An international study has found that China is on track to meet its carbon emissions goals up to one decade early.

China, one of the first countries to sign the Paris Agreement on climate change, has pledged to halt the rise in carbon dioxide emissions by around 2030.

Researchers from China's Nanjing University, Tsinghua University, Chinese Academy of Sciences and Harvard University in the United States examined carbon dioxide emissions from 50 Chinese cities from 2000 to 2016 and found a close relationship between per capita emissions and per capita gross domestic product.

Those 50 cities account for about 35 percent of China's total carbon emissions and 51 percent of the country's GDP.

According to Wang Haikun with Nanjing University, the leading author of the research, although diverse trajectories of carbon dioxide emissions are seen across the cities, the relationship between emissions and GDP follows the Environmental Kuznets Curve.

The curve means that as economic development growth occurs, the environment will worsen until a certain point where the country reaches a specific average income. Then money is invested back into the environment, and the ecosystem is restored.

The research study found that carbon emissions peak for most Chinese cities when GDP reaches about 150,000 yuan ($21,000) per person.

The researchers then used a computer model to simulate the peak of carbon emissions based on China's historical emissions and the data on future population size and economic development level from the World Bank.

According to the study published in the latest online monthly journal Nature Sustainability, carbon emissions in China should peak between 2021 and 2025, about five to 10 years ahead of the Paris target.

The researchers said that cities are the front line for global climate change action, and there is clear evidence that progress has been made in the Chinese cities.

The progress reflects China's great efforts in mitigating climate change, Wang said.

Among the National Determined Contribution that China proposes to achieve by 2030 as part of its Paris Agreement pledge, China has committed to reducing its carbon intensity 60 to 65 percent from 2005 levels by 2030, reaching its carbon emissions peak by 2030, increasing non-fossil fuel energy to 20 percent of its energy mix and expanding forested land.