What is climate change?

Climate change is the alteration of the climate either due to human intervention or to natural mechanisms. To understand this we need to know what the definition of climate is. Climate is the average weather pattern of a region over a period of time, often this period is 30 years [1]. When you see climate change in the media, often times it's referring to the global climate.

Next we need to know what is meant by natural mechanisms and human intervention. Natural mechanisms involve cyclic changes in the climate that caused by a variety of factors such as changes in the sun, volcanoes, Earth’s orbit and CO2 levels [2]. If the sun's output increases or decreases, the global average temperature in the Earth will change accordingly. If the Earth's orbit strays slightly away from the Sun, the global temperature will cool sending the planet into an ice age.

Human intervention is when activities humans participate in (such as manufacturing or construction) release greenhouse gasses (GHG) which fortifies the Earth's natural greenhouse. Check the GIF out for a simple explanation of how the Earth's greenhouse gasses impact the Earth. The Earth's atmosphere is a combination of different gasses, the main greenhouse effect contributors are water vapor, nitrous oxide, carbon dioxide and methane. Carbon dioxide is released through the burning of fossil fuels, an activity that humans have been extensively utilising since the industrial revolution. Farming and agriculture cause the release of methane due to activities like rice cultivation and livestock waste management [3].

Are GHGs bad?

The short answer is no, in fact they are essential for life. However as with many topics, it is more complicated than that.

GHGs make the planet warm enough for life to exist. Take water vapor for example, as the Earth gets warmer, more water from the oceans and seas evaporate which leads to more water vapor in the atmosphere. The increased water vapor will in turn heat the planet up (creating a positive feedback loop) but it also increases the chance of clouds forming and eventually rainfall. CO2 is also essential for life as plants (and very few animals/insects! [5]) use it for photosynthesis [4].

People tend to believe that greenhouse gasses are inherently bad because they're strongly associated with climate change [6] but this is far from the case. In reality, it is the excess GHGs in the atmosphere that are the issue especially 'forcing' GHGs. These gasses last a relatively long time in the atmosphere and don't respond to climate alterations. An extreme example of what too much CO2 in the atmosphere would be like is the planet Venus. It has 154,000 times the amount of CO2 in its atmosphere compared to the Earth which helped increase the surface temperature to sizzling heights (hot enough to melt lead!) [1].

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References:

[1] NASA - What's the Difference Between Weather and Climate? [Internet]. NASA. 2005 . Available from: https://www.nasa.gov/mission_pages/noaa-n/climate/climate_weather.html

[2] A natural climate cycle - Committee on Climate Change [Internet]. Committee on Climate Change. Available from: https://www.theccc.org.uk/the-science-of-climate-change/climate-variations-natural-and-human-factors/a-natural-climate-cycle/

[3] The Causes of Climate Change [Internet]. Climate Change: Vital Signs of the Planet. [cited 5 August 2020]. Available from: https://climate.nasa.gov/causes/

[4] Society N. Greenhouse Gases: Good or Bad? [Internet]. National Geographic Society. Available from: https://www.nationalgeographic.org/media/greenhouse-gases-good-or-bad/

[5] Rybak S. 4 Incredible Photosynthetic Animals [Internet]. Uloop. 2013 Available from: https://umich.uloop.com/news/view.php/77109/4-incredible-photosynthetic-animals

[6] Andersson B, Wallin A. Students' understanding of the greenhouse effect, the societal consequences of reducing CO2 emissions and the problem of ozone layer depletion. Journal of Research in Science Teaching. 2000;37(10):1096-1111.