“Climate change is one of the most formidable challenges of our time. The science is clear. The danger is very real. The stakes are high. We must act.”
The Climate Institute

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The Earth would be much colder if not for the ‘greenhouse’ gases that provide a blanket that warms the atmosphere. Some of the gases in the atmosphere transmit the short-wave radiation from the Sun to the Earth, warming its surface.

Some of this warmth is emitted in the form of long-wave (infrared) radiation from the Earth to the atmosphere and some of the gases in the atmosphere absorb and re-emit radiation of this wavelength, effectively enhancing the warming of the lower atmosphere.

These gases are called greenhouse gases because their effect is similar to the function of a glass greenhouse that heats up as infrared radiation is trapped by the glass. The main greenhouse gases are water vapour, carbon dioxide, methane and nitrous oxide, all of which occur naturally in the atmosphere.

Water vapour is the major contributor to the greenhouse effect. Water vapour concentrations fluctuate regionally due to natural impacts, and human activity generally does not directly affect water vapour concentrations except at very local scales. However, climate models are now predicting the concentration of water vapour in the upper troposphere may increase in response to increasing concentrations of other greenhouse gases. This increase in water vapour could play a key role in amplifying the rate at which the climate warms.

The gases that contribute directly to the enhanced greenhouse effect because of anthropogenic activities are carbon dioxide, methane and nitrous oxide emitted from combustion of fossil fuels, deforestation and agriculture, and sulphur hexafluoride, perfluorocarbons and hydrofluorocarbons arising from industrial processes. It is these six gases that are controlled under the UN Framework Convention on Climate Change. Some other gases, including carbon monoxide, nitrogen oxides and volatile organic compounds, contribute indirectly to global warming through chemical reactions in the atmosphere. Other emissions, such as sulphate aerosols have a cooling or dimming effect on the climate as they reflect some of the short-wave radiation before it reaches the earth’s surface.

The contribution of each of the greenhouse gases to global warming is dependent on its Global Warming Potential (GWP), expressed as carbon dioxide equivalent (CO2 e).

    The GWP takes into account:
  • the amount of radiation that the gas absorbs and the wavelength at which it absorbs,
  • the time that the gas stays in the atmosphere before reacting or being dissolved in rainwater or the ocean,
  • the current concentration of the gas in the atmosphere,
  • and any indirect effects of the gas (eg. methane will produce ozone gas in the lower atmosphere and water vapour in the stratosphere).

The GWP of nitrous oxide is 298 times that of carbon dioxide and methane is 25 times that of carbon dioxide when considered over 100 years. The concentration of CO2 in the atmosphere in 2005 was 379 parts per million (ppm), compared with the pre-industrial value of 280 ppm, and is rising at 1.9 ppm per year (1995-2005 average).

The increase in concentration of greenhouse gases in the atmosphere has altered the earth's radiative balance, resulting in more of the sun's heat being absorbed and trapped inside the earth's atmosphere, producing global warming. Without mitigation measures, the concentration of CO2 in the atmosphere is predicted to rise to at least 650 ppm and up to 1200 ppm by 2100 (IPCC 2001a), which is expected to increase average global temperature by 1 to 6°C.

Most scientists agree that global warming caused by anthropogenic greenhouse gas emissions is one of the most serious environmental problems facing the world today, with far-reaching consequences for all sectors of society. To avert catastrophic impact, it is generally agreed that atmospheric CO2 concentration should be constrained to 550 ppm, which is believed will limit the temperature increase to 2°C. Source

There is no country in the world that is not experiencing first-hand the drastic effects of climate change. Greenhouse gas emissions continue to rise, and are now more than 50 percent higher than their 1990 level. Further, global warming is causing long-lasting changes to our climate system, which threatens irreversible consequences if we do not act now.

It is still possible, with the political will and a wide array of technological measures, to limit the increase in global mean temperature to two degrees Celsius above pre-industrial levels. This requires urgent collective action.

Why 2 degrees?

Two degrees has been identified by scientists as the “tipping point” where abrupt regional climate shifts could occur due to global warming. In other words, that point where global warming is considered "dangerous".

view video on BBC News HERE.

Putting the science into a language we can all understand

In 2016 Northlakes High School students took on the challenge of the complex topic of Climate Change and created this magnificent book “Climate Change is a Shared Responsibility” so we could all understand the science and know how to take action.