How to estimate the effect of each gas?

♤ Each gas’s effect on climate change depends on three main factors:

1. How much of these gases are in the atmosphere?

♤ Concentration, or abundance, is the amount of a particular gas in the air. Greenhouse gas concentrations are measured in parts per million, parts per billion, and even parts per trillion.

♤ One part per million is equivalent to one drop of water diluted into about 13 galloons of liquid (roughly the fuel tank of a compact car).

2. How long do they stay in the atmosphere?

♤ Each of these gases can remain in the atmosphere for different amounts of time, ranging from a few years to thousands of years.

♤ All of these gases remain in the atmosphere long enough to become well mixed, meaning that the amount that is measured in the atmosphere is roughly the same all over the world, regardless of the source of the emissions.

3. How strongly do they impact global temperatures?

♤ Some gases are more effective than others at making the planet warmer and “thickening the Earth’s blanket (green house gas)”.

♤ For each greenhouse gases, a Global Warming Potential (GWP) has been calculated to reflect how long it remains in the atmosphere, on average, and how strongly it absorbs energy.