Here’s a follow-up post from the CleanTechnica reader who supplied us with “Not Crashing Our Boat — Finding Our Way Out of the Climate Crisis” (be sure to read that first post before proceeding):
As I reported a couple weeks ago, US CO2 emissions, after rising for many years, reached their highest level in 2005, and have fallen since.
People have assumed that the drop is due to the very significant economic recession we have experienced. First, let’s remember that the peak was in 2005 and the economic crash occurred in mid September 2008, with over 2½ years of a booming economy in between. CO2 dropped slightly, and certainly didn’t rise further, for two plus years during a booming economy.
Was, as some insist, the drop in CO2 due to a lower US GDP? Certainly not during 2006 and 2007. Let’s look at the data to see if GDP decline following 2008 supports that position. (And I’ll throw in electricity generation and oil consumption at the same time to save space.)
Nope, GDP post 2005 is higher every single year.
Is it because we quit making as much electricity? Nope, we’re making a bit more.
The one thing that does track CO2 output is oil consumption. Oil consumption in 2010 was 10.1% less than what it was in 2005. So, did the economic crash pull down CO2 emissions via less oil consumption?
Possibly, but US oil consumption stopped increasing after 2005 and it’s unlikely that the Fall crash of 2008 was early enough in the year to have accounted for all the 2008 drop. It’s not like everyone crawled under their beds and didn’t get on the roads. As I recall, major job losses did not start until late 2008, and extended into 2009.
In fact, US oil consumption hit a plateau in 2004 and did not increase in the ensuing 3¾ years in which the economy was in party mode.
What caused the oil consumption drop?
In 2010, miles driven was down 2% from 2005, and miles flown was down 1.6%. Together, they do not account for a 10.1% drop in consumption.
The next reason suggested was that oil in other applications dropped due to the recession.
Here we find a mixed bag….
Residential, electric power, railroad, vessel bunkering, on-highway, and off-highway are down. Industrial, oil company, and farm use are up.
On-highway: that 2% less driving mentioned earlier.
Electric power: a switch to renewables and natural gas. (Remember, electricity generation is up.)
Railroad and vessel bunkering: possibly due to lower economic activity resulting in less freight. But freight is down only 2.7%, 2007 to 2011. (Not cherry-picking, just the data I found without putting lots of effort into that question.)
Residential: and here let’s remember the claim that “it’s due to warm winters in 2010 and 2011.”
Residential heating oil consumption peaked in 1996 and began falling. In 2006, the year after the CO2 peak, heating oil consumption took a major drop. This was two years before the recession and four years before the “warm winters” explanation.
Is this drop due to warmer winters or more efficiency and fuel substitution? I didn’t take the time to research that. If it interests anyone, they can take on that project. The important thing is that CO2 levels are down and part of the reason seems to be less oil usage for heating and transportation.
(It might be worthwhile to point out that while our winters are warming, so are our summers, and we’ve had to work against rising air conditioner and refrigeration demand.)
While some of the post-2008 usage drop in driving, flying, and heating oil might be due to economic crimps, it is not safe to make that assumption without supporting data. It is also likely that some or all of the drop is due to higher efficiency and a decision on the part of the public to drive and fly less.
Here are a couple of graphs on our increased fuel efficiency (data from the Research and Innovative Technology Administration):
About a 40% improvement in passenger vehicle gas mileage. Over a 30% improvement in light truck mileage. Just think how those numbers will soar as we add more EVs and PHEVs.
In 1980, the CAFE standard was 20 mpg. By 1985, that requirement had risen to 27.5 mpg. It stayed at that level until 2010. The subsequent rise following 1985 is probably due to the retirement of pre-CAFE requirement vehicles. Gas prices (constant dollars) fall slightly until the mid 2000s (see graph above).
Gas prices take off around 2004. So does average vehicle mileage. The average mileage moved into the mid/high-30s by 2010, which argues that the price of oil drove people into more efficient vehicles.
How do I summarize all this?
1) US CO2 emissions peaked in 2005 and have fallen since.
2) The amount of fall was likely aided by poor economic conditions, which to some extent must have reduced driving, flying, shipping, and home heating, but since the reductions started prior to the country’s financial problems, it is likely that efficiency has also played a significant role.
We could probably replace the 2% drop in oil usage (on average, driving, flying, and shipping were each down about 2%) during a recovered economy without returning to previous CO2 emission levels, since in the intervening years we have continued to implement efficiency measures. We’ve replaced older, less efficient vehicles with more efficient vehicles and we’ve weatherstriped and insulated homes. We’ve increased non-hydro renewable grid share from 2.2% in 2005 to 4.1% in 2010, while cutting coal share from 49.6% in 2005 to 42.4% in 2011. (And, apparently, below 35% for the first half of 2012.) We’ve replaced some of the coal generation with natural gas, and while natural gas does bring its own set of problems to the table, it does lower CO2 emissions. (Additionally, natural gas generation, being dispatchable, will be easier to reduce than coal.)
In my view, we have passed a milestone. CO2 emissions in the US are dropping. We may have received a helping hand from an economic downturn and warmer winters, but we should accept that help and make more of the effort-based reductions. We should acknowledge our increased efficiency and renewable generation, and use that to encourage ourselves to increase our efforts further. It seems that what we have done has made a difference.
I'm the director of CleanTechnica, the most popular clean energy website in the world, and Planetsave, a leading green and science news site. I've been covering green news of various sorts since 2008, and I've been especially focused on solar energy, electric vehicles, bicycling, and wind energy for the past few years. You can also find my work on Scientific American, Reuters, Think Progress, GE's ecomagination site, several sites in the Important Media network, & many other places. To connect on some of your favorite social networks, go to zacharyshahan.com or click on some of the links below.