Climate change and the greenhouse gas factor

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Climate change and the greenhouse gas factor
Rising CO2 emissions from the burning of fossil fuels has affected global temperature much more than natural climate variability during the past century.


Glen Paul: G’day, and welcome to CSIROvod, I’m Glen Paul.

Climate change is a serious threat to the planet, and greenhouse gas concentrations are believed to be a major contributor.

In this vodcast, we're going to meet scientists working at measuring green house gas concentrations over time, and the finding that they've been rising rapidly over the past two centuries, in other words since the time of the industrial revolution.

It was at that time we began to burn large amounts of coal to power our steam engines for industry, and to generate electricity, and while the technology has greatly improved we’re still using fossil fuel in quantities thousands of times more than we did in the 1800s.

The fossil fuels we burn contribute to high concentrations of carbon dioxide, methane, and nitrous oxide, and the research clearly shows how the atmosphere was at the beginning of the industrial revolution, and how it is now.

Dr Etheridge: Here we have a picture of nitrous oxide concentrations increasing in the atmosphere over the last few decades. (Dr Etheridge is pointing to a chart on the wall).

These are from measurements of air from the Cape Grim station in Tasmania.

What we want to do, and what we have done here, is to show how that change in the recent decades compares to the long term changes in the atmosphere.

Glen Paul: And that can be achieved by extracting air from polar ice sheets that’s been trapped through snowfall and sealed over thousands of years.

Dr Etheridge: This is a sample from Law Dome, this is some 200 metres down, it’s a section of a core that represents around about one year of snowfall. (Dr Etheridge is holding a frozen core section).

And within the snow that fell are bubbles of air which are formed and sealed within that ice.

There’s a relatively large amount of air in there, around about 100 millilitres for a kilogram of ice, and we extract that in this laboratory and measure it for its various components, and that includes the greenhouse gases, the ozone depleting gases, and the isotopes of those gases, which tells us about the sources.

Glen Paul: One tale that’s often perpetuated is that natural events like volcanoes are responsible for the rise in atmospheric CO2. This is simply not true.

Dr Fraser: We’ve looked at volcanoes, and they don’t produce much CO2, they do produce a lot of gases, but not a lot of carbon dioxide. And there’s a classic example.

I mean there was a major volcano in South America last year, massive eruption, significant matter emitted to the atmosphere, we looked for the CO2 trace in our records at Cape Grim and found absolutely nothing.

It didn’t perturb the long term trend in CO2 that we’re seeing at all.

So it’s they’re important events, but they’re not large on the scale of the emissions of fossil fuel CO2 to the atmosphere.

Glen Paul: With misinformation doing the rounds, Atmospheric scientists are very keen to ensure people have access to factual greenhouse gas information.

Dr Fraser: So we decided to make an open website that the public could go to, and they could look at the greenhouse gas data, and they didn’t even have to ask a scientist to do that.

Now that’s great for people who are students, or people who want to use greenhouse gas data, but it’s also really good for those people who might in their mind be somewhat suspicious of the science, and they would rather access the data without going through a scientist so that they could look at it by themselves and make their own conclusions about the data.

So we wanted availability and we wanted transparency in the data, and that’s what we think we do with the website.

Glen Paul: To understand how these atmospheric changes might impact Australia’s natural and managed systems, the Australian Government is supporting a broad range of climate change science research activities.

Paul Holper: The Australian Climate Change Science Program is supplying a lot of information about how Australia and the world are changing, so we’re looking at past changes, we’re looking at what’s happening today, and we’re also working through how Australia’s climate is likely to change in decades ahead.

We have scientists who study the oceans, the atmosphere, the biosphere, we have scientists who develop and apply really sophisticated models of behaviour of the climate, to better understand the changes and to look to the future to establish what the changes are likely to be.

Glen Paul: With such a huge demand for climate change information Australian scientists are working on delivering the most detailed national climate change projections ever produced.

Dr Whetton: There are many people that want climate protection information.

It ranges from the general public, policy makers in Government, but also more technical applications in industry and Government agencies.

Managing things such as natural ecosystems, water resources, agricultural production, those three are probably three of the most important areas for... where climate change will have a significant impact.

Glen Paul: And impact it will. Climate change is most certainly being driven by increased concentrations of greenhouse gases in the atmosphere brought on by human activities.

Dr Etheridge: The question is to whether this is just a natural cycle in the levels of greenhouse gases in the atmosphere – well, it’s not.

We look at thousands of years; we don’t see concentrations anything like we have at the moment.

Dr Fraser: The fundamental driver of the increase in carbon dioxide is the burning of fossil fuels.