My travels this week take me to Detroit and Chicago for meetings and speeches. By the time I return home to California on Wednesday night, I'll have taken -- if my accounting is correct -- 51 plane flights during the first half of 2007.

I'm not bragging, mind you. Indeed, it's rather embarrassing (and more than a little exhausting). But like many of my environmental professional brethren, air travel is far and away my biggest personal and professional footprint. And it's not likely to change any time soon.

This reality notwithstanding, the airline industry seems poised to finally confront its environmental impacts -- and mine. The past few weeks have seen a flurry of activity, with airlines announcing greener planes, carbon neutral flights, and other initiatives aimed at lightening their environmental load, so to speak. Energy and climate friendliness are becoming competitive marketing positions for aircraft and engine manufacturers. And policy makers are making some tentative first steps to bring airline emissions back down to earth.

Those emissions are significant -- between 2 and 3 percent of global greenhouse gases, according to the International Governmental Panel on Climate Change, though other estimates are much higher. For example, according to U.K. government data released last month, emissions from flights departing the U.K. contributed approximately 13 percent of that country's greenhouse gas emissions in 2005 and could double by 2050. And experts point out that such figures do not take into account aviation's non-CO2 climate gases, which significantly contribute to the impacts of flying from hither to yon.

Indeed, air travel is growing "at unprecedented rates, yet substantial reductions of aviation greenhouse gas emissions are not possible in the short to medium term," write aviation consultants The Hodgkinson Group, authors of a new report on strategies for airlines on aircraft emissions and climate change. It notes that over the next 20 years, more than 27,000 new aircraft will be delivered, and the number of air travelers will double to 9 billion. The report (e-mail to request a copy) points out that

not only are emissions from air travel increasing significantly in absolute terms but, against a background of emissions reductions from many other sources, their relative rate of increase is even greater.

Moreover,

without government action to significantly reduce aviation growth within the U.K., for example, aviation emissions may be greater than those forecast for all other sectors of the economy. As a result, aviation may exceed the carbon target for all sectors by 2050;

There are signs that the world's airline executives are starting to feel the heat. Earlier this month, at the annual meeting of the International Air Transport Association in Vancouver, executives acknowledged that public pressure is leading them to change course. ""We've lost the PR battle and we're not going to win the emissions battle by chattering with more PR about the past. They (the public) want to see action," Leo Van Wijk, chief executive of KLM Royal Dutch Airlines, told his colleagues, according to Reuters.

Activists are paying attention, too. Last week, Greenpeace handed out free "climate-friendly train tickets" at four U.K. airports to to travelers making domestic trips wiling to cancel their flights. The group aimed to demonstrate that flying causes ten times more damage to the climate than taking the train. Traveling a slightly different course, a group called Plane Stupid held demonstrations at the offices of EasyJet to protest what they dubbed the "climate-wrecking effects of short-haul flights."

It's not just air travelers and activists. Regulators around the world are starting to get on board. The European Union decided last year that airlines that fly within the bloc will have to trade pollution allowances beginning in 2011. (Not surprisingly, U.S. regulators vehemently oppose that.)

Even without public, activist, and regulator involvement, airline action would likely be taking off, and not because of climate concern. The real motivator: soaring fuel costs, which are cutting into many airlines' profit margins.

All of which explains why Boeing and Airbus, the world's two principal airline manufacturers, seem hellbent on out-greening each other, if one were to believe recent reports. Boeing's forthcoming and much-touted Dreamliner 787 colossus (it carries up to 330 passengers across oceans) promises to be 20 percent more fuel efficient than anything flying today. Meanwhile, Airbus says its A380 superjumbo is cleaner per passenger-mile than the competition.

As with so many other technologies, competition also is coming from upstarts. For example, discount airline EasyJet recently announced a prototype for an "ecoJet" that it claims could reduce CO2 emissions by half compared to existing short-haul aircraft. That should make the Greenpeace protesters happy(er). The company said that the ecoJet prototype was based entirely on existing technologies, including an "open rotor" technology designed in the 1980s after the OPEC oil crisis ratcheted up oil prices. According to reports:

It will cut fuel burn by a further 15 percent with wings and fuselage constructed from lighter aluminium composite material. A further 10 percent will be saved by slower inflight speed and, in a development not linked to the aircraft, changes to air traffic control across Europe.

And Virgin Atlantic impresario Richard Branson has announced a partnership with Boeing and engine maker GE to design biofuels that can be used in commercial aircraft. Branson aims to test the fuel in a Boeing 747-400 aircraft by the end of 2008.

In general, however, the response of the airline industry to climate change can be characterized as -- well, going nowhere fast. The Hodgkinson Group report points out that the most common airline responses have been, broadly: to continue, more or less, with business as usual; to argue that the problem can be solved by improving air transport technology and infrastructure along with more efficient operational practices; and arguing that a global industry solution should be developed, working through the International Civil Aviation Organisation -- a classic ploy in many industries to avoid any one company breaking from the pack.

Hodgkinson concludes that airlines should consider a mandatory emissions offset market as part of a long-term strategy -- along with technological, operational, and management improvements -- as a sustainable, long-term solution to deal with their climate impacts.

That's not likely any time soon, given the industry's historic recalcitrance on the issue. Meanwhile, some airlines appear to be seeking shortcuts to real action: A handful have resorted to selling offsets to customers to mitigate the climate impacts of their flights -- a decidedly imperfect solution, as I've noted in the past. This year alone, several airlines have introduced carbon-neutral schemes, including Air Canada, Cathay Pacific, Delta, SAS, and Virgin Blue. British Airways launched a similar plan in 2005, although it has been criticized for being under-marketed and poorly conceived.

Note the absence of most of the world's major carriers -- apparently, they're still in a holding pattern about whether and how to address this.

Will we reach a point where airline climate policies and performance become a decision point for consumers? Will airlines eventually compete on their greenness? Will travelers, especially business travelers, abandon their coveted frequent-flyer programs to switch loyalty to more eco-friendly flyers? Can we move airlines to act faster than they seem to be doing on their own?

Even better: Can we figure out ways -- really, truly effective ways -- not to fly at all?

As an unabashed road warrior, I'll be the first to admit that this is a journey that's going to be one bumpy ride.

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Joel Makower is Founder and Executive Editor of GreenBiz.com. This article was adapted from his blog, Two Steps Forward.