Climate and Change *Celsius 1 = 33.8 Fahrenheit

How and why has climate changed in the past? To understand that climate has changed in the past through natural causes, on timescales ranging from millions to hundreds of years. To begin to appreciate the Geological Time Scale Carbon dioxide and temperature levels over the last 800,000 years Changes in the Earth’s average temperature & projections. www.epa.gov www.epa.gov Sources of evidence for climate change taken from tree, sediment, ice & coral cores.

Ice cover in the last Ice Age anthro.palomar.edu A glacial period (or alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate between glacial periods. The last glacial period ended about 15,000 years ago; The Holocene epoch is the current interglacial.

Normally the Greenhouse Effect is like a blanket – you wouldn’t want to take it off because you would be too cold – however putting another blanket on would make you too hot. The human-produced greenhouse gases are like this extra blanket, resulting in what is called the Enhanced Greenhouse Effect. Gasses % of gas produced Sources Warming power compared to carbon dioxide % increase since 1850 Carbon dioxide 89% Burning fossil fuels (coal, oil, gas), deforestation which produces carbon dioxide 1 + 30% Methane 7% Gas pipeline leaks, rice in paddy fields, cattle farming. 21 times more powerful + 250% Nitrous oxide 3% Jet aircraft engines, cars and lorries, fertilisers and sewage farms. 250 times more powerful + 16% Halo-carbons 1% Used in industry, solvents and cooling equipment. 3000 times more powerful Not natural www.nps.gov Year ppm 1800 1820 1840 1860 1880 1900 1920 1940 1960 1980 2000 CO2 280 282 283 287 291 295 299 310 323 347 386 Methane 700 713 727 756 796 835 871 980 1430 1656 Nitrous oxide 270 271 275 276 286 290 294 304 311 318

What causes changes in climate? Natural Human The Earth’s atmosphere is affected by changes in the lithosphere, as well as by cosmic influences such as; the Sun’s activity (sunspots), variations in the Earth’s orbit (circular to elliptical), and volcano activity (Pinatubo-1991; sunlight reduced 10%, global temperature reduced 0.5o). GHG: The most abundant greenhouse gas (GHG) is water vapor. Carbon Dioxide is emitted from volcanoes, hot springs, geysers and other places where the earth's crust is thin. Humans effect changes in climate through the production and transport of coal, natural gas & oil, the decomposition of organic wastes in landfill sites, agricultural and industrial activities & combustion of solid waste & fossil fuels. Compound Formula % Water vapor and clouds H2O 36 – 72%   Carbon dioxide CO2 9 – 26% Methane CH4 4 – 9%   Ozone O3 3 – 7%  

5 Minute Quiz Describe some of the evidence that tells us climate was different in the past. What is the length of time between now and the previous warm period of time?...and the one before that…and before that… Describe the variations in the temperature graph. Does the Earth warm up faster, or cool down faster? How closely are temperature and carbon dioxide levels linked? Look at the map of the ice sheets – Ice cover in the last ice age. Which parts of the land were covered by ice 20,000 years ago, and are now ice free? Explain the significance of the Quaternary period? Which of the Greenhouse Gases is most common through natural processes & human activity? Extrapolation: What is a climatologist?