Thanks, guys. As always, you can only fit so many issues into 700 words!

Livio/popnperish: you are correct. Population is vital. I deal with it in Ch10 of The Coming Famine. The good news is that the young women of the world are not getting married and are not having children - and are not bothering to consult men about it. They will lower the population voluntarily, regardless. The challenge is we have to feed >10bn people for 50+ years while they are doing it.Condoms won't help reduce the number of people who are living longer, either.

Aspley: I deal with Reward in "Why farmers need a payrise". http://www.sciencealert.com.au/opinions/20103008-21271.html Submitted this to OO, but was told it was too long.

Curmudgeon,

The same sorts of concerns that are raised by popnperish about limits to growth are raised in this paper by Rockstrom et al. from Nature, probably the most respected peer-reviewed science journal in the world. It discusses the dangers from our interference with a number of natural cycles

http://www.nature.com/nature/journal/v461/n7263/full/461472a.html

Open version at

http://www.ecologyandsociety.org/vol14/iss2/art32/

Now which is more likely, that Rockstrom et al., the authors of the papers they reference, the referees, and the editors of Nature are all wild-eyed lunatics, or that you are in denial?

The reason why all these issues are coming to a head now was recently explained by the geologist Mike Sandiford in the Sydney Morning Herald: humans now have the numbers and impact to be a major geophysical force.

http://www.smh.com.au/opinion/society-and-culture/the-scale-of-the-effect-we-have-on-the-planet-is-yet-to-sink-in-20110522-1eyqk.html

Jeremy Grantham of Grantham, Mayo, van Otterloo (GMO), with $107 billion under asset management according to the Wikipedia article on him, doesn't think that the commodities market is going to soon start trending down again. He is saying a lot of the same things as popnperish. See

http://www.gmo.com/websitecontent/JGLetterALL_1Q11.pdf

Clownfish,

It is true that Paul Ehrlich was unable to predict the success of the Green Revolution. Neither were a lot of other people, including the agronomist William Paddock, who would have been much better placed to understand its potential. However, you are implying that because we got lucky once, we are going to go on being lucky forever. You are like a gambler who has won big at the casino and now wants to go back and bet the house.

There have been a number of Malthusian collapses in history and in the archaeological record, when people weren't so lucky. You might want to consider the Irish Potato Famine, for example. The Spanish brought the potato back to Europe from South America in the 16th century, and it proved to be an immensely productive crop, able to feed up to 4 times as many people to the hectare as grain, when the growing conditions were right. It was hard to develop varieties for Northern Europe because of day length issues, but the farmers eventually succeeded with a few and potatoes were widely introduced. The population of Ireland grew from perhaps 1.2 million in 1600 to 8.5 million by the 1840s, even though Ireland's British overlords had commandeered much of the best land to grow export crops. Growth was especially rapid because traditional inheritance customs and colonial laws required land to be subdivided among all the sons, so all could marry and have children.

In the 1840s, the late blight arrived from Mexico, and none of the local potato varieties had any resistance to it. Whole crops were completely wiped out all over Ireland. By this time, a significant proportion of the population was living on plots of land that were too small to feed a family on anything but potatoes. 1 - 1.5 million people starved, and another 1.5 - 2 million were forced to emigrate. As Tom Kenneally points out in "Three Famines", many of the emigrants were so weakened by hunger that they died on the ships or soon after reaching the New World.

So, an extremely localised famine somehow proves the Malthusians? I think not.

The simple truth is that today, more people are better fed than ever before.

We did not 'get lucky once'. Humans applied human ingenuity to a problem and came up with a solution. It's kinda what humans do.

A provocative article, with much food for thought.

Though I agree with most of the author's suggestions for improving food production (whether or not this is as critical an issue as portrayed), one suggestion is of concern:

"frontier science such as re-engineering the photosynthetic pathways of crops and trees, to boost yields and lock up more carbon."

This proposition is suggestive of large scale genetic engineering, and, if so, I would have to disagree, on the simple grounds that traditional cross fertilisation to produce improved and genetically sustainable varieties, though a slower process, offers considerably greater assurance of improved yields without jeopardising tolerance to environmental stresses - and thereby ensuring longevity. The "quick fix" of artificial modification may risk emergence of an Achilles heel in future food reliability.

From Popnperish,

"Stephanie Alexander has made a great start in Australia by introducing kitchen gardens to schools. We have to go beyond that so every school leaver has significant knowledge of gardening/horticulture/agriculture/animal husbandry to enhance food production locally."

Urban gardens and an organic fresh food diet. An attractive proposition. Given the popularity of cooking and lifestyle TV programs, a movement such as that suggested may gain wide traction through the influence of youthful enthusiasm, and provide another creative and productive family pursuit.

Some, however, appear to think that agricultural production is a menial "falling off a log" pursuit, and suited only to the intellectually challenged. This is so very far from the truth, and a segment of society more closely in touch with the vagaries and trials of nature one will be extremely hard pressed to find. Farmers should be respected and lauded for persevering in spite of the rubbish they have to put up with, and the challenges presented by our largely duopoly-engineered and externally manipulated market place.

Let us also not forget that quality food production is under constant threat from the introduction of exotic pests and disease, in both plant and livestock arenas, and only vigilance and inviolable quarantine may be all that lies between abundance and extraordinary hardship.

*Humans applied human ingenuity to a problem and came up with a solution*

Quite correct Clownfish. Humans simply nick more land and resources
from other species, wiping them out in the process. As only
humans seemingly matter, that is apparently not a problem.

So we'll overfish the oceans to the point where whole species
vanish, we'll load it with plastic, so that seabirds will cark
it when they eat the stuff, we'll shoot anything that moves
in Africa's forests, for its meat and can be eaten. We'll knock
down more rainforest when the population pressure becomes
unsustainable, we'll knock out the mangroves, which used to filter
the oceans and act as a breeding ground for many species.

Never forget Clownfish. Without biodiversity, there won't be
a humanity. But learn the hard way. That seems to be what
we are best at.