Jennifer Marohasy

a forum for the discussion of issues concerning the natural environment

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Drought & Temperature: An Update for Australia from David

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Jen,

I’ve noticed your recent thread on the long-term hydrological drought affecting eastern Australia. I’ve whipped off a few charts for you which put this into an historical context based on rainfall data going back to 1900 (some limited earlier data is available).

In terms of eastern Australia, the current meteorological drought started in early 2002 with the emergence of an El Nino event and continues to the present. The first figure below shows essentially drought “deciles” for this period.

BOM jan02-06 rainfall deciles blog.JPG

As you can see a significant part of SE Queensland has experience its driest 55 month period on record. The data are not spatially dense enough to resolve structures at the catchments scales (though Warwick’s graphs suggest ~5 yearly rainfalls which are lowest on record).

Note that the analysis only shows those areas which are experiencing severe or serious meteorological drought (almost all of eastern Australia has experienced below average rainfall through this period).

Rainfall is only part of the drought story (drought is a function of both water supply and water demand), but it does support the general conclusion that it has been abnormally dry and probably the driest period in “of order” 100 years.

This is just one of three protracted drought periods which Australia is experiencing. Probably the most important from a water management perspective is that which started in early 1997/late 1996 in southern Australia. This is shown in the second figure.

BOM jan97-06 rainfall deciles blog.JPG

This has seen the Perth, Canberra and Melbourne catchments all experience their lowest (or nearly so) rainfall on record. The third protracted drought event is that which commenced in SW Western Australia in the 1970s and which has been linked to a combination of greenhouse gas increases, ozone depletion and natural variability by the Indian Ocean Climate Initiative (see http://www.ioci.org.au/).

An aspect which is not covered in these analyses is the high temperatures. The third figures shows the mean temperature deciles for the period starting in 2002.

BOM temp deciles jan02-jul06 blog.JPG

This analysis is based on the post 1950 period only (though temperatures before this time were generally considerably cooler) and uses only the high quality national temperature network discussed at http://www.bom.gov.au/climate/change/reference.shtml .

These stations have minimal or no urban heat island effects. There are a number of papers published on the increasingly warm temperatures which we now experience with droughts (as a result of global warming interacting with climate variability). As you can see almost everywhere has been warmer than average and most of Queensland has experienced its warmest 55 month period on record.

Regards,

David

Something About Russell

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I would like to think that debates at this weblog were won and lost on the quality of the information provided and the logic of the arguments presented, but so often information is judged on the perceived standing of the commentator based on the prejudices of the reader.

Some months ago I started a ‘people category’ and suggested regular commentators and readers send me some information about themselves.

Russell posted the following information at an earlier thread in response to some misguided comment from others. He has agreed for me to post it as a new thread:

“I have lived in Nigeria for the last three years where I am a freelance consultant on projects in Nigeria, Ghana, and lately Indonesia.

I am currently engaged on projects in urban planning, coastal and land-use management, reconstruction (Aceh), rural development (primary health care, water and sanitation at village level).

Prior to that I spent a year in Germany where I was the technical advisor to Iraq in their defence of claims against them at the UNCC for damages caused to the coastlines of Saudi Arabia, Kuwait and Iran by the largest oil spill in history.

For two years before that I lived in Townsville where I was the head of an environmental sciences group for one of Australia’s largest consulting engineering companies and ran projects in Australia (QLD, WA, NT, SA, TAS) and New Zealand.

Before that I lived and worked for two years in Indonesia running a mangrove reforestation project.

Prior to that I lived for 3 years in Brisbane and ran my own consulting company, working in Queensland, the Northern Territory, Indonesia and Vanuatu.

I was also the unfortunate owner of a restuarant in Brisbane during that time.

Prior to that I lived and worked for 15 years in the Northern Territory for the NT government as a marine and coastal ecologist and spent a lot of time engaged in coastal management and planning. I also completed my PhD parttime and was resident on a bushland block at Humpty Doo.

Prior to that I was at Uni for 4 years where I studied zoology and botany, statistics, chemistry.

Before that I wandered and worked around Australia, mostly the south west of Western Australia and have worked as a truck driver, storeman and packer, share cropper (wheat and sheep), on the mutton chain in an abbatoir, fruit picking, builders and brickies laboring, casual farm laboring, factory hand, ships chandler (Victoria), and numerous others.“

Thanks Russell to telling us something about yourself.

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This post will be filed under the category titled “people”. As a reader and/or commentator at this blog you may like to tell us something about yourself. Contributions encouraged and you may use a pen name …please email to jennifermarohasy@jennifermarohasy.com.

What is Special About This Drought?

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On Monday I posted a graph of rainfall history and suggested that it indicated south east Queensland was not experiencing the worst drought in 100 years – that the current dry spell is not unusual in the scheme of things.

I was surprised how many comments in the thread following the post, and also in the many emails I received, were supportive of the notion that this is a worst drought ever.

Some argued that I didn’t understand definitions of drought and that a drought could simply be a result of too many people squashed into a region without the infrastructure to supply adequate water. Comment was also made that it would be interesting to see the rainfall history for the catchment averaged over 10 years.

Warwick Hughes has sent me the following graph, showing the rainfall history averaged over 10 years:

Bris10yrav blog 2.GIF

Mr Beattie has been reported in the Courier Mail stating that:

“Rainfall in the region has been well below average for the past six years and in fact it is the worst 10-year period in history,” he said. “It has been dry after dry, year after year, which has led to major storage deficits in our dams.”

Looking at the above graph Beattie may be technically correct, we may have had the worst 10-year period in recorded history, and those who want to define drought based on ‘supply’ rather than ‘rainfall’ may also be correct because we have never had so many people living in south east Queensland and probably never as many trees growing in the catchment.

But the above graph, and the graph posted on Monday, does indicate that south east Queensland has experienced comparative periods of low rainfall during the 1920s and 1940s. The current dry period is not unusual in the scheme of things.

My point is that: If we can not reconcile ourselves with our history, how can we hope to prepare for the future? It is important we understand what is special about this drought.

If we could perhaps start to acnowledge that rainfall has not been exceptionally low, we might, for example, be able to more clearly focus on other variables, including population.

There is also the issue of tree cover. A heavily timbered catchment generally produces less runoff. Page 7 of yesterday’s The Land reports Malcolm Turnbull, federal parliamentary secretary for water, explaining that the West Australian Water Corporation is thinning catchment forestry to increase run off by 6,000 megalitres a year. Mr Turnbull said the method could deliver “new water” at about 20c/kilolitre – far cheaper than piping or desalination.

I am not necessarily advocating tree clearing in the Wivenhoe catchment, but rather my issue is that here in Queensland, we tend to invoke ‘exceptional circumstances’ whenever there is a flood or a drought rather than taking a more evidence-based, and dare I suggest, more responsible approach.

Peak Oil & Agriculture: Comments & Links

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Jennifer,

Following are two disturbing reports on “peak oil” you may not have seen.

They could have a big impact on intensive agriculture regarding costs. May be some opportunities for communities to grow and supply a lot more of their own produce, using permaculture or more sustainable/regenerative farming practices.

Certainly glad that I don’t rely on big tractors and high inputs. Also highlights the futility on the current debate over ethanol/biofuels etc. We need a better answer than that.

http://www.aph.gov.au/hansard/senate/commttee/S9515.pdf
http://www.spinninglobe.net/iraq&oil.htm”>http://www.spinninglobe.net/iraq&oil.htm”>http://www.spinninglobe.net/iraq&oil.htm

Cheers, Graham F.

And another reader, also called Graham, sent me this note:
Some important concepts in here, without endorsing all of it:
http://www.workingforchange.com/article.cfm?itemid=21263 .

And John Quiggin had something on peak oil yesterday:
http://johnquiggin.com/index.php/archives/2006/08/23/is-peak-oil-here-already/#more-3146.

Note On Herbicide Resistance: Chris Preston

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Thirty-three different species of weeds are now reported to have developed resistance to herbicides commonly used in Australian farming systems, says Dr Chris Preston, programme leader for the Weeds CRC.

The worst offenders are annual ryegrass, wild radish and wild oats.

And of the thirteen ‘families’ of chemicals used to control weeds, resistance to ten has now been found in various agricultural weeds, Dr Preston says.

“Those ten groups of herbicides, as you’d expect, are the ones that are most commonly used in our cropping systems,” he adds.

In a few areas of Australia the herbicide resistance problem has become so acute that there are no longer any herbicides available to control particular weeds – such as annual ryegrass – in some crops.

You can read more here.