 | The Bullroarer - Wednesday 16 July 2008 | The Oil Drum: Australia/New Zealand | The National Energy Essay Competition |  |
20 comments on The Bullroarer - Thursday 17th July 2008
Comments can no longer be added to this story.
| Show without comments | PDF version
20 comments on The Bullroarer - Thursday 17th July 2008
Comments can no longer be added to this story.
| Show without comments | PDF version
User login
Contact
- anz at theoildrum dot com
License
This work is licensed under a Creative Commons Attribution-Share Alike 3.0 United States License.
Archives
- November 2009
- October 2009
- September 2009
- August 2009
- July 2009
- June 2009
- May 2009
- April 2009
- March 2009
- February 2009
- January 2009
- December 2008
- November 2008
- October 2008
- September 2008
- August 2008
- July 2008
- June 2008
- May 2008
- April 2008
- March 2008
- February 2008
- January 2008
- December 2007
- November 2007
- October 2007
GAIA Host Collective
Very informative links Gav. Thanks.
I've now added "astroturf" to my lexicon! ;-)
Lefty,
The important point for you to realise about Evans' piece is that "disputing the cause" delays the solution.
There are powerful established interests in Australian society who imagine that they'll be dead before anything happens on Climate Change, and that they certainly don't want their gushers of income to be shut off in the meantime. It's amazing that the amount of lobbying money available hasn't bought better shills than David Evans, but there you go.
But in fact their actions are an enormous threat to the future viability of Australian lifestyles in our own lifetimes. The most frightening risk from climate change is that most of our coastal infrastructure (up to an elevation of 6m) will suddenly go under sometime within the next 20 years. This potential damage makes the risks from terrorism look like a joke.
Lefty, since you're an "Australian" reader, maybe you spotted this...
http://www.theaustralian.news.com.au/story/0,25197,23053212-11949,00.html
...But how's *this* for an update...
http://www.abc.net.au/science/articles/2008/06/25/2283071.htm ... !
(Hey Gav, we in Sydney may actually need Morris Iemma's second airport if Mascot goes under - although Williamtown is only 8m above Sea Level! The good news is that Badgery's Creek is 82m ASL.)
Hmm. Rapidly melting antarctic ice kinda shoots down the theory that ice melting is caused by rising ocean rather than air temperatures, originating from something in the sun or deep in the earth itself - most antarctic ice rests on frozen land, not water.
However, the article also mentions the occurence of several warming and melting events over the past 75 000 years - cleary unrelated to human activity. How can we be certain that this is not just another of the same? That's a fair question isn't it?
I haven't read Gav's links yet, I'll do that before commenting further.
Hi again Lefty,
Yes, a very fair question. You're quite right that there have been several Antarctic melting events in the last 75,000 years. However Science has a pretty good handle on explaining the causes.
The main cause of ice-ages is the steady wobbling of the Earth as it spins on its axis, a bit like a wobbling spinning top. The wobble is caused because the Earth's spin is offset by 23 degrees from our plane of orbit around the Sun, and then our Moon has a further orbital offset of 28 degrees from the Earth's plane of rotation as well.
(Did you ever have a Spirograph when you were a kid? http://www.pietro.org/Astro_Util_StaticDemo/MethodsNutationVisualized.htm )
Anyway, the result of this wobbling is a big variation in the amount of solar energy landing on the surface of the Earth at various latitudes. These variations have been named the "Milankovitch Cycles". I'll let you read about them here:
http://en.wikipedia.org/wiki/Milankovitch_cycles
My point in laying out all of this data is to say that because Science can now explain the past history of ice ages, that's why we can be so sure that the current warming is "not just another of the same", as you put it. The West Antarctic ice will melt in the usual unstable way, but the cause of it will be *us* this time, not the wobbling of the planet.
At the moment, the natural Milankovitch cycle should be taking us towards global *cooling*, but in fact this "natural" signal is being completely overwhelmed by the "Greenhouse Effect" of our own emissions. Every year it ticks inexorably up (http://www.esrl.noaa.gov/gmd/ccgg/trends/), and we are probably already well past the "safe" level.
(http://blog.wired.com/wiredscience/2007/12/nasas-james-han.html)
There are further impacts on the planetary temperature from effects acting longer-term than 75,000 years, such as Continental Drift changing the pattern of ocean currents, and the natural balance of CO2 in the air. For instance, most of our oilfields appear to have been originally deposited in hot anoxic ocean conditions during natural runaway greenhouse events. (http://www.abc.net.au/science/crude/resources/)
But once Nature has sequestered enough carbon, things settle down again.