Greenhouse gases and the atmosphere

James Renwick, Gregor Macara and Drew Bingham explain the relationships between greenhouse gases in the atmosphere and some of their effects.

Questions for discussion:

• What does James mean when he says, “If something happens in one place, it’s going to be communicated all around the world.”

• Why will emissions we add now be felt for generations to come?

Transcript

PROFESSOR JAMES RENWICK

There’s one planet, one atmosphere, and that atmosphere is whizzing round pretty quickly, so if something happens in one place, it’s going to be communicated all around the world.

GREGOR MACARA

Our atmosphere is where our greenhouse gases are stored. Our greenhouse gases are a really important component of making Earth habitable and climate and climate change. If we didn’t have greenhouse gases, the Earth would be far too cold, so they trap heat in the Earth’s atmosphere and make it liveable.

DREW BINGHAM

Greenhouse gases are any gas that goes up into the atmosphere and causes the atmosphere to become warmer by retaining heat from the Sun. There’s many greenhouse gases. Carbon dioxide – we really care about that because it stays in the atmosphere for thousands of years, and so any emissions that we put up there now will be up there for generations to come. And as it builds up, that warming effect grows.

But there is also other greenhouse gases like methane and nitrous oxide. And methane is an example of a gas that stays up for a shorter amount of time, but while it’s up there, it has a greater warming effect than carbon dioxide. And so as long as we’re topping up methane emissions, we’re keeping the climate warmer than it would be with just the carbon dioxide warming. Most of the methane comes from our livestock.

Nitrous oxide lasts in the atmosphere for a bit over a century. In New Zealand, nitrous oxide mainly comes from dung and urine of livestock. It goes into the soils, gets transferred by microbes and gets released as nitrous oxide.

Acknowledgements
Professor James Renwick, Victoria University of Wellington
Gregor Macara, NIWA
Drew Bingham, Ministry for the Environment
Greenhouse effect animation adapted from NASA animation What is the Greenhouse Effect?