Diesel fuel and heating oil have topped $4 a gallon, and gasoline is destined to soon break that price plateau. Those prices are double and triple what they were just a few years ago. On the other end of the equation, Exxon Mobil netted a profit of over $40 billion in 2007. Analysts say the current oil-based fuel prices have more to do with speculation and the value of the U.S. dollar than with supply and demand. Even the invasion and occupation of Iraq can’t be blamed, because production there is now above pre-invasion levels.

The time for short-term fixes, such as President Bush’s call for drilling for oil in the Alaska wilderness and Sen. John McCain’s proposal (embraced by Sen. Hillary Clinton) to drop the federal gasoline tax for the summer, is over. The U.S. must commit to a vastly different approach on energy or risk seeing the national economy slide into a long and steady decline.

It’s easy enough to blame the Bush administration for the dire straits Americans now face. Vice President Dick Cheney met in secret with representatives of the oil and gas industries in crafting the administration’s energy policy, which was heavy on tax breaks for those in the business and light on conservation and investment in new technologies. The president also can be blamed for economic policies which devalued the dollar, which in turn makes oil cost more for Americans.

In the long view, though, Mr. Bush’s biggest failing is to have deferred for eight years the move toward a post-petroleum economy. Government has an important role in launching, nurturing and sustaining such innovation. And that means spending money.

Candidates Clinton and Obama call for increasing vehicle fuel efficiency standards, and each would dedicate funds to create new fuels. Sen. Obama’s plan would help manufacturers retool their plants to build more energy-efficient vehicles, and would invest $150 billion over 10 years “to advance the next generation of biofuels [and] accelerate the commercialization of plug-in hybrids,” according to his Web site. Sen. Clinton also would help manufacturers retool production facilities through $20 billion in “green vehicle bonds.”

Sen. McCain’s policies would “promote the diversification and conservation of our energy sources that will … break the dominance of oil in our transportation sector just as we diversified away from oil use in electric power generation 30 years ago.” He champions “flexible fuel” vehicles and raising fuel efficiency requirements, as well as developing alcohol fuels, fuel cells and biodiesel.

Tax breaks for buying vehicles that get over 35 miles per gallon, investing in public transportation, mandating the use of nonfood-based fuel additives in gasoline and funding research and development for technologies that show promise all will impact government coffers. But without a clear signal from our leaders that a change in course is coming, the transportation and fuel industries will keep one arm wrapped around the oil barrel.