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Write down 5 key words to summarise these pictures. Global warming intro…. Learning outcomes All of you should be able to: Identify the different greenhouse gases (GHGs) Most of you should be able to: Describe the role of greenhouse gases (GHGs) in maintaining mean global temperature.
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Global warming intro… Learning outcomes All of you should be able to: • Identify the different greenhouse gases (GHGs) Most of you should be able to: • Describe the role of greenhouse gases (GHGs) in maintaining mean global temperature. • Describe how human activities add to greenhouse gases (GHGs)
Greenhouse gases Which of these gases are greenhouse gases? • water vapour (H2O) • carbon dioxide (CO2) • methane (CH4) • nitrous oxides (N2O) • ozone (O3) • CFC’s • (Greenhouse gases) trap the radiation from the sun that is reflected back from the Earth.
Source: Solcomhouse.com About 45% of the incoming light is reflected before it reaches the surface. 51% is absorbed by Earth’s surface and 4% is reflected.
The Greenhouse Effect • Essential for life to exist on the planet. • Without it the planet would be 33°C cooler. HOWEVER • As humans increase emissions of some GHGs the greenhouse effect is exaggerated or enhanced. • Most climate scientists believe that this is causing global warming and climate change.
Recall… • Describe the greenhouse effect? • Explain the process? • Give 3 examples of a greenhouse gas.
The concentration of carbon dioxide in the atmosphere from 1958-2004
carbon dioxide temperature
NASA’s Goddard Institute for Space Studies. (2006) “Global temperature change”. Proc. Natl. Acad. Sci. 103: 14288-14293. Following the common practice of the IPCC, the zero on this figure is the mean temperature from 1961-1990. As you can see... global temperatures are rising!
Changes in carbon dioxide concentrations during the Phanerozoic era. Three estimates are based on geochemical modelling: GEOCARB III (Berner and Kothavala 2001), COPSE (Bergmann et al. 2004) and Rothman (2001). These are compared to the carbon dioxide measurement database of Royer et al. (2004) and a 30 Ma filtered average of those data. Error envelopes are shown when they were available. The right hand scale shows the ratio of these measurements to the estimated average for the last several million years (the Quaternary). Courtesy: Robert A. Rohde, Global Warming Art
Explanations for these trends? • The onset of global industrialisation and pollution derived from fossil fuels • Deforestation (particularly of rainforest) • Volcanic activity • Sunspot activity Assume a link between carbon dioxide emissions and temperature increase Suggest possible natural phenomena that may have increased temperatures.
Think, pair, share What do you think are the main human activities releasing GHGs? Hint: use your knowledge of what the main GHGs are.
The direct warming influence of all long-lived greenhouse gases in the atmosphere today attributable to human activities. CO2’s warming influence of 1.7 watts/m2 is equivalent to the heat from nearly 9 trillion 100-watt incandescent light bulbs placed across Earth’s surface. The combined influence of the non-CO2 greenhouse gases is equivalent to the heat from about 5 trillion bulbs. The category “other” includes a few very long-lived chemicals that can exert a climate influence for millennia. (Credit: NOAA - National Oceanic and Atmospheric Administration)
Checking outcomes All of you should be able to: • Identify the different greenhouse gases (GHGs) Most of you should be able to: • Describe the role of greenhouse gases (GHGs) in maintaining mean global temperature. • Describe how human activities add to greenhouse gases (GHGs)
Confirm you know them… • What are 4 greenhouse gases? • Describe how GHGs maintain the mean global temperature? • List at least 4 human activities that add to GHGs. • Describe how each one adds to GHGs.