Argo Blockchain and DMG Blockchain, cryptocurrency mining firms that are publicly traded in the U.K. and Canada, respectively, have joined the Crypto Climate Accord (CCA), an advocacy group that pushes for lower carbon emissions in the crypto-mining industry. 

The two firms said Friday they are now working with the CCA to develop a new working group to promote the accord’s objectives, while also working to increase transparency around energy sourcing by crypto mining operations.

The CCA is a private sector-led initiative that sets out to reduce overall emissions in cryptocurrency mining, which has become a cause for concern for some high-profile investors such as Elon Musk. The organization is encouraging the industry to achieve net-zero greenhouse gas emissions by 2040.

“The Crypto Climate Accord helps lay the groundwork for real, tangible action to address Bitcoin mining’s impact on the environment, and we are both eager and determined to ensure that Supporters and Signatories remain committed to the group’s goals,” Argo Blockchain CEO Peter Wall said.

Argo and DMG said it’s estimated that crypto mining worldwide accounts for up to 0.5% of global power usage, though they did not provide a source for the data.

The two firms are already working on environmental initiatives, having signed an agreement in March to launch a bitcoin mining pool that would be completely powered by clean energy. On Thursday, Argo Blockchain announced the purchase of two data centers in Canada that are largely powered by hydroelectricity.

See also: What Bloomberg Gets Wrong About Bitcoin’s Climate Footprint