With the election on our doorstep, I think it makes sense to talk about the US future in terms of presidential terms again.
Climate change is one of the key issues of the 21st century and requires immediate presidential action. But what kind of immediate action? The current federal climate policy on the table (a cap and trade system poised to pass in 2009) targets reducing US emissions to 1990 levels by 2020. This blog describes interim goals for the first and second presidential terms (by 2012 and 2016) to get us toward the 2020 goal.
Based on my estimates that US greenhouse gas emissions will fall in 2008 by more than 1.5% (derived from US EIA Short Term Energy Outlook data), 2008 emissions are ~14% higher than in 1990 (6.16 Gt net carbon dioxide equivalent emissions vs. 5.41 Gt). To reduce emissions to the 5.41 Gt level in 2020 we will need to reduce emissions an average of 1.1% per year. Obama/Biden and McCain/Palin, please keep that number in mind. We can make the sustainable energy transition a relatively smooth one by starting with a 1.1% per year reduction in 2009. This is a big change from the 1990s when our emissions grew ~1.6% annually, but in line with continued progress in the 2000s since our emissions have essentially flat-lined over the last eight years (thanks largely to higher fossil fuel prices).
What would such reduction look like? There are many routes to -1.1%, but a strategy that co-mitigates our dependence on foreign oil would focus on lowering oil consumption. A scenario that seems plausible would be to reduce oil demand by 2% per year, coal by .5% per year, and to allow only tiny growth in natural gas use of .2% annually. By 2020, such oil demand reduction would free us from our current dependence on precarious imports from Mexico, Norway and Russia (geologically declining production) as well as Venezuela and Iraq (where politics and above-ground factors threaten production). It would require an acceleration in fuel efficiency progress (gaining market share for plug-in hybrid electric vehicles along with improvements in bike/ped and transit infrastructure should do the trick). Filling the gaps of lower oil and coal consumption would be a mix of efficiency and wind, solar and geothermal energy substitutes. Other scenarios that would work include faster reductions in oil consumption (this year we reduced demand by more than twice the 2% rate) or allowing coal to grow but making it CCS coal (where the carbon is captured and stored — this technology may be available by the second presidential term or soon afterward). Success at the end of the first term would put US emissions at ~5.95 Gt carbon dioxide equivalent in 2012 and then ~5.7 Gt by the (potential) second term finale in 2016.
In sum, the sustainable energy transition does not have to be a scary prospect for the next president. It can be started by reducing greenhouse gas emissions by just 1.1% per year (a rate slower than this year’s 1.5+%) and doing so can simultaneously help solve our crippling dependence on foreign oil, create jobs in renewables and efficiency, and put our economy in the enviable position of driving global technological progress in the multi-trillion dollar energy sector. Getting started in 2009 helps provide some insurance in case further study and experience shows that NASA scientist Jim Hansen is right that we need to keep GHG concentrations below 450 parts per million (from today’s ~385 ppm) to prevent runaway melting of Greenland and western Antarctica in the decades ahead.