Since 2005, total US carbon dioxide emissions from fossil fuels have dropped 20 percent, according to the US Energy Information Administration. In 2023, CO2 emissions were the lowest they had been since 1987. At the same time, US population has increased 14 percent, making this an average 30 percent decrease per capita.
The vast majority of this decrease in emissions has come from the electric power sector, where coal-fired plants have been largely replaced by natural gas and renewables. Since natural gas releases only one-quarter the amount of carbon dioxide as coal to produce the same amount of electricity, the switch to natural gas has been the main driver behind this decrease
Because of the reduction in emissions from the electric power sector, transportation is now the largest-emitting sector in many US states—especially on the East and West Coasts. In most Midwestern states, electricity remains the largest emitter, partially because these states still have some coal-fired plants and partially because they export electricity to other states with higher urban populations.
There’s one major exception to this trend—Iowa. While Iowa has made stunning progress in decarbonizing electric power—a 54 percent decrease in carbon emissions since 2005, thanks in part to the state’s huge number of wind turbines—its total CO2 emissions have only fallen a modest 13 percent. That’s because carbon emissions from the industrial sector actually increased a whopping 53 percent in that 18-year period.
Most of the other states that have shown this kind of increase—like Texas, Louisiana, Alaska, and North Dakota—produce and refine oil. Iowa, in contrast, is predominately agricultural. But its industrial carbon emissions were 7 million metric tons more in 2023 than in 2005—the largest increase in any state except for Texas (which had an increase of 32 million metric tons).
So what’s driving this increase in Iowa’s industrial carbon emissions? According to the EIA, the culprit is “large agriculture and biofuels production.” The irony here is that one of the justifications for ethanol production is that it supposedly lowers carbon emissions by replacing gasoline. Those savings, if there were any, would show up in the transportation sector in the EIA’s dataset. But national transportation emissions have remained relatively constant since 2005, dropping significantly only in 2020—because of the pandemic, not because of ethanol.
Eco-ag farmers should be the first to point out that if ethanol production increases carbon emissions at a similar rate to oil production, that’s a problem. In contrast, converting cornfields to pastures with deep-rooted grass and legume crops can significantly reduce fossil fuel use and help rebuild those deep, rich Iowa mollisols that were originally formed under tallgrass prairie. That would help Iowa’s carbon emissions profile look less like an oil-producing state and more like a carbon-sequestering one.
