Climate change has already been causing serious problems in Japan, affecting everything from agriculture, fisheries and water supply to ecosystems, the government said Wednesday.

In a report compiled by the Environment Ministry's study panel on global warming, possible effects are spelled out through 2020 to 2030.

Climate change is taking a toll on the quality of rice and other produce, while causing irregular weather conditions such as increased torrential rain, the report says. It calls for urgent action to prevent the situation from worsening.

"Effects of global warming are feared to have dealt a devastating blow to Japan," the report says in calling for potentially affected regions to prioritize measures in accordance with the local situation.

It says food-quality problems are believed to have occurred in all 47 prefectures due to higher temperatures.

The study panel cited a need to develop crop varieties resistant to disease and high temperatures.

It is also proposing new cultivation strategies, in which rice and fruit are not exposed to high temperatures while they are grown. Fruit, for example, can avoid high temperatures if orchards are cultivated in cooler locations, the report says.

Fish harvesting businesses have been affected by an increase in sea temperatures that has changed migratory routes, the report says.

In the fish breeding business, the timing and location for releasing farm-raised fish should be changed, the report says.

It says efforts must be made to protect endangered species, including refraining from building artificial structures in rivers that can block fish from escaping warmer waters.

On disaster prevention, it calls for building up riverbanks and improving drainage while curbing construction of houses and buildings in areas most likely to be affected by heavy rain and higher tides.