Where is the climate change debate taking us?

June 19, 2009
By: David Walker, Executive Officer

There has been quite a discussion on climate change in local radio and print media over the last couple of weeks, a ClimateSmart Forum put on by LPLM, TMLA and TAFE in Somerton, and further afield, with Senator Steve Fielding asking some hard questions of the Minister for Climate Change, Penny Wong and Australia’s Chief Scientist, Professor Penny Sackett.

The talkback radio program on the local ABC Radio station created spirited debate with apparently about 2 climate change ‘sceptics’ calling in for every person who indicated that they accept that climate change/warming is occurring. 

It seems to me that there is quite a bit of confusion about what ‘climate change’ is, and what, if anything, is different about what we are likely to face in the future compared to what we, our parents, our grandparents and those who came before them have already experienced.

There is further confusion about whether or not there is a relationship between ‘greenhouse gas’ emissions and global warming. This is not surprising, as there is still plenty of disagreement being aired, and followers of either doctrine can find experts to support their beliefs. 

In coming weeks I shall try to provide more information on some of the topics that are being so hotly debated, along with some references for those of you who want to do their own research. 

The first, and most important point to make is that the current debate is not about climate variability. We all know that no two years are the same. The question is: are we in a period of change that is not explained by year-to-year variability?

We already know that there are trends in climate. For example, the second half of last century in the Liverpool Plains was some 24% wetter than the first half.

This Bureau of Meteorology chart of annual rainfall certainly shows plenty of variability between years, but also definite differences over longer periods.

Since 2001, the average annual rainfall has dropped to 587 mm. It’s a relatively short period, but if it means we are going back to a drier period like 1896 to 1946, then it will have a significant impact on the viability of our agriculture and the security of our food production.

There has been a definite upward trend in global temperatures over the last 100 or so years, and there has been a marked acceleration over the last 30 or 40 years. According to the NASA’s Goddard Institute for Space Sciences, all eight of the hottest years for global temperature have been since 1998, and 14 of the hottest years ever have been since 1990. 

It’s very unlikely that this is just random variability.

This Bureau of Meteorology chart of temperatures and temperature trends shows that in the period 1910 to 2008 the average temperature rose by 0.12ºC in each decade. But if we look at the period since 1975, the rate of warming has doubled to 0.25ºC per decade.

This may not seem much, but it will mean that by 2020 our coolest years will be hotter than our hottest years were 100 years ago. This will have serious implications for the crops we grow, how our livestock perform, and the reliability of our production systems. At this rate of change, by 2030 Gunnedah’s climate will be like Collarenebri’s current climate (and having worked out there, I can tell you it’s hot!).

One reason that is given for the number of people who believe that figures such as these are just ‘not real’, is that they are too catastrophic to contemplate. Unfortunately ignoring the problem won’t make it go away.

Farmers have always been resilient and innovative, and have already been adapting to the changes that have occurred. Having an understanding of what we face just makes it that much easier to manage.

The Bureau of Meteorology Climate Change page has lots of information.