The EPA’s Draft Inventory of U.S. Greenhouse Gas Emissions and Sinks, 1990 – 2012 was released on February 21, 2014. I have been looking it over and have noted some things about it that I wanted to comment on here. I may make further postings in the future as I work my way through it.
The Executive Summary has some interesting figures and numbers. For instance, there is this pie chart of 2012 greenhouse gas emissions by gas (CO2 equivalent)
But, this is the one I found the most interesting, the greenhouse gas emissions by gas, over time:
The significance of this chart is the downward trend in greenhouse gas emissions in this country. Total emissions and emissions of CO2 are both down to levels not seen since before 1994. This is a very good trend. I have yet to see it specifically stated in this report, but I read elsewhere that this was occurring due to the greater use of natural gas versus coal for electrical plants. With all of the fracking going on, there is a surge in natural gas production, so this trend will hopefully continue. The report also states that methane emissions have decreased by 10.7% since 1990. Methane is 23 times more potent as a greenhouse gas than CO2 is, so this is also good news.
There is also bad news.
During the same period, aggregate weighted emissions of HFCs, PFCs, and SF6 rose by 60.1 Tg CO2 Eq. (66.6 percent). From 1990 to 2012, HFCs increased by 99.6 Tg CO2 Eq. (269.7 percent), PFCs decreased by 15.2 Tg CO2 Eq. (73.8 percent), and SF6 decreased by 24.2 Tg CO2 Eq. (74.3 percent). Despite being emitted in smaller quantities relative to the other principal greenhouse gases, emissions of HFCs, PFCs, and SF6 are significant because many of these gases have extremely high global warming potentials and, in the cases of PFCs and SF6, long atmospheric lifetimes.