An overwhelming majority of California residents support the state's mandate for reducing heat-trapping greenhouse gas emissions, so long as they do not bear the higher costs of cleaner energy themselves, a new public opinion poll shows.

Eighty percent of adults surveyed believe climate change poses a serious threat to California's economy and lifestyle, and 68 percent back a 2006 law for lowering statewide greenhouse gas emissions to 1990 levels by 2020.

But support for specific initiatives to reach the goal appeared to wane sharply in the face of higher energy costs, the Public Policy Institute of California found in a poll released late on Wednesday.

For example, 76 percent of adults agreed with California's requirement that at least a third of all electricity it generates should come from renewable sources, such as solar and wind power, by 2020.

The same level of support was found for requiring oil refineries to produce gasoline and other fuels that yield lower carbon dioxide emissions.

But support for renewable energy quotas dropped to 46 percent when respondents were asked to factor in higher electricity rates for consumers. Likewise, approval of lower carbon fuel standards fell to 39 percent if they brought higher pump prices for motorists.

Enthusiasm for clean-energy initiatives in the face of rising consumer costs fell even further among those with lower income levels.

Fewer than a third of individuals earning less than $40,000 a year said they would favor tougher carbon fuel standards if they pushed gasoline prices higher, compared with 54 percent approval among those with annual earnings of at least $80,000.

"The belief in climate change and support for state and federal action in climate change remains very strong in California today," said Mark Baldassare, president of the Public Policy Institute. "But as discussions about cost get introduced, the group that expressed the most concern is lower-income Californians, which is where the support drops off."

The survey also found that overall approval of immediate action by the state government to curb greenhouse gases continued to climb, growing to 61 percent this year from 59 percent last year, a rise of 15 percentage points since 2012.

The poll surveyed 1,705 adult California residents by telephone from July 8 to July 15 in English and Spanish, with a margin of error of plus or minus 3.7 percentage points.