Wired Science outlined six ways in which humans are already geoengineering the Earth, arguing that the world has moved from the Holocene to Anthropocene era. “From diverting a third of Earth’s available fresh water to planting and grazing two-fifths of its land surface, humankind has fiddled with the knobs of the Holocene, that 10,000-year period of climate stability that birthed civilization. The consequences of our interventions into Earth’s geophysical processes are yet to be determined, but scientists say they’re so fundamental that the Holocene no longer exists. We now live in the Anthropocene, a geological age of mankind’s making.”
According to Wired Science, there are six forms of human-caused geoengineering already having an impact worldwide. We’ve further expanded their discussion of these impacts:
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.
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.
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.
Wired Science reported that over the last century, Arctic temperatures have risen by an estimated 3.4-degree-Fahrenheit, and scientists estimate that half of this rise can be attributed to black-carbon pollution. It’s likely that black carbon has altered weather patterns in a way that’s reduced rainfall over South Asia and West Africa. Also, scientists believe that black carbon has played a role in causing Himalayan glaciers to melt, threatening water supplies for hundreds of millions of people.
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.
According to the Union of Concerned Scientists, three billion tons of CO2 enters the atmosphere every year from deforestation. That destruction amounts to 13 million hectares destroyed annually, much of which occurring in the Amazon rain forest. Here, the regional cycle of evaporation and condensation has been disrupted, raising the possibility of the remaining forest becoming a savannah. Furthermore, because the rain forest is shrinking, its carbon-dioxide absorbing capacities are being diminished, which in turn means more of the heat-trapping gas is reaching the upper atmosphere, causing global temperatures to rise.
Fertilizers used in farming have had far-reaching effects. Their use has injected vast amounts of nitrogen and phosphorous into regional ecosystems. Wired Science reports that 120 million tons of nitrogen are removed from the atmosphere each year and 20 million tons of phosphorous is mined from the ground in order to produce fertilizer to be used for farming. These practices add a tremendous amount of nitrogen and phosphorus to the biosphere than would occur naturally. Runoff from farmland often carries large amounts of fertilizer into rivers and streams that eventually drain into the sea. All of this fertilizer runoff creates rapidly-expanding marine dead zones.
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.
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. Today, the world produces approximately 300 million tons of plastics each year. About 20-40 percent of that ends up in landfills, and another 10-20 million tons makes it way to the oceans, disrupting sea life. According to the World Watch Institute, “a recent study conservatively estimated that 5.25 trillion plastic particles weighing a total of 268,940 tons are currently floating in the world’s oceans.”
At high concentrations, these chemicals can disrupt animal endocrine systems, alter reproduction patterns, and cause cancer. Organic pollutants and plastic-derived endocrine disruptors have been discovered in low concentrations all over the world, even in areas where they’ve never been used, such as Antarctica and at the bottom of the oceans. While the effects of low doses of these chemicals are less understood, they are widespread stresses that ultimately change ecosystems. The damage to marine ecosystems is estimated to be around $13 billion a year.