America’s estimated greenhouse gas emissions rose by 2.4% last year — which is a big deal since they had been steady or falling in 2023 and 2024. More ominously, U.S. emissions grew faster than our gross domestic product last year, suggesting that the economy got less efficient from a climate pollution perspective.

Is this Trump’s fault? The AI boom’s? Or was it a weird fluke? In this week’s Shift Key episode, Rob talks to Ben King, a climate and energy director at the Rhodium Group, about why U.S. emissions grew and what it says about the underlying structure of the American economy. They talk about the power grid, the natural gas system, and whether industry is going to overtake other emissions drivers as once thought.

Shift Key is hosted by Robinson Meyer, the founding executive editor of Heatmap, and Jesse Jenkins, a professor of energy systems engineering at Princeton University. Jesse is off this week.

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Here is an excerpt from our conversation:

**Robinson Meyer: **At the same time there’s been rising total electrification of the vehicle fleet, there’s also been rising hybrid and plug-in hybrid sales. Do we have a sense of how that breakdown is happening, in terms of reduced carbon intensity of the transportation sector and the light duty fleet?

Ben King: It’s a good question. We haven’t disaggregated the … When I say electric vehicles, I’m talking broadly about both full battery electric, and then plug-in hybrids. And then, I think we say this in paper, but I think there was pretty robust growth for gasoline hybrids as which, you know, relative to just a pure gas car, is better from an emissions perspective.

**Meyer: **Well, it’s funny because if you care about decarbonization and getting to net zero as soon as possible, you could have to poo poo hybrids. But if you’re actually involved in the game to just keep as much emissions out of the sky as possible, and you’re looking to net those 2% declines every year, hybrids are pretty important because they are basically a drop-in replacement to gasoline car use that burns less gasoline.

**King: **The other interesting thing that gasoline hybrids does for the sector is it finds interesting unanticipated uses for all this battery manufacturing capacity that we’ve built in the U.S., or that we stand to build. Our forecast for pure EVs — so battery electrics, plug-in hybrids — looks a little worse in the out years because of the tax credits going away, because of the EPA tailpipe regulations going away at the same time that the anticipated demand pull from those policies, plus the advanced manufacturing tax credit — the 45X tax credit — has really been wildly successful in standing up a battery manufacturing industry here in the U.S.

If you want that capacity to be around, one thing that you could do with those batteries is put them into hybrids, right? You might have to retool the line a little bit to accommodate different sizes and stuff, build the expertise, build the workforce, etc., such that when the floodgates open again for electric vehicle adoption, for instance, we’ve got substantial battery manufacturing capacity here domestically.

Mentioned:

Rhodium Group: Preliminary US Greenhouse Gas Emissions Estimates for 2025

Rob on Rhodium’s 2023 emissions report

And here’s Rhodium’s 2024 emissions report

This episode of Shift Key is sponsored by …

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Music for Shift Key is by Adam Kromelow.