There are various gases which create a “greenhouse effect”, letting heat from the sun through but not letting it escape out again.
These include carbon dioxide, methane and, very importantly, water vapour. When land-ice melts and seas expand and warm up, more water evaporates and this increases the warming effect. The burning of fossil fuels is a particular problem, putting huge amounts of carbon dioxide, Co2, into the atmosphere.
Before the Industrial Revolution, these issues weren’t so prevalent. Machinery and lifestyles requiring fuel in the form of coal, oil and gas changed that. However, the very most rapid increase in both Co2 emissions and – consequently – global warming has occurred since 2000. At the same time, deforestation has been occurring on a massive scale, reducing the technology that nature provides to absorb Co2 and avoid over-warming (also known as trees).
Ed Hawkins of Reading University has created some great visual aids, including Climate Spirals: and Warming Stripes, showing the change in average annual temperature for different areas around the world:
The Intergovernmental Panel on Climate Change report of October 2018 made it clear that we are in an absolutely desperate situation. We have 12 years to stop adding Co2 to the atmosphere, or the damage will be irreversible, with the resulting cycle of breakdown threatening human existence.
There are many things that can and must be done to tackle climate change. The food industry, and in particular the meat and dairy, contributes enormously to the problem, as does our own travel and simply heating or powering our homes. National governments must urgently co-operate to tackle these issues, and we as consumers can help nudge them and big corporations, by choosing how we spend our money.