For me, the big speech of the year so far was Al Gore's A Generational Challenge to Repower America made in Washington in July. He called for the complete re-engineering of much of the US economy. "Rustbelt" Detroit, for example, would find new life in developing and deploying green technologies. The implications for business could be profound, particularly if Europe and Asia followed suit.

Gore set the scene by saying: "I don't remember a time in our country when so many things seemed to be going so wrong simultaneously. Our economy is in terrible shape and getting worse, gasoline prices are increasing dramatically, and so are electricity rates. Jobs are being outsourced. Home mortgages are in trouble. Banks, automobile companies and other institutions we depend upon are under growing pressure. Distinguished senior business leaders are telling us that this is just the beginning, unless we find the courage to make some major changes quickly."

Then came climate. "The climate crisis, in particular, is getting a lot worse much more quickly than predicted," he warned. "Scientists with access to data from navy submarines traversing underneath the north polar ice cap have warned that there is now a 75 per cent chance that within five years the entire ice cap will completely disappear during the summer months."

Warming to his subject, he underscored that "Our dangerous overreliance on carbon-based fuels is at the core of all three of these challenges—the economic, environmental and national security crises." Then came the stinger: "We're borrowing money from China to buy oil from the Persian Gulf to burn it in ways that destroy the planet. Every bit of that has got to change."

His solution? He challenged America "to commit to producing 100 per cent of our electricity from renewable energy and truly clean carbon-free sources within 10 years. This goal is achievable, affordable and transformative," he said.

Whoever wins the next US election, Gore's speech offers the man moving into the White House a template for change. Happily, history suggests it is risky to underestimate America's ability to reinvent itself and lead the way under sustained pressure.