Following the earthquake and tsunami in March 2011, Japan's reactors have all been been powered down for safety tests, with the last operational reactor going off line May 5, NewScientist.com reported Thursday.
As a result, Japan has had to fall back on fossil fuels, and has used 40 per cent more coal, oil and gas in the first four months of 2012 than in the same period in 2011.
The resulting increase in the country's greenhouse gas emissions has led to the scrapping of a plan to cut emissions to 25 percent below 1990 levels by 2020, officials said.
Japan's environment ministry Central Environment Council said without nuclear power emissions will only drop by between 2 and 11 per cent of 1990 levels by 2020.
Proposals to restart the country's reactors have met with public protests.
Deputy Prime Minister Katsuya Okada said government is now considering setting new emissions targets.