In 2007, climate change finally became a reality in the wider public's consciousness.

So what about this year?

With a U.S. presidential election slated for November, it's a good bet that 2008 will mark the first time our planet's health plays a prominent role in U.S. national politics. Global warming and resulting climate change could fuel nearly as much debate as issues of national security and the economy.

And so they should. Climate change is as much a security and economic issue as an environmental one. It will challenge the status-quo thinking on everything from food, agriculture and marine resources to transportation and energy — meaning that climate change and abatement policies should be near the top of every candidate's agenda.

The downside is that climate change is just too big a concept to grasp: With its myriad impacts, it defies sound-bite simplicity.

So expect climate change to be reduced to just a few simple issues that the candidates can get their heads around, and voters can identify with, such as energy and transportation. Specifically, cars and the fuel they burn.

Americans love their cars and they love to drive, and as American television and advertising are mainstays of programming worldwide, viewers across the globe are being seduced into the same love affair.

Unfortunately, cars are not the benign love toys that advertisers would have us believe.

We now have about one car on the road for every 10 people on Earth — and counting. "Transportation has the fastest-growing carbon emissions of any economic sector. Proliferating numbers of automobiles are a key reason. More than 600 million passenger cars are now on the world's roads, and each year some 67 million new ones roll out of manufacturing plants," writes Michael Renner, a senior researcher at the Washington-based Worldwatch Institute environmental research organization, in a piece published online last week.

Greater numbers mean more problems, including traffic jams, accidents, local and global pollution impacts, declining oil supplies, and rising gasoline prices.

But the environmental impacts of cars are not limited to the carbon dioxide and other pollutants emitted during a car's lifetime. Other impacts, created when cars are manufactured and junked, add to the total environmental cost of each vehicle. The steel, aluminum and copper that are used, as well as the oil needed to make plastic components, are extracted, processed and refined, requiring further energy use. Intentional and inadvertent environmental degradation costs include strip mines and oil spills.

Thousands of gallons of water, too, are used to produce each car that rolls off the assembly line, and from cradle to grave toxic chemicals are released into the atmosphere as byproducts of production and in exhaust gases.

Our car culture also demands clearing, construction, paving and concrete to provide roads, highways and parking space for our burgeoning fleet of cars and trucks.

Multiplying these impacts by the hundreds of millions of vehicles in use around the world today, it is obvious that cars will continue to cause serious environmental degradation simply because there are so many of them — despite increasing efforts to produce more and better hybrids and energy efficient vehicles.

Still, however much I'd love to see fleets of energy-efficient buses and light-rail train networks replacing our car dependence, I don't expect that to happen anytime soon. Particularly in the United States — which has lagged so far behind much of the world in energy conservation policies at the national level — public transportation networks will require unprecedented capital investment.

In the meantime, along with much of the world's population, I'm hoping that the November election will bring new American leadership on global environmental issues.

To get a look at where the remaining candidates stand on energy and cars, a good place to begin is the League of Conservation Voters in the U.S.

LCV, a progressive nongovernmental organization that evaluates and rates the environmental records of politicians, has released a "2008 Presidential Primaries Voter Guide" that offers a comparison of the candidates' environmental positions. It also ranks the politicians, giving each an "LVC lifetime score" on their voting records and policies.

"In the race for the Democratic nomination, all of the candidates have shown a commitment to addressing global warming. Senators (Hillary) Clinton and Barack] Obama and Representative (Dennis) Kucinich have cosponsored the strongest global-warming bills in Congress. Each of the top-tier candidates, including Sen. (John) Edwards, have put forward aggressive plans to reduce greenhouse-gas pollution by at least 80 percent below 1990 levels by 2050," notes the Voter Guide.

"On the Republican side, the differences are much more stark. . . . Each candidate has acknowledged that global warming is a problem. But that is where the similarities end. Sen. (John) McCain has offered legislation to reduce global-warming pollution by 65 percent by 2050. None of the other Republican candidates — Former Mayor (Rudolph) Giuliani, Former Gov. (Mitt) Romney and Gov. (Mike) Huckabee — have offered any kind of comprehensive plan to address global warming. Moreover, aside from Sen. McCain, only Gov. Huckabee has signaled support for a cap on emissions," write the authors.

"As a cautionary note: then-Gov. George W. Bush said in 2000 that he considered the leading greenhouse gas, carbon dioxide, to be a pollutant that should be regulated, then spent his entire term in office trying to stop and subvert efforts to do just that," warns the Guide.

Forewarned, and recognizing that any candidate, Democrat or Republican, can flip-flop once in office, here are the highlights of the LCV Guide.

First, the LCV environmental- performance scores (out of 100) for the Democrat and Republican candidates still in the race, based on their voting records:

* (D) Sen. Barack Obama: 96

* (D) Sen. Hillary Clinton: 90

* (D) Sen. John Edwards: 59

* (R) Rep. Dennis Kucinich: 92

* (R) Arizona Gov. Mike Huckabee: No voting record as governor, but the report notes: "He has placed a higher priority on energy issues than some of his Republican rivals . . . but he has not offered a detailed plan."

* (R) Former Massachusetts Gov. Mitt Romney: No voting record as governor, but the report notes: "Demonstrating his reluctance to lead, Gov. Romney often says: 'They don't call it America warming, they call it global warming.' "

* (R) Sen. John McCain: 26

* (R) Former Mayor Rudolph Guliani: No voting record as governor, but the report notes: "Through the end of the third-quarter fundraising period, Giuliani had received more than $500,000 [in campaign contributions] from the oil and gas industry, more than any other presidential candidate."

The Guide also has its own standards for comparison with the candidates' positions. The LVC is calling for: A mandatory cap of carbon dioxide emissions and 100 percent auction of pollution permits; at least 80 percent reductions in greenhouse gases by 2050; at least 40 mpg [approx. 17 km/liter] minimum standard for all cars and light trucks in 10 years; 20 percent renewable energy sources by 2020; and energy consumption reduced by 10 percent by 2020 from current levels.

Among the candidates, only Clinton, Obama, Edwards and Kucinich have platforms calling for equal or greater environmental responsibility. For more on the presidential candidates and other politicians, visit: www.lcv.org

As for the impending global car glut, I agree with the sentiments of Mahesh Mehta, an environmental lawyer based in New Delhi. "Can you imagine if even half of the 1.1 billion Indians owned a car? We should not be following the Western model of car ownership. I think this will be disastrous in India," he explained in a Washington Post article last August.

Mehta suggests that India focus its resources on public transportation — and I agree wholeheartedly.

But one final thought: Why should only India be saved from disaster? The Western model of car ownership has already proved disastrous in major cities across the globe, from Tokyo to Los Angeles to London — and it's a disaster waiting to happen in dozens more.

Let's hope India, China and others learn from our mistakes and develop buses networks, bike paths, and pedestrian ways from the outset, rather than trying to shoehorn them in later, as is too often the case today.

Stephen Hesse welcomes readers' comments at [email protected]