Thousands of people with colorful costumes and banners marched in central Lima on Wednesday to call for leaders to ensure a global shift to 100 percent clean energy by 2050.

Organizers estimated that about 15,000 people, including indigenous groups, environmentalists and students, joined Latin America's largest-ever climate march.

Only 35 years remain. I back clean energy, but doubt the feasibility of the timetable.

Is it possible for oil and natural gas companies to make the transition in three decades? Do they share the same awareness of climate change risks as negotiators and observers at the climate change conference?

Countries will submit their intended nationally determined contributions by the first quarter of 2015, according to the conference's agenda.

The three biggest players - China, the European Union and the United States - have already announced their targets. China pledged to increase the nonfossil fuel share of all energy to around 20 percent by 2030. The EU set a target of 27 percent by 2030.

The targets announced by the two economies are ambitious, but still indicate that it will be nearly impossible for the two to switch to zero emissions by 2050.

Some nations have moved faster. Denmark is an unparalleled pioneer in clean energy. It plans to reach 100 percent renewable energy in electricity and heating by 2035 and run its economy entirely on renewable power by 2050. Meanwhile, Finland plans to increase its renewable energy output to 38 percent by 2020, from 35 percent in 2012.

These targets for cutting greenhouse gas emissions may be opposed by some of those countries' citizens. But surely renewable energy will be the future to keep a global temperature rise within 2 C Scientists believe exceeding that threshold could trigger dangerous levels of global warming.

Jim Yong Kim, the president of the World Bank, suggested this week a more realistic emissions target: The global community should aim for zero net emissions by 2100. He called on countries to eliminate fossil fuel subsidies and create conditions that favor renewable energy.

But will the current five-year low in oil prices affect the future of renewable energies and lower investors' enthusiasm if the trend lingers?

The price-drop effect is indirect as oil affects mainly transportation, and most electricity is based on other sources of energy in the US, said Leonardo Martinez-Diaz, US deputy assistant secretary for energy and environment.

"If it lasts too long, it could be an issue," he said, "If it lasts for a long time, it will slow the development and consumption of electric cars and efficient cars."

But those in the clean energy industry think such a trend would actually favor the expansion of renewable energy.

"I think it's good for us because it's hurting the oil industry more than it's hurting us," said Jeremy Leggett, a British green-energy entrepreneur and funder of Solarcentry. Historic low prices exacerbate the volatility of the oil industry and encourage them to think about alternatives, he said.

Zhou Dadi, a Chinese energy expert and a member of the national expert team of China for Climate Change, said the positive actions of pioneering countries indicate the world is swiftly switching to the next generation of technologies.

Nations need to generate internal demand as opposed to facing outside pressure to cut greenhouse gas emissions, Zhou said.

China should set challenging goals for capping its energy and coal consumption, otherwise, the goals cannotwork as an efficient forcing mechanism for low-carbon transition, he added.

Contact the writer at lanlan@chinadaily.com.cn