Greenhouse gases are gaseous components of the atmosphere, both natural and resulting from human activity, that absorb and emit infrared radiation. This property causes the greenhouse effect.

The increase in the concentration of greenhouse gases in the planet’s atmosphere aggravates the greenhouse effect phenomenon, thanks to the increase in quantity and variety of some of the gases that make up the phenomenon. The extreme variations in the greenhouse effect, caused by the change in the concentration of these gases, generates the variability of the world’s climate, better known as climate change.

Types of Gases

Carbon Dioxide (CO2)

In addition to being emitted as a consequence of biological processes, such as respiration, CO2 is released into the atmosphere as a result of the consumption of fossil fuels, such as coal or oil, to produce the energy currently consumed.

Its correlation with climate change has been more than proven. Just focus on the time when climate change began, which coincides with the Industrial Revolution. During those years, carbon dioxide levels were 280 parts per million (ppm), while today that figure has surpassed 400 ppm.

Methane (CH4)

This is a greenhouse gas with a high heat absorption capacity. According to their data, in 100 years, one ton of methane could warm the Earth 23 times more than one ton of carbon dioxide. However, it can be 100 times more destructive than CO2 in the medium term.

Unlike carbon dioxide, the main source of production of this gas is the decomposition of organic matter in biological systems, thus making livestock the sector that produces the largest amounts of this gas (,Vaidyanathan, 2015).

Nitrous Oxide (N2O)

Greenhouse gas with a long-term heat retention capacity 300 times greater than carbon dioxide and which can remain in the atmosphere for 150 years. The main human activity that generates emissions of this gas into the atmosphere is agriculture, since the application of chemical nitrogen fertilizers releases, among other things, this gas, which accumulates in the atmosphere, groundwater, and soil.

Intensive agriculture has caused the sterility of soils, where the natural nitrogen in the soil is no longer available to plants. Therefore, to ensure crop productivity, large amounts of chemical fertilizers are added which stimulate microbes in the soil that convert nitrogen into harmful nitrous oxide (,FAO, 2006; ,EIA, 2011).

Carbon Monoxide (CO)

Carbon monoxide (CO) is a gas emitted by many of the industrial smokestacks we have in our cities and towns, by the exhaust pipes of our cars, etc. However, these are not the only sources of emissions of this pollutant, and its concentration in the atmosphere can be increased by processes derived from the decomposition of organic matter, the incineration of agricultural waste, combustion in stoves and kitchens in our homes, and/or in domestic biomass boilers.

Main Sources of Greenhouse Gases

Animal Agriculture

The livestock sector generates more greenhouse gases, 18%, measured in carbon dioxide equivalent, than the transport sector (,FAO, 2006). Not all meat pollutes equally, since cows are the animals that generate the most gases, with 150 billion gallons of methane per day in their digestive processes, compared to chickens and fish, which pollute the least. In addition to this, humans are responsible for agricultural farms or landfills. (,Goodland & Anhang, 2009; ,Ross, 2013; ,Miller et al., 2013).

If emissions from land use and land change are included, the livestock sector is responsible for 9% of carbon dioxide from human activity. This percentage is higher when it comes to more dangerous greenhouse gases such as nitrous oxide, which comes from manure and is 296 times more harmful than carbon dioxide.

Livestock emits 37% of all methane, equivalent to 32 billion tons of CO2 (,Hickman, 2009).

Transportation Exhaust

From the perspective of climate change, transportation is a particularly relevant sector. In addition to being responsible for a significant share of global emissions, the dynamics of its emissions show it to be the fastest growing and fastest-accelerating sector. In terms of global greenhouse gas emissions, transport is responsible for 13.1% of the total and 22% of those from energy consumption, second only to electricity generation and heating. Between 1970 and 2006, global emissions from the sector grew by 130% (,FAO, 2006; ,EPA, 2016).

Future Greenhouse Effect

It is estimated that if the current trend in greenhouse gas emissions continues, there will be a 20% increase in emissions by 2040. And by the year 2100, the global concentration of CO2 could be between 540 and 970 parts per million. To put this in perspective, remember that the current concentration is 385 and in pre-industrial times it was only 280 parts per million (Energy Global, 2015).

Global meat production will rise from 229 million tons five years ago to 465 million tons in 2050, and milk production will increase in that period from 580 to 1,043 million tons. “That rapid development comes at a high price for the environment.

Change in Energy Production

In December 2015, as a result of the COP21 in Paris, an international agreement was signed that established the objective of maintaining, before the end of this century, global warming below 2 degrees compared to pre-industrial levels and, if possible, limiting it to 1.5 degrees. To achieve this goal, the main tool is the energy transition, i.e. to change from an energy system based on fossil fuels to one with low or zero carbon emissions, based on renewable sources.

However, the energy transition is not limited to the progressive closure of coal-fired power plants and the development of clean energy but is a paradigm shift of the entire system that could take more than 20 years and cost more than 43 trillion dollars. However, there is still hope and it is possible (,Chang, 2013).