As Laudato Si’ states, climate scientists around the world have clearly shown that the Earth’s atmosphere has been heating up rapidly since the early 1800s. Carbon is the main building block of life on Earth, and it is constantly being stored in living things or buried in the ground, or released into the atmosphere and oceans. This is called the “carbon cycle” (pictured). Since the Industrial Revolution (around 1750-1850) our burning of fossil fuels such as coal, oil, and natural gas in our homes, cars, power plants, and factories has released large amounts of carbon dioxide (or CO2) into the atmosphere. The amount of CO2 in the atmosphere is already higher than it has been for more than 800,000 years. Left unchecked, the CO2 in the atmosphere will soon be higher than it has been for many millions of years.

A basic physical property of CO2 is that it traps heat in the atmosphere. We know that the Earth’s climate shifts naturally due to things like volcanic eruptions and solar activity, but since CO2 traps heat so effectively it is now the main “driver” of climate change. The build-up of CO2 in the atmosphere has already led to global warming, especially in the Arctic regions of Earth; more severe weather patterns such as heavier storms and longer droughts; and faster melting of Earth’s mountain glaciers and ice caps. Temperatures have been rising almost steadily since the late 1970s, and the six-month period from January to June 2015 has been the warmest in 135 years. Other evidence shows that  this is being caused by the rising concentrations of CO2 in our atmosphere due to the burning of fossil fuels.

If we don’t act soon to reduce our generation of CO2 in the atmosphere, global temperatures may rise as much as 8 degrees Celsius (14 degrees Fahrenheit). Climate change is not something that will happen in the distant future, it is happening right now, and it threatens our prosperity, our society, and our very civilization. It is one of the most urgent and complicated problems humanity has ever faced.