SEOUL, April 23 (Reuters) - One of South Korea's highest courts began on Tuesday a public hearing into a case filed by two dozen young environmental activists against the government, claiming that it had failed to protect them by not addressing climate change.

The hearing at the Constitutional Court is the first climate-related litigation first in Asia, the plaintiffs said, and includes four petitions from children and infants dating back to 2020, including one by a foetus at the time who was nicknamed Woodpecker.

It also comes weeks after Europe's top human rights court ruled that the Swiss government had violated the human rights of its citizens by failing to do enough to combat climate change, and as courts in Australia, Brazil and Peru also consider human rights-based climate cases.

"South Korea's current climate plans are not sufficient to keep temperature increase within the 1.5 degrees Celsius, thus violating the state's obligation to protect fundamental rights," the plaintiffs said in a media statement.

Scientists say a global temperature rise beyond 1.5C, or 2.7 degrees Fahrenheit, above the preindustrial average will trigger catastrophic and irreversible impacts, from melting ice sheets to the collapse of ocean currents.

Burning of fossil fuels, and the carbon this emits, has been linked to rising temperatures, and South Korea's economy relies heavily on such fuels for growth. It has sought to reach carbon neutrality by 2050.

Lawyers for the government told the court that the authorities were doing everything possible to reduce carbon emissions and not violate basic rights of its people.

The lawyers also argued that the government did not discriminate against youth, and that there could be adjustments for annual carbon reduction goals.

Several activists, however, said the government's response was unsatisfactory.

Dozens of youth, including the now one-year-old Woodpecker, gathered outside the Constitutional Court, to criticise what they said was the government's inaction on climate change.

"Carbon emission reduction keeps getting pushed back as if it is a homework that can be done later. But that burden will what our children have to bear eventually," said Woodpecker's mother, Lee Donghyun.

The mother of an eight-year-old plaintiff said her children lived in constant fear.

"Because there’s a mountain behind our house, the kids say our house can get hit by a landslide. And who knows? That can happen," said her mother, Namkung Sujin.

Last year, South Korea revised down its 2030 targets for reducing greenhouse gas emissions in the industrial sector but maintained its national goal of cutting emissions by 40% of 2018 levels in what it called a reasonable adjustment. (Reporting by Ju-min Park and Minwoo Park; Editing by Josh Smith and Miral Fahmy)