Christiana Figueres, the former UN climate chief, has issued a stark warning about the world's reliance on fossil fuels, stating that countries are being "held hostage" by their addiction. Speaking in an exclusive interview, Figueres described the health impacts of climate change as the "mother of all injustices". Figueres will soon co-chair a new Lancet Commission which will examine the profound effects of sea-level rise on health, wellbeing and inequality. Climate change is already having a devastating impact on global health, with rising temperatures and more frequent extreme weather events putting millions of people at risk. In her role as UN climate chief from 2010 to 2016, Figueres played a key part in brokering the Paris Agreement, a landmark deal that aimed to limit global warming to well below 2°C and pursue efforts to limit it to 1.5°C. However, despite this progress, the world remains heavily reliant on fossil fuels, with many countries continuing to invest in new oil, gas and coal projects. Figueres believes that this reliance is a major obstacle to achieving the goals of the Paris Agreement and says that it is "inexcusable" that governments are still allowing new fossil fuel projects to be developed. "We are being held hostage by our addiction to fossil fuels," she warns. "We know the impacts of climate change are real, they are devastating, and they are disproportionately affecting the most vulnerable members of our communities." The Lancet Commission, which Figueres will co-chair, will examine the ways in which sea-level rise is reshaping health, wellbeing and inequality. The report is expected to highlight the growing threat of climate change to global health and will call for urgent action to reduce greenhouse gas emissions and transition to renewable energy sources. Figueres says that the commission's findings will be "a wake-up call" for governments and will highlight the need for a rapid transition to clean energy. "We have to stop investing in fossil fuels and start investing in renewable energy," she says. "We have to act now to avoid the worst impacts of climate change and to create a more just and equitable world." The Lancet Commission's report is expected to be published later this year and will provide a stark reminder of the need for urgent action to address the climate crisis. In the meantime, Figueres' warning about the "mother of all injustices" will serve as a stark reminder of the devastating impact of climate change on global health.