Someone asked for my opinion on purchasing carbon offsets to account for travel mileage recently. This topic is interesting to me because there is more than meets the eye; it's a little more nuanced than it seems at first glance. The problem of emissions seems easy to solve: take as much carbon out of the atmosphere as you put into it. And, honestly, we already know how to do this; all you need to do is plant some trees somewhere and voilà! The average North American 2000 mile flight will pump out a little over 1000 pounds of carbon dioxide per sardine can packed class passenger . Sadly, there is no such thing as the average tree, but you can still find data on tree growth rate and carbon content for individual species out there. Solve for time and you'll get how many years it would take a single newly planted tree to sequester as much carbon as you released.
This sounds like it should work, right? Well, yes... but no. My main problem with this style of emissions offsetting is one of accountability. If we're doing everything right, trees should only be planted in their native ranges. That is, avoiding planting eucalypti in California or any kind of tree for this purpose in the western side of the Plains. The implication here is that we're planting a tree where there used to be one in times past. My generation is inheriting a world with dwindling forests, which makes this a good problem to solve, alas it's an entirely different one from the emissions problem. For whatever now unimportant reason, someone else in the past chopped a tree in close proximity to the spot where the carbon offset purchaser is now given the opportunity to plant their emission offsetting tree. At the end of the day, though, whenever the tree is done growing there will still be less carbon underground and more carbon in the biosphere. The only way to truly offset fossil fuel emissions is to pump carbon back into the ground. To be fair, we also know how to do this , but this technology seems to be in its infancy and the capture rate given the number of operational facilities and the current levels of emissions within the United States  seems insufficient. To top all of this off, there is a limited amount of space where we could be planting trees, so the solution won't scale forever. Planting some trees has the side effect of being an okay stopgap solution to atmospheric carbon emissions until we get our act together, but it is by no means a panacea.
My second problem with consumer carbon offsets is just as important as the first. They encourage behaviors that are noxious in the long run. One might find himself entitled to, for instance, fly far more often than they otherwise would if the opportunity presents itself to plant some trees or fund some landfill methane capture initiatives or any other climate change mitigation effort. But again, accountability; these are things we should be doing anyway. I'm not an idealist either. I know first hand how important RnR and vacation time away form home are and what their lack does to people, but we should always strive to reduce our environmental impact whenever possible, even if that means a wee bit of time loss in the process. Some of the things we can do to meet this goal include carpooling, using rail (have you ever heard of Amtrak? It's awesome, give it a whirl some time and see for yourself 😉), or choosing destinations that are somewhat local to you; I'm sure there's plenty of unexplored beauty within your state.
The truth of the matter is that the only viable way to reduce emissions right now, carbon or otherwise, is to consume less until the energy or products we use come from renewable or virtually renewable sources. Fossil fuels have had more than a 200 year lead for engineers to improve processes ranging from discovery and extraction to delivery and storage. Plus, the infrastructure to get energy from the ground to the consumer already exists. This and other logistic considerations make it really hard for renewables to be competitive in today's economy. The environment is one of the very few areas of policy in which I advocate for strong government regulation, although I'm of the opinion that we're approaching the problem from the wrong angle. Current policy revolves around providing tax credits for investing in or using renewable energy , most notably for installing solar panels in your roof. This is a well intentioned policy, but it hasn't been enough to decisively tip the balance in favor of environmentally friendly sources of energy .
In my opinion, the solution to the energy problem is a very steep and preferably progressive commercial carbon tax. Clear yearly guidance on the nature of the curve would help businesses to adjust prices accordingly and provide a good incentive to source the energy they use from carbon tax free sources to stay competitive. This tax would spike the prices of worse offending means of transportation, like air travel, which would make travel by rail more competitive, increasing ridership and driving down the cost in the medium run if properly managed (but this is an entirely different topic). Businesses managing to stay competitive without switching or businesses incapable of switching due to current logistic issues would provide an alternate stream of revenue for the government to invest in the infrastructure necessary to make non-fossil energy sources even more competitive, fund DoE research projects, or clean up some of our worst environmental messes as, contrary to what Billy Joel might want to tell you, some fires we did start ourselves.