Jennifer Marohasy

a forum for the discussion of issues concerning the natural environment

Archives for August 28, 2006

Rats Destroyed the Forests on Easter Island: Terry Hunt

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Easter Island has been described by Jared Diamond as the “clearest example of a society that destroyed itself by overexploiting its own resources”.

Prof Diamond has told and retold the story and drawn a parallel between the ecological disaster he says befell Easter Island and our likely fate because we are cutting down too many trees and consuming too much energy.

In the September-October issue of American Scientist Online Terry Hunt details findings from his work on Easter Island.

It is an interesting read in which Hunt concludes that rats introduced by the Polynesians negatively impacted on recruitment in Jubaea palms resulting in forest decline. In contrast, Jared Diamond says the Polynesians simply cut down all the trees.

Furthermore Hunt suggests that the downfall of the original Polynesian civilization resulted not from internal strife associated with ecological disaster following destruction of the forest, but rather from contact with Europeans.

I read a lot of James Michener books when I was a bit younger. Civilizations destroyed by new arrivals is a consistent theme in Michener’s stories.

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.