EXPLORE: Consequences of the Green Revolution

The Green Revolution and Overpopulation

Pesticides are hazardous in large quantities and some are toxic in small quantities. It's easy for these pollutants to circulate through the air, water and land. Photo courtesy of CK-12. 

The Green Revolution also led to environmental impacts to the planet. One such impact was the loss of natural landscapes to farming activities. Forests and other landscapes have been cleared for farming (as well as urban areas). Rivers have been dammed and the water transported by canals for irrigation and domestic uses. Ecologically sensitive areas have been altered: wetlands are now drained and coastlines developed. 

Another impact has been pollution. Modern agricultural practices produce a lot of pollution from pesticides and fertilizers. Dead zones grow as fertilizers drain off farmland and introduce nutrients into lakes and coastal water ways. Farm machines and vehicles used to transport crops produce air pollution because they run on fossil fuels. Moreover, many types of pollutants easily cycle between the air, the water and the land. As a result, the entire earth system is affected; not location or organism - not even polar bears in the remote Arctic - is free from pollution.

The Green Revolution helped the human population to grow. The increased numbers of people have impacted other resources as well. Humans need clean water, shelter and a place for waste. A large percentage of people expect much more than to simply have their basic needs met; this has led to an overconsumption of resources by some members of the human population.

For about one quarter of the world's population, there is an abundance of food, plenty of water, and a secure home. Comfortable temperatures are made possible by home heating and cooling systems, rapid transportation by cars, instant communication and many other luxuries. All of these require resources to be produced, primarily powered by fossil fuels. The production and use of these materials produces waste that must be disposed of. 

Source: Overpopulation and Overconsumption. Retrieved from http://www.ck12.org/book/CK-12-Earth-Science-Concepts-For-High-School/r16/section/13.3/ on December 27, 2013. 

Agriculture and Soil Resources

Soil is a mixture of eroded rock, minerals, partially decomposed organic matter, and other materials. It's essential for plant growth, so it's the foundation of all land ecosystems. Soil is important for other reasons as well. For example, it removes toxins from water and breaks down wastes.

While soil is considered a renewable resource, it takes a very long time to form (up to hundreds of millions of years). So, for human purposes, it's considered a nonrenewable resources. It can be depleted of nutrients through careless use, poor farming practices, wind and water erosion. Farmers were forced off their lands during the Dust Bowl in the 1930s when the rains stopped and the topsoil blew away. 

Farming can accelerate soil erosion because of the amount of land that is farmed and how much farming practices disturb the ground. Farmers remove native vegetation and then plow the land to plant new seeds. While these farmlands lay fallow, wind and water can eroded the exposed soil quickly. Also, tractor tires make grooves, which are natural pathways for water to erode. Grazing similarly accelerates soil erosion. Animals expose soil by removing the plant cover in an area and churn up the ground with their hooves. 

Agriculture provides food for the world's human population. Most of the best land for farming is already being cultivated. With human populations continuing to grow, it is extremely important to protect our soil resources. There are several strategies that farmers can follow to prevent soil loss, such as crop rotation, terracing fields, growing cover crops, and planting wind breaks around fields to buffer soil from wind erosion.

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Sources: Soil Erosion. Retrieved from http://www.ck12.org/book/CK-12-Earth-Science-Concepts-For-High-School/r16/section/13.5/ on December 27, 2013. and Avoiding Soil Loss. Retrieved from http://www.ck12.org/book/CK-12-Earth-Science-Concepts-For-High-School/r16/section/13.6/ on December 27, 2013. and USOE OER Resource Guide for earth Systems. 

Agriculture & Water Pollution

Water pollution comes from many sources. One of the biggest is runoff from agriculture. Runoff picks up chemicals such as pesticides and fertilizers and carries the chemicals to bodies of water. The added nutrients (particularly nitrogen and phosphorus) often cause excessive growth of algae, creating algal blooms. They algae use up oxygen in the water so that other aquatic organisms cannot survive. This has occurred over large areas of the oceans, creating dead zones, where low oxygen levels have killed all ocean life.A very large dead zone exists in the Gulf of Mexico. 

The problem begins on midwestern farms, where plants like corn, wheat and soybeans need nitrogen and phosphorus to thrive. Unfortunately, the fertilizer doesn't just stay on the farm fields. Forty-one percent of the continental US drains into the Mississippi River, and the majority of that soil is farmland. In peak growing season, 8 million pounds of nitrate flows off farms into the Mississippi River a day.  The Mississippi River then flows to the Gulf of Mexico, fueling the rapid growth of algae. When the algae die, their decay robs the water of oxygen, killing plants, fish and other marine life. 

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Sources: USOE OER Resource Guide for Earth Systems and Agricultural Runoff and the Gulf of Mexico Dead Zone. Retrieved from http://utah.pbslearningmedia.org/resource/envh10.sci.life.eco.deadzone/agricultural-runoff-and-the-gulf-of-mexico-dead-zone/ on December 27, 2013. 

Agriculture & Water Consumption

Agricultural activities use a lot of the world's water resources for irrigation, to avoid years in which farmers would otherwise be able to produce little or not food. However, there are wasteful and non-wasteful methods of irrigating crops. Wasteful methods include overhead sprinklers, trench irrigation (canals carry water from a stream to the fields) and flood irrigation (in which fields are flooded with water).  They are considered wasteful because between 15-36% of the water never reaches the crops; it either evaporates or leaves the fields as runoff. Non-wasteful methods, such as drip irrigation, minimize evaporation and runoff by delivering small amounts of water directly to the soil.

Drip irrigation delivers water to the base of each plant so little is lost to evaporation and runoff. Photo courtesy of CK-12. 

If non-wasteful irrigation methods are available, why don't farmers use them? One is cost; drip irrigation is more expensive than trenches, flooding and sprinklers. Second, in the US, the government pays for much of the cost of water used for agriculture, so farmers do not directly feel the cost and therefore have little financial incentive to use a more efficient method. 

Source: Uses of Water. Retrieved from http://www.ck12.org/book/CK-12-Earth-Science-Concepts-For-High-School/r16/section/13.11/ on December 27, 2013. 

Water Scarcity

Water scarcity can have dire consequences for the people, economy and the environment. Without adequate water, crops and livestock dwindle and people go hungry.  Industry, construction, and economical development all come to a stand still, and can lead to more poverty. The risk of regional conflicts over scarce water resources can arise.  People die from disease and thirst, or even wars over scarce resources. 

As water supplies dwindle, conflicts can arise between individuals, states and nations that have and abundance of clean water and those that do not. There are examples of non-violent water conflicts in the United States. For example, western states use the Colorado River Compact to manage the Colorado River's water resources. In the southeastern United States, there are also regional conflicts over water. Alabama, Georgia and Florida are unsure how to handle conflicts between their states' growing populations and the availability of surface and groundwater resources.

Listen to the following short podcast:

Listen to the following short podcast:

Some of today's greatest tensions are happening in places where water is scarce. Water disputes may add to tensions between countries where differing national interests and withdrawal rights have been in conflict. By 2025, it is estimated that water resources will not be able to keep up with the growing population rate in many countries; these countries will not have sufficient water resources to maintain their current level of agricultural output or maintain domestic, industrial and environmental needs. 

By 2025 it is projected that many nations will face water scarcity. Image courtesy of USOE OER Resource Guide for Earth Systems. 

Water disputes are happening along 260 different river systems that cross national boundaries. Some of these disputes are potentially very serious. National and international water laws help interpret water rights among states and countries.  New ways to grow more food with less water and water conservation programs are essential to provide enough clean water for the world's growing population.

Listen to the following short podcast:

Listen to the following short podcast:

Sources: USOE OER Resource Guide for Earth Systems and EarthSky Podcasts.