Ever since the 2008 financial crisis and subsequent economic malaise, corporate sustainability has lost a bit of its luster as companies strayed away from "green" messaging and more toward job creation and technological innovation.

Even GE's Jeff Immelt, at one time the leader of corporate green converts, said in 2011 he regretted the company's green messaging: "If I had one thing to do over again, I would not have talked so much about green. [...] I'm a businessman. That's all I care about, is jobs," he said.

Behind the scenes, however, some of the biggest companies in the world -- including GE -- are still chipping away at their energy consumption by making their operations more efficient, procuring more clean energy, or finding less wasteful ways of producing goods.

But are these efforts really making an impact?

A new report examining carbon emissions from the world's largest 500 companies bluntly concludes that the answer is no.

Well, at least not cumulatively.

Every year, the Carbon Disclosure Project (CDP) surveys leading companies about their CO2 output on behalf of major investors worth $87 trillion. This year, 81 percent of the companies in the Global 500 list participated. And although 84 percent of big firms surveyed have emissions reductions targets, the top 50 companies on the list are together increasing their emissions, not dropping them.

The news comes as the world surpasses 400 ppm concentration of CO2 in the atmosphere and scientists at the UN Intergovernmental Panel on Climate Change prepare a report concluding with 95 percent certainty that humans are warming the planet.

"With the initial IPCC report only weeks away, corporate emissions are still rising. Either business action increases, or the risk is regulation overtakes them," said Malcolm Preston, head of global sustainability and climate change at PwC, the global financial consulting firm that assisted with the report.

It would be easy to blame big consumer companies like Apple and Wal-Mart for failing to live up to their sustainability goals (although Apple did not participate and Wal-Mart is on the list of top emitters). The problem is much simpler. The top 50 companies in the world are largely made up of huge energy companies, utilities and materials producers. Not surprisingly, those three sectors are the worst CO2 emitters and have helped raise emissions within the top 50 global companies by 1.65 percent since 2009.

Some of the emitters in the top 50 include Chevron, ConocoPhillips, ExxonMobil, Occidental Petroleum, Dow Chemical, American Electric Power, Duke Energy and Exelon. It's probably not a huge surprise that these fossil-fuel-based companies are seeing their emissions rise, not fall.

CDP reports that 97 percent of companies surveyed disclosed their direct emissions and indirect emissions from energy consumption. However, they are frequently reporting on the easiest -- and less intensive -- operations.

For example, the chart below shows that only one-quarter of companies report use of "sold products" -- a category that represents nearly three-quarters of emissions. But business travel, which only makes up 0.2 percent of emissions, is reported by 72 percent of companies.

Although CDP provides a detailed glimpse into the emissions profiles of the top companies, nearly half of potential emissions sources are unaccounted for in the analysis. That's because companies aren't disclosing that activity.

Not great comfort for CDP's target audience: some of the largest investors in the world worried about the financial risk of climate change.