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Simple Explanation of Greenhouse Effect

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Imagine your house is the earth, and your boiler is the sun, and the boiler runs at constant output non-stop, like the sun. As there is no control throughout the year with seasons, the house may get too hot in summer or too cold in winter, like the seasons on the earth. Overall, the average temperature will be constant give or take on a yearly basis.

Now, if you increase insulation in the walls and windows, the boiler is still putting out the same energy and the house on average will get hotter with usual seasonal variations.

When you continue to add insulation every year, eventually your house will become unbearably hot.

The addition of CO2 to the atmosphere by the burning of fossil fuels mainly and some other gases like methane, is the same as adding insulation to the walls of your house. The more CO2 that is added, the warmer the earth will become.

Where do greenhouse gases come from?

The main greenhouse gases present in the atmosphere are Carbon Dioxide CO2 and Methane CH4. CO2 is more prevalent by weight in the atmosphere, even though it’s not as efficient at trapping heat as Methane. Both gases occur in nature:  

  • methane by decomposing vegetation and biomass and flatulence from ruminating cattle
  • CO2 is emitted from active volcanoes.

The rise in CO2 in the atmosphere really began at the start of the industrial revolution in the mid-1900s with the burning of coal in steam engines and industrial boilers, and later in the 20th century by the combustion of coal, oil and natural gas in internal combustion engines and the manufacture of fertilizers and cement. The charts below are self-explanatory.

Source: The Times & Sunday Times: Is the 1.5 degree climate target realistic – and does it matter?

Where are we at with Greenhouse gases?

At present, if we stopped burning fossil fuels, there would be a residue of approx. 35billion tonnes of CO2 in the atmosphere.  Some of this will be absorbed by the forests, the oceans, and the land over the next generations, but this is unlikely to happen with the present rate of progress from the industrialised countries, the present energy crisis, and the return to coal-fired power by China and Germany to alleviate the power short take in their countries.

The main effect on the environment of the presence of these gases will be:

  • Increased global average temperatures. The aim of COP in Paris was to limit global warming to 1.5⁰C, but as we are already approaching 1.1⁰C and CO2 levels for 2021 are an increase on the previous year, this target seems unlikely to be reached.
  • More flooding. As the atmosphere warms up, its capacity to hold water increases, and as a consequence when it precipitates, the amount of water increases.
  • Rising sea levels. As more of the ice caps and continental glaciers melt and the sea expands because of heating, the sea level will rise. This will give rise to islands in the Pacific becoming uninhabitable and parts of Bangladesh, which are only 4m above sea level, and home to >120m people, being evacuated with resulting migrant crisis.  Also, as most capital cities in the world are on coastlines, preventative flood measures will be required to save them.
  • More and longer droughts, as is being witnessed in the western USA and East Africa.
  • The extinction of some species of mammals and fish and the destruction of the ocean’s coral.      

Hope

The present climate situation while very bleak is not irreversible or irretrievable but will require a lot more of a concerted effort on behalf of the developed world.  Effort, because the effects of global warming are having a bigger effect on the poorer countries that did not contribute proportionally to the problem.

As the cost of renewable energy from wind and solar and developing wave power drops, and the incentives to use these technologies both politically and economically increase, they are having an increased effect on the reduction in greenhouse gas emissions.  If the level of reduction plus the natural processes that contribute to the reduction – such as forestation, etc – can not match or exceed the level produced, then the temperature will continue to rise. The hope is this scenario will happen by 2050.

The nuclear fusion option, if it is ever made viable, will be another 25-30years before entering service, by which time the die may be cast. The proven fission nuclear power plant options with lead times of 12-15 years and increasing costs of disposal after service is not the answer.

Politicians and Nimbies (Not In My Backyard, referred to as NIMBYism) – will have to agree for the better good of civilization that short-term measures like having wind turbines in their back yard will be necessary until more environmentally-friendly technologies are developed, and then the Nimbies’ grandchildren can have their back yard back.

Author:  James Nolan’s expertise is in analysing thermodynamic cycles and primary energy to power or fuel.  He advises on utilities and carbon credit incentives and tariffs. 

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