What Causes Global Warming?

Global warming refers to an increase in the earth’s temperature which is believed to be caused in part by the greenhouse effect or the excessive releases of gasses such as carbon dioxide, methane and nitrous oxides as well as the depletion of the ozone layer which is mainly the result of chlorofluorocarbons and halocarbons that are released into the atmosphere.

Many people believe that global warming is largely due to the effects of human activities, especially industry and agriculture. However, while human activity is very likely a big contributing factor, we are not the sole cause of global warming. In addition, the issue of rising global temperatures is not an exact science.

Scientists believe that over the last 400,000 years, there have been four almost identical weather cycles, lasting a little over 100,000 years each. During each cycle it was cold for almost 100,000 years. Then there was a much warmer period lasting 10 to 20 thousand years with average temperatures comparable to the present. By studying weather patterns in terms of 10’s of thousands of years, it is likely that year to year fluctuations in temperature and a gradual increase in the average global temperature indicates a natural "global warming" cycle.

In the past few hundred thousand years, the major cause of climate change has been due to the cyclic variation of earth's orbit around the sun which has changed the average amount of energy that the earth receives from the sun. These variations in earth's orbit have created some very long lasting "astronomic seasons", similar to "regular seasons" over a year. They have been the major cause of climate change and have generated the series of ice ages and "warm" periods like the ones we are now experiencing.

This natural astronomical cycle has a domino effect on the planet which further increases the incident of global warming. One very important factor involves the arctic regions. The slight rise in temperatures is enough to begin to melt the earth’s permafrost which is the ground that has been frozen since the last ice age. When this happens, the layers of dead plant material and other organic compounds in the soil begin to decay which creates byproducts of carbon dioxide and methane gases. This process releases more greenhouse gases into the atmosphere creating a vicious cycle that snowballs global warming. Volcanic eruptions also contribute to the presence of gases in the atmosphere.

Global warming is primarily caused by the increase in greenhouse gases like carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) in the Earth's atmosphere. These gases trap heat from the sun, leading to a rise in global temperatures. Human activities, such as burning fossil fuels for energy, deforestation, and industrial processes, are significant contributors to these emissions.

Carbon dioxide (CO2) is the most significant greenhouse gas emitted by human activities, especially the burning of fossil fuels like coal, oil, and natural gas. CO2 molecules absorb infrared radiation and re-emit it in all directions, causing the Earth's surface to warm. According to the EPA, CO2 accounted for about 79% of all U.S. greenhouse gas emissions from human activities in 2020.

Natural processes can contribute to global warming, but the current trend is largely driven by human activity. Volcanic eruptions, solar radiation variations, and natural greenhouse gas emissions do affect climate. However, the Intergovernmental Panel on Climate Change (IPCC) has found that the rapid increase in global temperatures over the past century is primarily due to anthropogenic factors.

Deforestation plays a significant role in global warming by reducing the planet's capacity to absorb CO2. Trees act as carbon sinks, removing CO2 from the atmosphere through photosynthesis. When forests are cleared, not only is this carbon-absorbing capacity lost, but the stored carbon is also released back into the atmosphere, exacerbating the greenhouse effect.

Methane (CH4) and nitrous oxide (N2O) are potent greenhouse gases with a stronger heat-trapping ability than CO2. Methane, released during the production and transport of coal, oil, and natural gas, as well as from livestock and other agricultural practices, is over 25 times more effective at trapping heat over a 100-year period. Nitrous oxide, from agricultural and industrial activities, as well as combustion of fossil fuels and solid waste, is about 298 times more potent than CO2 over a century.

While some effects of global warming may be irreversible, such as the loss of certain species, it is possible to mitigate its progression by significantly reducing greenhouse gas emissions. Transitioning to renewable energy sources, increasing energy efficiency, reforestation, and adopting sustainable agricultural practices are key strategies. International agreements like the Paris Agreement aim to limit global temperature rise by reducing emissions globally.