When you cut open a piece of fruit, you discover something about its intrinsic nature.
The fruit is divided into sections.
A cross-section reveals a floral pattern - you might even think that you have discovered straight lines in nature (a rarity).
But if you look closely you will see an ever so slight gentle curve in the lines. These are called observations.
If you were a scientist, an agrarian economist even, you'd create an avalanche of statistical data: where does it grow, how much is harvested, how much is exported, the sugar content level optimals...
Observations and data make up the weight of evidence about the nature of the thing...
An artist's perspective is different to a scientist's which is different to a grocer's view or a shopper's view. But all views take in a level of uncertainty: cost versus quality (is it rotten inside?), how much can I sell (popularity?), why does the season shift (climate change?).
Your personal interest and taste determines whether or not you buy and eat the fruit - your personal taste may run against popular taste or industry interests.
So when does it become necessary to put personal interest - or industry interests - aside?
You can't keep growing persimmons if the cost of production skyrockets. Similarly, the cost of production for many industries (affecting many people's personal interests) are going to skyrocket if we fail to make a transition to a low-carbon economy.
This is true whether or not Australia takes action to reduce the human carbon footprint - as Ross Garnaut says, any money raised by a carbon tax should benefit the future not be used to "smooth the pillows of dying economic activities". This is not a threat to our way of life. Even coal-fired power plants like Tarong are looking clean alternatives such as bio-sequestraion - they see the need to make the transition.
At the CSIRO's Greenhouse 2011 Forum in Cairns last week, economist Ross Garnaut reiterated the point he has been making since 2008 when he presented his report to then Prime Minister Kevin Rudd.
"Economics says it's worth doing something about the issue (of climate change) and that it won't be unmanageably expensive if we do it well," Garnaut preached to the converted.
It was an assembly of representatives of the mainstream scientific view: human contribution to climate change must be mitigated as it poses a significant threat to our civilization (and our global economy).
"We can't solve the problem on our own," Garnaut said, "but we make it much harder if we don't participate." The lowest possible cost way is to put a price on carbon.
"China has moved emissions growth a long way from business as usual and that makes quite a big difference to the risks humanity faces. Even they have a long way to go but we have even further."
The awful reality is that Australia is not pulling its weight. Our skyrocketing consumption of electricity and excessive use of motor vehicles makes us one of the most wasteful countries (per capita) on Earth.
"Setting an economy-wide price for carbon on external costs will gie us the lowest cost solution," Garnaut advises.
Australia is richly endowed with renewable energy resources and with the technical expertise (engineering, geological and earth sciences) to thrive in a low-carbon global economy, he says.
"Uncertainty is not a case for not acting that's an unanalytical way of approaching this," Garnaut said. Humans take out insurance against uncertainty - what's the difference here, he asks. "It would be a reckless country and a reckless species that turned its back on the weight of authority coming from mainstream science.
"We know from that the world is warming. We know that from observation without much science except statistical analysis."
Shifting seasons, flowering plants, bird migration - these are observations biologists and gardeners have been making for years.
Watch the whole of Ross Garnaut's speech on the National Science Week video blog.
This is an article I wrote for a newsletter sent to financial planners - I'm publishing it here because the comments made in response might be of interest. I'm not identifying the authors of the comments.