YES EVIDENCE THAT EARTH’S CLIMATE IS CHANGING• The polar ice caps are melting• Sea level is rising 1993• Extreme weather events 2000 Mount Kilimanjaro in February Artic Sea Ice in September
WHAT COULD BE CAUSING THESE CHANGES?• POLLUTION • Cars and factories emitting carbon dioxide
CARBON DIOXIDE CONCENTRATION: THEN ANDNOW• Then (over the past 650,000 years) • The concentration varied between a low of 180 ppm and the highest being 300 ppm• Now (last decade) • Concentration of CO2 has rapidly increased and is now at 379 ppm
It usually takes about 5,000 years for an 80 ppm increase in CO2 concentration
Rise in the temperature matches the rise in CO2 concentration after 1950
CLIMATE: THEN AND NOW• Climate change is a gradual process• Then: • Medieval times were warm, and in the 17 th 18th and 19th century it began to cool• Now: • Global temperatures are increasing at a very rapid rate
CONCLUSIONIt is not unusual for the climate to change, but how fast and why it is changing is what is unusual.