On 12 September 2025, Harvard University’s School of Engineering and Applied Sciences hosted a lunchtime seminar organized by Harvard SEAS, featuring Dr Denise Mauzerall, the WilliaSchool of Engineering and Applied Sciencesm S. Tod Professor of Environmental Engineering and International Affairs at Princeton University. In her hour-long presentation, Dr Mauzerall outlined her group’s interdisciplinary work on how a clean energy transition in China and India can yield co-benefits for air quality, public health, climate mitigation, and even food security.

Why Focus on China and India?

Dr Mauzerall opened by noting that China and India together account for the planet’s most severe air pollution hotspots, with annual fine particulate (PM₂.₅) levels far exceeding the World Health Organization’s 5 µg/m³ guideline. China’s CO₂ emissions have surged since the early 2000s to roughly 12 Gt in 2024—double U.S. levels—while India’s emissions are now growing at about 5 percent annually, mirroring China’s trajectory from a decade ago. Both countries are simultaneously grappling with the health impacts of toxic aerosols and the long-term threat of climate change. Dr Mauzerall argued that their choices in energy technology and policy will shape global efforts to decarbonize and clean the air.

China’s Emissions Trajectory and Renewable Leadership

Using historical data from 1960–2024, Dr Mauzerall showed how China’s per-capita CO₂ footprint rose above the EU by 2010 and now rivals Japan’s, even as India’s per-capita emissions remain low. Yet China has also become the world leader in renewable deployment—generating some 600 TWh of solar electricity in 2023 versus 250 TWh in the U.S.—and ranks first in installed wind capacity. In Europe, renewables already supply 40 percent of electricity in countries like Germany and Spain, but China’s scale means its choices will determine global clean-energy markets.

Mitigating Residential Emissions: From Coal Stoves to Heat Pumps

Dr Mauzerall described a landmark study modeling the winter 2010 air-quality impacts of replacing rural coal stoves around Beijing. Removing small coal-fired stoves in the broader Beijing–Tianjin–Hebei region cut modelled PM₂.₅ by up to 40 percent, prompting a nationwide stove-removal policy. Her team then evaluated stove replacements: simple electric resistance heaters made winter air cleaner but raised CO₂ emissions on China’s coal-dominated grid, while natural gas reduced particulate pollution yet risked carbon lock-in through persistent pipeline infrastructure. Air-source heat pumps emerged as the optimal solution: highly efficient, they deliver large PM₂.₅ reductions today and automatically lower CO₂ emissions as the grid decarbonizes.

Diversifying Urban District Heating to Avoid Carbon Lock-In

Urban district heating in northern Chinese cities traditionally channels waste heat from coal-fired power plants into residential networks. While efficient for heat recovery, this arrangement can perpetuate coal plant operation and undermine China’s pledge to peak CO₂ by 2030 and reach carbon neutrality by 2060. A scenario analysis comparing “high-coal,” “mid-coal,” and “low-coal” pathways showed only rapid decommissioning of coal-based combined-heat-and-power plants—and their replacement with alternative heat sources—would align emissions with a 2 °C global target. This research, reviewed by the China State Council, underscores the urgency of phasing out coal-based district heat.

Transport, Hydrogen, and Power Co-Benefits

In another study, Dr Mauzerall’s team assessed alternative-energy vehicle (AEV) deployment under varying grid decarbonization levels. They found that when renewables exceed 40 percent of generation, electrifying transport delivers simultaneous cuts in tailpipe PM₂.₅ and CO₂. Below that threshold, added coal-based electricity can actually worsen climate impacts. Investigating hydrogen, they showed that subsidizing grid-powered electrolytic hydrogen in a coal-heavy system would increase national CO₂. Only green hydrogen—produced from dedicated renewable capacity—avoids this pitfall, yet diverting renewables from the broader grid to isolated hydrogen production can raise overall emissions, emphasizing the need for holistic energy planning.

Untangling India’s Air Pollution Trends

Turning to India, Dr Mauzerall described how her group assembled and quality-controlled data from the Central Pollution Control Board’s expanding network of PM₂.₅ monitors—a task made possible by web-scraping and rigorous cleaning. India’s National Clean Air Programme aims for a 40 percent reduction in PM₂.₅ by 2026 relative to 2017. Using WRF-Chem model runs with both fixed emissions and year-by-year meteorology, her team found that improved dispersion conditions (rather than emission cuts alone) account for over half of Delhi’s air-quality gains since 2017.

Mapping Sectoral Contributions with WRF-Chem

To guide targeted interventions, the group performed source-tagging simulations in WRF-Chem for 2022 emissions. They updated inventories for residential cooking, power generation, industry, open burning and more, then quantified each sector’s share of annual and seasonal PM₂.₅ across the Indo-Gangetic Plain. Residential burning remains the single largest contributor in many cities, while power-sector emissions and agricultural stubble fires dominate in others. Background influx from neighboring countries also emerged as a significant factor.

Policy Implications and Next Steps

Dr Mauzerall concluded that integrated strategies—combining demand-side efficiency, clean energy supply, and cross-sector synergies—are essential to capture both air-quality and climate co-benefits. In China, policy must phase out coal-based district heat, subsidize efficient heating technologies, and align vehicle electrification with renewable growth. In India, robust monitoring, transparent data, and sector-specific controls can strengthen the Clean Air Programme. Her team is now coupling these WRF-Chem results to energy systems models to optimize power-sector investments for maximum health and climate returns.

By linking atmospheric science with policy-relevant analyses, Dr Mauzerall’s work offers a roadmap for emerging economies to pursue clean-energy transitions that deliver healthier air and a more stable climate.

---

The Harvard School of Engineering and Applied Sciences (SEAS) is a forward-looking hub where engineering, applied science, and design converge to solve society’s most pressing problems. By championing interdisciplinary research—from bioengineering and robotics to data science and climate technology—SEAS cultivates global partnerships and nurtures innovators who are equipped to advance healthcare, infrastructure, and sustainability for a rapidly changing world.

The Conf is a platform that reports on scholarly conferences, symposia, roundtables, book talks, and other academic events. It is managed by a group of students from leading American and European universities and is published by Alma Mater Europaea University, Location Vienna.