by Cecilia Neave, Environment and Business Student, University of Leeds
Firstly, let’s set the record straight: the earth’s climate has been naturally changing since the beginning of time. However, humans are now causing the global climate to change at a much faster rate than ever before … and this is bad for the earth and all earth-dwellers. It is this accelerated change that people are referring to when they say ‘climate change’.
The main cause of this climate change is a build-up of greenhouse gases in our atmosphere. Greenhouse gases absorb infrared radiation (heat), acting like the glass on a greenhouse, trapping the heat. The most abundant greenhouse gases in Earth’s atmosphere are:
• Water vapour (H2O)
• Carbon dioxide (CO2)
• Methane (CH4)
• Nitrous oxide (N2O)
• Ozone (O3)
• Chlorofluorocarbons (CFCs)
• Hydrofluorocarbons (HFCs)
These gases exist in the environment naturally. At a lower concentration in the atmosphere, they would allow most of the Sun’s infrared radiation to escape. And of course they used to do this. So the Earth’s climate could remain relatively consistent year-on-year. However, greenhouse gas emissions have significantly increased since 1900. In fact, since 1970,
CO2 emissions have increased by about 90%.
Along-side this, we have also seen a depletion of green, photosynthesising plants, such as rain forests and ocean algae, which absorb atmospheric
CO2 . This compounds the effect of increasing CO2 emissions. As a result the average temperature on earth is rising drastically.
For a visual depiction of our changing climate see: https://climate.nasa.gov/vital-signs/global-temperature/ their ‘TIME SERIES: 1884 TO 2017’ is particularly sobering.
To quote NASA …
“17 of the 18 warmest years in the 136-year record all have occurred since 2001, with the exception of 1998. The year 2016 ranks as the warmest on record”
These greenhouse gases that scientist believe are behind this come from a number of sources. There is no doubt among mainstream scientists that their increase has been caused by many human actions. Find out more about these in Part 2.