The global energy transition is seen as an important response to the growing security challenge of climate change. Going low-carbon will alter the way we produce, what we trade, and with whom we exchange goods and services. It will also impact the security landscape: the pathways toward carbon neutrality will unleash political tensions between those with more and those with less ambition and lead to heated debate around how to get to the final destination. As the EU positions itself as a global climate leader through its European Green Deal, it needs to prepare for new types of external policy challenges and must retool its approach to climate security to meet those challenges. This will involve not just the mainstreaming of climate security into standard instruments of EU foreign policy but also questioning how the EU’s determination to be a global decarbonization leader will impact ecological security more broadly.