As I see it, one of the problems of responding to climate change is the need for a response coordinated across industries and countries. Lots of industries like to trumpet what they are doing on their own to reduce their carbon footprints, but what if these reductions simply shift the climate change contribution onto another sector of the economy without reducing net impact? Case in point: aviation biofuels. Airbus and Boeing both affirm biofuels’ importance. Japan Airlines is running a biofuel test flight soon, and Air New Zealand will test biofuel made from jatropha, which meets its criteria of environmental sustainability without competing with food production, quality equal to today’s jet fuel, and significant cost savings. Much has been made of plans like benign megalomaniac Richard Branson’s to expand use of biofuels, not only to reduce emissions but also to save money:
Virgin’s much-ballyhood flight from London to Amsterdam used 5% coconut-oil biofuel . . . to show biofuel could take the high-altitude cold. But the test flight alone used 150,000 coconuts, Petroleum Review says—and at least 3 million would have been needed for a full biofuel flight. Multiply that by world air traffic, and the problem comes into focus.
The other options? Flavor-of-the-month jatropha biofuel would be fine—except aviation would require a land area twice the size of France to grow the stuff. . . . How about biomass, like bits of wood and useless plants? Well, they still need to grow somewhere—and commercial aviation would need to harvest an area three times the size of Germany.
My question: if aviation washes its hands of its climate change impact (estimated to be 2-3 percent) with biofuels, and since biofuels require more arable land and lead to the clearing of forested areas, how much does that add to deforestation’s estimated 25 percent contribution to anthropogenic climate change? The airline sector currently has no incentive to worry about this transfer of emissions, and every incentive (financial, PR, etc.) to just do it.
I’ve written before about a similar but not identical problem in “green taxation,” in which one country’s aviation taxes reduce one country’s aviation carbon footprint but not the world’s, because the flights shift to other countries’ airports. In the case of biofuels, will the airline industry be able to “greenwash” away its climate sins without actually making a difference in manmade CO2 emissions?
As for the extent to which widespread use of aviation biofuels will mitigate climate change, or what kind of policies or institutional structures can prevent this problem, I will leave further discussion up to those much better versed in this subject than I. Ahem, ahem.
Evan Sparks's Aviation Policy Blog 
The trials using biomass are only designed to establish whether aircraft can fly with mixed fuel – there have been issues about freezing. The airlines’ goal is algae-based biofuel, which will limit concerns over land take, and the major manufacturers have established consortia to develop next generation fuels. No one expects them to be a perfect panacea but they will make a difference.