Climate change added a month of risky heat for 1.5 billion people; 117 million affected in India
A climate research analysis found that more than 1.5 billion people worldwide experienced at least one month of "risky heat" between June and August 2026, with human-driven climate change identified as a significant contributing factor
India recorded 117 million people exposed to at least 30 risky heat days linked to climate change, the highest count among Asian nations, ahead of China (94 million) and Indonesia (83 million)
Europe recorded the most pronounced warming relative to its historical baseline, with about 89% of its population experiencing at least a month of risky heat; France and Vatican City recorded average temperatures 3.5°C above historical norms
Fifty-four countries recorded their hottest June-August period since 1970, and several African nations recorded prolonged runs of risky heat days
Climate Attribution Science and the Climate Shift Index
Climate attribution science quantifies how much human-caused climate change has increased the likelihood or intensity of a specific extreme weather event, using counterfactual climate modelling that compares observed conditions against a simulated world without industrial greenhouse gas emissions. The analysis behind this report used a Climate Shift Index-type methodology, defining "risky heat days" as days exceeding the 90th percentile of local temperatures recorded over a 1991-2020 historical baseline for the same calendar period — the threshold at which heat-related health risks are considered to begin rising.
Key Details
- Attribution methodology typically involves: defining the event and region, building a historical baseline from decades of observed data, running climate model simulations with and without anthropogenic emissions, and publishing rapid findings ahead of full peer review
- The concept is distinct from simple weather forecasting: attribution answers "how much did climate change contribute" rather than "what will happen"
- Comparable attribution work is conducted by initiatives such as World Weather Attribution, which pioneered rapid post-event attribution studies for heatwaves, floods, and droughts
- The IPCC's Sixth Assessment Report (AR6, 2021-2023) formally recognised increased confidence in attributing individual extreme heat events to human-induced warming
The 117-million figure for India and the 1.5-billion global figure are direct outputs of this attribution methodology — they represent people affected by heat days that were made more likely or more intense specifically because of climate change, not simply an unusually hot season.
India's Heat Wave Classification and Heat Action Plans
In India, heat waves are officially classified by the India Meteorological Department (IMD) based on departure from normal maximum temperature, with heat waves notified as a disaster-category event that state Heat Action Plans (HAPs) are designed to respond to. The National Disaster Management Authority (NDMA), together with IMD, has been coordinating with states to develop and strengthen these plans.
Key Details
- IMD heat wave criteria: where normal maximum temperature is ≤40°C, a heat wave is declared at a 5-6°C departure from normal (severe heat wave at ≥7°C); where normal maximum exceeds 40°C, a heat wave is declared at a 4-5°C departure (severe at ≥6°C); an absolute maximum of 45°C or more can independently trigger a heat wave declaration
- Criteria require at least two stations in a meteorological subdivision to report qualifying temperatures, or at least one station for two consecutive days
- NDMA and IMD have been working with over 20 states to prepare or update Heat Action Plans, which cover early warning systems, cooling shelters, work-hour adjustments, and health system preparedness
- Heat wave mortality and morbidity data in India are compiled through IMD and state health department reporting mechanisms
The 117 million Indians identified as exposed to climate-change-linked risky heat represent the population base that India's Heat Action Plans and IMD's heat wave warning system are meant to protect, underscoring the scale mismatch between exposure and current adaptation infrastructure.
UNFCCC, Loss and Damage, and the Global Stocktake
Extreme heat exposure of this scale feeds directly into the UNFCCC's loss and damage framework and the periodic Global Stocktake, which assess the growing gap between current adaptation efforts and the physical impacts of warming already "locked in" by cumulative historical emissions.
Key Details
- The Loss and Damage Fund was operationalised following COP27 (2022) and formally launched at COP28 (2023), intended to support vulnerable countries facing climate impacts beyond adaptive capacity
- The first Global Stocktake, concluded at COP28, found the world off track for the Paris Agreement's 1.5°C and well-below-2°C goals
- India's updated Nationally Determined Contribution (NDC, August 2022) targets a 45% reduction in emissions intensity of GDP by 2030 (from 2005 levels) and 50% cumulative electric power installed capacity from non-fossil sources by 2030
- The principle of Common but Differentiated Responsibilities and Respective Capabilities (CBDR-RC), under UNFCCC Article 3, underpins how adaptation finance obligations are apportioned between developed and developing countries
Large-scale heat exposure events of the kind reported for June-August 2026 are precisely the category of climate impact that the Loss and Damage Fund and Global Stocktake process are designed to track and address at the multilateral level.
- Over 1.5 billion people globally exposed to at least one month of climate-change-linked risky heat, June-August 2026
- India: 117 million people affected — highest in Asia, ahead of China (94 million) and Indonesia (83 million)
- Asia overall: approximately 2.8 billion people (58% of the continent's population) experienced 30+ risky heat days
- Europe: approximately 89% of the population experienced at least a month of risky heat; France and Vatican City averaged 3.5°C above historical norms
- 54 countries recorded their hottest June-August period since 1970
- "Risky heat day" defined as exceeding the 90th percentile of local temperatures over the 1991-2020 baseline for that calendar period
- India's NDC target: 45% emissions-intensity reduction by 2030 (vs 2005 levels); 50% non-fossil power capacity by 2030