BEIJING - Footage of a snow leopard wandering down a street in a county in Northwest China's Qinghai province captured by an onlooker went viral last month, with netizens calling it a sign of environment recovery.

The endangered animal, which lives on the Qinghai-Tibet and Pamir plateaus at altitudes over 3,500 meters, has rarely been spotted in the wild since 1980s due to loss of habitat and poaching.

As China shifts away from the obsolete GDP-obsessed evaluation system and prioritizes environmental protection, the whole country is reaping the benefits.

Yet, as China prepares to include an environment clause in its five year plan for the first time, experts warn that there are more challenges ahead.

Beijing's environment authority on Monday said that the capital's PM2.5 density, an indicator of air pollution, has dropped by over 20 percent during the first 10 months of the year from the same period last year.

During the first nine months, there were 31 more good air quality days in Beijing than the same period last year, and the number of days with heavy pollution dropped by 16; the result of air pollution control measures and favorable weather conditions.

The city has removed some 280,000 old cars from its roads, shut down 315 polluting companies, and increased green areas by 6,000 hectares during the first 10 months.

Nationwide coordination has also be carried out.

"Provinces have boundaries but pollution has not," said Wu Jianjun, an official from the environmental protection bureau of Tangshan city, Hebei province. "The best lessons we learned over the years is that we must work together to tackle pollution."

In January, the new Environmental Protection Law came into effect, with tougher-than-ever measures against polluters, and a clause allowing NGOs to initiate environmental lawsuits.

According to Chen Jining, minister of the Ministry of Environmental Protection, during the past five years, discharge of pollutants has decreased significantly and a comprehensive pollution control plan covering air, water and soil has been carried out.

It is estimated that China had invested more than 5 trillion yuan (about $789 billion) in environmental protection during its last five-year plan period, according to Chen.

However, according to an Environmental Performance Index (EPI) released by Yale University, China's GDP rose from fourth in the world in 2004 to second, while its EPI dropped from 65 out of 100 in 2006 to 43 in 2014.

Experts believe discharge of pollutants in China will continue to rise, following the developing phase of the country's heavy industry, and reach a peak in 2020. Therefore, more environmental problems are expected over the next five years.

Wu Shunze, vice president of the Chinese Academy for Environmental Planning, said the government will likely have to deal with difficulties resulting from industrial restructuring, an intensive outbreak of environmental problems, increased public interest in the environment and a growing demand to balance domestic and international environment issues.

Many suggest the environment protection industry will inject more vitality into the economy as well as develop green growth points, which could also help reduce losses caused by pollution.

The return of the snow leopard is an encouraging sign that we have contained the degradation of the local environment, said Qi Ming, chief engineer of the environmental protection bureau of Qinghai province.

However, the ecological restoration project of the three-river source region will take at least 30 to 50 years, Qi said.

"Now the arduousness and time consuming nature of the project begins to show and we have to be prepared."