Japan's draft proposal for a carbon emission reduction target sparked calls for deeper cuts from experts as well as from within the ruling coalition, as the world's fifth-biggest carbon emitter struggles to reduce its dependence on fossil fuels.

The government last month presented a draft plan to aim for a 60% cut in greenhouse gas emissions by 2035 from 2013 levels, a commitment that would align with Japan's future energy mix currently under consideration and other energy policies.

As Japan is the world's second-largest importer of liquefied natural gas and a major consumer of Middle Eastern oil, its energy strategies are closely followed by oil, gas and coal producers.

The draft assumes a linear trajectory between Japan's existing 46% reduction target by 2030 and net zero by 2050, as the government emphasizes the importance of balancing economic growth and energy security with decarbonization efforts.

Climate activists have branded the proposed target as insufficient, saying that it falls short of a target set by the United Nations' main scientific body as necessary to limit global warming to 1.5 degrees Celsius above preindustrial levels.

According to the Intergovernmental Panel on Climate Change (IPCC), the world needs to cut its emissions from 2019 levels by 60% by 2035 to safeguard the 1.5 C goal, which translates to a 66% cut from 2013 levels for Japan.

A push for deeper cuts also comes from within Japan's ruling camp, as Komeito, the Liberal Democratic Party's junior coalition partner, calls for a 66% cut to align with the IPCC target, adding to pressure on the government.

"We believe that Japan should set a target based on a scientific approach, meaning that it should be equivalent to the target suggested by IPCC," said Masaaki Taniai, the lawmaker in charge of climate issues at Komeito.

Signatories of the Paris Agreement, a key global treaty on climate change, are required to update self-defined national climate pledges, called the nationally determined contribution (NDC), every five years. The next round of NDC updates are due in February 2025.

Some countries have announced stronger commitments, with Britain pledging an 81% reduction by 2035 from 1990 levels.

Japan hopes to finalize the target by the year-end after further discussions at a government panel, although some panel members have questioned the target-setting process as too hasty.

Separately this week, the industry ministry released a draft of its revised basic energy policy, aiming to roughly double the share of renewable energy in its electricity mix to up to 50% by fiscal year 2040.

Advocates for renewable energy have criticized the draft as lacking a roadmap for phasing out coal-fired power.