The Greenhouse Effect
The Greenhouse Effect is a natural phenomenon which allows life as we know it to flourish on earth.
1. The Sun shines
2. The solar energy travels through the earth's atmosphere.
3. This heats up the sea and land.
4. Some heat escapes back into space.
5. The earth is warm enough to sustain a massive variety of life.
If the earth had no atmosphere with which to trap this heat energy the planet would have an average temperature of about -40C. The current average global temperature is 15C.
The problem is that since the industrial revolution, the concentration of carbon dioxide and methane has increased, and will carry on increasing, because of human activity.
Global Warming and the Consequences
Global warming is the heating up of the globe. Global warming occurs when carbon dioxide and other air pollutants like methane collect in the atmosphere and absorb sunlight and solar radiation that have bounced off the earth’s surface. Normally, this radiation would escape into space—but these pollutants, which can last for years to centuries in the atmosphere, trap the heat and cause the planet to get hotter.
Combustion of any type of fuel releases carbon dioxide into the atmosphere. Carbon dioxide is one of the main greenhouse gases. By using fossil fuels, millions of tons of carbon dioxide which was stored underground is being released.
Methane is 30 times more efficient at trapping heat energy than carbon dioxide. The concentration of methane in the atmosphere is also increasing at an alarming rate.
The graph below shows the main sources of methane which is released into the atmosphere in the US.
Enteric fermentation is the breaking down of food into molecules to be absorbed by the digestive system. A was product of this digestive process is the production of methane. Methane is released from animals as burps and farts... but it's the burps that release more methane than the farts. You can read more here
Another source of methane entering the atmosphere is the melting permafrost in the Arctic Circle. As the earth warms, the previously frozen vegetation is now melting and rotting. This is releasing more and more methane into the atmosphere.
Water vapour is also a greenhouse gas. Water vapour is the most abundant greenhouse gas. Humans do not directly increase the amount of water vapour in the atmosphere, but because the planet is getting warming, there is more evaporation from the oceans and so there is more water vapour in the atmosphere.
Over the past 50 years, the average global temperature has increased at the fastest rate in recorded history. And experts see the trend is accelerating: All but one of the 16 hottest years in NASA’s 134-year record have occurred since 2000.
2018 was one of the fourth hottest years ever and the warmest oceans have every been.
*The average temperature in January in Australia was above 30C. Sydney and Melbourne both experienced day time temperatures of about 45C, and over half a million cattle died in flooding in Queensland.
Read more here
* A polar vortex hit the US in January killing over 20 people and plunging temperatures down to -35C. Read more here
* July was the hottest month on record ever. Read more here
* August saw huge fires in the Amazon Rainforest. Read more here
* September and October had the warmest temperatures ever recorded for those months
East Africa received 200% more rain than normal in October causing floods.
* November has seen unprecedented bush fires in New South Wales, Australia. Read more here
2010 - 2019 was the hottest decade on record.
The oceans reached the hottest temperatures on record. This causes sea level rise because of expansion, coral reefs to die and speeds up ice melting at the poles.
Records set in 2020: (as of the 10th of February)
*January was the hottest January on record.
*Brazil recorded the highest amount of rainfall in 110 years with 173 mm in 24 hours, which killed 30 people.
*The Antarctic recorded temperatures of 18.3 degrees celsius.
*Kenya and other east African countries are suffering with the biggest locust outbreak in 70 years.
*Australia has had a record 391.6mm of rain in the past four days (7-10th February) in Sydney, more than three times the average rainfall for February.
The consequences of the average global temperature increasing
1. Sea levels rise as the glaciers and the Arctic and Antarctic melt.
2. Species of animals and plants become extinct because they cannot adapt to changes in their biomes quickly enough
3. Storms become more frequent and more violent
4. Weather patterns change - droughts across areas like Africa will become more frequent and more devastating. The northern hemisphere will become milder and wetter. Areas will also experience more heatwaves
5. The permafrost in the Arctic Circle melts, releasing more methane into the atmosphere = more warming
6. Less sea ice the less heat is reflected back into space so the seas become warmer = melting more ice
7. The Arctic and Antarctic lose more and more ice which causes a greater increase in global temperature.
8. Diseases like malaria will become more prevalent
9. Fresh water will become scarce and there will be food shortages