Climate activist Greta Thunberg is among 600 young people suing the Swedish state over its alleged environmental “inaction”.
The lawsuit, which has been in the works for two years, is the biggest of its kind to date, activists said.
It urges a court to require that the government shoulder its “fair share” of the burden of keeping greenhouse gas emissions consistent with the Paris Agreement goal to limit global warming to 1.5 degrees above pre-industrial levels.
“If we win, there will be a verdict that says the Swedish state is required to do its share of the global measures needed for the world to meet the 1.5-degree target”, Ida Edling, a climate activist behind the lawsuit, Aurora, told AFP.
“There has never been such a large-scale case in the Swedish legal system.”
In 2017, Sweden adopted a climate law that requires the government to work to reduce emissions of planet-warming gases to net zero by 2045.
Cutting greenhouse gas emissions is key to meeting the 2015 Paris Agreement target.
However, Russia’s invasion of Ukraine in February led to a scramble for energy that has set back efforts and this year’s UN-sponsored climate talks in Egypt failed to step up ambitions.
Sweden’s cabinet, which assumed power following elections in September, has announced plans to scrap the country’s environment ministry altogether.
Its 2023 budget has been criticised for including measures that are set to increase emissions from the transport sector.
Ms Thunberg, a 19-year-old Swede, said she believed climate laws should be tightened.
“We don’t have laws that provide long-term protection from the consequences of climate and environmental crises, but we need to use the methods at our disposal and do everything we can,” she told Swedish daily Dagens Nyheter.
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Moa Widmark, 19, a student who took part in a demonstration outside a Stockholm district court on Friday before the lawsuit was filed, said: “The climate crisis is worrying and scary. We're headed for a catastrophe.”
Although the lawsuit is a first in the Swedish courts, six Portuguese youths have taken Sweden and 32 other countries to the European Court of Human Rights, accusing them of failing to adequately address the climate crisis.
A growing number of organisations and citizens have turned to the courts in recent years to criticise what they claim is government inaction on climate.
In December 2019, the Dutch Supreme Court ordered the government to slash greenhouse gases by at least 25 per cent by 2020, in a landmark case brought by an environmental group.
In a similar case in France, more than two million citizens took the state to court for failing to act against climate change.
In a report published earlier this week, the Swedish Meteorological and Hydrological Institute said the average temperature in Sweden had risen by nearly two degrees Celsius (35.6 degrees Fahrenheit) since the late 1800s, twice as fast as the global average.
Snow cover now lasts two weeks less, while rain has increased.