Monday, November 29, 2010

Reaching 2050 Climate Goals: The Magnitude of the Challenge

As we launch this blog on climate change and resource efficiency in the built environment, it is worth taking a moment at the beginning to reflect upon the "big numbers" of climate change and the goals that have been set out before us. Though it has been said before, it is worth saying again: moderating climate change (it has already begun and can't be prevented entirely) will require epochal transformations in most aspects of our society and economy -- most especially including the built environment.

Consensus has emerged among scientists that the world must limit global temperature increases to 2 degrees Celsius (about 3.6 degrees Fahrenheit) over pre-industrial levels (not today's levels) to avoid the worst of the possible consequences of climate change. Indeed, at the Copenhagen conference last year, President Obama and numerous other world leaders committed their nations to achieving this goal, even in the absence of any enforceable treaty mechanism to achieve it.

Numerous research and policy efforts, including the Intergovernmental Panel on Climate Change (IPCC) have concluded that this will require cutting global greenhouse gas emissions 60 to 80 percent below 1990 levels by 2050. California, alone among American states so far, has accepted this challenge in the form of Executive Order S-3-05, which sets a target of an 80 percent reduction below 1990 levels by 2050. (The state's more heralded climate law, AB32, requires the state only to return to 1990 levels by 2020, then establishes a cap-and-trade mechanism to achieve the deeper reductions in later decades).

That 80 percent number is even more daunting than it looks, for four reasons:

1. An absolute emissions level that is 80 percent below 1990 levels by 2050 is actually more like 88 percent per capita below today's levels in California, which is perhaps the more relevant figure for policy making. That is because California's emissions levels have grown another 10 percent since 1990 (according to the EPA), and because the state's population is expected to grown by 62 percent between now and 2050 (according to the California Department of Finance).

2. Emissions cuts this deep mean that all major sectors of the economy must achieve approximately that much reduction -- there just isn't enough wiggle room for tradeoffs between sectors. According to the AB 32 Scoping Plan released by the California Air Resources Board, transportation generates about 38 percent of the state's GHG emissions, electricity about 23 percent, industry about 20 percent, and commercial and residential activities about 10 percent (with the remaining 9 percent classified as 'other').

For the sake of illustration, let us suppose that the transportation sector is able to achieve "only" a 75 percent per-capita reduction by 2050, still an arduous political and technological challenge. That would mean that all other sectors -- including all buildings, industry, commercial activity and agriculture -- would have to achieve about a 96 percent reduction by 2050 for the economy to meet the overall 88 percent per capita reduction target. Thus, even a "miracle" breakthrough in one area (say, complete decarbonization of the electricity system) would not relieve other sectors of the economy from the need to achieve profound changes.

3. All of this must occur in just 40 years. That is very little time in the planning world. In the state of California, single mega-projects such as the Bay Bridge retrofit now take nearly that long from conception to completion.

4. On top of all that, there is a large embedded infrastructure problem that must be overcome. Efficiency experts have long realized that most consumers will not buy a new water heater (or refrigerator, stove, etc) until the old one wears out, even if something significantly more efficient is already on the market. The same is true for buildings, roads, and infrastructure, except that these are designed to last for even longer, several decades at a minimum. Why would society replace these paid-for assets with something new before they wear out? Most likely, we won't, or simply won't be able to afford to. That means that we will be living with at least portions of our current energy-intensive landscape for a long time to come.

I'll have more to say about the implications of this monumental challenge for transportation and land use planning in future posts.

No comments:

Post a Comment