As a newly minted PhD arriving in Akron, Ohio, in the mid-1960s, I encountered a range of alarming media commentaries including: newspapers proclaiming that US oil production had peaked and would forever decline; earth scientists assuring Ohioans that nearby Lake Erie, bordering the USA and Canada, would become a peat bog by 2000; and Cornell University astrophysicist Carl Sagan foretelling global cooling with the coming of the next ice age. Not to be outdone in Malthusian pessimism, Stanford University’s Paul Ehrlich followed in 1968 with his best-selling book, The Population Bomb, which declared that 250 million people would starve by 2020 due to diminished food supply.
All of these self-proclaimed oracles and their pronouncements of decades ago were wildly inaccurate because they carelessly neglected the importance of human innovation concerning the supply of food and energy. Science produced the Green Revolution’s super-crops that prevented the predicted food crises of the 20th century, while shale gas is displacing coal in US power plants, resulting in lower operating costs and reduced carbon emissions.
Today, our news sources declare that the planet is heating up, sea levels are rising and the glaciers are melting due to global warming. Nothing new here: the climate has been changing for millennia. The negative consequences of climate change are well publicized by the media. The lesser-known realities of global warming are that some changes will benefit planet Earth and its inhabitants: more usable land for agriculture, longer growing seasons for crops, and added carbon dioxide (CO2) for robust plant growth. Further, cold weather kills more people than hot weather. Danish climate skeptic Bjørn Lomborg has estimated that about 0.5% of all human deaths are heat-related, while more than seven percent are cold-related. In the USA alone, over 100,000 premature deaths could be prevented annually by global warming!
So how do we assess the environmental impact of tires on the present global warming frenzy? We all realize that keeping tires properly inflated will reduce greenhouse gas (GHG) emissions, but will not save the planet. First, some facts about the sources of global warming: fossil fuels (coal, natural gas and oil) contribute about 65% of the GHG emissions – principally CO2 – responsible for warming the planet; direct emissions from livestock, land use change (such as logging) and waste decomposition contribute the remaining 35%. And, from an accepted but simple physics model, without atmospheric greenhouse gases, the average temperature of Earth’s surface would be much colder – about -18°C (0°F), rather than the present average of 15°C (59°F). Second, the road transportation sector, using fossil fuel resources, produces about 10% (of the 65%) of the GHG emissions. And tires – like braking, accelerating and the vehicle’s power absorbing options – consume fuel, around 4-7% for automobile tires and about 13% for medium- and heavy-truck tires. Consequently, tires in worldwide operation are responsible for producing decidedly less than 1% of total GHG emissions.
While this is a measurable amount, it seems to be marginally meaningful. Consider that today’s most fuel-efficient tires still possess twice the rolling friction as steel wheels on steel rails. For the worldwide vehicle fleet to at some distant date match the performance of vehicles on rails would halve the tire’s contribution to GHG emissions. Even with no improvement, I suspect that the planet’s predicted temperature rise over the next 100 years due to tire rolling resistance would remain small compared with the contribution of other, sometimes uncontrollable sources. For example, the contribution of vehicle thermodynamic losses alone to emissions is more than 10 times that of tires, mainly by exhaust heat leaving the tailpipe.
For the short term, it seems prudent (due to the regulatory environment) for the tire and automotive industries to continue their quest for improved energy efficiency without inflicting too much economic harm on the motoring public. At the present time, wind and solar power programs, along with fuel derived from grain ethanol, remain a sinkhole for government subsidies – but hopefully not so in the future. In any case, when warmer weather does arrive I suspect that humans will be enjoying a higher standard of living while driving on more fuel-efficient tires due to our innovative spirit.
