Image caption Within a few decades renewable energy will be much cheaper

The future is always uncertain. The future of world resources is dominated by a particularly large uncertainty - climate change.

Let's start by taking an optimistic view. Suppose mainstream scientists' projections are wrong and the world proves fairly resilient to our over-shooting the advised limits on greenhouse gases. Because we surely will overshoot.

In that scenario many of our resources may be able to be sustained. We'll be helped if world population stops growing around the middle of the century then starts to fall, which it might.

Fewer people on the planet is likely to mean less consumption of resources, although that's not guaranteed.

Some experts are cautiously optimistic that if we avoid severe climate change we'll be able to provide nine billion people with food and water, if we're willing to make political compromises and bold investments. That's two big ifs, of course, but the resources are potentially there if they're used right.

We'll have plenty of energy, too, from fossil fuels if it proves safe for us to burn them. Within a few decades renewable energy will be much cheaper anyway.

If you're an optimist you'd hazard we'll either find more of the metals we use, or discover substitutes for them.

Some things will be in noticeably shorter supply, though. Wildlife will be one, as we seize more and more land for farming.

Some wildlife areas will be set aside for tourism.But those areas in turn will be much more crowded as half a billion Chinese take to budget airlines.

Kenya's game parks are already scrums on wheels. Before long you'll probably have to book in advance to see a lion in the semi-wild.

And ordinary wild places worldwide will become more scarce too, especially near towns with populations growing and becoming more affluent.

Compromised stocks

If you like solitude you may have to find it in a virtual reality game on your laptop rather than jostling on a crowded hilltop.

Image caption The supply of metals will come under presure as mining demands more energy

Then there will be regional shifts. Let's suppose Europe's economy stagnates whilst China's races ahead. That'll leave the Chinese with more cash for globally-traded goods.

The resource of Welsh mountain lamb or Scottish wild salmon may become unaffordable to the average English family.

Already ordinary people in Senegal can't afford their own favourite fish because it's all been sold to Europe. Europe may suffer a taste of its own purchasing power.

Fish stocks may be compromised anyway because the oceans are becoming acidified from the CO2 that also causes global warming.

But overall, without climate change, maybe we can muddle through the century relying on a combination of belt-tightening and invention. And some resources, particularly digital ones, will surely get better and better.

Alternative scenario

That's the optimistic scenario - one that world leaders with their reluctance to cut CO2 emissions appear to be gambling on - at least by default.

Now let's take what the scientific establishment would call a more realistic scenario in which the climate changes as projected. If they're right, we're probably heading for several degrees of warming unless there's a surprise shift in policy.

Now, climatologists are fairly confident in projecting future temperature but some admit they're not very clever on future rainfall. Some areas will get wetter and some drier but they're not certain which.

That'll make it very hard to plan for agriculture and for water supplies, two resources likely to be badly squeezed in a warmer world.

Fisheries will be affected as water warms.

We'll be under pressure not to burn more fossil fuels but short of cash to invest in renewables instead because we're spending it adapting to changes in the climate.

Even the supply of metals may be hit as mining demands more and more energy, currently supplied by fossil fuels which we'll be trying to avoid.

If if gets so bad that the global economy is badly disrupted, then we'll all be generally short of resources because we won't be able to afford them.

But that's a pessimistic scenario on resources. Isn't it?