[MUSIC] Hi learners. Welcome to the 80th lecture of my course, Ecology from Cells to Gaia. Today we will talk about human impacts on ecosystems. People physically degrade or chemically polluting natural ecosystem when generating power or developing land for agricultural, urban, or industrial purposes. Human beings are not unique among species in degrading their environment and when our population density was low, and prior to our harnessing of non-food energy. Humans probably had no greater impact than many other species. But now the scale of human effects is proportional to our huge numbers and advanced technologies. Habitat degradation has costs in terms of human health and loss of ecosystem services, including provisioning services such as wild food or drinking water, cultural services including education or recreational opportunities. Regulating services, such as the ecosystem's ability to break down pollutants or regulate climate, and supporting services including primary production and soil formation. The intensive production of livestock in factory farming is seriously polluting, and the agricultural law we made need to be thinly dispersed over extensive farmland to deal with it to a level that natural decomposers can deal with it. Intensive agriculture is associated with an increase in the nitrate and phosphate deliverance into rivers, lakes, and oceans. The consequent eutrophication may be counteracted by matching fertilizer supply to crop demand, restoring natural wetlands, or constructing artificial ones. To take up some of the excess nutrient before they enter rivers and the lakes by manipulating, biomanipulating the level [INAUDIBLE] phytoplankton to increase water clarity. Many manufactured pesticides have become important environmental pollutants. Problems arise when pesticides are toxic to many more species than just the target, and particularly when they drift beyond the target areas and persist in the environment. The organochlorines insecticides have been particularly problematic because they are progressively biomodified in animals farther up the food chain. Top predators in aquatic and terrestrial food chains which were never intended as targets can then accumulate very high doses. Cultivation can also physically degrade the landscape through the loss of habitat diversity, while heavy irrigation depletes water in rivers and changes the pattern of flow with adverse consequences for river inhabitants. The polluting effects of burning coal and oil include acid rain which can affect lakes in forests in neighboring countries. And a dramatic increase in the atmospheric carbon dioxide which is responsible for climate change on a global level. Recent emphasis has been placed on developing alternative energy sources that do not release carbon dioxide. The cleanest and safest technologies are expected to derive from hydropower schemes. Already at the chrononological advanced state in many part of the globe, together with wind farms, rapidly developing but with potential adverse consequences for migrating birds, and solar and wave power. Nuclear power, whose popularity has declined because of concern over security and radioactive waste disposal, is receiving renewed consideration because it doesn't release greenhouse gases. But there is the fundamental problem of where and how to store the radioactive wastes. Our feces and urine create large disposal problems in towns and cities because density is so high. At the simplest primary sewage treatment simply removes most of the solid organic matter. Secondary treatment mimics natural decomposition processes, eliminating organic matter, but leaving high concentration of nitrate and phosphate in the wastewater. Tertiary treatment chemically remove these nutrients. Industrial chemicals also find their way into waterways and the atmosphere, where they cause diverse problems. For example, chlorofluorocarbon compounds, CFCs, developed as aerosol and refrigerant and used on a very large international scale, were found to pose a threat. The chlorine content could interact with and destroy atmospheric ozone, which normally protects the world's biota from harmful UV radiation. The chlorine content could interact with and destroy atmospheric ozone, which normally protects the world's biota from harmful UV radiation. International agreement to phase out CFCs is expected to solve the problem by 2050. Including recovery of the substantial ozone hole that form annually over Antarctica. Mining activities whether for fossil fuels or metals, also cause physical and chemical degradation to surrounding ecosystems. For example more than one million tons of oil enters the world's waterways every year from wells drilling into the sea bed, or from oil tankers with adverse consequences for marine life. Mining for metals such as copper may also pollute at every stage of extraction, purification, and disposal. Land that has been damaged by mining is usually unstable, liable to erosion, and devoid of vegetation. The simplest solution to land reclamation is the re-establishment of vegetation cover, because this will stabilize the surface, be visually attractive, and self sustaining. Candidate plans for reclamation are those that are tolerant to toxic heavy metal present. The concept of ecosystem services brings into focus three very different ways of looking at our effect on natural world. The triple bottom line on environmental, economic, and sociopolitical perspectives. Planning for sustainable use of natural resources usually needs to be carried out at regional or global scales. The impact of agriculture depends on the proportion of landscape that is used for production. And planning needs to be done at the regional scale and involve the knowledge of experts in environmental, economic, and sociological disciplines. Dealing with the diversity of view among neighbors is difficult enough. But our biggest environmental problem, such as climate change due to large measure to the burning of fossil fuels requires a multinational global level of planning. So at the end of this lesson, I have some question for you as usual. What's the pollution problems are you contributing to? How are we causing the loss of tropical forest? What are the main drivers for biodiversity decline? So try to answer these questions, and see you at the next lecture. [MUSIC]
