1. Climate Cycles
&
Recent Climate Change

2. Earth experiences many climate changes in its history
Earth experiences many climate changes in its history. Scientists use evidence from ice cores, or ice drilled from layers in glaciers, fossilized pollen, ocean sediments and growth rings of trees to gain information on past climates. Long-Term Cycles Ice ages – long cold periods lasting from hundreds to millions of years when glaciers cover much of Earth Interglacial – long warm periods that occur between ice ages

3. Short Term Cycles Seasons – short periods of climate change due to amount of solar energy an area receives during different times of the year El Niño – an occasional climatic event (occurs every 3-8 years) in which the trade winds weaken, reversing the normal pattern of high and low pressures across the Pacific Ocean monsoon – a wind circulation pattern that changes directions with the seasons

4. Recent Climate Change Average temperature on Earth has been increasing for the past 100 years, which is often referred to as global warming greenhouse gases – gases in the atmosphere that absorb Earth’s outgoing infrared radiation; higher levels of greenhouse gases which include carbon dioxide (CO2) create greater greenhouse effect

5. Humans have impacted climate change:
burning of fossil fuels increases amount of carbon dioxide
deforestation – the large-scale cutting and/or burning of forests which also increases carbon dioxide
aerosols – tiny liquid or solid particles released from burning of fossil fuels which prevent Sun’s energy from reaching Earth

6. Dendroclimatology