Human Impact on the Biosphere Those Pesky Humans! Humans have a large impact on the environment and the organisms we share it with. This is due to our Ever increasing population size. Ever increasing use of both renewable and non-renewable resources. Humans Affect the Biosphere in 4 Essential Ways: A. Global Climate Change and Acid Rain B. The Ozone Layer C. Biological Magnification/Bioaccumulation D. Threatening Biodiversity Global Climate Change Human activities have increased the concentration of carbon, sulfur, and nitrogen compounds in the atmosphere. The increase in these compounds has resulted in changes in the natural climate and weather patterns. Remember the Carbon Cycle? The Carbon Cycle Carbon cycles through the environment mainly in the form of CO 2 and carbohydrates. Photosynthesis is the main process that removes carbon from the atmosphere. Cellular respiration is the main process that releases carbon into the atmosphere. Human Activity and the Carbon Cycle Human activity is releasing CO 2 and other related forms of carbon into the atmosphere at a much faster rate then they are absorbed. This is due to the ever increasing rate at which we: Clear-cut and burn forests for housing and farming Burn fossil fuels These activities have resulted in the phenomenon of global warming. Global Warming The greenhouse effect : The suns light hits the earth as UV light. It is reflected back to space as IR light. UV light can get through the atmosphere. IR light gets trapped by greenhouse gases such as CO 2 and CH 4. This traps the heat energy around the planet, warming the Earth. Increase in greenhouse gases (CO 2 and CH 4 ) = warmer temperatures *******This is Global Warming******** Possible Affects of Global Warming These include: Flooding of coastal areas. Increased spreading of disease. Drought across inland areas. Acid Rain The burning of fossil fuels also releases nitrogen and sulfur compounds into the atmosphere. These compounds combine with water vapor in the air to produce acids. The acids then migrate for miles and fall as acid rain. Effects of Acid Rain The Ozone Layer The ozone layer protects us from UV light. UV light causes cancer, eye damage, and can damage plant tissue.25&w=301&sz=78&hl=en&start=3&tbnid=NL- HDAmXoPwZ2M:&tbnh=126&tbnw=89&prev=/images%3Fq%3Dozone%2Blayer%26gbv%3D2%26svnum%3D10%26hl%3Den%26safe%3Dactive The hole in the ozone layer South PoleThere is currently a large hole in the ozone layer over Antartica. What Destroys the Ozone Layer? Chlorofluorocarbons (CFCs) are broken apart by UV light. This causes a chain of chemical reactions that results in ozone being broken apart. CFCs were used in aerosol cans, and as coolants in freezers and air conditioners. They are now banned, but some are still used in less developed areas. Even with decreased use of CFCs it will take another 50 years before the hole in the ozone layer begins to shrink and disappear. Biological Magnification/ Bioaccumulation Biological magnification/ Bioaccumulation occurs when pesticides build up in animal tissue as you move up a food chain. Biological MagnificationoconcentrationandBioaccumulation.htmhttp://techalive.mtu.edu/meec/module02/Bi oconcentrationandBioaccumulation.htm DDT in Borneo DDT was used in Borneo to kill mosquitoes. Lizards ate the mosquitoes. Cats ate the lizards. Cats began dying. With no cats, the rat population grew. Rats began spreading disease. They came up with an interesting solution.. Parachuting Cats DDT in the United States DDT was used to kill mosquitoes. DDT bioaccumulated and was found in high levels in the bald eagle. DDT caused the birds to lay eggs with pores in their shells. When the parent birds sat on the eggs, the eggs broke. Our national bird almost went extinct. DDT is still in the environment despite the fact that the last time it was sprayed was over 20 years ago. Threatening Biodiversity There are 4 basic ways that human actions threaten biodiversity: Introducing non-native species Hunting organisms to extinction Introducing toxins into the environment Habitat destruction Biodiversity is important because. Many medicines come from nature We get digitalis, a heart medication, from foxglove. Taxol is a chemical extracted from the Pacific Yew tree It is used for treating cancer patients. Imagine the possible undiscovered medical miracles that could be hiding in the areas/species that have not been studied yet. We get genetic diversity Most crop plants have wild relatives with useful traits. We will visit this library when we need genes to improve our crop plants. Ecosystems are more stable Ecosystems with more organisms are more stable (or homeostatic). What can you do to help? Are your actions sustainable? References /000f1/000f1c7d.jpgDDTInFoodChain-L.jpg Referencestany/images/Digitalis/Digitalisflowers.jpgcommons/b/bc/Rainforest_Fatu_Hiva.jpg