China's carbon emissions saw the largest drop in years as the nation furthers structural readjustment to improve growth quality, Chinese Premier Li Keqiang said on Wednesday.

The country's carbon intensity was cut by about 5 percent in the first half of the year, the largest drop in many years, the premier said in an address to the Summer Davos forum, currently being held in Tianjin.

Meanwhile, energy consumption per unit of gross domestic product (GDP) dropped 4.2 percent year-on-year during the period, the premier said.

"In the first half of the year, the growth of investment and production of industries with high energy consumption and emissions noticeably slowed down," Li said.

Through reform and innovation, the country has moved to reduce overcapacity and foster new growth areas. China has been promoting business mergers and reorganization while redoubling efforts to conserve energy and cut emissions, Li said.

China has consumed less coal, electricity and oil and eased pressures on transport capacity in achieving the same GDP growth, he said.

Tackling climate change is not only China's binding international obligation as a major responsible country, but also a pressing need for the country's own development.

"We have declared war on pollution and earnestly fulfilled international responsibilities," he said.

The country is studying action targets on greenhouse gas emissions control, including the peak of carbon dioxide emissions, carbon emissions intensity reduction and increases in the share of non-fossil energy by 2030 and beyond.

Meanwhile, China will also work with other countries to tackle global climate change, he said.

The Chinese government has pledged a 40 to 45 percent reduction of carbon dioxide intensity by 2020 from the levels in 2005 and is committed to making every effort to achieve the target.

Carbon dioxide emissions per unit of GDP had dropped 28.56 percent by 2013 from the levels of 2005, or a reduction of 2.5 billion tons of carbon dioxide emissions, according to the National Development and Reform Commission, the country's key economic planning body.