Many governments are wary of providing transparency around their militaries' emissions, and campaigners can be hesitant to focus on the carbon footprint of conflicts, rather than more obviously humanitarian issues.
But Ukraine has helped to shift opinion this year, after pushing for more accountability for wartime environmental harm. Recent estimates put the CO2e cost of Russia's invasion of Ukraine at 175 million tonnes, and day to day military operations - not including conflicts - at a staggering 5.5% of global emissions.
Bertie spoke to Lindsey Cottrell, Environmental Policy Officer at the Conflict and Environment Observatory, about the military emissions gap in carbon accounting, and the campaign for UNFCCC rules to be changed to acknowledge it.
Further reading:
Click here to read our investigation into the UK biomass supply chain, or watch a clip from the BBC Newsnight documentary.