Human Population causes carbon pollution

The concentration of carbon dioxide in the atmosphere has gone through various fluctuations throughout the history of the planet. In the past few million years, Earth has had previous known ice ages and warm interglacial period. However, since the 1700s, the Earth has seen a great increase in CO2 in the atmosphere as a result of humans burning fossil fuels and cutting forests. This month, the atmosphere concentration of CO2 exceeded 400 ppm, marking the largest concentration on Earth in nearly 3 million years, which is well before the existence of human species. Thus, this rapid global warming phenomenon has been dubbed as the “anthropogenic global warming,” with human actions of the last few hundred years as the primary driving force for these changes.

 Anthropocene and Carbon Emissions

A dramatic rise in the global concentration of carbon dioxide began at the start of the Anthropocene Epoch. The Anthropocene Epoch is the period in the geologic timescale that extends from 250 years ago to the present. During this epoch, humans and our societies have become a global geophysical force. The Anthropocene Epoch is marked by three stages, the Industrial Era, the Great Acceleration, and the Stewards of the Earth System.

The Industrial Era, spanning from 1800 to 1945 CE, marked the first stage of the Anthropocene Epoch. Prior to the widespread use of fossil fuels, the energy harvest available to humans bottlenecked human population. However, the invention of the steam engine in 1770s and 1780s and the turn to fossil fuels shattered the bottleneck, as there were looser constraints on energy supply. The burning of fossil fuels contributes to adding carbon dioxide into the atmosphere. Also, deforestation is a significant source of greenhouse gases. With fewer trees, there is less conversation of carbon dioxide to oxygen. In addition, the Haber-Bosch synthesis revolutionized agriculture and sharply increased crop yields across the world. As a result, between 1800 and 2000, the population grew more than six-fold while human economy increased 50-fold. Furthermore, only about 10% of the global terrestrial surface had been “domesticated” at the beginning of the Industrial Era, but this figure rose to 25-30% by the year 1950. Thus, the transformation of forests to agricultural space, coupled with inventions fueled the burning of fossil fuels, resulted in increasing the concentration of carbon dioxide in the atmosphere.

During this Industrial Era, the carbon dioxide concentration rose by about 25 ppm, surpassing the upper limit of natural variation through the Holocene Epoch. This provides the first indisputable evidence that human activities were affecting the environment at the global scale.

The Great Acceleration, spanning from 1945 to the present day, marks the second stage of the Anthropocene Epoch. The Great Acceleration refers to the human enterprise suddenly accelerating upon the end of World War II in 1945. In merely 50 years, the population doubles from 3 billion to 6 billion. In addition, humans develop many new technologies, which result in new applications of fossil fuel consumption. These new inventions include the pressurized cabin, radar, synthetic rubber and oil, television, computers, nuclear energy, and modern medicine. Also, public health efforts, such as water sanitation, vaccination, and epidemic control, allow births to consistently outnumber deaths in urban environments. With these new inventions and the large increase in global population, the accumulation of carbon dioxide in the atmosphere continues through the burning of fossil fuels and cutting of forests.

During this period, manmade chemicals, such as CFCs, contributed to loss of stratospheric ozone. Chlorofluorocarbons, such as Freon 12 (CF₂Cl₂), are very stable molecules that slowly diffuse to the stratosphere, where they are subject to the energetic UV rays that ruptures their chlorine bonds. The collision with ozone molecule forms O₂ and ClO, which later reacts with molecular oxygen to form Cl and O_2. Ultimately, the presence of CFCs results in the decomposition of ozone, which filters potentially damaging ultraviolet light from reaching the Earth’s surface. These UV rays can cause defects and cancer in many species, including humans. Hence, the use of these chlorofluorocarbons has been curtailed recently to reduce the loss of the ozone layer.

As a result, the pressure on the global environment during this period results in change to the ecosystem occurs more rapidly and extensively than ever before. During this Great Acceleration, the carbon dioxide concentration rose by about 70 ppm, with about 48 ppm rise occurring in last 30 years (Table 1). The Great Acceleration is marked by human neglect of the impacts on the world. However, as we reach the present, humans quantify and recognize their vast impact on the world. 

From the present date to the unknown future marks the final stage of the Anthropocene Epoch, Stewards of the Earth System. In this final stage, collected data shows negative impacts on the Earth, such as greenhouse gases, ozone layer depletion, and rising sea levels. More importantly, humans begin to recognize their human impact on structure and functioning of Earth System as a whole. Furthermore, this recognition proceeds to decision-making at many levels of human society.

Awareness is increased through advances in research, power of the internet and media, and democratic political systems. Today, technology and research have shown the effects of carbon pollution in plethora of measurable ways. With the carbon emissions into the atmosphere, there are rising levels of carbon dioxide in the ocean as well. As more carbon dioxide accumulates, the pH of the ocean decreases, which results in the removal of a carbonate ion and making calcium ion unavailable to organisms.

In addition to acid acidification, the global rise in temperature has posed various problems as well. The rise in temperature results in the melting of large glaciers, which contribute to rise of sea levels. For example, the partial deglaciation of Greenland and West Antarctic ice sheets adds nearly six meters to sea levels rise. With so much of human population residing by the coast, this rise in sea level threatens the habitat of billions around the world. Also, the rise in carbon dioxide concentrations in the atmosphere has altered total rainfall across the world. The changes in rainfall affect the many species depending on the rain, from humans to trees to amphibians.

In addition to impact on humans, the global climate changes from carbon pollution affect many species living on Earth. For example, amphibians populations have diminished greatly over the last forty years, as nearly 40% of amphibian species are in danger of extinction. As mentioned earlier, climate change plays indirect role in affecting tropical forests. For amphibians, changes in rainfall alters breeding behavior, as larvae may not survive due to these different conditions. Furthermore, UV-B radiation results in decrease in ozone levels, which reduces the chances of survival for larvae. Hence, the human actions have impacted the world and many of its inhabitants.

The problems created during the Anthropocene Epoch are reaching a critical point. The structural and functioning of the Earth System has been altered greatly by humans in the last two centuries. The global demand for fossil fuels is overwhelming, yet the consequences of its use increase every day. Together, society must choose an approach to change the future, or else the future of the planet and human existence as we have come to know will be bleak.