1. P2c(i) Global Warming You will learn about: How atmospheric gases prevent heat radiating into space Where greenhouse gases come from www.PhysicsGCSE.co.uk

2. Global Warming Scientists have calculates the mean average global temperatures between 1951 and 1980. They then looked at the data for global temperatures for July 2010. Orange and red show temperature increases and blue and purple temperature decreases. Alarmingly some areas have risen by as much as nearly six degrees Celsius. www.PhysicsGCSE.co.uk It is now more common than ever to see tropical fish in much cooler waters. The warming of the oceans is causing some fish to migrate to places never been seen before. Environmental scientists are worried that if the global temperatures are to rise even more then we will see catastrophic events. These include strange weather patterns, sea level rises and flooding to name just a few.

3. It is easy to forget water vapour as a greenhouse gas. But it is the most significant greenhouse gas where practically all of it occurs naturally. Half of the greenhouse effect is due to water vapour and another quarter is due to clouds! Amazingly, we only contribute around 0.001 % of water vapour into the atmosphere. www.PhysicsGCSE.co.uk Greenhouse Gas Origins: Water Vapour Greenhouse gases from a variety of sources. Some are natural and some are manmade. The main three are water, carbon dioxide and methane.

4. Greenhouse Gas Origins: Carbon Dioxide www.PhysicsGCSE.co.uk Natural forest fires, volcanic eruptions, decay of biomass, evaporation of oceans and respiration by animals all produce carbon dioxide, a greenhouse gas, into our atmosphere. When the Earth first formed our atmosphere was mostly carbon dioxide. Over the last few hundred million years carbon dioxide levels have decreased due to photosynthesis by plants. However, in the 18 th Century the Industrial Revolution began. Burning fossil fuels increases the amount of carbon dioxide in out atmosphere and levels are now rising again. Today, natural sources release approximately 150 billion tonnes of carbon dioxide every year. The UK produces, from power stations, 150 million tonnes of carbon dioxide each year whereas the world produces a staggering 7 billion tonnes. If all the carbon dioxide emissions stopped right now it would take plants hundreds of years to absorb enough to reduce levels to below the Industrial Revolution.

5. Sometimes organic matter decays without oxygen being present. Methane is then produced. www.PhysicsGCSE.co.uk Greenhouse Gas Origins: Methane There are many ways that methane is released into our atmosphere. The natural sources are: Wetlands Termites Oceans The manmade sources are: Mining and burning of fossil fuels Digestive processes of cows (and other cattle) Rice paddies Waste buried in landfills

6. What does the data suggest? These three graphs show a worrying fact. Since the Industrial Revolution atmospheric carbon dioxide and methane have increased dramatically. As a result the global temperatures have also increased. If we do not act together what will the future hold? www.PhysicsGCSE.co.uk REMEMBER: You must be careful with data. Make sure you can rely on where it came from.

7. The Greenhouse Effect The Sun is very hot and emits short wavelength infra-red radiation. This has enough energy to pass through our atmosphere to the land. The earth re-radiates this infra-red radiation upwards. But because the earth is much cooler than the sun the infra-red radiation has a longer wavelength. It is this long wave infra-red radiation which cannot pass through the greenhouse gases in our atmosphere. Most of it is re- radiated back to the earth and the cycle continues all along warming the earth and the atmosphere. The same thing happens when you sit in a car on a hot day and leave the windows closed. The infra red radiation goes in to the car and cannot escape warming the inside of the car. www.PhysicsGCSE.co.uk

8. Questions 1.Look at the image above. What do you think it is trying to get across? 2.What is a greenhouse gas? 3.Look at the table below. Methane has an effect 21x greater than carbon dioxide so its pre-industrial baseline is (21 x 848) = 17,808 ppb. The relative total contribution of other gases is 104,011 ppb. Compared to carbon dioxide what is the relative total concentration of methane? Calculate the relative percentage contributions from carbon dioxide, methane and other gases. www.PhysicsGCSE.co.uk Greenhouse GasConcentration in parts per billion (ppb) Pre-Industrial Baseline Natural Additions Man-made additionsTotal Concentration% of total greenhouse gases CO 2 288,00068,52011,880368,40099,438 CH 4 8485773201,7450.471 other31012173390.091 total289,15869,10912,217370,484100.000

9. Questions 1.Look at the image above. What do you think it is trying to get across? If global warming continues the ice caps will melt and sea levels will continue to rise. This would flood any low lying countries, islands or cities. 2.What is a greenhouse gas? A gas that contributes to the greenhouse effect by absorbing infrared radiation. 3.Look at the table below. Methane has an effect 21x greater than carbon dioxide so its pre-industrial baseline is (21 x 848) = 17,808 ppb. The relative total contribution of other gases is 104,011 ppb. Compared to carbon dioxide what is the relative total concentration of methane? Calculate the relative percentage contributions from carbon dioxide, methane and other gases. www.PhysicsGCSE.co.uk Looking at the table: Methane’s relative total concentration compared to carbon dioxide will be 21x more. So 21 x 1,745 = 36,645 ppb. So Total Concentrations are: Carbon dioxide : 368,400 ppb Methane : 36,645 ppb Other : 104,011 ppb(given in question) Total : 509,056 ppb Now we need to calculate the relative percentage contributions: Relative percentage contributions: Carbon dioxide : (368,400/509,056)x100 = 72.4% Methane : (36,645/509,056)x100 = 7.2% Other : (104,011/509,056)x100 = 20.4% Greenhouse Gas Concentration in parts per billion (ppb) Total Concentration % of total greenhouse gases CO 2 368,40099,438 CH 4 1,7450.471 other3390.091 total370,484100.000