Apple CEO Tim Cook has not been known for taking a strong stand on, well, just about anything. Caution has been the watchword of Cook's three-year tenure at the top of the world's wealthiest technology company. So far his legacy is largely comprised of incremental improvements in established products, tweaks to the supply chain, and more corporate transparency.

But Cook does care about the environment — and that became very clear on Friday, when the CEO had a terse exchange with a lobbying group that is extremely skeptical on climate change.

Apple has made vast improvements in its use of renewable energy since Cook took over from Steve Jobs. More than three-quarters of the company's facilities worldwide, including all of its data centers and its Cupertino HQ, now run on solar, wind, geothermal or hydro power, up from about a quarter under Jobs. Last year, Cook hired Lisa Jackson, former head of the EPA, to lead the company's sustainability efforts.

None of that sits well with folks who don't think climate change is a big deal — such as the National Center for Public Policy Research, a conservative think tank based in Washington, D.C. and an Apple shareholder. The group calls climate change a "chimera" and claims that "over 95 percent of all climate models have over-forecast the extent of predicted global warming."

At the company's annual shareholder meeting in Cupertino, the NCPPR urged Cook and the board to pledge that Apple wouldn't pursue any more environmental initiatives that didn't improve its bottom line. "We object to increased government control over company products and operations, and likewise mandatory environmental standards," wrote NCPPR general counsel Justin Danhof in a statement before the meeting. "This is something [Apple] should be actively fighting, not preparing surrender."

Danhof raised this question with Cook three times during the meeting. On the third time, clearly frustrated, Cook's response was blistering. First of all, he insisted, environmental efforts also make economic sense. Secondly, "we do a lot of things for reasons besides profit motive," the CEO said:

We do things because they are right and just and that is who we are. That’s who we are as a company. I don’t…when I think about human rights, I don’t think about an ROI. When I think about making our products accessible for the people that can’t see or to help a kid with autism, I don’t think about a bloody ROI, and by the same token, I don’t think about helping our environment from an ROI point of view.

Anyone who had a problem with that approach? They should sell their Apple shares. "If you only want me to make things, make decisions that have a clear ROI, then you should get out of the stock," Cook said to applause. Danhof's proposal was voted down by shareholders.

It's a measure of the strength of Apple's position that Cook can afford to irritate such a large and powerful shareholder on a matter of principle. But it also offers hope for environmentalists frustrated by the lack of progress on climate change that — in Apple's drought-ridden home state, at least — now seems all too real. Greenpeace recently applauded Cook for working to reduce the number of "conflict minerals" in Apple products. Now it has one more reason to cheer.

Editing note: this story was updated with quotes from a transcript of the meeting.