In London, climate diplomacy did not wait for Washington.
California Governor Gavin Newsom signed a memorandum of understanding with UK Energy Secretary Ed Miliband deepening cooperation on climate and sustainable development, formalizing an alliance that positions California as a subnational actor in global climate governance. The visit concluded with UK clean-tech firm Octopus Energy committing nearly $1 billion to California-based clean energy, carbon removal, and nature-based projects.
Federal posture may narrow. State alliances expand.
A parallel channel of diplomacy
The memorandum builds on longstanding ties between California and the United Kingdom, reinforcing collaboration on clean energy innovation, climate resilience, and sustainable development. While formal treaty authority rests with the federal government, subnational governments have increasingly constructed their own cooperative frameworks.
Authority is layered.
At a moment when U.S. federal climate engagement has retrenched, California is widening its international network. The partnership underscores how states can pursue Paris-aligned goals through domestic policy coordination and cross-border agreements, even absent federal participation.
The perimeter shifts.
Capital follows policy
The diplomatic gesture was paired with capital commitment. Octopus Energy announced nearly $1 billion in investment targeting California companies and projects focused on clean technologies and nature-based solutions, signaling investor confidence in the state’s regulatory trajectory.
Policy clarity attracts capital.
Octopus Energy Generation CEO Zoisa North-Bond said California’s supportive policy environment and entrepreneurial ecosystem make it a natural destination for long-term investment partnerships. The company’s expansion illustrates how subnational policy signals can anchor international capital flows.
This is not symbolic.
California officials argue that statutory clean energy targets, market-based programs, and regulatory continuity provide the confidence required for long-term infrastructure and technology deployment.
Building a global state network
The UK agreement adds to an expanding portfolio of subnational partnerships spanning Chile, Colombia, Nigeria, Brazil, Australia, Denmark, China, and others. These agreements address methane reduction, wildfire response, carbon pricing, clean transportation, biodiversity protection, and grid modernization.
The network is dense.
California also co-chairs the U.S. Climate Alliance, representing 24 governors and roughly 60 percent of the U.S. economy, and plays a leadership role in international coalitions such as the Under2 Coalition and the Beyond Oil and Gas Alliance.
Subnational coordination is no longer peripheral.
Filling a leadership void
The broader message is strategic. While the Paris Agreement requires federal participation to formally bind the United States, California has positioned itself as a durable climate actor regardless of federal shifts. Since 2000, the state reports greenhouse gas emissions down 21 percent even as GDP increased 81 percent, and clean electricity now powers roughly two-thirds of the state’s grid.
Recent moves by other states reinforce the trend. In New York, lawmakers have advanced legislation requiring large corporations to disclose greenhouse gas emissions, signaling that disclosure and oversight may increasingly be shaped at the state level as federal authority recalibrates.
The regulatory map is evolving
Battery storage capacity has surged under the Newsom administration, and additional grid resources continue to come online. Officials frame these metrics as evidence that emissions reduction and economic expansion can coexist.
The question is whether such subnational momentum can substitute for national alignment. If federal climate authority continues to contract, international partners may increasingly look to state capitals as anchors of continuity. If federal engagement returns, these parallel alliances could become reinforcing rather than compensatory.
In London, the scaffolding of climate cooperation did not hinge on a treaty. It was constructed through memoranda, capital commitments, and policy signals. Whether that architecture endures without federal reinforcement will define the next phase of American climate diplomacy.
The full text of the MOU signed is available here.
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