Climate change is happening all around us, and it’s caused by both natural and human causes. That’s according to the Intergovernmental Panel on Climate Change (IPCC), who just released their latest report on the matter, detailing how the climate will change in the coming decades, how much of this can be blamed on humans, and what can be done to prevent climate change from getting worse. To get you up to speed before this weekend’s summit in Paris, we’ve put together this brief summary of what the IPCC found and what it means for us now and in the future.
Fossil fuel combustion
Carbon dioxide is released when fossil fuels like coal and oil are burned for energy. Greenhouse gases such as carbon dioxide trap heat in the atmosphere, causing Earth’s temperature to rise. Burning fossil fuels also releases other harmful pollutants, like sulfur dioxide and nitrogen oxides, into the atmosphere. These chemicals contribute to respiratory diseases and smog. In addition, burning fossil fuels releases mercury into the air. Mercury has been shown to cause brain damage and has been linked with autism spectrum disorder. The natural gas industry includes hydraulic fracturing, which can produce fugitive methane emissions. Methane traps 25 times more heat than carbon dioxide over a 100-year period. Other sources of greenhouse gas emissions include deforestation and agricultural practices that emit nitrous oxide. Agricultural fertilizers emit ammonia, a precursor to both NOx and NH3. Ammonia is typically emitted by farms during daytime hours because their fertilizer contains ammonium nitrate or urea, both of which break down to form ammonia if exposed to sunlight and oxygen in the presence of moisture. Waste management from municipal landfills emits methane from decomposing organic material. Coal mining and processing produces substantial amounts of methane. Methane also comes from livestock digestion and agriculture. Energy production and use (combustion) accounts for about one third of total anthropogenic greenhouse gas emissions worldwide, mostly from coal power plants, followed by transportation (27%), industrial processes (16%), residential and commercial building heating (9%) and food production/agriculture/forestry (8%).
Human-caused deforestation and land use change
Deforestation and land use changes, which includes agriculture and urbanization, contribute to climate change. Deforestation is the most obvious cause for concern because forests store carbon that is released when trees are burned or cleared, but any changes in land use can also have an effect. If a forest that was previously storing carbon is cut down and turned into farmland, it will release more CO2 than if it remained a forest. On the other hand, when agricultural land is abandoned and allowed to regrow with natural vegetation, it will eventually store as much CO2 as if it had been left untouched. Other types of land use changes can have less dramatic effects on emissions. For example, urban areas may emit more CO2 than rural ones because they require energy to heat buildings and power transportation systems. But cities may also sequester more carbon through their plant life since they often contain a lot of green space that absorbs carbon dioxide from the air around them. In addition, some studies show that dense urban areas like New York City may actually be more efficient at producing renewable energy (such as solar panels) than rural areas like North Dakota. It’s important to remember though that these are generalities and each type of landscape has its own set of advantages and disadvantages. Some landscapes might produce more CO2, but others might produce more renewable energy. Ultimately, understanding the complex interplay between different types of landscapes and how they affect greenhouse gas emissions is one way that humans can fight climate change by adapting our behavior to better match our surroundings.
Industrial agriculture
The industrial agriculture system relies on fossil fuels to produce huge quantities of pesticides, herbicides, and fertilizers. These chemicals contribute to air pollution and acid rain while also exacerbating global warming. In addition, the intensive use of these inputs contributes to water pollution and soil degradation. Other factors such as deforestation, overgrazing, and poor agricultural practices also lead to the loss of natural carbon sinks that help regulate the amount of greenhouse gases in the atmosphere. Furthermore, livestock production is a major contributor to emissions of methane and nitrous oxide, which have significant impacts on the environment.
The industry is responsible for an estimated 18% of total anthropogenic greenhouse gas emissions- more than all transportation combined. It is estimated that the world’s livestock population generates 7 billion tons of CO2e per year – nearly one-fifth (18%) of total annual worldwide GHG emissions. Livestock’s contribution to climate change can be seen through many different processes, including deforestation and land conversion; enteric fermentation; feed production; manure management; transport of animals and feed; processing and packaging meat products, eggs, and dairy products for consumption. One way we can reduce our carbon footprint is by adopting a vegan diet! A recent study showed that if every American were to switch from their current diet to a vegan or vegetarian diet, it would cut U.S. food-related emissions by approximately 10%.
Burning biomass, including forest fires
One significant human contribution to climate change is the burning of biomass, including forest fires. Biomass is anything that comes from living organisms and can be used as fuel such as wood or paper. Burning biomass releases CO2 into the atmosphere which contributes to the greenhouse effect, but it also releases other air pollutants such as soot, which is made up mainly of black carbon. Black carbon absorbs sunlight, heats up and darkens ice crystals in snow and ice, causing them to melt faster. As a result of the greenhouse effect created by excess CO2 emissions, the Earth is getting hotter every year. In fact, 2016 was the hottest year on record since 1880 with global temperatures averaging 1.38 degrees Celsius above pre-industrial levels. And this temperature increase has been accelerating; an average of 0.13 degrees per decade for 1880-1900 and 0.17 degrees per decade for 2000-2016 respectively. These increases lead to more extreme weather conditions such as droughts and wildfires like California’s recent firestorms which have caused billions of dollars worth of damage and destroyed thousands of homes throughout Southern California.
