By Siena Cicarelli and Erin Sikorsky

In his first speech as Foreign Secretary on 17 September, David Lammy provided a comprehensive and compelling case for the importance of climate change as a national security issue for the United Kingdom. Not only did he identify continued fossil fuel use as an existential risk, but he also argued forcefully that investment in climate finance in the Global South is in the UK’s best interests. He said: 

“Demands for action from the world’s most vulnerable and the requirements for delivering security for British citizens are fundamentally aligned.  And this is because this crisis is not some discrete policy area divorced from geopolitics and insecurity. The threat may not feel as urgent as a terrorist or an imperialist autocrat. But it is more fundamental. It is systemic. It’s pervasive. And accelerating towards us at pace.”

Such a viewpoint represents a critical inflection point in the UK’s climate security trajectory—and a potential return to its early leadership on the issue. The past decade-plus of Conservative government yielded limited progress on the UK’s initially bold climate ambitions, with London’s High Court ruling in May 2024 that the government’s climate action plan was unlawful, and widespread public criticism of plans for additional oil field drilling, and delayed regulations limiting the sale of petrol and diesel cars. 

Luckily, the UK’s security and defense actors have quietly established themselves as global leaders in climate security strategic assessments, including the 2021 Ministry of Defense (MoD) Climate Change and Sustainability Strategic Approach. Over the last decade, these actors have recognized that climate change is a core risk to the UK’s energy security, food security, foreign policy interests, and economic growth. Furthermore, like Secretary Lammy, they acknowledge this issue cannot be addressed in silos or solely within national borders, making investments in climate security at home and abroad more important than ever. 

With the Foreign Secretary’s comments as a foundation, the new Labour government has an opportunity to elevate and reinvigorate the UK’s existing climate security approach—starting with the Strategic Defence Review (SDR) this fall. While climate security has featured in previous overarching policy documents like the Integrated Defence Review and in internal assessments, this comprehensive review marks a key opportunity to publicly redefine climate security in the United Kingdom. 

Over the next few months, the SDR will take stock of the top challenges for the country, examining the overall readiness of MoD’s infrastructure and personnel. Mainstreaming climate considerations throughout this review—from assessing whether energy supply chains are future-fit to assessing gaps in military training and education—would be an essential first step in institutionalizing climate security throughout the government. 

Beyond the SDR, as CCS Director Erin Sikorsky argued in testimony before the UK Parliament in May 2024, the nation must expand its current approach to build a climate-strong national security workforce. This will require both a recognition that climate change is a cross-cutting priority that affects equities outside of the Foreign, Commonwealth, and Development Office (FCDO), Home Office and MoD, as well as a willingness to invest in the skillsets needed to translate climate science and data into sound policy. This mainstreaming must also be underpinned by a cross-government architecture that is capable of bridging interagency silos and more effectively integrating the perspectives of climate scientists.  

The government will undoubtedly face significant challenges in implementing its agenda at home and abroad. Beyond domestic pushback on green transition measures like wind farms and fossil fuel tariffs, Labour faces a 20+ billion pound budget deficit and an increasingly complex geopolitical environment. But this resource-constrained environment only further underscores the need for mainstreaming, silo-busting, and more effective climate finance. 

Leveraging co-benefits wherever possible—such as investments in climate-smart agriculture that also build local resilience or efforts to transition away from fossil fuels that also reinvigorate struggling economies—are key. Furthermore, building climate considerations into existing FCDO and MOD programming will help maximize the government’s impact. 

As Secretary Lammy said, “ultimately there will be no global stability, without climate stability.” As climate impacts accelerate, the UK government must now adjust its posture and resources accordingly.