Chapter 19 Global Change

Global Climate Change and the Greenhouse Effect Module 62 Global Climate Change and the Greenhouse Effect Learning Objectives After this module, you should be able to: distinguish among global change, global climate change, and global warming. explain the process underlying the greenhouse effect. identify the natural and anthropogenic sources of greenhouse gases.

Weather vs. Climate Weather: a local area’s short-term physical conditions such as temperature and precipitation. Climate: a region’s average weather conditions over a long period of time (at least 30 years). “Climate is what we expect, weather is what we get.” -- Mark Twain “If you don’t like the weather, wait 5 minutes; If you don’t like the climate…MOVE.” -- Paraphrased Mark Twain

Climate Climate variability: variations in climate from season to season or year to year. Explains why one winter may be warmer to colder than last year to next year. Influenced by large scale natural processes like El Niño Averaged out over longer periods of time http://www.weather.gov/dvn/climategraphics?n=climategraphics https://www.youtube.com/watch?v=cBdxDFpDp_k

Climate Climatology: the study of Earth’s climate and the factors that cause past, present, and future climate changes Over the Earth’s history the climate has been altered by: Volcanic emissions Changes in solar input Movement of the continents Impacts by meteors

Global Warming vs. Climate Change Important distinction: Global Warming vs. Climate Change Global warming = the warming of the troposphere and the oceans as a result of an increase in the natural greenhouse effect Global climate change = a broader term referring to any changes in the Earth’s climate over a period of decades

Global Warming vs. Climate Change More detailed definitions: Global warming: Rise in global temperatures because of the trapping of more heat in the lower atmosphere. Average temp. of Earth has already risen by 1.4°F since 1880 Predicted to rise another 2.5°F during this century (IPCC 2015) Global climate change: Long-term change in average weather conditions in an area. Changes may include: Temperature – warmer or cooler Rainfall – more or less Wind patterns

Global Change Global change: Change that occurs in the chemical, biological, and physical properties of the planet. Global change includes a wide variety of factors that are changing over time.

 The Greenhouse Effect At our distance from the Sun, the Earth should have an average global temp. of around -2º F (-19º C). Instead, the Earth’s average temp is 57º F (14º C) WHY?? The Earth’s natural greenhouse effect

The Greenhouse Effect The Greenhouse Effect (GHE): Absorption of infrared radiation by atmospheric gases and re-radiation of the energy back toward Earth. As solar energy reaches Earth’s surface, a small amount of it is reflected; most of it is absorbed. The absorbed energy warms the earth, which radiates heat back towards space as infrared energy (heat). Greenhouse gases absorb some of the outgoing infrared energy. Heat energy remains trapped near earth’s surface, keeping it warmer.

 The Greenhouse Effect

Greenhouse Effect vs. Global Warming The greenhouse effect is a natural process and without it, Earth would be too cold to support life. However, the natural GHE can be “enhanced” by too many greenhouse gases in the atmosphere Too much energy trapped means rising temperatures on earth = GLOBAL WARMING

The Gases That Cause the Greenhouse Effect The major greenhouse gases are: Water Vapor (H2O): the most abundant greenhouse gas, warmer air holds more water vapor (positive feedback) Carbon Dioxide (CO2): enters the atmosphere through the burning of fossil fuels, solid waste, trees and wood products, etc. It is removed from the atmosphere or “sequestered” when it is absorbed by plants as part of the carbon cycle. Methane (CH4): emitted during the production and transport of fossil fuels, from livestock and other agricultural practices, and by the decay of organic waste in municipal solid waste landfills. Nitrous Oxide (N2O): emitted during agricultural and industrial activities and during combustion of fossil fuels and solid waste.

The Gases That Cause the Greenhouse Effect Other greenhouse gases: Tropospheric Ozone (O3): A secondary pollutant created at ground level that absorbs infrared energy. Chlorofluorocarbons (CFCs): Do not exist naturally. In the troposphere, they absorb infrared energy. We know what they do in the stratosphere…

Greenhouse Gases Greenhouse warming potential: How much a GHG molecule can contribute to global warming over a period of 100 years relative to a molecule of CO2. The contribution of each gas to global warming depends on its greenhouse warming potential and its concentration.

Natural Sources of Greenhouse Gases Volcanic eruptions Ash: reflects sunlight; short-term cooling effect Carbon dioxide: significant amounts added over time Decomposition and digestion Carbon dioxide: high oxygen conditions Methane: low oxygen conditions (under water or in guts) Denitrification Nitrous oxide: low oxygen wet soils Evaporation and evapotranspiration Water vapor: evaporation from land or bodies or water; transpiration from plants.

Anthropogenic Sources of Greenhouse Gases Anthropogenic sources of greenhouse gasses: Burning of fossil fuels Carbon dioxide: burning coal produces the most CO2, following by gasoline. Natural gas produces the least. Particulates: reflects sunlight, but also coats snow/ice lowering albedo so it melts faster. Agricultural practices Nitrous oxide: excess nitrates in the soil Methane: livestock manure lagoons Deforestation Carbon dioxide: loss of trees decreases CO2 taken out of atmosphere; if trees are burned, excess CO2 is put into atmosphere

Anthropogenic Sources of Greenhouse Gases Anthropogenic sources of greenhouse gasses: Landfills Methane: decomposition of organic matter Industrial production CFCs: refrigerant, coolant, propellant Hydrochlorofluorocarbons (HCFCs): CFC substitutes that do not harm the ozone layer, but act as greenhouse gases. Phased out by 2030

Anthropogenic Causes of Greenhouse Gases Can you name the greenhouse gases emitted by the following human activities?

Anthropogenic Causes of Greenhouse Gases Methane Bacteria that breakdown livestock manure Landfill decomposition Leaks from production, storage, and transport of natural gas and petroleum products. Nitrous oxide Nitrogen from applied fertilizers Combustion of fossil fuels Industrial production of fertilizers Carbon dioxide Burning of fossil fuels in different forms

63 The Evidence for Global Warming Module Learning Objectives After this module, you should be able to: explain how CO2 concentrations have changed over the past 6 decades and how emissions compare among the nations of the world. explain how temperatures have increased since records began in 1880. discuss how we estimate temperatures and levels of greenhouse gases over the past 500,000 years and into the future. explain the role of feedbacks on the impacts of climate change.

The Consequences of Global Climate Change Module 64 The Consequences of Global Climate Change Learning Objectives After this module, you should be able to: discuss how global climate change has affected the environment. explain how global climate change has affected organisms. identify the future changes predicted to occur with global climate change. explain the global climate change goals of the Kyoto Protocol.