Natural Hazards Climate and Climate Change Chapter 12 Learning Objectives Understand the difference between climate and weather, and how their variability is related to natural hazards Know the basic concepts of atmospheric science such as structure, composition, and dynamics of the atmosphere Understand how climate has changed during the last million years, through glacial and interglacial conditions, and how human activity is altering our current climate Learning Objectives, cont. Understand the potential causes of climate change Know how climate change is related to natural hazards Know the ways we may mitigate climate change and associated hazards Climate and Weather Weather = short periods of time. Climate = a long period of time. Climate zones Defined using Koeppen System Uses monthly average temperature and precipitation What information is provided in a climograph? Climographs - Annual Temperature and Precipitation Notice that in the northern hemisphere June and July are warmest months. Notice that in the southern hemisphere June and July are coldest months. Notice that some places have a DRY season. The United States exhibits all of the major world climate zones E = Polar D = severe continental C = mild B = dry A = tropical H = mountains Koeppen’s Classification System A-tropical, temp>18oC (64oF) year round B-Dry, evaporation > precipitation C- Mild Mid-latitude, 18oC (64oF)>coldest month> -3oC (27oF) D- Severe Mid-latitude, coldest month< -3oC (27oF) E – Polar, temp < -3oC (27oF) year round H-Highland, Mountain areas Allred’s climate zone summary for the United States E Polar B cold C mild Marine West Coast B hot D cold-wet C warmwet C mild A coastal Mediterranean Tropical H mountains are mostly in the western United States Hawaii also has tropical “A” Atmospheric Conditions Permanent gases Variable gases Gases whose proportions Water is key to everything else. CO2 is now above 400 ppm Permanent Gases Nitrogen, oxygen, and argon About 99% of the atmosphere Relatively unimportant to atmospheric dynamics Permanent Gases Nitrogen in the air is mostly inert. However, if you put energy into making nitrogen compounds, you can get that energy back later: Fertilizer Rocket fuel Explosives Oxygen is largely inert until it ‘oxidizes’ other elements and compounds, creating powerful, variable atmospheric gases. Humans create far more variable gases than nature needs to maintain earth stability. Oxygen is also relatively inert as an atmospheric component. However, oxidation combines oxygen with carbon, nitrogen and many other elements to produce molecules that are complex, reactive and important. Are combustion, fire and explosion forms of oxidation? <Yes.> Consider the variable gases that result. Variable Gases – Carbon Dioxide (CO2) Extremely important, but still only about 400 parts per million in the air Released naturally by volcanic activity, plant and animal respiration, decay of organic material. Released unnaturally by anthro (human) processes. Don’t forget the carbon monoxide also results from combustion and is a genuine poison. Variable Gases – Carbon Dioxide (CO2), Anthropogenic (human) sources Burning of fossil fuels increases CO2 . Deforestation means that excess CO2 not removed. Atmospheric levels are increasing by 2 ppm per year. Soil and oceans may be reaching their limits in how much CO2 they can absorb. Let’s look at variable gases – starting with water vapor Water processes are a solar energy function Water vapor is humidity created by evaporation Storing energy in the atmosphere as vapor is an efficient way to move energy and provoke vast earth changes and life processes. Storing heat as water vapor is also a source of energy for violent storms. . Ice contains substantial heat energy. Liquid water contains a lot more heat Water vapor contains dangerous amounts of latent heat Variable Gases – Ozone O3 Forms when atomic oxygen (O) collides with oxygen molecule (O2) – ozone is produced by collision with incoming ultraviolet solar energy. Mostly found in stratosphere Acts as a shield for ultraviolet light and is essential to life on earth Chlorofluorocarbons (CFCs) partially destroyed ozone shield Increases skin cancer, cataracts, caused local crop failures Ozone is also created by sunlight interacting with oxides of nitrogen and sulfur. True or False? 1. If human activity can reduce the earth’s ‘ozone layer’ then doing so should help make the surface of the earth warmer. 2. A small increase in ocean temperature represents a vast increase in energy. 3. A small change in atmospheric gases can warm the atmosphere and the ocean beneath. Consider current Salt Lake area news: The Stericycle company uses high heat to kill pathogens in medical waste. Neighbors want the waste management plant shut down. Questions: 1. Does burning waste contribute to climate-changing greenhouse gases? <yes> 2. Can the process simply fail at times -- releasing excess air pollution? <yes> 3. Does high heat reduce halogens (chlorine, fluorine, bromine-based chemicals), heavy metals and other toxins, such as radio-active isotopes? <many toxic substances are not destroyed by fire> 4. If Uv and Ozone are dangerous, then can they be used to sterilize food and kill pathogens? <yes> Variable Gases – Methane (CH4) Primary constituent of natural gas Occurs naturally from bacterial decay, intestinal tracks of termites, cows, and sheep Anthropogenic sources: coal mines, oil wells, leaking natural gas pipelines, rice cultivation, landfills, and livestock Levels have doubled since 1700 and is a significant contributor to warming Methane is more than 20 times per unit more powerful than CO2 as a ‘greenhouse’ gas. Variable Gases – Oxides of Nitrogen (N O, NO , NO, etc.) 2 2 Nature makes some oxides of nitrogen through wildfires, ocean waves and soil building. Human sources include fertilizers and burning fossil fuels. Contributes to atmospheric warming. N2O is also “laughing gas” at the dentist’s office and dragster racing fuel. Variable Gases – Halocarbons Chemical compounds containing halogen elements bonded with carbon Include CFCs and are almost entirely anthropogenic Used in industrial processes, fire fighting, and as fumigants, refrigerants, and propellants Contribute to warming in troposphere and ozone depletion in stratosphere Halocarbons are extremely useful, inexpensive and not particularly toxic when in appropriate use. Replacements are less competent and cost more. Aerosols (microscopic particles including ice) Provide surfaces that help water vapor condense back to liquid – rain/snow may not occur without a place to go. Associated with air pollution Natural sources: desert dust, wildfires, sea spray, and volcanoes Human sources: burning of forests and fossil fuels Aerosols can be dense enough to cool the earth by screening out solar energy. Aerosols During a drought “rain makers” might throw dust in the air to provide ‘condensation nuclei’ How does that process compare to what your car is doing right now in the parking lot? On “911” when airliners were grounded, the absence of vapor contrails allowed the earth to warm-up by about one degree. Rain sometimes occurs after bomb blasts toss dust and smoke into the air. Montreal Protocol (banned CFCs – ozone layer is slowly repairing itself) Kyoto Protocol (tries to limit CO2 but has not been fully ratified CO2 is still increasing in the atmosphere) Structure of Atmosphere, revisited Defined by changes in air temperature Troposphere is where weather happens Stratosphere dry, cold layer Little weather occurs here Strong winds circulate aerosols Atmospheric Circulation Responsible for location of climate zones At equator, warm air rises towards poles Dry air descends near 30o North and South latitude Descending air produces high pressure and low rainfall High pressures at North and South Poles – dry/cold dense air Mid-latitude storms are the ‘battleground’ between the dry heat of deserts to the south and polar deserts to the north. Mid-latitudes host the world’s most violent storms and the most people. Pleistocene Epoch Multiple ice ages Glaciers covered 30% of Earth (today 10%) Maximum extent 21,000 years ago Global sea level >100 m (330 ft) lower than today The Greenhouse Effect Earth’s temperature depends on three things: 1. Amount of sunlight received – variations in solar flow 2. Amount of sunlight reflected 3. Degree to which the atmosphere retains heat • • Water vapor, carbon dioxide, methane, nitrous oxides, and halocarbons absorb IR radiation Gases act as “blanket” to retain heat in troposphere Key factor: mostly shortwave solar energy gets in easily. Once converted to mostly long wave energy, it is harder to get back out. Over-warming happens rather easily. How solar energy enters the atmosphere and then leaves See simplified version next page We can simplify the earth’s “solar budget” For each 100 incoming: 31 reflected back out 69 absorbed: - 45 by land and water - 21 by the atmosphere - 3 by the ozone layer Total for atmosphere = about 24 percent 69 total absorbed How much leaves quickly by longer-wave radiation? <69> The “Greenhouse Effect” is vital to keep the earth at a healthy temperature (average 59°F) However, human air emissions appear to be making the earth too warm: CO2, CO, CH4, Nox, Sox, O3. Carbon Dioxide and The Greenhouse Effect Carbon dioxide accounts for most of humancaused greenhouse effect. Air Temperature and Carbon Dioxide Notice that air temperature varies with carbon dioxide in the atmosphere – more CO2 => more heat Atmospheric Carbon Dioxide Concentrations Burning fossil fuels raises world CO2 concentration exponentially. Human industrial age Atmospheric Carbon Dioxide Concentrations, cont. CO2 levels go down in summer when plants absorb it. CO2 goes up in winter when plants are dormant and humans continue to drive cars and run power plants. Global Temperature Change–Last 140 Years 1750, warming trend begins until 1940s. 1910 to 1998, global temperatures rise. Temperatures in past 30 years are warmest since monitoring began. Volcanic Forcing Ash from eruptions becomes suspended in the atmosphere, reflects sunlight having a cooling effect. Mount Tambora, 1815 eruption contributed to cooling in North America and Europe. Mount Pinatubo in 1991 counterbalanced global warming during 1991 and 1992. Effects of Climate Change November 11, 2013 New York Times article on concerns in Miami and environs. High-tide flooding. Desertification and Drought Climate change increases human induced conversion of land to desert Causes soil and natural vegetation degradation Long-term loses for agriculture and grazing Increase in drought events Wildfires may become more common and more violent As the atmosphere gets warmer Sea level should rise. In a sense, Geography 1700 is not as much about the earth as it is about how people think, wherever they are. Systematic thinking is helped by systematic visualizing. Consider two ‘climate change’ problems: Problem 1. The sequence of building a thunderstorm. Problem 2. The sequence of atmospheric gas interaction. Problem #1: The Sequence of building a thunderstorm Step 1: The Big Six Characteristics of the Atmosphere (and sequence) Air temperature Air pressure Wind Humidity Cloudiness Precipitation Step #2 Storms are a SOLAR Process Air warms Warming air expands pressure Pressure wind Wind and heat evaporate water Vapor is latent heat hidden in humidity Warm vapor is light-weight rises Rising air decompresses Decompressing air cools by expansion Cooling leads to saturation condensation – vapor goes to liquid Liquid precipitates rain, snow With enough heat, the process repeats and builds Anything that alters the atmosphere to retain more heat will lead to more energy for: - severe storms - drought - rising sea levels Example #2 – Climate Change is About Atmospheric Warming 99% Permanent Gases – neutral (except as plant food) Humans burn fossil fuel adds more oxides of carbon and oxidizes nitrogen and sulfur 1% Variable Gases include greenhouse’ gases (GHG) that keep the earth warm. More GHG more earth warming More warming more evaporation smog (Nox, Sox) more energy for storms Sunshine and Nox, Sox ozone (more smog) bigger deserts more heat worsens smog “Bottom Line”? Burning fossil fuels returns vast amounts of ancient “stored sunshine” back into the atmosphere, promoting: - More heat More acidity Air pollution Even neutral nitrogen gets pulled into the fire and converts to more acidic oxides and more ‘smog.’ Sunshine then combines with smog oxides to produce more ozone. What is the “Ozone” story? Atmospheric ozone is made naturally in the stratosphere by Uv colliding with oxygen. That process absorbs 95% of dangerous Uv. Man-made CFCs destroy atmospheric ozone. Ground-level ozone is made by natural & human processes. Nasty stuff. Solution: Humans have banned CFCs, but we still produce vast quantities of hazardous groundlevel ozone. Excessive ozone is the #1 reason for Utah air-quality alerts. Bicycles are the answer.