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UEI Teacher Summer Institute 2009 URBAN ECOLOGY AND CLIMATE CHANGE A space-filling model of carbon dioxide (CO2). This simplest of organic molecules is the chemical basis for the food web and is the critical anabolic fuel for plants. Life would be impossible without it… however, too much of it in the atmosphere puts our species and the biosphere at risk. Global Climate Change Summary Climate change of the past 35 years is not consistent with natural variations over the last 400,000 years Evidence clearly shows that radiative forcing due to anthropogenic greenhouse gases has contributed half of the warming of the last 35 years Mitigation efforts, urgently needed, will have little effect on global warming until the end of the century Adaptation strategies should be developed for the next 50 years Polar Ice melt, from Scientific American Radiative Forcing - a tool for understanding climate change The Term, Radiative Forcing as used by the IPCC has a specific meaning: In the context of climate change, the term forcing is restricted to changes in the radiation balance of the surface-troposphere system imposed by external factors, with no changes in stratospheric dynamics. Cloud trails such as these created by jet exhaust exert both a negative forcing (blocking sunlight) and a positive forcing (trapping longwave radiation). The net result is a positive forcing Integrated Science for Society and the Environment Net anthropogenic Change in radiative forcing 1750-2005 from UNIPCC Greenhouse effect of the atmosphere Simple Greenhouse Gasses: Water vapor Carbon Dioxide Methane Nitrous oxide Ozone The gases in the atmosphere that act like glass in a greenhouse are called greenhouse gases. • Light from the sun includes the entire visible region and smaller portions of the adjacent UV and infrared regions. • Sunlight penetrates the atmosphere and warms the earth’s surface. • Longer wavelength infrared radiation is radiated from the earth’s surface. • A considerable amount of the outgoing IR radiation is absorbed by gases in the atmosphere - these molecules reradiate energy to earth. From the Standpoint of Radiative Forcing on Earth We can think of it as a system of gains & losses Energy from the sun in the form of photons reaches the earth and propels both biotic & abiotic systems. Earth temperature is a dynamic balance of absorbtion & radiation The carbon cycle - with anthropogenic (human) “enhancement” Increased energy consumption from fossil fuels burdens the earth system Global mean surface temperatures have increased Have Humans changed the climate? Climate models capture the last 100 year's warming only if we include the human effects Natural Climate Influence All Climate Influences Energy Consumption is directly linked to Carbon Emissions World production of carbon dioxide from anthropogenic sources in 2001 (in Gigatons) Greenhouse Gas Emissions Have Rising The industrial revolution of the mid nineteenth century initiated the surge in combusted gases… these impacts are anthropogenic in origin and are linked to urbanization Petroleum Era Begins Industrial Revolution We face significant threats from greenhouse gases - most of which are anthropogenic in origin and related to industrialization. These gases act as a thermal blanket in the earth’s atmosphere, causing the earth to heat up. The chart below shows the various greenhouse gases that are produced , their anthropogenic source and their relative contribution to the overall effects of global warming. Methane Production from Cattle and Other Sources The 100 million cattle in the United States account for 20% of our nation’s methane production! There are 1.3 billion cows worldwide. Every cow “pie” contains enough energy (3 kwh) through the combustion of nitrogen to power a 100 watt light bulb for over 24 hours. Cows produce 100 lbs of “poop” per day While passenger cars, trucks and busses are an appropriate target for regulation with respect to air pollution, other internal combustion machines remain “dirty” especially those using “two-cycle” technology. The frontier for air pollution abatement lies in the control of emissions from these machines. The problem is especially challenging in cities where the population density is so high. The chart below reveals the pollution impacts of other combustion engines and measures them in relation to the pollution produced by cars in “miles traveled”. The greenhouse effect SUN Some sola r radiation is reflected by the ea rth’s surface and the at mosphere Some of the infrared radiation is absorbed and re-em itted by the gre enhous e gases . The effe ct of this is to warm the surface and the lower atm osphere ATMOSPHERE Solar radiation passes through the clear a tmosphere Mos t solar radiation is absorbed by t he surf ace, which wa rm s EARTH Hadley Centre for Climate Prediction and Research Infrared radia tion is e mit ted from the Earth’s surface GJJ99 3 Ecology of the Ozone Layer The ozone layer resides in the stratosphere and surrounds the entire Earth. UV-B radiation (280- to 315- nanometer (nm) wavelength) from the Sun is partially absorbed in this layer. As a result, the amount of UV-B reaching Earth’s surface is greatly reduced. UV-A (315- to 400-nm wavelength) and other solar radiation are not strongly absorbed by the ozone layer. Data Gathered from the Total Ozone Mapping Spectrometer (TOMS) satellite system The Ozone Hole over the Antarctic The natural ozone layer at the earth’s poles provide a layer of protection for the earth. That layer has been shrinking dramatically over the past fifty years as a result of pollutants. This graph tracks the thickness of the ozone layer over Antarctica over a recent 35 year stretch of time. The most probable cause is the anthropogenic release of CFC’s from refrigerants. Distribution of acid precipitation in North America and Europe Above: Areas of highest acid rain precipitation in Europe and North America in 1999. Right: Averaged yearly rainfall across the United States in 1999. The highly integrated nature of trophic dynamics intensifies the impacts of lead in ecosystems for all organisms Lead poisoning is an epidemic in animal populations as well… 1.5-2.0 million waterfowl (ducks and geese) die annually from ingesting anthropogenic lead. Certain types of air pollution can cause Acid Rain When combustion leads to the production of sulfur and nitrogen, these chemicals can be converted to a highly toxic acid in the upper atmosphere. These compounds return to the earth during rainstorms in the form of liquid acids (acid rain) and cause tremendous damage to ecosystems - especially lakes and ponds. Tipping Points: Ice Ages vs. Interglacial Periods Last 150yrs: greenhouse gases driving temperature change greenhouse gases change in response to climate change Warm periods (warm, wet, calm) Ice Ages (cold, dry, windy) Understanding Pollution & Biomagnification involves thinking about where pollutants are found • In an ecological context, pollutants can be thought of as found in “compartments” • These pollutants are produced at a source, where they move from the air to water and soil - plus into the biota (living organisms) • The chart on the next slide helps us to envision this relationship. Different pollutants can be found in the different compartments and remain there for various amounts of time. The Fates and Movements of Chemicals in the Environment The bold text represents physical compartments for various chemicals; the processes and drivers that move and sequester the chemicals are depicted in parentheses The Physical environment and thermodynamics determine magnification Inherent inefficiencies of energy transfer within an ecosystem exaggerate the impacts of toxic substances - especially for long-lived, high metabolic rate organisms. Pioneering author, scientist and environmental activist, Rachel Carson and her watershed book Silent Spring which day-lighted the adverse impacts of agricultural pesticide use in the United States (first published in 1962) Periodic Table of the Elements. The toxic elements are highlighted and tend to clumped by virtue of their similar properties. Lead (Pb) is a heavy metal, along with mercury (Hg), Thallium (Tl) and Bismuth (Bi). Lead is highly toxic, even in small doses and enters the human environment in a variety of chemical pathways. • Most widely distributed of the toxic elements • Enters environment through smelting of ores • Also enters through batteries, pipes, conduit, pewter, solder and tetraethyl lead in gasoline • Lead tetroxide is a corrosion resistant additive to paint • Lead monoxide is an additive in leaded crystal • Lead arsenate is an additive in many pesticides. • Most damaging by far is lead tetraethyl Lead tetraehtyl molecule featuring a very useful weak bond. Much happens to this bond in the violent world of Inside the high compression world of internal combustion. Major Sources of lead exposure According to the Centers for Disease Control Occupational • Plumbers, pipe fitters, Lead miners, Auto repairers, Glass manufacturers, Shipbuilders, Printers, Plastic manufacturers, Lead smelters and refiners, Police officers, Steel welders or cutters, Construction workers, Rubber product manufacturers, Gas station attendants, Battery manufacturers, Bridge reconstruction workers, Firing range instructors Environmental • Lead-containing paint, Soil/dust near lead industries, roadways, leadpainted homes, Plumbing leachate, Ceramicware, Hobbies and Related Activities, Glazed pottery making, Target shooting at firing ranges, Lead soldering (e.g., electronics), Painting, Preparing lead shot, fishing sinkers, Stained-glass making, Car or boat repair, Home remodeling, Folk remedies, Cosmetics (kajal), Moonshine whiskey, Gasoline "huffing" Lead has many toxic affiliations with the human body with various negative outcomes. • Lead has many chemical forms which make it both water (lead chloride), and fat soluble (lead acetate) - thus entering the body in many ways. • Lead blocks pathways to heme biosynthesis - disrupting the transport of oxygen (ferrochelatase). • Lead can replace calcium in bone and disrupt osteoclast (stem bone cells) activity. • Lead disrupts the process of the formation of Acetyl-CoA, a critical intermediate in in metabolism. • Lead disrupts calcium function in nerve cells, disrupting CNS function, leading to lead encephalopathy. Possible relationship with Protein Kinase C (PKC) • Lesser effects include hyperactivity, decreased attention span, reduced I.Q.; linked to criminal behavior. Lead Blocks Several Steps in the Synthesis of Heme Pigments Heme pigments are the critical oxygen carrying parts of a hemoglobin molecule, found in red blood cells. Critical enzymes, ALA dehydratase and ferrochelatase, are inhibited by lead. This prevents the porphyrin ring from being built, which is the key functional part of the heme unit. Above: Stippling in red blood cells as a function of the disruption of heme formation by lead Environmental Lead is Ubiquitous, Especially in Urban Landscapes Blood Levels of Lead as a Function of Demographics in Children Children suffer an increased risk of lead poisoning as a the degree to which the urban character of their community increases. Children living in industrial areas where heavy industry such as coke smeltering takes place are at the highest risk. Recent Data indicate that tiny particles do indeed have toxic effects From: Nell (2005) Science 308: 04-806 Photomicrographs from tiny particles captured in Los Angeles. Top photo shows soot from diesel emissions. Bottom photos reveal impacts of soot on mitochondrial anatomy. Healthy control mitochondria are shown at left. These particle residues can cause cellular pathologies. Human Behavior can Alter the Environment in Positive Ways. The combined affects of new laws, high technology and increased awareness have improved some critical elements of air quality especially with respect to lead.