Friday, July 09, 2010

The Climate Change debate - what path do you want to be on?

Our climate is changing. Media reports from around the world are showing us on a daily basis the truth of our changing climate. Locally, when Carolina and I first moved to south west Western Australia in the mid 1970s, the Scott River area on the south coast was receiving almost two metres of rainfall each year. Today, the annual rainfall has halved, with rain gauge recordings proving that the climate in this part of the world has changed profoundly in less than 40 years.

What then is causing the climate to change? Scientists believe that the large high pressure cells in the northern part of the southern hemisphere have become larger, in turn pushing the low pressure cells which contain rain-bearing cold fronts further to the south. This then causes these cold fronts to drop most of their rain 200 or 300 kilometres further south than before, resulting in much lower rainfall for the most parts of the south west of the state.

We then need to ask why are these high pressure cells larger than they once were. The obvious answer, once again confirmed by scientific data, is that the world is getting warmer. As air heats up, it expands and this is a plausible explanation of why our climate is changing.

But now we come to the hard part. Why is planet earth warming up? Here, there are many theories, the most popular one being a human-caused increase in carbon dioxide in the atmosphere. There is no doubt that CO2 is a greenhouse gas: it traps heat from the sun that would otherwise escape back out into outer space after being reflected off clouds and the surface of the planet. However, water vapour is also a greenhouse gas and it is the most abundant greenhouse gas in the atmosphere. It plays critical roles in regulating global climate, yet the US government's National Oceanic and Atmospheric Administration (NOAA) division admits that "though the basics of the hydrological cycle are fairly well understood, we have very little comprehension of the complexity of the feedback loops. Also, while we have good atmospheric measurements of other key greenhouse gases such as carbon dioxide and methane, we have poor measurements of global water vapor, so it is not certain by how much atmospheric concentrations have risen in recent decades or centuries, though satellite measurements, combined with balloon data and some in-situ ground measurements indicate generally positive trends in global water vapor." NOAA further states "The feedback loop in which water is involved is critically important to projecting future climate change, but as yet is still fairly poorly measured and understood."

We also know that the burning of fossil fuels has increased CO2 levels from about 280 parts per million to about 370ppm. Since CO2 is a greenhouse cause, it is reasonable to accept that the higher CO2 levels are trapping more heat. Unfortunately, as NOAA has implied, there are still many important uncertainties about the exact level of warming we should attribute to different components of our atmosphere.

To summarise, we have excellent scientific records to show that climate change is occurring; we know that CO2 levels have gone up; we know that water vapour is a greenhouse gas; and we know that we don't know all the answers.

At this point in the climate change debate, we can choose to go down one of several different paths.

Path # 1: we can accept the widely held scientific view that the human-induced rise in CO2 is the cause of the problem and agree to reduce our burning of fossil fuels. This has profound economic and social consequences for billions of people in developing countries who aspire to a standard of living close to that enjoyed by most Australians, Americans and Europeans. To date, no global agreement on reducing CO2 levels has been reached (forget about the Kyoto agreement - it never had a chance of making a difference to global CO2 emissions). Even so, the lack of meaningful action to date has not stopped many scientists and environmental activists from urging radical change to the way in which we live on this planet.

Path # 2: we can accept that rising CO2 levels are just one cause of global climate change and that other factors such as water vapour and heat from the sun are equally or far more important. Since human beings have virtually no control over the amount of water vapour in the atmosphere nor over the amount of heat put out by the sun, there seems to be no action we can take to make any difference to global warming and to all the adverse social and economic consequences which are likely to manifest themselves over the next century or two.

Path # 3: we can accept that climate change is occurring, that we human beings don't know all the possible causes and, as a result, we can't know all the possible solutions, but that we can act now to minimise the impacts of climate change on the millions or billions of people who will be adversely impacted by a warming planet over future years. People who accept this path believe it is a waste of time to enter into long and spiteful debates about whether one is a climate change denier or skeptic or supporter: these are just labels which define or denigrate people and which ignore the need for action, whatever that action might need to be. Instead, people on path # 3 accept that we need to conserve our fossil fuels which exist in finite amounts on the planet and which we should not be wasting in ways that will disadvantage future generations. These people also believe that we should be planning for a hotter, dryer future with higher sea levels. By planning ahead, we can mitigate or reduce the severity of future impacts on human beings if the worst of the climate change predictions come about.

At present, we have people such as Hrimnir Benediktsson from Dalyellup who, as politically motivated environmental activists, want everyone to accept path #1, regardless of how difficult it is to achieve a political solution to rising CO2 levels - just ask former PM Kevin Rudd how hard it was. We also have the so-called deniers such as Professor Ian Plimer who believe no action is needed by human beings since the climate will continue to change no matter what we do.

And then we have the least vocal group - path # 3 - of which I happen to be a member, where we accept that climate change is occurring, we admit that we don't know for sure what's causing it, but we agree to act appropriately to conserve our limited supplies of fossil fuels and to reduce the adverse impacts of the climate changes which we believe will occur over the coming centuries.

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