In the last couple of decades, the knowledge and awareness of increasing risks to human health posed by climate change have grown. According to the first Lancet commission on health and climate change (2009), climate change is the largest global health threat in the 21st century. Succeeding findings demonstrated that although human health has improved dramatically between 1950 and 2010, this gain was accompanied by unprecedented environmental degradation that now threatens both human health and life-support systems.
Climate change impacts human health in many direct and indirect ways. The disruption of eco-services has a global impact and influence all populations. It causes frequent and extreme weather events, such as floods, storms, and droughts, entails an increased risk of deaths and injuries, mental health disorders, infectious diseases, and large-scale displacement of people. Increased concentrations of ground-level ozone could aggravate respiratory illnesses and increase cardiopulmonary mortality. There are shifts in the incidence and distribution of some vector-borne diseases like dengue, particularly at the edges of the distributions and growing risk for emerging infections among livestock and humans. Accelerating urbanization also poses health risks related to climate change, including heat island effect and poor air quality. In the majority of the world’s big cities, air quality does not meet WHO recommendations. Unplanned, rapid urbanization and the increasing number of motorized vehicles in many low- and middle-income country cities contribute to the negative trend.
There is a growing recognition and evidence that many of the suggested and required actions to meet the Paris Agreement’s 2°C climate target (mitigation) would have a positive health impact. This includes efforts in key sectors such as agriculture, energy, transportation, and waste management. However, with prevailing emission trends and overexploitation of natural resources, the agreed temperature targets are not expected to be met, and the last half-century's progress on health in the world is endangered.
In September 2019 two important high-level meetings will co-inside at the UN; the Secretary-General’s Climate Summit and the High Level Meeting on Universal Health Coverage (UHC). There is an opportunity to connect those two agenda through a stronger focus on enabling people to make healthier choices for themselves, their families and for the planet. UHC needs to be seen within the context of megatrends as climate change and environmental threats, shape global health. Pathways for health effects are complex with many factors interacting, and climate change will intersect with different significant trajectories, e.g., in urbanization, equity, aging population, and social behavioural change. Understanding the contribution of both mitigation and adaptation action to sustainable development and improved health outcomes, is critical for designing policies and actions that successfully realize co-benefits and achieving UHC. For example, one third of greenhouse gas emissions and 70% of use of fresh water are linked to our food production. By changing food production and consumption as well as food waste we could not only scientifically contribute to the climate targets but also improve nutrition and avoid 11 million premature deaths each year (appr.20% of total global mortality).
To keep the global average temperature rise well below 2°C and to achieve SDG3 as well as the UHC target there is a need for transformation across all sectors of society, including energy, transport, spatial infrastructure, food and agriculture, and building resilient health systems. These transformations may in turn help tackle the root causes of the world's most significant public health challenges.