In 2009, scientists argued that climate change was the Ôbiggest global health threat of the 21st centuryÕ, and 6_years later Ôthe greatest global health opportunity of the 21st centuryÕ. While a minority of populations may experience health benefits (mostly due to a reduction in diseases related to cold weather), the global burden of disease and premature death is expected to increase progressively. For instance, one study showed that heat-related deaths would be expected to rise by around 257% by the 2050s from a current annual baseline of approximately 2000 deaths. Much of the policy development on climate change comes from the negotiations between the 195 parties to the United Nations Framework Convention on Climate Change (UNFCCC), working towards a common long-term vision of limiting global warming.The 21th Conference of the Parties (COP21) in Paris in December 2015 was one milestone in the fight against climate change, as all countries agreed to take action by curbing greenhouse gas emissions (GHGE) and keep global warming well below 2¡C. The agreement also included a regular review of national commitments every 5_years to check progress. Moreover, it represented an important step to protect and promote health in the face of climate change: for the first time Ôthe right to healthÕ was mentioned in the global agreement on climate change. The WHO referred to the COP21 as Ôa historic win for human healthÕ, and this climate treaty might actually become a public health treaty as countries take action to develop adaptation plans that will protect human health from the worst impacts of climate change. This opinion article seeks to present the role of health concerns in the scientific debates on climate change, but also in actual climate policies and international negotiations.