The Greenhouse Effect. Stephanie Seto. The Carbon Cycle. Changes in Atmospheric Carbon Dioxide Level.
The Greenhouse Effect Stephanie Seto
Changes in Atmospheric Carbon Dioxide Level • Since the Industrial Revolution (1800’s), humans have increased quantities of carbon dioxide from factories, transportation, fossil fuels (coal and oil), and burning forests to make way for farmland. • Human pollution has produced enough carbon dioxide to raise its percentage in the planet’s atmosphere. • Estimated over 25% increase since pre-industrial revolution
Plants, phytoplankton, and photosynthetic bacteria are generally more active in the summer, during which more carbon dioxide is removed from the atmosphere. • NASA graph shows in 47 year time period, there has been a 19.4% increase in the mean annual concentration of carbon dioxide
The Enhanced Greenhouse Effect • There is already a natural greenhouse effect that occurs, but human pollution intensifies this, causing the overall temperature to increase; otherwise known as global warming. • How a greenhouse works: Sunlight enters through glass, reaches plants and becomes heat, heat is trapped.
The Enhanced Greenhouse Effect (Continued) • 1. Sunlight enters atmosphere because gases of atmosphere are transparent to light. • 2. Light energy is converted into heat energy and warms the Earth. Most of this heat radiates back into the atmosphere. • 3. Greenhouse gases retain some heat and trap it in the atmosphere. • 4. Earth’s natural greenhouse effect is that the atmosphere is warmer than outer space.
Greenhouse Gases • Carbon dioxide, methane, and oxides of nitrogen • Human production of greenhouse gases is increasing • Human activities that produce oxides of nitrogen: - burning fossil fuels (gasoline in cars) and using catalytic converters for their exhaust systems • The use of organic and commercial fertilizers to improve the growing of crops. • Industrial processes (production of nitric acid)
Greenhouse Gases (continued) • Methane has flammable properties which are useful for cooking and heating • Human activities that produce methane (CH4): • Cows and bulls produce methane in their digestive processes. • Waste disposal in landfills (organic wastes like uneaten food decompose and release methane) • Production and distribution of natural gas (when made for use in homes, leaks in containers release methane into the air)
Impacts of Global Warming • Human activity intensifies Earth’s natural greenhouse gases to a point where it can be thrown off balance • This could potentially cause: • Increase in photosynthetic rates • Change in climate with varying effects on ecosystems • Extinction of certain species • Melting of glaciers • Rise in sea level leading to flooding in costal areas
The Precautionary Principle • In 1988, The Intergovernmental Panel on Climate Change (IPCC) set out to find if human activities have an impact on climate. • Conclusions: • Global temperatures are increasing; global warming is confirmed. • There is over a 90% chance that the cause is the production of greenhouse gases by human activity. The chance that it is caused by natural phenomena is less than 5%. • Sea levels are expected to rise between 18cm and 59cm. • Increased likelihood of severe weather (heat waves, drought, heavy rains, etc.) The research does not indicate whether this will have an effect on ecosystems or how severe the consequences may be.
The Precautionary Principle (continued) • The precautionary principle is an “ethical theory” that action should be taken to prevent harm to the environment, even if there is not sufficient evidence that the activity will have severe negative consequences. • If people want to engage in any potentially harmful activity, they must first find evidence that it will not cause harm. • Without this, industries and consumers tend to proceed until it is clear that harm is being done to the environment.
Evaluation of the precautionary principle • Farmers, manufacturers, and transportation providers wonder why they should invest in using new and expensive techniques to reduce greenhouse gases if there is not sufficient evidence of harmful consequences. Industries that do invest make themselves less economically viable than their competitors. • Unless all companies take preventive action, there will always be polluting competitors that will offer products at a lower price, thus driving the eco-friendly companies out of business. • Well-informed customers are more likely to choose eco-friendly companies, which, if done on a larger scale, would drive companies that are not eco-friendly out of business.
Evaluation of the precautionary principle (continued) • Scientists say that money invested in taking preventive action is not wasted; it is better to stop the problem in its tracks than to try and fix it. • However, there is an ethical dilemma: many of those who suffer the global warming consequences are not the ones creating and contributing to the problem. This also includes the organisms in the biosphere which are negatively affected by human activity.
Human Impact on Arctic Ecosystems • The Arctic includes: the arctic ocean, parts of North America, Greenland, Iceland, Norway, and Russia which are north of the arctic circle. • Changes in ecosystems: • more ice is melting every year • Less snow and more frozen rain in winter • Regions that never had them before are populated with mosquitoes • Certain woody shrubs are growing on warmer soils where there used to be moss and lichens on tundra • Bird species, such as robins, have migrated to areas where they are so foreign to the local people that they have no name for them in their language.
Human Impact on Arctic Ecosystems • A consequence of global warming on the Arctic is that it is changing the ecosystems. For instance, ice has the capacity to support algae on its underside. The surface area allows for the algae to attach and the transparency of ice allows sunlight to pass through, making photosynthesis possible. Since algae are important in Arctic ecosystems, any decrease in their population would cause harm to the rest of the food web. • Polar bears rely on seals for hunting. Their way of hunting is by standing on ice near a hole so they can catch the seal when it comes out. The melting of ice makes this more difficult, as seals have more open places for air. • As temperatures rise, habitats of organisms extend northwards. With new species arriving, it is likely that more pathogens will come about.