Many of the world's biggest companies publicly support U.S. President Barack Obama's climate change agenda, but a new review by Reuters reveals that these same companies support his rivals and climate change skeptics.

There is a clear inconsistency between the public advocacies of companies like PepsiCo, Google and Dupont, and their political contributions, the review revealed. Most corporations donate funds to the different political parties with little regard to environmental causes and positions.

The review of Reuters studied the political donations for the 2016 elections by 30 of the biggest publicly traded U.S. companies that signed the "American Business Act on Climate Change Pledge" in 2015. This Obama-initiated act is an agreement to enact climate-friendly corporate policies and support climate change actions.

While signing is a commendable move by the corporations, it's revealed that 25 of these 30 companies are actually contributing funds to the campaigns of lawmakers who are known as "climate deniers," according to a list from non-profit Organizing For Action that's organized by Obama aides.

Among the companies found to heavily support politicians who are part of the list are PepsiCo and DuPont, who both gave half or more money from their top donations. Google, AT&T, GE, Verizon and Mondelez are others that gave over a third of their contributions.

"There really needs to be a process that looks at these issues ... at C-suite and board levels on a periodic basis," Jon Lukomnik, head of the Investor Responsibility Research Center Institute, said.

However, lawmakers who found themselves on the list point out that there are other issues that companies consider when choosing whose campaign to support. Republican Congressman Kevin Cramer of North Dakota is a self-described climate skeptic who said, "It is not a black and white issue, like if you agree with Obama you're enlightened, and if you don't you're in the dark. It is more of a spectrum."