The negative impacts of humans on the environment

White polar bear with open mouth standing on lower ice cube of three ice cube layers in the sea showing negative impacts of humans on the environment

Ever since humans have walked on the Earth, they have changed the environment in one way or another, certainly not to harm or destroy it but rather to be more comfortable. Humans have reshaped the environment through agriculture, travel and urbanization and more recently, the unparalleled introduction of alien materials into the environment. Scientists believe that ‘original nature’ no longer exists. Now as we proceed into the 21st century, the impacts of humans on the environment are phenomenal.

1.      Overpopulation and overconsumption

Currently, the worldwide population is estimated to be around 7.7 billion people. By 2100, this number is expected to reach 11.2 billion. Since mortality rates have decreased thanks to better medicine, wider food distribution and better lifestyles, the population has been increasing. Vulnerable nations have the densest populations while richer countries have lower rates of population growth.

The situation is quite alarming, especially for the environment. More humans mean more resources – food, space, fossil fuels. All that we consume and use come from finite sources. The more we want to have, the greater pressure we put on our environment and more waste is produced. Socio-biologist, Wilson Edward estimates the Earth’s maximum carrying capacity to be around 9-10 billion people [1]. Currently, humans are exceeding the Earth’s sustainable productivity by 60%.

2.      Pollution

Pollution is the introduction of foreign material into the environment, which can eventually change it. Sadly, as a result of development and industrialization, humans pollute the environment massively, be it the land, air and water bodies. In China alone, air pollution caused by industrialization has a death toll of 1 million people per year [2].

Marine habitats worldwide are being affected by land-based activities such as the release of sewage and contaminants into oceans, agricultural runoff and dumping of plastic trash. Excessive nutrients into the oceans have created 500 dead zones globally – oxygen deprivation – covering an area of 245,000 km2 [3].

a)      Acid rain

Activities like the burning of fossil fuels, manufacturing and the use of heavy vehicle equipment release sulphur dioxide and nitrogen oxides into the atmosphere. These gases mix with condensing clouds and fall to the ground and into water bodies as acid rain. Acid rain can ruin solid materials on land like statues as well as change the soil pH. In the developing countries of Asia, where air pollution is quite problematic, a decrease in crop yields and tree growth has been observed as a result of acid rain [4].

The effects of acid rain in water are even more drastic. It changes the pH of the water which can cause entire marine populations to collapse.

b)      Ocean acidification

Ocean acidification occurs when carbon dioxide mixes with seawater creating a weak, carbonic acid. This, however, reduces the pH of seawater and can have deadly effects. The amount of carbon dioxide in the ocean is now higher than it has been during the past 800,000, increasing sea pH by 0.1 unit [5]. Changes in pH affect the formation of calcium carbonate which is needed for coral growth and the formation of shells of crustaceans.

3.      Climate change and Global warming

The greatest cause of impact on the environment is, without a doubt, global warming. On the one hand, there has been an ever-increasing release of greenhouse gases into the atmosphere and on the other hand, there has been deforestation and the removal of elements that can absorb these gases.

Before preindustrial times, the level of carbon dioxide was less than 300 PPM; this has now peaked to 440 PPM [6]. 97% of climate scientists around the world now agree that changes in the climate are significantly due to human activities. The International Panel on Climate Change states that scientific evidence for warming of the climate is unequivocal.

An increase of 0.9°C in temperature since the late 19th century is having severe impacts as in warming oceans, shrinking and melting glaciers, glacial retreat, decreased snow cover, an increase in the frequency of extreme events and sea level rise.

4.      Agriculture and gene modification

Agriculture itself has its load of environmental impacts like

  • point source pollution,
  • excessive use of water for irrigation and stream modification,
  • use of pesticides and herbicides that leak into water bodies,
  • clearance of forests and riparian zones for growing crops,
  • grazing by cattle and the
  • release of greenhouse gases into the atmosphere by cattle and the use of fossil fuels.

In addition to these, humans have manipulated both plants and animals so as to get better and higher yields and to make them more resistant. Genetically modified organisms are organisms whose genomes have been altered for specific traits that are beneficial to humans.

Over the years, there has been a lot of advance in gene modification such that now genes from a different species can be incorporated into an organism in order to get the best results. This has helped greatly in the medicinal and food sector.

However, gene manipulation is a very risky process; the outcome may neither be what was intended nor be directly related to the process. What’s more, over the years, even plants and animals have undergone mutation to become more resistant to our products. Superweeds, for instance, are now threatening agriculture by choking crops. 249 species of weeds are now resistant to 22 out of 25 known herbicides.

5.      Deforestation and forest degradation

Since the 1960s, more than half of the tropical forests have been destroyed. In Europe also, some 3.7 million hectares of forests have been damaged by cattle, diseases, fire and human activities [7]. Every year, 18.7 million acres of forests are lost due to agriculture and illegal logging [8]. 17% of the rich Amazonian forest has been cleared during the past 50 years to give way to cattle ranches.

Forest clearance and degradation threaten biodiversity directly. Some plant and animal species may go extinct in the wild when their habitats are cleared. Animals, such as elephants, may migrate towards human settlement, cause damage and get killed by frightened and angry villagers.

Forests are the lungs of the planet. They filter the polluted air and release oxygen for us to survive. With an increase in carbon dioxide in the atmosphere, forests are vital to take in the gas. Ironically, houses, hotels, cropland and grazing grounds are now popping up in the places where forests used to be.


  1. Wolchover, N. (2011). How many people can Earth support? LiveScience. [Online]. Available at [Accessed 23/04/2019]
  2. Kao, E. (2018). Air pollution is killing 1 million people and costing Chinese economy 267 yuan a year, research from CUHK shows. South China Morning Post. [Online] Available at [Accessed 23/04/2019]
  3. Marine pollution. UNESCO. [Online]. Available at [Accessed 23/04/2019]
  4. Acid rain. Earth Journalism Network. [Online]. Available at [Accessed 23/04/2019]
  5. Fabricius, K.E., De’ath, G., Noonan, S. and Uthicke, S. (2014). Ecological effects of ocean acidification and habitat complexity on reef-associated macroinvertebrate communities. The Royal Society Publishing. [Online]. Available at [Accessed 23/04/2019]
  6. Climate change: how do we know? NASA. [Online]. Available at [Accessed 23/04/2019]
  7. Deforestation and forest degradation. IUCN. [Online]. Available at [Accessed 23/04/2019]
  8. Deforestation and forest degradation. WWF. [Online]. Available at [Accessed 23/04/2019]

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