1Much of the world now lives in an industrial civilisation.
2But this has only become possible because we have the necessary natural resources.
3There are three types of natural resource without which industry could not exist.
4One of these is metal,
5without that we'd have no machines and no transportation.
6Another is fossil fuels, which we need to power those machines.
7But there's a third resource that's essential to connect the different parts of a machine together
8with belts and pipes and shock absorbers,
9and that is rubber.
10It's now used in over 40,000 products,
11from waterproof footwear to surgical gloves.
12At present, we have two types of rubber in common use.
13One is natural rubber, which nearly all comes from the Para rubber tree.
14This was originally native to Brazil,
15but is now cultivated on plantations in South-East Asia.
16Recently, however, concern's been growing that supplies may soon be insufficient for the world's needs.
17So what exactly is limiting the supply of natural rubber?
18Well, for one thing, rubber trees don't just spring up overnight.
19It can take eight to ten years for a tree to start producing rubber,
20so cultivating them's a slow process.
21And this leads to another problem.
22With most crops, farmers don't have to think very far ahead,
23so they can easily change what crop they produce,
24or how much of a crop they produce,
25if they find the demand for that crop is rising or falling.
26But if you have to plant eight or ten years ahead,
27that's much harder.
28And also the rubber tree's very choosy about where it grows.
29It needs the right temperature, the right amount of rainfall, and the right altitude,
30not too high and not too low.
31The result is that it can't be grown in the northern or southern parts of the globe,
32only around the equator.
33Another problem is that the rubber is basically extracted in the same way as it's been done for hundreds of years,
34and that's by hand,
35by making small cuts in the trunk of the tree,
36and putting a little cup there to catch the latex, as the rubber is called.
37It's very labour-intensive.
38And it's not just the initial production that's limiting supplies.
39With other resources such as water and glass,
40when we've finished using them we can recycle them,
41but although this is also possible with rubber, it's very difficult,
42so that also reduces the amount we have available.
43And in the last few years, there have been new threats to the supply of natural rubber.
44One problem is linked to the fact that nearly all the rubber trees in South-East Asia
45are descended from just a small number of seeds brought from Brazil
46in the 19th century.
47This means that there's very little genetic diversity among the trees,
48which in turn makes them very vulnerable to disease.
49The most dangerous threat is a fungus,
50which destroyed large numbers of rubber trees in Brazil,
51and which could cause devastation to plantations worldwide.
52Another problem is that farmers in South-East Asia are increasingly turning to the cultivation of palm oil,
53which is easier and more profitable for them.
54And finally, in recent years South-East Asia, like other parts of the world,
55has been repeatedly hit by extreme types of weather,
56and this looks likely to continue in the future.
57However, as well as using natural rubber,
58it's also possible to make rubber synthetically.
59This works very well for some purposes,
60for example, making engine parts, or silicone pots and pans used for cooking.
61But compared with natural rubber, it's not anything like as strong,
62and this means it can't replace natural rubber in other products.
63For example, while a mixture of natural rubber and synthetic rubber works well in car tyres,
64only natural rubber can stand up to the extreme speeds of aircraft tyres during take-off and landing.
65So for some time, scientists have been looking for alternative sources of natural rubber.
66One that's been known about for some time seems initially to be a rather unlikely source.
67It's a wild plant with yellow flowers that we normally regard as a weed when we see it in our gardens.
68But when it's pulled up and its roots cut open,
69they're found to contain rubber.
70Now, compared to the rubber tree, dandelions produce relatively small amounts of rubber,
71but unlike rubber trees, they're very adaptable.
72They'll grow in all sorts of places, and they don't need rich soil.
73So at present, there are several projects underway investigating the possibility of using dandelions as a source of rubber.
74Another possibility is a desert shrub grown in Mexico and Texas...