When oil and gas executives were called before a House committee for a hearing on climate change last fall, one congresswoman came prepared with props.

During her moment of questioning, Rep. Katie Porter, a California Democrat, appearing remotely for the hearing, opened the trunk of a minivan packed with 479 pounds of rice. Each grain, she said, represented one of the 13.9 million acres of public land available to oil companies that had so far not been used for drilling.