"GLOBAL CLIMATE CHANGE"
GLOBAL CLIMATE CHANGE - Mr. Nolan Name: _________________ GREENHOUSE EFFECT (UV Energy Input vs. IR Energy Output) Q) What is the Greenhouse Effect? Solar light energy passes through Earth’s atmosphere. This light energy is known as ultraviolet (UV) energy. When UV light energy hits the Earth, most of it is converted into heat energy, known as infrared (IR) energy. Some of this infrared heat energy is absorbed by Earth’s land and water masses; and some of the IR heat energy is radiated up from the Earth into the atmosphere. Greenhouse gases (GHGs) in the atmosphere trap some of the heat energy the Earth emits and prevents it from radiating out into space. This heat trapping adds more heat to the lower atmosphere and the Earth’s surface. In fact, without the greenhouse effect, the average global temperature would be 60oF colder than it is today and there would be no life on Earth. However, as you add more GHGs, you trap more heat and increase global temperatures. You experience all this when you sit in a car on a sunny day with the windows closed. UV energy hits the dashboard and seats and is converted to IR/heat energy. These materials radiate heat, causing the interior of the car to get warmer. Some of the heat escapes through the glass and metal, but some is also trapped inside the car. 1 GREENHOUSE GASES The major greehouse gases (ranked in order of global heat trapping impact) are: #1) Water vapor #2) Carbon dioxide #3) Methane As the graph below shows, atmospheric concentrations of human-source greenhouse gases have increased enormously during the last 150 years since the industrial revolution when humans began burning fossil fuels like coal, oil, gasoline, and natural gas (methane). BURNING FOSSIL FUELS GENERATE CARBON DIOXIDE What are fossil fuels made of? And, why does burning them release carbon dioxide? Here’s a balanced formula for combustion of coal: 2(C10H2) + 2102 --> 2H20 + 20CO2 The common chemical formula for gasoline is C8H18. Burning it gives you: C8H18 + 12.5 O2 ---> 9 H2O + 8 CO2 Natural gas (methane) for gas stoves and furnaces: CH4 + O2 --> CO2 + H2O (unbalanced reaction) Heating oil is very similar to diesel fuel. Heating oil's chemical formula is between C14H30 and C20H42. And why does burning fossil fuels release carbon dioxide (CO2)? It’s just like breaking down C6H12O6 into CO2 and H20 during cellular respiration. Break bonds of bigger molecules to get the energy. The by-products are smaller molecules made up of the same atoms. 2 RECENT GLOBAL WARMING As the concentration of greenhouse gases (GHGs) in the atmosphere increases, they prevent more IR heat energy from escaping into space. It is something like having a thicker blanket covering you. As the graph below shows, over 100 years, Earth has experienced a correlated global average temperature increase or approximately 1.4oF. The rate of warming is increasing. In fact, 11 of the warmest years in recorded history have occurred in the past 13 years. REGIONAL VARIATIONS IN WARMING As shown in the figure below from Accuweather, not all regions warm the same. For example, the poles are warming faster than the equator. Central Canada is warming faster than other regions. Southern Africa and Argentina have even cooled slightly. Variations have numerous causes, ranging from air and ocean currents, and impacts of forests. This figure compares September 2009 with the average for the period 1951- 1980 by region. 3 POPULATION CHANGE & THE CLIMATE CRISIS What happens when you have: 1) a rapidly increasing human population …and 2) every year each individual releases more GHG emissions? Answer: Global GHG emissions increase every year due to: (1) rapid population increase, and (2) annual increases in per capita GHG emissions. (“per capita” means per person) 4 POPULATION STATISTICS World Population in 1900 = 1.6 billion World Population in 2008 = 6.7 billion (FYI: US Population = 305 million) World Population estimate for 2050 = 9.3 billion The world population has grown significantly in the 20th century and is projected to grow exponentially in the 21st century mostly in the developing regions. Population growth is simply due to a reduced death rate relative to birth rate. The three main causes of the reduced death rate are: Increased food production and distribution Improved public health Improved medical technology Q) What are main implications of population growth? More people consuming more fossil fuels per person = more GHG emissions. Decreasing availability of adequate food, water, safe shelter, and income. Why is Human Population Growth So Catastrophic? “At the root of all the converging crises of the World Problematique is the issue of human overpopulation. Each of the global problems we face today is the result of too many people using too much of our planet's finite, non-renewable resources and filling its waste repositories of land, water and air to overflowing. The true danger posed by our exploding population is not our absolute numbers but the inability of our environment to cope with so many of us doing what we do. “It is becoming clearer every day, as crises like global warming, water, soil and food depletion, biodiversity loss and the degradation of our oceans constantly worsen, that the human situation is not sustainable. Bringing about a sustainable balance between ourselves and the planet we depend on will require us, in very short order, to reduce our population, our level of activity, or both. http://www.paulchefurka.ca/Population.html Deforestation & Desertification Starvation 5 WHO IS PRODUCING ALL THESE GREENHOUSE GASES? Americans burn far more green house gases per capita than people of other nations. Annually Americans produce 20 tons CO2 per capita Most Europeans produce <10 tons Chinese produce 4 tons India per capita is 1 ton. As China and India are developing rapidly, so is their energy production. Total emissions from China have just surpassed that of the U.S. As India develops, and has an enormous, predominantly rural, population explosion, its total emissions may also surpass the US in the more distant future. http://rainforests.mongabay.com/09-carbon_emissions.htm Still, on a per capita basis, the Chinese and Indians release far fewer GHG’s than Americans. They individually hold far less responsibility for global warming than you do. 6