Appendix: Methodology and assumptions Several major reports – including ones from The White House, World Bank and Lancet Countdown – make similar arguments underscoring and collectively reinforcing the significant climate change-driven health risks highlighted in this report. For instance, the Lancet Countdown estimates that heat exposure, intensified by climate change, has resulted in $863 billion in global income losses over the past eight years. It also predicts increasing heat- related labour losses and deaths. Furthermore, the Lancet Countdown projects that over 500 million additional people will face food insecurity due to climate-driven heatwaves and droughts, along with a more than 30% increase in dengue transmission potential by mid-century. It also predicts an expansion of malaria transmission areas and a longer transmission season. These figures support the projections around climate-linked health and economic impacts of heat-related disease, stunting, malaria and dengue that are used as the basis of this report – including $7.1 trillion in economic losses from heat-related diseases and 900 million DALYs from stunting by 2050. The World Health Organization (WHO) forecasts 250,000 additional annual deaths by the 2030s, which is directionally in line with assumptions used in the calculations described below. The World Bank projects 21 million climate-related deaths by 2050, compared to the figure of 14.5 million found in this report and the World Economic Forum’s January 2024 report, Quantifying the Impact of Climate Change on Human Health. The difference arises mainly from the exclusion of diarrhoea-related deaths, as they are influenced by complex factors beyond climate change, such as poor sanitation, lack of clean water, malnutrition and socioeconomic conditions. Together, these reports reinforce the focus on key disease areas in the current report and the scale of the impending crisis. The report’s methodology follows a three-step approach as follows (see Figure A1): 1. Assess the burden of diseases most aggravated by climate change. 2. Prioritize unmet needs for those diseases. 3. Develop a climate and health investment case for the priority unmet needs. The assessment of health and economic impact leverages the climate-related health impact matrix described initially in the Forum’s Quantifying the Impact of Climate Change on Human Health report. It is based on an overview of climate databases and meteorological forecasts, as well as research insights from more than 50 scientific and medical studies. The health matrix establishes connections between climate events and heightened disease prevalence and its health and economic impacts. In this follow-up report, the analysis went a step further to assess what could be done to reduce these impacts. The starting point was an analysis of the highest-affected disease areas and their related unmet medical needs that result in unfavourable health outcomes. The unmet medical needs and their priority were validated through consultations with 14 leading academic experts, researchers and clinicians from institutions such as the Swiss Tropical and Public Health Institute, the Planetary Health Alliance, Yale University, the New York Academy of Medicine and the US Department of Health and Human Services. This ensured alignment with real-world challenges across geographies. The most pressing unmet medical needs were then prioritized to identify innovation opportunities for the life sciences sector and to evaluate their potential to reduce the health and economic impacts of climate change. This analysis informed the development of investment cases for each unmet need, by comparing required investments with the monetary and human value of expected health and economic benefits. Overview Healthcare in a Changing Climate: Investing in Resilient Solutions 32

Healthcare in a Changing Climate 2025