How global warming leads to harmful climate change

As the earth gets warmer, our climate and weather both change, and this impacts on people and the natural world. Read on to see, in non-scientific language, how this occurs.

Temperature and energy

The burning of coal, gas and oil since the Industrial Revolution (about 1800) has increased the concentration of carbon dioxide (CO2) and other gases in the earth’s atmosphere.

This traps more of the sun’s heat and so has increased the earth’s temperature by more than 1 degree Celsius. (To read more detail on this, see The science of global warming.)

Higher temperatures put more energy into the biosphere (the earth’s surface and atmosphere, containing most life on earth) and this (in the words of NASA) “supercharges” the atmosphere.

More extremes

This increased energy and temperature means that, other things being equal, we can expect greater extremes of weather, for example:

  • worse heatwaves,
  • melting glaciers and polar ice,
  • more intense bushfires,
  • changes in rainfall patterns (including lower rainfall in south eastern Australia),
  • worse floods and droughts,
  • more intense storms,
  • rising sea levels,

Some of these effects are already observable.

Sometimes one effect works against another. For example, you’d expect extreme rainfall events to lead to more extreme floods, but in some cases this is counterbalanced by the drier condition of the catchments, meaning more of the rain is taken up by the soil and less runs off to form a flood.

As scientists learn more about climate and build better and better models, these details are gradually being worked out.

This affects Australia

Australia is significantly affected by climate change. The Australian Government lists these effects already evident in 2019:

  • Australia’s warmest year on record, with the annual national mean temperature 1.52 °C above average
  • Both mean annual maximum and minimum temperatures above average for all States and the Northern Territory
  • Annual national mean maximum temperature warmest on record (2.09 °C above average)
  • Widespread warmth throughout the year; January, February, March, April, July, October, and December all amongst the ten warmest on record for Australian mean temperature for their respective months
  • Significant heatwaves in January and in December
  • Australia’s driest year on record
  • Nationally-averaged rainfall 40% below average for the year at 277.6 mm 
  • Rainfall below average for most of Australia 
  • Rainfall above average for parts of Queensland’s northwest and northern tropics 
  • Much of Australia affected by drought, which was especially severe in New South Wales and southern Queensland
  • Widespread severe fire weather throughout the year; national annual accumulated Forest Fire Danger Index highest since 1950, when national records began

References

Main photo: Hurricane Katrina in the Gulf of Mexico, 2005 (NASA)