The United Nations' top climate official joined California Gov. Jerry Brown on Thursday to call for renewed efforts in the state to more quickly adapt to the risks that extreme weather and a rising sea pose to agriculture and the coastline.

Rajendra Pachauri, chairman of the United Nations Intergovernmental Panel on Climate Change, joined Brown, scientists, former Gov. Arnold Schwarzenegger and billionaire Sir Richard Branson at a conference at the California Academy of Sciences in Golden Gate Park.

Brown organized the conference, he said, to urge people to "wake up" to extreme weather patterns caused by manmade global warming that he said are already causing damage, and to start thinking about what California ought to do to prepare for worse threats.

He said the state needs to gird itself against floods caused by the faster snowmelts that are already happening, putting pressure on aging levees and threatening the state's agriculture industry.

Warming climate also means longer and more intense wildfire seasons that will threaten homes and infrastructure such as power lines, and affect air quality.

"The greatest obstacle we face is a deep sense of complacency, a sense that things were this way yesterday and were OK and will continue," Brown said.

"It's difficult to see what's not completely obvious ... the buildup of greenhouse gases and climate change, we see it, it's pretty clear," he said.

Brown lumped together global-warming skeptics, including GOP lawmakers and the Cato Institute, calling them a well-funded "cult" that disagrees with the vast majority of published, peer-reviewed climate science.

"The main thing we have to deal with in climate change is the skepticism, the denial and the cult-like behavior of the political lemmings that would take us over the cliff," Brown said.

"The Cato Institute has speakers that say environmentalism is a greater threat to capitalism than Marxism itself," he said, evoking laugher from the audience.

Patrick J. Michaels, a senior fellow in environmental studies at Cato, said the institute has never denied climate change but disputes temperature projections by the UN, saying the sensitivity of temperature to changes in carbon dioxide levels have been overestimated.

"Gov. Brown clearly has not read anything that the Cato Institute has published on global warming. Rather than deny it, we believe that indeed the surface temperature of the planet is about one degree Celsius warmer than it was 120 years ago and that increasing atmospheric carbon dioxide has contributed to this," Michaels said in a statement to The Associated Press.

"On the other hand, it is also clear that the rate of observed warming is falling beneath the midrange projections from the United Nations' Intergovernmental Panel on Climate Change."

Pachauri said UN studies show that 95 percent of human deaths associated with extreme weather events happen in developing countries.

Yet he said the world's large economies, such as California, can make great strides toward helping reduce global greenhouse gas emissions, especially through the simple task of retrofitting existing buildings.

"If one could retrofit buildings to make them more efficient, and if new buildings could be built to current standards, it's really a win-win situation," Pachauri said. "Overall, the building sector has the largest potential for the reduction of emissions."

In a rare public appearance since leaving office, Schwarzenegger, a Republican, attributed the success California has had in passing its landmark climate change laws to bipartisan cooperation.

While in office, the former governor frequently promoted California's landmark 2006 global warming law, called AB32, which paved the way for the state's cap-and-trade system for controlling greenhouse gas emissions by the worst polluters.

He called the debate over bankrupt solar panel maker Solyndra "narrow minded" in a world moving ever faster toward renewable energy.

"At the same time (as Solyndra) there were restaurants that failed, manufacturers that failed ... all kinds of businesses that failed and no one talks about that," Schwarzenegger said during a short interview.

"They did the best that they could and they made mistakes. That's what happens in business _ if you make mistakes you fail."

Not everybody watching Thursday's conference agreed that California was on the right path.

Dorothy Rothrock of the AB32 Implementation Group said the state has isolated itself by adopting stringent regulations that come at too high a cost.

"As we discuss the risks of climate change and California's future, it is appropriate to consider whether our greenhouse gas emissions reduction strategies will have an impact on climate change," Rothrock said in a statement.

"California has failed to design a cap-and-trade market that will be adopted by other states and jurisdictions in the near future and our efforts alone will not make a difference in global emissions."

___

Associated Press Writer Juliet Williams contributed to this story.