and shrunk back several times Climate can change from natural events Earth’s climate can change from a large volcanic eruption for instance or from slight changes in the amount of energy from the sun Gases released from a volcanic eruption can change the climate 7
