Brothers David and Charles Koch each have personal fortunes valued above $20 billion, a hostility toward environmental causes — and a secret (until recently) fund for exploiting new political money rules.

Koch Industries, a holding company, has interests in oil, refining, chemicals, fertilizer, paper, minerals, and other sectors with large environmental impacts. Over the years, they have funded many anti-regulatory lobby groups and politicians, with particular emphasis on opposing regulation of greenhouse gas emissions and discrediting climate science.

News broken this month by Politico revealed the existence of a fund, Freedom Partners, that quietly handed out some $250 million to conservative causes during the 2012 elections. Under U.S. law, such groups are tax-exempt, can raise unlimited amounts of money, and do not have to disclose their donors.

• "Exclusive: The Koch Brothers' Secret Bank," [2] Politico, September 11, 2013, by Mike Allen and Jim Vandehei.
• "Koch Brothers Break New Ground in Dark Money," [3] National Journal, September 13, 2013, by Alex Seitz-Wald.
• "Dealing in Doubt: The Climate Denial Machine vs. Climate Science," [4] Greenpeace USA, September 2013.
• "Koch Industries Still Fueling Climate Denial," [5] Greenpeace USA, April 14, 2011.
• "Dark Money: Keeping an Eye on 501(c) Groups," [6] Citizens for Responsibility and Ethics in Washington (CREW), ongoing blog aggregation accessed September 25, 2013.