Globally, banks and environmental advocates are seeking to make things easier by developing best practices and other voluntary standards. Citigroup, JPMorgan Chase and Morgan Stanley helped initiate the Carbon Principles, which aim to standardize the assessment of “carbon risks in the financing of electric power projects” in the United States. Several international financial institutions  including HSBC, Munich Re and others  have formed the Climate Principles, which aim to encourage the management of climate change “across the full range of financial products and services,” according to the compact’s Web site.

In the United States, mountaintop removal mining has become both increasingly common and contentious, as coal companies vie to feed the nation’s appetite for inexpensive electricity. An expeditious and disruptive form of surface mining, it involves blasting off the tops of mountains and dumping the debris in valleys and streams below.

A report published in May by the Sierra Club and the Rainforest Action Network estimated that nine banks were the primary lenders for companies engaged in mountaintop removal mining in Appalachia, and that they had provided nearly $4 billion in loans and bond underwriting to those companies  chiefly Massey Energy, Patriot Coal, and Alpha Natural Resources  since 2008.

The Rainforest Action Network, which has headed a campaign to highlight financial institutions with connections to the mining, said this month that the policy shifts were chipping away at the financing.

Citing Bloomberg data, for example, the group noted that Bank of America  listed as recently as 2008 as one of the “syndication agents” on a $175 million revolving line of credit to Massey Energy  has eliminated that and all other connections to the company. The group also pointed to JPMorgan, which had previously underwritten $180 million in debt securities to Massey, but no longer has any financial ties to that company. In May, the bank said it would be subjecting all future engagements with companies involved in mountaintop removal mining to “enhanced review.”

Some environmental groups have criticized that and other policies as providing too much wiggle room  and whether any of it has any real impact is an open question. Mining industry representatives say such policies often fail to consider laws already in place requiring coal companies to limit their environmental impact, and to restore former mine sites when they are finished.

Carol Raulston, a spokeswoman for the National Mining Association, an industry group, said that most of the policies in question position the banks to phase out lending over time  and only to companies that primarily engage in mountaintop removal mining. “Companies are still getting financing for their projects,” she said.