Greenhouse Gases Explained
The greenhouse gases in the atmosphere play a decisive role in the earth's temperature. The most important are:
- H2O (Water Vapour)
- CO2 (Carbon Dioxide)
- CH4 (Methane)
- N20 (Nitrous Oxide)
- Tropospheric O3 (a key constituent of some areas of stratosphere known as the ozone layer, it absorbs harmful UV-radiation)
Damage is caused principally through the production of greenhouse gases, so called because they have an effect similar to the glass roof of a greenhouse. They allow the sun's rays to penetrate the atmosphere so as to heat up the earth, but they perform an almost shield-like effect, preventing part of the energy from being radiated back into space. As a result, the earth and its atmosphere are slowly heating up. This is the famous greenhouse effect.
Without the greenhouse effect, the average temperature would hover around minus 18 degrees. The key here is differentiating between the natural greenhouse effect, triggered by naturally occurring greenhouse gases in the atmosphere, and the anthropogenic, man-made, additional greenhouse effect which enhances the natural greenhouse effect and encourages current global warming.
The latter occurs when additional greenhouse gases are released into the atmosphere, primarily via the following ways:
- Burning fossil fuels like oil, gas, and coal
- Deforestation or soil extraction (more info can be found here Forests – Our Green Lungs)
- Loss of soils, permafrost, and wetlands releases stored CO2 and methane (and prevents reabsorption)
- Waste disposal, animal husbandry and rice cultivation release methane
- Fertilisers consisting predominately of nitrogen
- Man-made chlorofluorocarbons (CFCs) and other cooling, quenching and propellant gases
A Brief History of Climate Science
The human impact on the climate has been hypothesised, analysed and discussed since as far back as ancient Greece, when Theophrastus, a student of Aristotle, indicated how human activities in the local area (such as draining marshes and chopping down trees) had either a cooling or warming effect on the climate. Various scientists toyed with the the effect of carbon dioxide on the planet's temperature, an area of research that started to slowly scale up once the industrial revolution went into full swing. In 1896, Swedish scientist Svante Arrhenius published his theory that the burning of coal, which released carbon dioxide into the air, caused a ''greenhouse effect'' that could lead to an increase in temperature over a number of centuries.
Arrhenius' theory was largely decried as implausible and it wasn't until mid-way through the 20th century that the idea of humans influencing global temperature really started to gain traction. In the 1950s, US scientist Charles David Keeling developed techniques that could accurately measure carbon dioxide in the air. Dr. Keeling gleaned readings that showed that the amount of carbon dioxide in the air was rising year after year with tests later showing that this increase was a result of fossil fuels combusting. Dr. Keeling's research became, and remains to this day, the touchstone for modern climate science.
How Can We Forecast Climate Change?
As we can see, thanks to daily weather forecasts, changes in the weather can be predicted a few days in advance. Does this also apply to the climate? In a way, yes. As mentioned previously, talking about the climate leads towards discussions about average temperatures over long periods of time. In that sense, we need to think about how to change these averages. Since it is now well and truly established that greenhouse gases play a central role in climate change, one way that scientists measure climate change is by looking at these gases and their effect in raising average global temperatures.
Since the Copenhagen Climate Conference in 2009, and affirmed in the 2015 Paris Climate Accord, 2 degrees celsius (above pre-industrial levels) has been widely accepted among policy makers as the benchmark for allotted global average temperature increase. However, scientists say this target doesn’t go far enough. James Hansen, today one of the world’s most prominent climate scientist, said that the 2 degree target “is actually a prescription for long-term disaster”. Bill McKibben, an American writer who authored the first book on climate change for the general public, suggested the benchmark was a suicide pact of political realism. It doesn’t take much digging into current temperature trajectories related to climate outcomes to understand why.
From the time global measurements first became possible, 2017 marked the second warmest year in modern history according to NASA scientists. This warming hasn’t occurred gradually. Of the 0.8 degree celsius increase in average global temperatures since the industrial revolution, two-thirds of this warming has occurred since 1975. This change is at a rate of about o.15-o.20 degrees celsius per decade. Though discourse revolves around deceptively small upticks in temperature, current projectories promise catastrophic implications for the future of the planet. Already, low-lying islands in the Pacific Ocean are purchasing land in neighbouring nations due to rising tides. As oceans absorb much of the excess carbon dioxide from the air, they have become 30 percent more acidic, effectively sickening the Great Barrier Reef and its ecosystems, and threatening food security in coastal communities around the globe. The world is almost halfway through its emissions budget, and anthropogenic climate change is already changing the landscape of the only assemblage of life known in the universe.
What Happens as the Climate Changes?
The warming of the earth has many consequences:
- Polarcaps and glaciers melt
- Sea level rise
- Biodiversity is threatened (due to loss of habitat and compromised food sources)
- Extreme weather patterns occur more frequently
This change to our ecosystem also present some difficult effects for humanity, namely:
Food supply: productive agricultural areas will shift geographically and the productivity of grazing land could drop
Water supply: Higher rates of evaporation and increased intensity and duration of droughts will elevate water scarcity in some parts of the world
Climate refugees: exacerbated droughts, soil erosion, desertification and natural disasters can all lead to population displacement and human migration. (Find out more via our Knowledge article on Environmental Refugees)
Even if there was an abrupt end to greenhouse emissions, the climate would still change and global warming would still progress by about 0.8 degrees. The reason behind this lies in the large amount of greehouse gases that exist in the atmosphere. The climate reacts relatively slowly meaning it would continue to change.
What Can Be Done to Combat Climate Change?
The challenge is limiting the extent of climate change so that consequences of it remain within a manageable framework that still allows us to survive on this planet. Some of the proposed solutions centre on the need to reduce and stop the level of greenhouse gases being released into the atmosphere and, where possible, undo some of the existing damage. A functioning, regulated emissions trading scheme can be an effective instrument to reduce greenhouse gas emissions.