This is why I think the best bet is on technology, not apocalyptic cataclysm. Britain was the epicenter of the BSE (mad cow) threat. The problem was real and people of science took it seriously and guess what? They a) discovered the cause and worked to minimize the risks and 2) they found a great solution: GM cattle.
As new variant Creutzfeldt-Jakob disease (vCJD), the human form of the condition, can be contracted by consuming beef or beef products infected with rogue prions, the work could pave the way for breeding cattle that cannot infect people with prion disease.
This could be exploited by the meat industry, which could raise guaranteed BSE-free beef cattle, though the disease has become a much less significant problem since the practice of feeding cows on meat and bone meal from dead animals was banned. Such beef would also have to overcome public resistance to the idea of eating meat from GM livestock. [More]
The human ability to adapt to challenges is undiminished. From global warming to bird-flu, smart money will follow dogged disciples of truth, who sift tirelessly through data to tease out solutions. This is how genetic-modification will win wide acceptance - the absence of harmful outcomes (despite hysterical predictions) and the methodical elimination of problems.
It may take more time than the Internet generation can tolerate easily, but in the end, what works, works.
We may be a problem-creating species, but we are also a problem-solving species.