Discuss the relationship between climate and biomes. 1.2 What are the temporal patterns of climate change? • Short term climate change • Long term climate change Today • How has climate changed in the past? • How do we know climate has changed in the past? • Past • Present • Future Characteristics of ice ages: Characteristics of interglacial: • Climate changes naturally through a series of cycles. Colour code the causes to differentiate between human and physical causes Key Question: • What is short term climate change? Causes of short term climate change Individually these mechanisms cannot explain the Little ice age but a combination of these and other factors will have caused cooling: » Volcanic eruptions » Variations in solar energy » An increase in the Albedo Volcanic eruptions: • Can effect climate for a year or two • They inject large quantities of sulphur dioxide and dust into the stratosphere • Aerosol effect- incoming solar radiation is reflected. Variations in solar radiation • 11 year cycle of sunspots • During LIA, there was a decrease in sunspots Increase in Albedo • Low temperatures cause more snow and ice. • This causes positive feedback • http://www.ngfl-cymru.org.uk/vtc/ngfl/200708/geog/G1%20Climate%20change/index. html • http://www.ngfl-cymru.org.uk/vtc/200910/geog/climate-change/eng/ • http://www.wjec.co.uk/uploads/publications /8369.pdf Short-term climate change Short-term climatic disruptions that some people think are becoming more frequent and intense because of global warming. La Nina • El nino Refers to warmer than average waters in the eastern Pacific. • La nina: Refers to colder than average waters in eastern Pacific These events distort jet stream flows Short-term climate change • http://www.ngfl-cymru.org.uk/vtc/200910/geog/climate-change/eng/short-termclimate-change-1-global.html Long-term climate change In the last billion years there have been 6 or more ice ages lasting between 100-300 years. Between these ages there have been periods of global warming referred to as inter-glacial periods. These periods are much shorter in time length. Vostok ice core What mechanisms influence Earth’s climate on this scale. Milankovitch theory The Milankovitch theory is an explanation of long term climate change. Precession is the change in orientation of the Earth's rotational axis. In simple terms precession is simply a wobble. Obliquity is the variation of the tilt of the earth's axis away from the orbital plane. The tilt varies between 22.1° and 24.5° and the average is 23.5°. Eccentricity is a term used to describe the shape of Earth's orbit around the sun. The variation of Earth's orbit around the sun ranges from an almost exact circle to a slightly elongated shape. Geometry of the Oceans Thermohaline circulation