Barbara Boxer (D-CA), chairman of the Senate environment committee, isn’t yet ready to start debating a long-term transportation bill — but she is reportedly prepared to move on climate change legislation that includes targets for diminishing auto dependence and encouraging transit use.

Boxer’s panel will begin debate on its climate bill during the last week of July, using the soon-to-be-considered House measure as a starting point, according to the Capitol Hill newspaper Roll Call (sub. req’d.).

The House bill features several mandates for diminishing the carbon footprint of the transportation sector, which currently accounts for about one-third of total U.S. greenhouse gas emissions.

It requires states to set emissions reduction benchmarks for transportation that would then be incorporated into future land use and zoning decisions. In addition, the Obama administration’s recent increases in auto fuel efficiency would serve as a minimum for future emissions improvements, and states would be able to use 10 percent of their total energy-efficiency allowances to pay for transit or bike path expansions.

If Boxer preserves those elements of the House bill during Senate consideration, an attempt to strip them would have to win over nearly half the Democrats on the environment committee, which is split 12-7 betwene the parties.