the Liberal party's decision to use a 29-year-old Boeing 737-200 for campaigning, saying that the older airplane's poor fuel efficiency demonstrates hypocrisy on environmental matters. Daniel Lauzon, a spokesperson for the Liberals, denied their airplane was substantially less efficient than the Conservatives' Airbus A319. The Tories have been previously criticized for backing out of Canada's commitments under the Kyoto Protocol. Their new plan requires industries to reduce the rate at which they generate greenhouse gases, with a goal of reducing overall emissions by 45 to 65 percent by 2050. The plan has been criticized by groups such as the Sierra Club, who called it "completely inadequate". Criticism has focused on the use of "intensity-based" targets, for which emission reductions are relative to overall production, so overall emissions could potentially increase if production also increases. This is in contrast to a "hard cap" on emissions, for which the overall amount cannot increase. The Conservatives' plan includes a hard cap to begin in 2020 or 2025, while environmental groups have advocated for an immediate hard cap. The Liberals have developed a "Green Shift" plan, creating a carbon tax that will be coupled with reductions to income tax rates. The proposal was to tax greenhouse gas emissions, starting at $10 (Canadian) per ton of CO2 and reaching $40 (Canadian) per ton within four years. The plan would engage in revenue recycling by matching the tax with reductions in the income tax. Criticism of the Green Shift plan has focused on its economic effects, with the Conservatives predicting it would cause a "big recession". When pressed by reporters to provide evidence of this impact, Harper "wasn't able to cite a study that specifically modelled the impact of the Liberal Green Shift plan", instead citing an older economic model about the implementation of the Kyoto Protocol. One trucking association claimed the Liberal carbon tax plan could put up to 10,000 jobs in jeopardy in Moncton alone. Environmental activist David Suzuki has come out in support of Dion's plan, saying "To oppose [the carbon tax plan], it's just nonsense. It's certainly the way we got to go" and giving an interview explaining why it is the most effective way to solve the environmental crisis. The NDP's plan for the environment has focused on emissions trading, claiming their system will decrease greenhouse emissions by 80% by 2050. The plan includes a series of financial incentives to retrofit