Are humans to blame for worsening heat waves in China?

A new study suggests that even hotter events will follow unless greenhouse gas emissions are reduced.

By Emily Underwood

At least 40 people died during China’s record-breaking 2013 heat wave, when temperatures spiked to more than 105°F. The deadly event was just one of a string of intensifying heat waves that have hit the country over the past 50 years, and a new study finds that these events can be attributed in part to human-made climate change. Under business-as-usual carbon emissions, such extreme temperatures will become the new normal across roughly 50% of China’s landmass, the authors warn.

Sun et al. investigated heat waves across China from 1961 to 2015 using daily temperature and precipitation data from more than 2400 monitoring stations across the country. Then, the researchers used computer models to assess past and future changes in heat waves. In some simulations, they included only natural drivers of heat waves and drought, including climatic oscillations such as El Niño, and volcanic eruptions. In other simulations, they included known human contributions to heat waves, through warming caused by greenhouse gas emissions.

A new study examines whether humans may be to blame for heat waves in China The increasing probability of observed maximum heat wave under the Representative Concentration Pathway 4.5 scenario, one of four potential futures for greenhouse gas conditions described by the Intergovernmental Panel on Climate Change in its Fifth Assessment Report. Credit: Chiyuan Miao

The simulations that most closely resembled China’s real heat wave history were those that included the human influences, showing that natural causes alone were not enough to explain the country’s observed heat waves. In fact, including factors such as rising greenhouse gas emissions from burning fossil fuels led to more than a tenfold increase in the likelihood of the most intense heat waves occurring again in the future, the scientists found.

Under even a “moderate” future emissions scenario, the Intergovernmental Panel on Climate Change’s Representative Concentration Pathway 4.5, these once unusual heat waves will occur more frequently, last longer, reach higher temperatures, and occur in more regions of China, the authors expect.