Chapter 19 lecture

Chapter 19 Global Change Global change- any chemical, biological or physical property change of the planet. Examples include cold temperatures causing ice ages. Global climate change- changes in the climate of the Earth. Global warming- one aspect of climate change, the warming of the oceans, land masses and atmosphere of the Earth. Global Change When radiation from the sun hits the atmosphere, 1/3 is reflected back. Some of the UV radiation is absorbed by the ozone layer and strikes the Earth where it is converted into low-energy infrared radiation. The infrared radiation then goes back toward the atmosphere where it is absorbed by greenhouse gasses that radiate most of it back to the Earth. The Greenhouse Effect Water vapor Carbon dioxide Methane Nitrous oxide Ozone Greenhouse Gases Volcanic eruptions- mainly carbon dioxide Methane – from decomposition Nitrous oxide- from denitrification Water vapor Natural Greenhouse Gases Burning of fossil fuels Agricultural practices Deforestation Landfills Industrial production- CFC’s are an example Anthropogenic Causes of Greenhouse Gases David Keeling began measuring CO 2 in 1958. Increasing CO2 Concentrations Emissions from the Developed and Developing World Since 1880 temperatures have increased 0.8°C. Global Temperatures since 1880 No one was around thousands of years ago to measure temperatures so we use other indirect measurements. Some of these are Changes in species compositions Chemical analyses of ice Temperatures and Greenhouse Gas Concentrations in Past 400,000 Years We know that an increase in CO2 in the atmosphere causes a greater capacity for warming through the greenhouse effect. When the Earth experiences higher temperatures, the oceans warm and cannot contain as much CO2 gas and, as a result, they release CO2 into the atmosphere. Putting It Together Feedbacks Melting of polar ice caps, Greenland and Antarctica Melting of many glaciers around the world Melting of permafrost Rising of sea levels due to the melting of glaciers and ice sheets and as water warms it expands Heat waves Cold spells Change in precipitation patterns Increase in storm intensity Shift in ocean currents Consequences to the Environment Because of Global Warming Wild plants and animals can be affected. The growing season for plants has changed and animals have the potential to be harmed if they can’t move to better climates. Humans may have to relocate, some diseases like those carried by mosquitoes could increase and there could be economic consequences. Consequences to Living Organisms The fundamental basis of climate change- that greenhouse gas concentrations are increasing and that this will lead to global warming is not in dispute among the vast majority of scientists. What is unclear is how much world temperatures will increase for a given change in greenhouse gases, because that depends on the different feedback loops. The Controversy of Climate Change In 1997, representatives of the nations of the world went to Kyoto, Japan to discuss how best to control the emissions contributing to global warming. The agreement was that emissions of greenhouse gases from all industrialized countries will be reduced to 5.2% below their 1990 levels by 2012. Developing nations did not have emission limits imposed by the protocol. The Kyoto Protocol An approach involving taking CO2 out of the atmosphere. Some methods include storing carbon in agricultural soils or retiring agricultural land and allowing it to become pasture or forest. Researchers are looking at cost-effective ways of capturing CO2 from the air, from coal-burning power stations, and from other emission sources. This captured CO2 would be compressed and pumped into abandoned oil wells or the deep ocean. Carbon Sequestration