The PBS moderators of last night's Democratic presidential primary debate never uttered the words “climate change.” But Senator Bernie Sanders did.

As we have progressed through the primary debate season, this has happened again and again. The media figures hosting the debates keep failing to bring up climate change, so the Democratic candidates for president are taking matters of our planet's future into their own hands.

According to a Media Matters analysis of Democratic debate transcripts, Senator Sanders, former Secretary of State Hillary Clinton, and the Democratic candidates who are no longer in the race have thus far brought up climate change on their own 17 times combined, proactively addressing climate change in their opening or closing statements, or connecting climate change to a question they were asked on another topic. That's more than twice as often as the moderators of the debates, who have only asked seven questions about climate change to the Democratic candidates so far.

Here are the 17 times that Democratic presidential candidates brought up climate change on their own:

• In his opening remarks at the October 13 CNN debate, former Rhode Island Governor Lincoln Chafee said: “I want to address climate change, a real threat to our planet.” [CNN, 10/13/15]
• In his opening remarks at the CNN debate, former Maryland Governor Martin O'Malley said: "[W]e must square our shoulders to the great challenge of climate change and make this threat our opportunity." [CNN, 10/13/15]
• In his opening remarks at the CNN debate, Sanders said: “Today, the scientific community is virtually unanimous:  climate change is real, it is caused by human activity, and we have a moral responsibility to transform our energy system away from fossil fuel to energy efficiency and sustainable energy and leave this planet a habitable planet for our children and our grandchildren.” [CNN, 10/13/15]
• In her opening remarks at the CNN debate, Clinton said she has put forward a plan to “tak[e] the opportunity posed by climate change to grow our economy.” [CNN debate, 10/13/15]
• O'Malley was asked during the CNN debate to name “the greatest national security threat to the United States.” He replied: “I believe that nuclear Iran remains the biggest threat, along with the threat of ISIL; climate change, of course, makes cascading threats even worse.” [CNN debate, 10/13/15]
• Sanders was also asked during the CNN debate to name “the greatest national security threat to the United States.” He replied: “The scientific community is telling us that if we do not address the global crisis of climate change, transform our energy system away from fossil fuel to sustainable energy, the planet that we're going to be leaving our kids and our grandchildren may well not be habitable.  That is a major crisis.” [CNN debate, 10/13/15]
• During the CNN debate, Clinton responded to O'Malley bringing up her position on the Keystone XL pipeline by saying: “I have been on the forefront of dealing with climate change, starting in 2009, when President Obama and I crashed a meeting with the Chinese and got them to sign up to the first international agreement to combat climate change that they'd ever joined.” [CNN debate, 10/13/15]
• Former Senator Jim Webb was asked during the CNN debate whether he is “out of step with the Democratic party” because "[y]ou're pro-coal, you're pro-offshore drilling, you're pro-Keystone pipeline." Webb responded, in part: “Well, the question really is how are we going to solve energy problems here and in the global environment if you really want to address climate change? And when I was in the Senate, I was an all-of-the-above energy voter.  ... And really, we are not going to solve climate change simply with the laws here [in the United States].” He added: “So let's solve this problem in an international way, and then we really will have a way to address climate change.” [CNN debate, 10/13/15]
• During the CNN debate, Chafee was asked which “enemy” he was “most proud” of making. He responded: “I guess the coal lobby.  I've worked hard for climate change and I want to work with the coal lobby.  But in my time in the Senate, tried to bring them to the table so that we could address carbon dioxide.  I'm proud to be at odds with the coal lobby.” [CNN debate, 10/13/15]
• In his closing statement at the CNN debate, Chafee said: “America has many challenges confronting us - ending the perpetual wars, addressing climate change, addressing income inequality, funding education, funding infrastructure, funding healthcare, helping black Americans, helping Native Americans.” [CNN debate, 10/13/15]
• During the November 14 debate on CBS, O'Malley was asked whether he would use the tax increases he implemented in Maryland as a “blueprint” to pay for his family leave plan. O'Malley replied, in part: “I believe that we paid for many of the things that we need to do again as a nation, investing in the skills of our people, our infrastructure and research and development and also climate change -- by the elimination of one big entitlement that we can no longer afford as a people. And that is the entitlement that many of our super wealthiest citizens feel they are entitled to pay, namely a much lower income tax rate and a lower tax rate on capital gains.” [CBS debate, 11/14/15]
• During the CBS debate, Clinton was asked a question about her use of a private email server as Secretary of State. Clinton replied, in part, that it is important to “start talking about the issues that the American people really care about.” She then noted that although “there are differences” among the Democratic candidates, “the differences among us pale compared to what's happening on the Republican side,” and pointed out that unlike the Republican candidates, "[a]ll of us believe climate change is real." [CBS debate, 11/14/15; Media Matters, 7/1/15]
• In his opening statement at the December 19 debate on ABC, Sanders said: “I'm running because we need to address the planetary crisis of climate change and take on the fossil fuel industry and transform our energy system away from fossil fuel to energy efficiency and sustainable energy.” [ABC debate via The Washington Post, 12/19/15]
• In his closing statement at the ABC debate, O'Malley said: “The other big challenge we have is climate change. The greatest business opportunity to come to the United States of America in 100 years. We need to embrace this. I have put forward a plan that does this, that moves us to 100 percent clean electric grid by 2050.” [ABC debate via The Washington Post, 12/19/15]
• In the January 17 debate on NBC, O'Malley was asked to name his top three priorities for his first 100 days in office. He replied, in part: “I believe the greatest business opportunity to come to the United States of America in 100 years is climate change. And I put forward a plan to move us to a 100 percent clean electric energy grid by 2050 and create 5 million jobs along the way.” [NBC debate via The Washington Post, 1/17/16]
• During a discussion of campaign contributions in the February 4 debate on MSNBC, Sanders said: “Let's talk about climate change. Do you think there's a reason why not one Republican has the guts to recognize that climate change is real, and that we need to transform our energy system? Do you think it has anything to do with the Koch brothers and ExxonMobil pouring huge amounts of money into the political system? ... You know, there is a reason why these people are putting huge amounts of money into our political system. And in my view, it is undermining American democracy and it is allowing Congress to represent wealthy campaign contributors and not the working families of this country.” [MSNBC debate, 2/4/16]
• During a discussion of campaign finance reform in the February 11 debate on PBS, Sanders stated: “Why does the fossil fuel industry pay -- spend huge amounts of money on campaign contributions? Any connection to the fact that not one Republican candidate for president thinks and agrees with the scientific community that climate change is real and that we have got to transform our energy system?” [PBS debate, 2/11/16]

And here are the 7 questions that debate moderators managed to ask the Democratic candidates about climate change, some of which misrepresented the issue or downplayed its importance:

• During the October 13 CNN debate, CNN's Don Lemon rephrased a social media user's question about what candidates will “do to address climate change” by broadly asking O'Malley how he would “protect the environment better than all the other candidates.” As Vox's David Roberts explained, this “maddening segue” suggested that Lemon and CNN view climate change as a “special interest issue” that is only of concern to environmentalists. [CNN debate, 10/13/15; Vox, 10/14/15]
• During the October 13 CNN debate, CNN's Anderson Cooper asked Sanders: “Senator Sanders, are you tougher on climate change than Secretary Clinton?” [CNN debate, 10/13/15]
• During the October 13 CNN debate, Cooper asked Clinton to “respond” to Sanders' comments about climate change. Clinton said, in part: “When we met in Copenhagen in 2009 and, literally, President Obama and I were hunting for the Chinese, going throughout this huge convention center, because we knew we had to get them to agree to something. Because there will be no effective efforts against climate change unless China and India join with the rest of the world. ... [T]here will be an international meeting at the end of this year, and we must get verifiable commitments to fight climate change from every country gathered there.” [CNN debate, 10/13/15]
• In the November 14 debate on CBS, CBS' John Dickerson noted that Sanders said he wants to “rid the planet of ISIS,” and then asked Sanders if he “still believe[s]” the statement that he made one month prior that climate change poses the greatest threat to America's national security. In this context, Dickerson was bringing up climate change solely to challenge its importance relative to terrorism. [CBS debate, 11/14/15; Media Matters, 1/11/16]
• During the January 17 debate on NBC, NBC's Lester Holt asked Sanders: “How do you convince Americans that the problem of climate change is so urgent that they need to change their behavior?” [NBC debate via The Washington Post, 1/17/16]
• Holt also gave O'Malley “30 seconds” to respond to the question he had asked Sanders about climate change. But he did not give Clinton an opportunity to respond to the question. [NBC debate via The Washington Post, 1/17/16]
• During the February 4 debate on MSNBC, NBC's Chuck Todd asked Clinton: “So there are three big lifts that you've talked about: immigration, gun reform, climate change. What do you do first? Because you know the first one is the one you have the best shot at getting done.” [MSNBC debate, 2/4/16]

Denise Robbins assisted with the research for this analysis.