Research

Tropospheric ozone & climate

MIT · 2022–present

Schematic of drivers of tropospheric ozone: surface anthropogenic, aircraft, and biomass burning emissions of NOx, CO and VOCs, ozone-depleting substances in the stratosphere, and internal climate variability

Detection & attributionTropospheric ozone trends

Detecting and attributing tropospheric ozone trends

Tropospheric ozone is an air pollutant harmful to human health and crops near the surface and a greenhouse gas aloft, and it has risen substantially since preindustrial times. We separate human-caused ozone trends from internal climate variability, detect a human fingerprint in satellite records of upper tropospheric ozone, and attribute recent increases to precursor emissions.

Illustration of ozone molecules spread through the troposphere absorbing heat radiated from Earth's surface

Radiative forcingClimate response

Climate impacts of tropospheric ozone

Tropospheric ozone is a potent greenhouse gas, and the emissions that produce it also change methane's lifetime. We quantify ozone and methane radiative forcing from precursor emissions and from air pollution controls, and study how the climate system responds to tropospheric ozone changes.

Card illustrations: ChatGPT-generated.

PM_2.5 air quality & health

Peking University · 2016–2022

Illustration of a hazy city: policies change emissions, emissions and weather conditions shape PM2.5 air quality including black carbon, which affects exposure and health

Air quality & healthBlack carbon · PM_2.5

Emissions, air quality, and human health

Fine particulate matter (PM_2.5) is among the leading environmental risks to human health, and black carbon is a key component that also warms the climate. We examined the health benefits of cleaner household energy and air-quality policies, and distinguished the effects of emissions and meteorology on black carbon.