China’s bid to decarbonize may have hidden costs

ITHACA, N.Y. – Environmentalists rejoiced when China announced its commitment to reach carbon neutrality by 2060, but the decarbonization of China – which emits 27% of global carbon dioxide and a third of the world’s greenhouse gases – may come with hidden costs and hard environmental choices, according to new research. 

In a paper published in Communications Earth & Environment, Stefano Galelli, associate professor at Cornell University’s School of Civil and Environmental Engineering, and colleagues attempt to quantify how decarbonizing the China Southern Power Grid, which provides electricity to more than 300 million people, will negatively impact river basins, most of which run from China into downstream countries, and will reduce the amount of cropland in China. 

“If we think of any major technological change, they always have costs and unintended consequences,” Galelli said. “The sooner we realize and address them, the more sustainable and equitable the energy transition will be. We have to do it right.” 

Decarbonizing the grid by 2060 may be technically feasible, but would require building several dams for hydropower production (roughly 32 GW) and converting about 40,000 square kilometers of cropland to support growth in solar and wind, Galelli said. Most of the dams would be placed on transboundary rivers, meaning those shared by two or more countries, resulting in potential negative ecological impacts in both China and downstream countries. 

Two major transboundary river basins that will be impacted are the Salween and Mekong, both major biodiversity hotspots, Galelli said. The Salween is shared by China (upstream) and Myanmar; the Mekong by China (upstream), Myanmar, Thailand, Laos, Cambodia and Vietnam – thus the impacts of additional damming are shared. 

Dams block the transport of sediments and nutrients from the upper reaches to the river mouth, and this reduces the productivity of ecosystems and fisheries. Blocking the transport of sediments also affects river deltas: If sediments do not reach the delta, saline intrusion becomes a bigger problem. Dams can also impact migratory fish species. 

Decarbonization would also lead to ecological and sociological trade-offs in terms of land use, Galelli said. 

“Excluding sites that are protected – cities and national parks, for instance – what you’re left with is cropland on which to build solar and wind power,” he noted. 

Coal power plants have historically been the dominant source of electricity for the China Southern Power Grid – but building enough wind and solar arrays to replace the electricity supply guaranteed by conventional coal plants will take up a lot of space, Galelli said. 

And that space required for the construction of solar and wind plants may not be equitably divvied up: Their research shows that 43% of the total land requirements would likely be focused on the Guangxi province, where crop and grassland constitute the vast majority of land. This might be a heavy burden for the province and result in significant ecological, social and financial costs to local communities. 

As we make strides toward decarbonizing, he said, China is at the forefront. 

“Doing it in strategic ways is very important. We have to start with ones that are less impactful,” Galelli said. “We can make decisions that balance decarbonization efforts with the protection of local communities, water and land resources.” 

For additional information, see this Cornell Chronicle story.