DINA CAPPIELLOWASHINGTON (AP) ¿ As Congress begins to debate climate change in earnest, the science is taking a back seat to economics: How much will it cost to slow the Earth's warming because of man-made pollution ¿ and what's the cost of doing nothing? With a key House committee starting four days of hearings, Speaker Nancy Pelosi, D-Calif., vowed to get a climate bill approved this year. Noting that Earth Day will be celebrated on Wednesday, she told reporters by the next Earth Day "we want to celebrate what we've done this year" to address climate change and clean energy. But the challenge of getting bipartisan support immediately became apparent. The Energy and Commerce Committee hearing had barely begun when Republicans raised their concerns about higher energy prices produced by putting an added price for burning fossil fuels. "In its current form, this bill may do more harm to our economy than any bill that is likely to come before Congress for the rest of this year, or perhaps during my natural lifetime," declared Rep. Michael C. Burgess, R-Texas.