Hillary Clinton never purchased carbon offsets to make up for the carbon dioxide emitted from her private jet travel during the 2016 presidential election, breaking a campaign promise.

The Clinton campaign pledged nearly two years ago to go carbon neutral after the former secretary of state was caught flying a private jet the same day she gave a speech on the dangers of man-made global warming.

But the campaign did not follow through on that promise, according to a Daily Caller News Foundation review of federal election filings.

A Clinton campaign spokesman said in October 2015 that "offsetting our carbon footprint is still an important goal for this campaign," after media reports showed that the campaign had not purchased any carbon offsets. That comment came about three months after a Clinton aide pledged that "we'll be offsetting the carbon footprint of the campaign and that includes travel."

While Clinton's 2008 presidential campaign bought carbon offsets from Native Energy, the company said she did not purchase any offsets from them during the 2016 campaign.

"The Clinton 2016 campaign did not purchase offsets from us," a Native Energy spokesman told the Daily Caller News Foundation.

The Clinton campaign spent more than $900,000 with the private jet chartering company Executive Fliteways in 2015, more than half of which came after Clinton pledged to buy carbon offsets. The following year, the campaign spent more than $266,000 with Executive Fliteways, according to Federal Election Commission filings.

The Daily Caller News Foundation reached out to Jennifer Palmieri, director of communications for the Clinton campaign, but received no response.