What is the role of human activities in changing the surface of the earth
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Carbon Dioxide Emissions:
The human activity most widely viewed as changing the planet is the burning of fossil fuels. In order to produce the energy that drives the world’s economy, countries rely on carbon-rich fossil fuels like coal, oil, and gas. By burning these materials, humans have added nearly 400 billion tons of carbon dioxide into the atmosphere between 1870 and 2013. Right now, atmospheric levels of carbon dioxide are higher than at any point in human history ; the last time they were this high was 800,000 years ago. Carbon dioxide is a heat-trapping gas, and as a result of these atmospheric changes, average temperatures on the planet are rising and global weather patterns are changing. 2015 is expected to be the hottest year on record , following record high in 2014. Some of the carbon dioxide in the atmosphere is
absorbed into oceans, increasing their acidity by 30 percent over the past 100 years. This change has far reaching affects on oceanic ecosystems and the food chains that support underwater plant and animal life.
Draining Rivers:
Life depends heavily on the supply of fresh water that exists in rivers, lakes, and aquifers. According to Wired Science , it’s estimated that one fourth of Earth’s river basins run dry before ever reaching the ocean. This is the result of reduced rainfall caused by deforestation and the construction of man-made dams that divert water flow in inefficient ways. Less water flowing through river basins has also altered local weather patterns.
The Aral Sea , located on the Uzbekistan-Kazakhstan border, was once the fourth largest lake, but has now shrunk by 75 percent (see image above). The Aral Sea was once fed by two major rivers which now, due to human activity, run dry before they reach the lake. In the early 1960’s, the Soviet Union diverted water from the in-flowing rivers to irrigate rice and cotton crops in Central Asia. The reduced water flow caused salt concentrations to increase, making it inhabitable for the fish species that once lived there. The Aral Sea used to absorb heat during the summer and keep the temperature mild during the winters, but now that it’s drying up, the local climate is changing: in surrounding areas, summers are now longer and hotter and the winters are colder.
Black Carbon:
For centuries, humans have engaged in activities that produce black carbon particles. Black carbon particles are released into the atmosphere in the form of smoke that is produced by cooking with solid animal fuels, burning trees, and spewing diesel exhaust. When black carbon particles reach the atmosphere, they form a heat-absorbing layer that causes temperatures to rise. Raindrops tend to form around black carbon particles in the atmosphere, and when they fall to the ground, they absorb heat there too, thus magnifying their warming effect.
According to Science Daily , scientists estimate that 25 to 35 percent of black carbon in the global atmosphere was emitted by China and India from the burning of wood and cow dung in household cooking and coal to heat homes. Nations that rely heavily on diesel fuel for transportation also contribute large amounts.
Industrial Agriculture
As the world’s population continues to grow, so does the amount of farmland needed to provide sufficient food. According to the UN Food and Agriculture Organization (FAO), over 40 percent of Earth’s surface is now comprised of agricultural lands, and a large portion of these lands were once covered by forests. Much of Europe, for example, was once covered with dense temperate forests but over time population growth-driven deforestation has led to more farm land.
Reef Destruction:
Ocean reefs make up the foundation of some of the world’s richest marine ecosystems. Their demise is disturbing the flow of nutrients and energy that support animal and plant life in our oceans. As a result of water pollution, ocean acidification, overfishing, and climate change, experts estimate that one-fifth of global reefs are now dead and one-quarter of reef species may be extinct by 2050. Furthermore, the livelihood of some 500 million people worldwide are dependent on reefs, as these are where many fish and other species start their lives.
Scientists believe northwest Mediterranean once supported a vibrant array of reefs, which provided home to plant and animal species. Today, however, the stripped-down ecosystem is dominated by bacteria and jellyfish, which exhibit a reduced capacity to regulate flows of nutrients and energy.
Plastic Production:
Technological development has led to the invention of new materials, such as plastics, that were previously unknown to the planet. Many of these new materials are made up of chemical compounds that can remain active in the environment for thousands of years and have lasting impacts on the delicate regulatory cycles and ecosystems.
The human activity most widely viewed as changing the planet is the burning of fossil fuels. In order to produce the energy that drives the world’s economy, countries rely on carbon-rich fossil fuels like coal, oil, and gas. By burning these materials, humans have added nearly 400 billion tons of carbon dioxide into the atmosphere between 1870 and 2013. Right now, atmospheric levels of carbon dioxide are higher than at any point in human history ; the last time they were this high was 800,000 years ago. Carbon dioxide is a heat-trapping gas, and as a result of these atmospheric changes, average temperatures on the planet are rising and global weather patterns are changing. 2015 is expected to be the hottest year on record , following record high in 2014. Some of the carbon dioxide in the atmosphere is
absorbed into oceans, increasing their acidity by 30 percent over the past 100 years. This change has far reaching affects on oceanic ecosystems and the food chains that support underwater plant and animal life.
Draining Rivers:
Life depends heavily on the supply of fresh water that exists in rivers, lakes, and aquifers. According to Wired Science , it’s estimated that one fourth of Earth’s river basins run dry before ever reaching the ocean. This is the result of reduced rainfall caused by deforestation and the construction of man-made dams that divert water flow in inefficient ways. Less water flowing through river basins has also altered local weather patterns.
The Aral Sea , located on the Uzbekistan-Kazakhstan border, was once the fourth largest lake, but has now shrunk by 75 percent (see image above). The Aral Sea was once fed by two major rivers which now, due to human activity, run dry before they reach the lake. In the early 1960’s, the Soviet Union diverted water from the in-flowing rivers to irrigate rice and cotton crops in Central Asia. The reduced water flow caused salt concentrations to increase, making it inhabitable for the fish species that once lived there. The Aral Sea used to absorb heat during the summer and keep the temperature mild during the winters, but now that it’s drying up, the local climate is changing: in surrounding areas, summers are now longer and hotter and the winters are colder.
Black Carbon:
For centuries, humans have engaged in activities that produce black carbon particles. Black carbon particles are released into the atmosphere in the form of smoke that is produced by cooking with solid animal fuels, burning trees, and spewing diesel exhaust. When black carbon particles reach the atmosphere, they form a heat-absorbing layer that causes temperatures to rise. Raindrops tend to form around black carbon particles in the atmosphere, and when they fall to the ground, they absorb heat there too, thus magnifying their warming effect.
According to Science Daily , scientists estimate that 25 to 35 percent of black carbon in the global atmosphere was emitted by China and India from the burning of wood and cow dung in household cooking and coal to heat homes. Nations that rely heavily on diesel fuel for transportation also contribute large amounts.
Industrial Agriculture
As the world’s population continues to grow, so does the amount of farmland needed to provide sufficient food. According to the UN Food and Agriculture Organization (FAO), over 40 percent of Earth’s surface is now comprised of agricultural lands, and a large portion of these lands were once covered by forests. Much of Europe, for example, was once covered with dense temperate forests but over time population growth-driven deforestation has led to more farm land.
Reef Destruction:
Ocean reefs make up the foundation of some of the world’s richest marine ecosystems. Their demise is disturbing the flow of nutrients and energy that support animal and plant life in our oceans. As a result of water pollution, ocean acidification, overfishing, and climate change, experts estimate that one-fifth of global reefs are now dead and one-quarter of reef species may be extinct by 2050. Furthermore, the livelihood of some 500 million people worldwide are dependent on reefs, as these are where many fish and other species start their lives.
Scientists believe northwest Mediterranean once supported a vibrant array of reefs, which provided home to plant and animal species. Today, however, the stripped-down ecosystem is dominated by bacteria and jellyfish, which exhibit a reduced capacity to regulate flows of nutrients and energy.
Plastic Production:
Technological development has led to the invention of new materials, such as plastics, that were previously unknown to the planet. Many of these new materials are made up of chemical compounds that can remain active in the environment for thousands of years and have lasting impacts on the delicate regulatory cycles and ecosystems.
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