Hard Facts

Aviation creates 5% of climate impacts and growing—more than most countries

"Work by the IPCC (International Panel on Climate Change) has been updated by the same authors. They estimate that aviation accounted for 4.9% of man-made climate impacts in 2005. This contrasts with the 2% figure that is constantly quoted by aviation lobbyists.Just two years ago the authors came up with a figure of 3% for aviation’s worldwide contribution to climate change. They have now revised their estimate for 2005."
— Aviation Environment Federation summary, based on "Aviation and Global Change in the 21st Century" by D.S. Lee et al

"In the United States, domestic aviation contributes about 3 percent of total carbon dioxide emissions, according to EPA data...Aviation Contributes about 3 Percent of All Human-Generated Emissions. When other aviation emissions—such as nitrogen oxides, sulfate aerosols, and water vapor—are combined with carbon dioxide, aviation’s estimated share of global emissions increases from 2 percent to 3 percent, according to IPCC."
— United States Government Accountability Office, Aviation and Climate Change report, June 2009, page 12

International aviation emissions from Annex 1 developed countries grew by 65.8% from 1990 to 2005.
—UN Framework Convention on Climate Change's National greenhouse gas inventory data for the period 1990–2005, October 2007, page 13

In Wikipedia's List of countries by 2007 emissions, only China, the US, India, Russia, and Japan individually generated over 3% of total global CO₂ emissions; aviation generated more CO₂ than every other country on the planet. Giving a free pass to aviation CO₂ would be like giving a free to all British CO₂. This is a global problem, and we need everyone to pull together.

We need to cut emissions in every part of the economy, including aviation

"Delegates at the Summit recognised the important work that all industry sectors and governments must undertake in the lead up to the UNFCCC climate change negotiations in Copenhagen in December 2009. The aviation industry has been working at an unprecedented pace to reduce its emission. Delegates urged policy-makers to support these efforts by developing and adopting a global sectoral approach to aviation emissions at Copenhagen."
—Aviation industry's internal Summit Communiqué from 4th Aviation and Environment Summit

Scientists say we need to cut emissions by 80-90% by 2050

Gar Lipow blogged about some of the back and forth around the 80% and 90% figures.

Aviation industry plans to cut only 50% by 2050 (experts doubt if any cuts will occur)

In June 2009, the International Air Transport Association (IATA) announced that the global aviation industry would halt CO₂ emissions (i.e. 0% cuts) by 2020, and would hit 50% reduction by 2050. It's nice that the industry is planning any cuts at all, but the planned cuts are tiny relative to what scientists and governments are mandating.
—"Carbon-Neutral Growth by 2020", June 2009

Adam Vaughn at the Guardian is concerned that the aviation industry's June 2009 statement didn't rule out the option of "lowering" emissions by buying offsets, instead of actually lowering emissions.
—"How green are the airline industry's environmental promises?", June 2009

"[E]ven the most ambitious scenario suggests that CO₂ production will increase by almost 100% from the base year...The analysis suggests that aviation emissions will continue to grow as a result of continued demand for civil aviation."
—"IPCC Fourth Assessment Report: Working Group III Report 'Mitigation of Climate Change'", 2007, page 364

Better technology probably won't lead to enough efficiency

"Although some airlines may adopt technologies to reduce their future emissions, these efforts may not be enough to mitigate the expected growth in air traffic and related increase in overall emissions through 2050....One expert we met with did a rough estimate of future emissions from aircraft assuming the adoption of many low-carbon technologies such as blended wing-body, operational improvements, and biofuels. He used IPCC's midrange forecast of emissions to 2050 as a baseline for future traffic and found that even assuming the introduction of these technologies, global emissions in 2050 would continue to exceed 2000 emissions levels. Had a lower baseline of emissions been used, forecasted emissions may have been lower. Another study by a German research organization modeled future emissions assuming the adoption of technological improvements, as well as biofuels, to reduce emissions. This study assumed future traffic growth averaging 4.8 percent between 2006 and 2026 and 2.6 percent between 2027 and 2050. While this study forecasted improvements in emissions relative to expected market growth, it estimated that by 2050 total emissions would still remain greater than 2000 emissions levels."
—United States Government Accountability Office, Aviation and Climate Change report, June 2009, page 34

Hard Conclusions

Aviation as we know it is fundamentally unsustainable.

Aviation's impacts are already too high. And they're growing. It's unlikely we'll find a technology solution that can reduce emissions 80-90%, and magically find a way to roll out it across almost the entire fleet of planes worldwide. This is simple math and logic.

We need to fly less. (Yes, this will be hard)

George Monbiot's arguments around aviation and "love miles" are devastating and hopeful. Read a good description of Monbiot's argument, or an excerpt from his book Heat, where he makes his case.

This is a difficult personal and social issue to grapple with. Ait travel, particularly international air travel, can be vital to our identity, as travelers, world citizens, and immigrants. But if we want a planet to call home, we need to work through some of the difficult, sticky, conclusions.

We deserve better science-based transportation policy.

Even the aviation industry's own website explicitly recommends taking trains, where they're a greener option (which is pretty often). Use tools like Trip Footprint to see what's greenest.

Travelers deserve to know (and pay) the true environmental cost of their travel. Movements around carbon pollution taxes and green data can be part of the solution.

Whether you're pushing for alternatives with Transportation for America, or challenging aviation industry PR like Plane Stupid, there's no time like the present for taking on transportation and climate change in your community.