Tell me what you really think.

Now that the Copenhagen climate-change summit is finally underway, do the thousands of delegates gathered there to save the planet have much of a mandate from their home countries? A pair of fresh surveys paint a very different picture of public concern about climate change—and enthusiasm for big fixes.

A new poll by the Nielsen Company shows public concern about climate change falling sharply in the last two years—roughly when the global economy started to sputter. A separate survey by Globe Scan/BBC still shows plenty of worry about climate change, but a very mixed picture about how far people are willing to go to combat it.

The Nielsen survey shows concern about climate change falling in 35 of 54 countries over the last two years. In the U.S., for example, the percentage of people describing themselves as “very concerned about climate change” fell to 25% in October, from 34% in October 2007. Other countries had even bigger declines: 29% of Australians are “very concerned,” compared with 51% two years ago. Concern in Sweden has halved to 17% in the last two years, and so on.

The Globe Scan/BBC poll offers a different picture, with nearly two-thirds of respondents in 23 countries describing climate change as “very serious,” and 61% supporting action to fight it, “even if these investments hurt the economy.”