renewable resources?

From: Bill Keiser
Date: 2 Jun 2009 17:44
"a couple hundred years ago, most of the necessary materials for technology were readily available at the surface of the planet, oil, coal and iron ore are probably the main 3. all you had to do was shovel or scoop them up where they intersected the surface. all those are now long gone."

While acknowledgingyour points on increasing complexity of mining, I think the comment shows a fantasy of how simple things were before global trade.
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Take the example ofa technologically simple civilization....the Pheonician,. One of the great empires of their time, they were primitive in many ways. Their home country was sparse of metal. Consider that they got silver from Spain, tin from Cornwall England, traded for gold,silver, copper, leadand iron wherever they could find it. The colorful dyes used came from Egypt. It was trade, commerce and emerging technology that made them great in their day. It was not because they could just shovel or scoop the metals and fuelsthey wanted right under their feet. Even today, with modern tools available,LEBANON(site ofPheonician empire)HAS NO MINING. -- unless you count quarries for gravel...

No great civilization has had all the raw materials they used in easyproximity. It was the need for more rawmaterials that created a hunger for trade and spread technology around the world. At no time has any great civilization hadeasy access to everything. Times are no different now.Modern technology is our differentiator.

As to your point, that we've wasted so much we may not survive unless we venture into space:

1. It is true that in many cases we are mining ores that would not have been possible decades ago. For example, we may mine gold at 1.5 parts per million (1.5 oz/metric ton) profitibly, whereas centuries agowe mined relatively high grade deposites where you could actual see the native gold. The trend is clear: advanced civilizations find ways to extract the raw materials needed to maintain the civilizations. If they don't, they perish.
2. In the future we may venture as a species into space.
3. If you think the solution to our earthlyfuture resource challenges would be space colonies, I think it is unlikely those on earth we receive any significant amount of physical raw materials from those colonies in space.Though we don't know what may be feasible with future technology, reciprical commerce would have some barriers.
Therefore: we will have to find our own resources terrestrially as far into the future as I can see. Recycling will play an ever greater role. Note: recycling is highest in industrialized nations. In developing countries, more materials (such as steel, copper, aluminium, etc.) are used in infrastructure and virgin developments, contributing to less recycling. Recycling increases with technological maturity. I am not worried on that count. As mining costs increase, recyclingbecomes more cost competitive and will therefore increase its share of our resource pool. One day we may even close the resource loop if the need and technology are up to it.