LOS ANGELES (AFP) - California aims to cut greenhouse gas emissions 40 per cent by 2030, the most ambitious target in North America and equalling that set by the European Union, its governor said Wednesday.

Governor Jerry Brown issued an executive order pledging to seek the cut - compared to 1990 levels - in the populous western US state, which is reeling from a historic four-year drought.

"With this order, California sets a very high bar for itself and other states and nations, but it's one that must be reached - for this generation and generations to come," Brown said.

California is on track to meet the current target - set in 2006 - of cutting emissions to 1990 levels by 2020, he said.

The new target will help reach the "ultimate goal" of reducing emissions 80 per cent by 2050, he added.

The announcement was welcomed by the United Nations and others, cited in a statement by the California governor's office.

"California and Governor Brown have clearly understood, internalized and articulated the science of climate change," said Christiana Figueres, executive secretary of the UN Framework Convention on Climate Change.

"Four consecutive years of exceptional drought has brought home the harsh reality of rising global temperatures to the communities and businesses of California," added World Bank chief Jim Yong Kim.

The 28-nation European Union set the 40 per cent by 2030 target last October, ahead of a UN climate change conference scheduled to take place in Paris later this year.

The United States, which accounts for 12 per cent of global emissions, announced its intention to reduce them by 26-28 per cent by 2025 compared with its 2005 level.