|
|
|
Mr Gunter makes some good points in his letter concerning rainfall in The Narooma News 10/2/10. He says there is nothing unusual about the current dry period. He implies that it is not possible to blame current rainfall patterns on climate change. I disagree with his first point, but agree with the second.
When looking at Bureau of Meteorology rainfall figures for Bega, it has never been this dry. Mr Gunter tells me that the drought from 1938-1946 was just as bad. Over those 9 years, the average rainfall was 630 mm/year. Compare that with the last 15 years from 1995-2009. Over those 15 years average rainfall has been 567 mm/year. It would seem to me that the current drought has been more intense and has gone on for longer than the previously worst drought of the early 40s. Not only that, but the last 10 years have been hotter than the 40s (2009 was the hottest year ever recorded for NSW). By any measure, the current drought is unprecedented if you look at the BOM figures for Bega. I accept that rainfall figures for the coastal fringe have not seen the same level of drought.
I think this discussion highlights the difficulty of trying to determine a rainfall trend when that rainfall is subject to natural variation, and is sporadic at the best of times. Recent heavy rainfall illustrates that point. Could this be the end of 15 dry years? It is a huge relief to see the dams and rivers full again.
I think it will be many years, or even decades before we can detect a significant rainfall trend, and until that time it is not be possible to blame droughts in SE NSW on climate change. I am sure that Mr Gunter and I agree on that point.
At a national level the Bureau of Meteorolgy has determined 4 trends;
• There has been a significant reduction in winter rainfall in south-west Western Australia since the 1970s.
• Rainfall has decreased substantially since 1950 on the east coast, and in Victoria. This decline is less marked if measured from 1900.
• The last decade has seen very low rainfall in southern and central Victoria
• Rainfall in north-west Australia has increased substantially since 1950.
The current drought in the Bega Valley (excluding the coastal strip) is unprecedented, but now hopefully over. To say that the drought is due to climate change is presumptive. To say that the impact of climate change is not worth considering is short sighted.
Matthew Nott
Our improving understanding of Earth's climate, and the changes that are being observed sometimes make it hard to keep up.
For example, last week NASA announced that the past 10 years was the warmest ever on Earth since records have been taken. There is nothing new about that, but the US space agency found that 2009 was the second warmest year on record since modern temperature records began in 1880. Last year was only a small fraction of a degree cooler than 2005, the warmest yet, putting 2009 in a virtual tie with the other hottest years, which have all occurred since 1998.
Our planet is warming, and change is being forced upon us. Could drought be one of the changes that we will need to adapt to.A few weeks ago I suggested that the current drought in SE NSW was unprecedented, and may be due to climate change. That comment has attracted some very polarised opinions.
There are many farms and farmers that have been coping with intermittent rainfall in the Bega Valley for generations. Is the current drought a fluctuation, or the start of a drying trend? That is a question that is more important to our farmers than just about anything else.
Many farmers, particularly ones that have been farming for a long time, have suggested very forcefully to me that the last 15 years of below average rainfall is just part of a natural cycle.
They may be right, and far be it for an orthopaedic surgeon to tell farmers what is happening to their rainfall. However, the CSIRO has had plenty to say on the subject. I would suggest than anyone with an interest in long-term rainfall patterns in SE NSW should have a look at the CSIRO’s South Eastern Australian Climate Initiative. It suggests that the drought in SE NSW is not just a natural dry stretch, but a shift related to climate change. An intensification and southern movement of a subtropical high pressure ridge is driving rain-bearing low pressure systems further south, into the Southern Ocean, and away from Australia. The net effect is for Southern Australia to become drier, as the Northern half of Australia gets wetter. Bertrand Timbal from the Bureau of Meteorology says “It’s reasonable to say that a lot of the current drought (in Southern Australia) of the last 12 to 13 years is due to ongoing global warming.”
The CSIRO and Bureau of Meteorolgy are linking drought in Southern Australia with rising global emissions. Not everyone agrees, but when you look at their scientific rationale, it would be foolhardy to ignore them. We will have good seasons again, but we cannot discount a drying trend.
Matthew Nott
The Australian Government has told coastal councils to prepare for a sea level rise of one metre by the end of the century. A one metre rise in sea level will have devastating consequences for coastal communities. It has enormous implications for the value of coastal real estate, it will threaten low lying infrastructure, and will greatly change the way that we think about coastal development. It will have an impact on coastal tourism and the quality of our beaches.
Is the warning of a one metre sea level rise reasonable? My reading of the literature tells me that it is.
Rob High feels that a concern about significant sea level rise is unfounded.
Is the Australian Government being hysterical, or has Rob High got it wrong. Rob and I will be debating the science of climate change at the Merimbula RSL at 7pm 19/1/10, and all are welcome. We will be looking at the impact of sea level rise, along with the threat of changing rainfall patterns and bush fire risk on our region, and there will be an hour for questions from the audience. The aim of the debate is to stimulate community discussion.
Matthew Nott
The Bega District News pointed out in it's front page story last Tuesday that 2009 was the driest year ever recorded in the Bega Valley. For comparison, the story highlighted other dry year years as being 1941, 1982, 2002, and 2006. Could these dry years be occurring sporadically as part of natural variation?
Looking at rainfall figures for the Bega Valley over the last 100 years shows a worrying trend.
Over the last 15 years, rainfall has been low. 2007 received 882mm of rain, bang on the long term average. The other 14 years were all significantly below average. The best rainfall year after 2007 was 1999, which was 20% below the average. 6 of the last 15 years received about half the average rainfall. The current drought is unprecedented.
Not only has rainfall been low, but surface temperatures been high. The last 6 months from July to December have been the hottest 6 months for that time period in recorded history in NSW. High temperatures increase surface evaporation and decrease run-off.
It has been dry, and it has been hot. The CSIRO has linked changing rainfall patterns to rising emissions, and atmospheric CO2 continues to rise. Farmers are tough, resilient and adaptable, but if the science of climate change is half way true, our farmers are going to be pushed to the limit.
Matthew Nott
CLIMATE CHANGE DEBATE
Dr Matthew Nott, founder and president of Clean Energy for Eternity, and Mr Rob High, well-known local climate change skeptic, will debate the science of climate change at the Merimbula RSL Club on Tuesday, January 19, 2010 at 7.00 pm.
Clean Energy for Eternity (CEFE) is a not-for-profit community group based in SE NSW, acting as a positive catalyst to inspire practical local initiatives to address climate change.
CEFE sees its key role as creating pathways to action and developing high profile models that encourage communities to seize the opportunity to create a sustainable future. Communities in five shires (Bega, Bombala, Cooma-Monaro, Eurobodalla, and Snowy River) have committed to CEFE's target of 50% reduction of energy use and 50% renewable energy by 2020. Potential impacts of climate change are very real for the 50/50 by 2020 rural Shires, where major economic keystones are tourism and agriculture.
Matthew Nott is an orthopaedic surgeon based in Bega. He and his family have lived at Tathra for ten years and since founding CEFE in 2006, Matthew and his CEFE colleagues have worked tirelessly to raise awareness of the effects of climate change in Australia and to raise money for solar panel installations across SE NSW, including pre-schools, surf clubs and rural fire service buildings, as well as St John's Anglican Church, Bega. Clean Energy For Eternity feel that the overwhelming scientific consensus suggests that climate change presents our region with a threat. CEFE believe that solutions to climate change present our region with a very real economic opportunity.
Rob High grew up locally and attended Bega High School before leaving in 1956 to do a degree in Chemical Engineering at the University of Sydney. He then worked in Australia and throughout the world mainly on sewage and energy projects before returning to Merimbula in 1988 and is now retired. Rob says, "I am even more passionate about science than about global warming which has come to dominate scientific discussion in recent years."
He says,"I am not an expert on global warming – or anything else – but have read a lot and am dismayed at the amount of time and money being wasted on global warming, while we virtually ignore our other real and disastrous impacts on the environment."
For further information please call Prue Kelly on (02) 6492 0505 or 0418 161 547
The last decade saw enormous change in the public’s perception of climate change. Most people had never heard of climate change until about 2005. Suddenly, public perception of the issue changed as people started to realise that climate change is real; that is going to have a direct impact on our lives, and will profoundly affect our children’s lives.
People started demanding political action, and leaders have slowly responded. Who would have thought 10 years ago that the largest collection of world leaders in the history of human civilisation would get together in Copenhagen in December 2009 to unanimously agree that human induced climate change is real, and presents a threat that requires immediate action. World leaders agree that we face a warming of our planet of at least 2 degrees by the end of the century, even with strong action. It was agreed in Copenhagen that a 2 degree warming will be catastrophic.
The science of climate change is compelling. Public perceptions of the problem have changed within a few short years, and world leaders have responded by recognising that a problem exists.
The last decade saw a rapid transformation in the way that people think about our environment. The next decade will see a response to the problem that might just come close to doing what the science demands.
Matthew Nott
|
|
