Global Warming And Climate Impact On The Hydrological Cycle

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Carbon dioxide (CO2) is the most important greenhouse gas, contributing to 60% of the enhanced greenhouse effect. The atmosphere now contains more carbon that at any other time in the last 2 million years. Each sink of the carbon cycle will change as this carbon makes its way through the cycle. The global warming caused by greenhouse gas emissions also accelerates the rate at which carbon is released. Permafrost contains rich deposits of carbon and large amounts are released as a result of their thawing due to global warming. In addition, due to global climate changes, changes in the distribution of plant and animal species and vegetation types due to habitat loss are occurring which directly impacts the carbon cycle as it changes the way matter …show more content…
The production of agricultural products takes 70% of the freshwater withdrawals from rivers and groundwater. The amount of water it takes each year to produce food for the whole human race is enough to fill a canal 10 meters deep, 100 meters wide, and 12.1 million kilometres long, long enough to encircle the globe 180 times. Impacts include water degradation, the depletion of rivers and groundwater as well as eutrophication when excess nutrients enter the water courses and cause algal bloom. Rivers are drying up because of greater agricultural production and water consumption and groundwater levels are declining rapidly, especially in densely populated areas of North Africa, North China, India, and Mexico because of overexploitation. Water resources are being degraded through erosion, pollution, salinization, nutrient depletion, and the intrusion of seawater due to rising sea levels as a result of global warming. Agriculture also disrupts natural water sources, disrupting the flow of water and increasing flooding leading to waterlogging (the saturation of soil with water) in some areas. Pollution and clogging of waterways also occurs. In addition, human adaptation to the water supply disrupts rainfall patterns. The use of water in agricultural purposes also raises issues of water sustainability as fresh water sources are depleting. Total global freshwater withdrawals are estimated at 3,800 cubic kilometres, with 2,700 cubic kilometres (70%) for irrigation. It is predicted the amount of water consumed by evapotranspiration in agriculture will increase by 70%–90% by 2050 with the total amount of water evaporated in crop production amounting to 12,000–13,500 cubic kilometres, almost double the 7,130 cubic kilometres of today. A decrease of renewable water resources of at least 20% is expected by the end of the 21st century and the number

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