Could a coalition of US states really slash emissions nearly as much as a coordinated national plan? At COP30 in Belém, Brazil, California Governor Gavin Newsom made the case that they can and that they must given the absence of federal leadership under President Donald Trump.
Newsom’s presence at the summit was conspicuous. On stage with Pará Governor Helder Barbalho, he boasted of the transformation of California into a renewable powerhouse, now two-thirds powered by clean sources. The state’s energy profile, as the world’s fourth-largest economy, is not simply a regional achievement it’s proof of concept for climate federalism. Between munching tropical fruit and sipping açaí juice, Newsom framed state action as both a moral imperative and an economic opportunity.
While regional leaders like Newsom and New Mexico’s Michelle Lujan Grisham have no formal role in COP negotiations, their influence lies in showing that subnational entities can deliver tangible results. “When the federal Government leans in, we do more, and when they lean out, we do more. It’s both.” said Lujan Grisham.
This potential has been quantified by the Center for Global Sustainability at the University of Maryland. Its analysis found that if US states and cities ramp up their ambition and a climate-friendly president is elected in 2028 emissions could decline by well over 50% by 2035, getting close to the Biden administration’s 61–66% reduction target. Without federal support, the same study demonstrated that cooperation among states could deliver a 45.7% nationwide reduction by mid-century with costs only marginally higher than a federal plan.
The technological pathways differ. In a state-led scenario, high-commitment regions such as California and the Northeast rely heavily on electrification, battery storage, and direct air capture (DAC) to offset hard-to-abate emissions. California, with a modeled 29.8 gigaton CO₂ storage potential, channels DAC toward geologic sequestration, while the Northeast uses DAC to produce synthetic fuels for transport. In contrast, a national approach would more aggressively deploy bioenergy with carbon capture and storage (BECCS) in resource-rich regions like the Southeast, leveraging low-cost biomass and expansive geologic storage.
But market forces remain a decisive factor. Texas leads the nation in wind generation and could soon surpass all states in solar capacity, despite its political hostility to climate policy. Yet its state legislators are moving to cap renewable growth at 50 percent of new projects, finance $10 billion in natural gas plants, and strip wind and solar of tax incentives. Energy researchers note that battery storage already scaling rapidly can provide the same dispatchable reliability as gas plants, storing surplus renewable power and releasing it during peak demand.
Trump’s federal retrenchment does not stop at home. His administration recently prevented a proposed global carbon tax on shipping-which produces about 3% of global greenhouse gas emissions annually-from moving forward. The tax, supported by the EU, Brazil, and vulnerable island nations, would have represented the first legally binding global carbon levy. By threatening action against countries that supported the tax, the US did more than block it; Washington signaled it could threaten other multilateral efforts to address climate change.
That stance reflects a second Trump pullout from the Paris climate accord, which robbed the US of its official seat at the table in crafting worldwide rules on climate change. As one of the agreement’s architects, Christiana Figueres, said, They cannot take the floor and directly bully other nations. For state leaders, this absence is a problem and an opportunity. Unimpeded by federal influence, they build alliances abroad, collaborate on technology strategies, and tout progress though the absence of federal coordination leaves gaping holes in industrial decarbonization and risks of emission leakage from unconstrained states.
Newsom’s message at COP30 was clear: “Trump is temporary. You stand up to a bully.” In the context of climate policy, that means sustaining momentum through state innovation, market-driven renewables, and international collaboration, even as federal leadership retreats. The engineering reality is that deep decarbonization requires a diverse toolkit-solar, wind, storage, DAC, BECCS, transmission upgrades-and the political reality is that, for now, much of that toolkit will be wielded at the state level.
