WASHINGTON — Governors from five Western states agreed yesterday to work together to reduce greenhouse gases, saying their region has suffered some of the worst of global warming with recent droughts and bad fire seasons.

The governors of Arizona, California, New Mexico, Oregon, and Washington said they would develop a regional target to lower greenhouse gases and create a program aimed at helping businesses reach the still-undecided goals.

“In the absence of meaningful federal action, it is up to the states to take action to address climate change and reduce greenhouse gas emissions in this country,” Governor Napolitano, a Democrat of Arizona, said. “Western states are being particularly hard-hit by the effects of climate change.”

Governor Schwarzenegger, a Republican of California, said a so-called cap-and-trade program, which lets companies that can’t meet their emission reduction targets buy credits from those that reduce carbon dioxide, would provide “a powerful framework for developing a national cap-and-trade program. … This agreement shows the power of states to lead our nation addressing climate change.”

The agreement — called the Western Regional Climate Action Initiative — builds on earlier efforts by several states.

Last year, Mr. Schwarzenegger signed California legislation imposing a first-in-the-nation emissions cap on utilities, refineries and manufacturing plants, with a goal of cutting greenhouse gases to 1990 levels by 2020. And Mr. Schwarzenegger and Britain’s Prime Minister Blair announced plans to work toward a possible joint emissions-trading market.

New Mexico and Arizona last year agreed to work to measure and report greenhouse gas emissions. A similar joint effort on climate change was agreed upon in 2003 by California, Oregon, and Washington.