Natural Capital Degradation (Part 1) PDF

Natural Capital Degradation (Part 1) Natural Capital: the Natural Resources and Natural Services that keep us and other forms of life alive and support our economies.  Protect your Capital and live on the income it provides. Deplete or waste your Capital, and you will move from a s...

Natural Capital Degradation (Part 1) Natural Capital: the Natural Resources and Natural Services that keep us and other forms of life alive and support our economies.  Protect your Capital and live on the income it provides. Deplete or waste your Capital, and you will move from a sustainable to an unsustainable lifestyle.  Are we living sustainably? The bad news is that, according to scientific evidence, we are living unsustainably by wasting, depleting, and degrading the earth’s natural capital at an accelerating rate. In many parts of the world, potentially renewable forests are shrinking, deserts are expanding, soils are eroding, and agricultural lands are being replaced by suburban developments. In addition, the lower atmosphere is warming, glaciers are melting, sea levels are rising, and floods, droughts, and forest fires are increasing, potentially renewable water tables are falling, rivers are running dry, fisheries are collapsing, coral reefs are disappearing, and various species are becoming extinct.  https://www.youtube.com/watch?v=5lrn4CDQZzo&feature=youtu.be Case Study: The Aral Sea Disaster The shrinking of the Aral Sea is the result of a large- scale water transfer project in an area of the former Soviet Union with the driest climate in central Asia. Since 1960, enormous amounts of irrigation water have been diverted from the Aral Sea and its two feeder rivers. The goal was to create one of the world’s largest irrigated areas, mostly for raising thirsty cotton and rice crops in a very dry area. The irrigation canal stretches more than 1,300 km. Since 1961, the sea’s salinity has risen sevenfold and the average level of its water has dropped by 22 meters. It has lost 90% of its volume of water and has split into two major parts, separated mostly by salt- covered desert. Case Study: The Aral Sea Disaster (cont.) About 85% of the area’s wetlands have been eliminated. About half the local bird and mammal species have disappeared. A huge area of former lake bottom is now a human- made desert covered with glistening white salt. The sea’s greatly increased salt concentration has caused the local extinction of 26 of the area’s 32 native fish species. This has devastated the area’s fishing industry, which once provided work for more than 60,000 people. Fishing villages and boats once located on the sea’s coastline now sit abandoned in a salt desert. Case Study: The Aral Sea Disaster (cont.) Winds pick up the sand and salty dust and blow it onto fields as far as 500 kilometers away. As the salt spreads, it pollutes water and kills wildlife, crops, and other vegetation. Aral Sea dust settling on glaciers in the Himalayas is causing them to melt at a faster than normal rate. Shrinkage of the Aral Sea has also altered the area’s climate. The once-huge sea acted as a thermal buffer that moderated the heat of summer and the extreme cold of winter. Now there is less rain, summers are hotter and drier, winters are colder, and the growing season is shorter. Case Study: The Aral Sea Disaster (cont.) The combination of such climate change and severe salinization has reduced crop yields by 20–50% on almost one-third of the area’s cropland. To raise yields, farmers have used more herbicides, insecticides, and fertilizers, which have percolated downward and accumulated to dangerous levels in the groundwater—the source of most of the region’s drinking water. Many of the 45 million people living in the Aral Sea’s watershed have experienced increasing health problems—including anaemia, respiratory illnesses, liver and kidney disease, eye problems, and various cancers— from a combination of toxic dust, salt, and contaminated water.  https://www.youtube.com/watch?v=FzvEW1FHc60  https://www.youtube.com/watch?v=5N-_69cWyKo&pbjreload=101 Case Study: Dust Bowl Americans learned a harsh environmental lesson in the 1930s, when much of the topsoil in several dry and windy mid Western states was lost because of a combination of poor cultivation practices and prolonged drought. oFarmers ploughed over 5.2 million acres of the deep-rooted grass that kept soil in-place. They had conducted extensive deep ploughing of the virgin topsoil. oThis had displaced the native, deep-rooted grasses that normally trapped soil and moisture even during periods of drought and high winds. Case Study: Dust Bowl (cont.) Years of over-cultivation meant the soil lost its richness. When the drought killed off the crops, high winds blew away the remaining unanchored topsoil. They raised enormous clouds of dust. It deposited mounds of dirt on everything, even covering houses. These choking billows of dust – named "black blizzards" or "black rollers" – travelled cross country, reaching as far as the East Coast and striking such cities as New York City and Washington, D.C. On the plains, they often reduced visibility to 1 m or less. Dust suffocated livestock and caused pneumonia in children.  https://www.youtube.com/watch?v=n-rBhbkvtm0 Case Study: Tropical Deforestation An old-growth forest is an uncut or regenerated primary forest that has not been seriously disturbed by human activities or natural disasters for several hundred years or more. A second-growth forest is a forest which has regrown after being removed by human activities such as clear-cutting or by natural forces such as fire, hurricanes, or volcanic eruption, until long enough period has passed so that the effect of the disturbance are no longer evident. Case Study: Tropical Deforestation (cont.) Deforestation is the temporary or permanent removal of large expanses of forest for agriculture, settlements, or other uses. Tropical forests cover about 6% of the earth’s land area—roughly the area of the lower 48 U.S. states. Climatic and biological data suggest that mature tropical forests once covered at least twice as much area as they do today. Most of this loss of tropical forest has taken place since 1950. Case Study: Tropical Deforestation (cont.) Satellite scans and ground-level surveys indicate that large areas of tropical forests are being cut rapidly in parts of Africa, Southeast Asia and South America. Studies indicate that at least half of the world’s known species of terrestrial plants and animals live in tropical forests. These species are highly vulnerable to extinction when their forest habitats are destroyed or degraded. Case Study: Tropical Deforestation (cont.) Many forest experts acknowledge this regrowth. However, they point out that these second-growth tropical forests do not have the biological diversity—especially the diversity of animals—or the important uninterrupted expanses of old-growth tropical forests. They note that these old forests harbour biodiversity that could not be regenerated in second-growth or commercial forests, simply because it took many millions of years to evolve along with the old-growth tropical forests. Case Study: Tropical Deforestation (cont.) oHundreds of millions of people in the developing world rely on forests to earn their living. oAbout two billion people use fuel wood as their main source of energy for cooking and for heating their homes. oRural households in developing countries collect food, fuel, medicinal plants and construction materials directly from the forest. oTens of millions of people supplement their cash incomes by collecting and selling such materials. Case Study: Tropical Deforestation (cont.) oOthers sell timber from their own traditional land areas to logging companies, or make and sell furniture and handicrafts, just to have enough income to support themselves and their families. oIndustrial logging provide millions of full- time jobs and steady earnings for people in developing countries. Case Study: Tropical Deforestation (cont.) oThe importance of forests cannot be underestimated. We depend on forests for our survival, from the air we breathe to the wood we use. oBesides providing habitats for animals and livelihoods for humans, forests also offer watershed protection, prevent soil erosion and mitigate climate change. oThey provide ecosystem services that are critical to human welfare. They provide habitat to more than half of the world’s land- based species. Stratification of specialized plants and animals in a tropical rain forest. Species avoid or minimize competition for resources and results in the coexistence of a great variety of species. Case Study: Tropical Deforestation (cont.) oForests absorb harmful greenhouse gasses that produce climate change. In tropical forests alone, a quarter of a trillion tons of carbon is stored in forest biomass. oProviding food and medicine. oServing as a buffer in natural disasters like flood and rainfalls. oProtecting watersheds and reducing or slowing the amount of erosion and chemicals that reach waterways. Case Study: Tropical Deforestation (cont.) oTrees intercept rainfall in their canopy, reducing the amount of rain that reaches the ground. A portion of this captured rain water evaporates from tree surfaces. oTrees take up water from the soil through their roots, which increases soil water storage potential and lengthen the amount of time before rainfall becomes runoff. oForested land produce very little runoff, which can reduce downstream flood flows that erode stream channels, damage property and destroy habitat. Case Study: Tropical Deforestation (cont.) Pressures of population growth and poverty push farmers and the landless poor into tropical forests, where they try to grow enough food to survive. Some Government subsidies can accelerate deforestation by reducing the costs of timber harvesting, cattle grazing, and establishing vast plantations of crops. Case Study: Tropical Deforestation (cont.) Southeast Asian forests are being replaced with vast plantations of oil palm, whose oil is used in cooking, cosmetics, and biodiesel fuel for motor vehicles. In Africa, people struggle to survive by clearing plots for small-scale farming and by harvesting wood for fuel, which is causing deforestation on that continent. Major interconnected causes of the destruction and degradation of tropical forests. The importance of specific secondary causes varies in different parts of the world.  https://www.youtube.com/watch?v=vJnnrpSDWPI Case Study: Forest Fires Two types of fires can affect forest ecosystems. Surface fires usually burn only undergrowth and leaf litter on the forest floor. They may kill seedlings and small trees, but they avoid most mature trees and allow most wild animals to escape. Occasional surface fires have a number of ecological benefits. They burn away flammable ground material and help to prevent more destructive fires. Case Study: Forest Fires (cont.) They also free valuable mineral nutrients tied up in slowly decomposing litter and undergrowth; release seeds from the cones of lodge pole pines; stimulate the germination of certain tree seeds and help to control tree diseases and insects. Wildlife species such as deer, moose, muskrat, and quail depend on occasional surface fires to maintain their habitats and provide food in the form of vegetation that sprouts after fires. Case Study: Forest Fires (cont.) Another type of fire, called a Crown fire is an extremely hot fire that leaps from treetop to treetop, burning whole trees. Crown fires usually occur in forests that have not experienced surface fires for several decades, a situation that allows dead wood, leaves, and other flammable ground litter to accumulate. These rapidly burning fires can destroy most vegetation, kill wildlife, increase soil erosion, and burn or damage human structures in their paths. Case Study: Forest Fires (cont.) A 2005 study by forest scientists found that widespread fires in the Amazon basin are changing weather patterns by raising temperatures and reducing rainfall. This is converting large deforested areas of tropical forests to tropical grassland (savanna)—another example of reaching an irreversible ecological tipping point. Models stated that if current burning and deforestation rates continue, 20–30% of the Amazon basin will be turned into savanna in the next 50 years, and most of it could become savanna by 2080. Case Study: Forest Fires (cont.) Large areas of tropical forest in Brazil’s Amazon basin are burned each year to make way for cattle ranches, plantation crops such as soybeans, and small-scale farms. The burning of tropical forests releases CO2 into the atmosphere, which is projected to warm the atmosphere and change the global climate at an increasing rate during this century. Case Study: Forest Fires (cont.) Scientists estimate that, globally, these fires account for at least 20% of all human-created greenhouse gas emissions, and that each year they emit twice as much CO2 as all of the world’s cars and trucks emit. The large-scale burning of the Amazon accounts for three-fourths of Brazil’s greenhouse gas emissions, making Brazil the world’s fourth largest emitter of such gases. Large areas of tropical forest in Brazil’s Amazon basin are burned each year to make way for cattle ranches, plantation crops such as soybeans, and small-scale farms.  https://www.youtube.com/watch?v=TcJUSMiKQyY&t=228s  https://www.youtube.com/watch?v=hKj6VSZLJy8  https://www.youtube.com/watch?v=mj75koAJBvY Case Study: Floods in Bangladesh A flood happens when water in a stream overflows its normal channel and spills into the adjacent area, called a floodplain‫ السهل الفيضي‬. oFloodplains, which usually include highly productive wetlands, help to provide natural flood and erosion control, maintain high water quality, and recharge groundwater. oPeople settle on floodplains to take advantage of their many assets, including fertile soil, ample water for irrigation, availability of nearby rivers for transportation and recreation, and flat land suitable for crops, buildings, highways, and railroads. Case Study: Floodplains in Bangladesh (cont.) Floods actually provide several benefits. They have created the world’s most productive farmland by depositing nutrient-rich silt on floodplains. They also recharge groundwater and help to refill wetlands, thereby supporting biodiversity and aquatic ecological services. Floods usually are considered natural disasters, but since the 1960s, human activities have contributed to a sharp rise in flood deaths and damages, meaning that such disasters are partly human-made. Case Study: Floodplains in Bangladesh (cont.) One such human activity is removal of water-absorbing vegetation, especially on hillsides. People usually replace such vegetation with farm fields, pastures, pavement, or buildings that cannot absorb rainwater. Case Study: Floodplains in Bangladesh (cont.) Building on wetlands, which naturally absorb floodwaters, is a second human activity that increases the severity of flooding. Another human-related factor that will increase flooding is a rise in sea level from projected climate change. Reports stated that living in many of the world’s largest coastal cities are likely to be at risk from such coastal flooding. Case Study: Floodplains in Bangladesh (cont.) Bangladeshis have adapted to moderate flooding. Most of the houses have flat thatch roofs on which families can take refuge with their belongings in case of flooding. The roofs can be detached from the walls, if necessary, and floated like rafts. Unfortunately, great floods can overwhelm such defences. In the past, great floods occurred every 50 years or so. But since the 1970s, they have come roughly every 4 years. Case Study: Floodplains in Bangladesh (cont.) Bangladesh’s flooding problems begin in the Himalayan watershed, where rapid population growth, deforestation, overgrazing, and unsustainable farming on steep and easily erodible slopes have increased flows of water during monsoon season. Monsoon rains now run more quickly off the denuded Himalayan foothills, carrying vital topsoil with them. This increased runoff of soil, combined with heavier than normal monsoon rains, has led to more severe flooding along Himalayan rivers and downstream in Bangladesh. Case Study: Floodplains in Bangladesh (cont.) Many of the country’s coastal mangrove forests have been cleared for fuelwood, farming, and aquaculture ponds for raising shrimp. It resulted in more severe flooding, because these coastal wetlands had sheltered Bangladesh’s low-lying coastal areas from storm surges, cyclones, and tsunamis.  https://www.youtube.com/watch?v=o75KSDVroGs