Greenhouse Gases and the Paris Climate Accords

For the longest time climate change had been a meaningful issue to me because I knew it was going to have a profound impact on the future of our whole planet. However, I didn't know what exactly was being done to combat climate change. When I heard we would get to research any topic relating to biology, I took the opportunity to educate myself on something I had vaguely heard of but wanted to know more about: The Paris Climate Accords. The Accords were signed, in December 2015, signifying the first time in history when all of the most powerful nations in the world agreed to a framework for how to handle climate change in the future. The goal of the accords was to reduce climate change by reducing worldwide greenhouse gas emissions. To understand the importance the Paris Climate Accords, it is necessary first to know what greenhouse gases are and how they work on a molecular level, and second to know the history of international climate change policy and conferences.

Greenhouse gases are gases that can absorb solar radiation. They include ozone, carbon dioxide, water vapor, and methane. While greenhouse gases might commonly be seen as problematic, in proper amounts, they are necessary to life on Earth because they keep Earth warm, protect Earth from solar wind, and prevent heat from immediately escaping Earth's surface. Greenhouse gases in the atmosphere keep the Earth warm because they refract infrared radiation (heat). When a photon of the infrared hits a greenhouse gas molecule, the gas molecule absorbs the radiation and starts to vibrate. The vibration forces the gas to emit a different infrared photon. Once the photon is released, the greenhouse gas molecule stops vibrating. All molecules vibrate when they are hit by a photon, but greenhouse gases vibrate in more ways because they are non-polar and have more atoms than the other gas molecules. As a result, when heat rises from the Earth, greenhouse gas molecules refract some of that heat back down, while the remainder passes through into space. The more greenhouse gases in the atmosphere, the more heat is trapped. (Still confused how the greenhouse effect works? Check out this zany video.)

Illustration of carbon dioxide absorbing and emitting infrared radiation.

It might be asked why greenhouse gases don't prevent heat from entering the atmosphere in the first place, since they can refract it back in the direction it came. But greenhouse gases don't keep heat out as they keep heat in. Part of the reason for this is because go the length of lightwaves. The sun releases shorter waves that are not as easily absorbed by greenhouse gases, but when these waves hit the Earth they elongate. The longer lightwaves coming from the surface of the Earth are more likely to be refracted back.

Lightwave length and the greenhouse effect.

In recent years the quantity of greenhouse gases in the atmosphere has increased because of a variety of human activities. These activities include increased combustion (cars and other machines rely on fossil fuels that release carbon dioxide), increased methane emissions (large numbers of cows and other animals bred by humans emit methane as farts), and deforestation (fewer plants are taking in carbon dioxide). The excess greenhouse gases in the atmosphere keep infrared light radiation trapped near Earth's surface for longer, as they are more likely to be refracted down, slowly heating the planet. Leading climatologists estimate that if the trend regarding greenhouse gas emissions continues as is, the Earth's average temperature will rise by 3.8 degrees Celsius by 2100. This could spell disaster for the future. Coastal communities will be flooded, freshwater sources will be depleted, ecosystems will be ravaged, and species will go extinct. The list of the possibly terrible consequences could fill a book.

Cow farts are a serious contributor to increased levels of methane in the atmosphere.

Worldwide governments have started to recognize the threat of increased temperature and climate change. Since the 1990s, the United Nations has been hosting annual conferences focused on climate change, but these have been relatively unsuccessful (or worse) because more developed nations have tried to impose idealistic policies (like regulating coal production worldwide) that would be a great burden for developing nations. After two decades, the United Nations decided to change their approach. Instead of trying to enact global policies, each country would present a specific national plan and goal to limit its own greenhouse gas emissions at the 2015 Paris Climate Conference.

All United Nations member nations presented their own targets, called Intended Nationally Determined Contributions (INDCs), at the Paris Climate Conference. Different nations and groups of nations set goals appropriate to their own societies and economies. The United States and Australia put emphasis on reforming their cattle industries. The United States and Japan, both countries with large auto industries, focused on imposing fuel-efficiency standards on their vehicles. Japan and the European Union announced new reforestation efforts. The European Union and India planned to make their heavily used transportation systems environmentally friendly. China and India made pledges to transition from using coal to using renewables and nuclear energy to power their factories.

Every United Nation member nation except for Syria and Nicaragua signed the Accords.

After a month of negotiations, all member states of the United Nations signed onto the agreement. Over 190 countries, from different kinds of government, from different economies, from different languages, from different locations, all came together to sign the agreement. Scientists estimate that if the INDCs are followed, Earth's temperature will only rise by 2.5 degrees Celsius by 2100. While a 2.5 degree increase in temperature is not ideal, it is significantly better than a 3.8 degree rise, as the effects of climate change are exponential. The countries agreed to meet again in 2020 to discuss the progress they in implementing their INDCs.

The red shows the forecast with current policies. The yellow shows the forecast adjusted to the Paris Climate Accords.

Even with the signing of the Paris Climate Accords, climate change is by no means solved. Greenhouse gas emissions are still at extremely high levels, the 2010s have been the hottest decade on record, and many countries still rely on fossil fuels for energy. The agreement has its flaws too. The agreement cannot be easily enforced and funding is only guaranteed through 2020, when the next meeting is planned. Although The Paris Climate Accords does not directly resolve anything, it shows that the world is willing to address climate change and that is an accomplishment in itself. We now have a framework for the world to combat climate change in order to secure the future safety of our species. The Paris Climate Accords gives me a glimmer of hope in a time when progress regarding reducing greenhouse gas emissions seems helpless. We must not resign ourselves to a feeling of hopelessness, instead we should realize the strides the Paris Climate Accords have made to reduce combat climate change and make our leaders uphold our commitments to future generations.