On Thursday, former Vice President Al Gore told former TIME editor-in-chief Nancy Gibbs that he thinks that, while unlikely, there’s a possibility that the Senate could vote to convict and remove President Donald Trump from office if he’s impeached in the House of Representatives.

Speaking at the TIME 100 Health Summit on Thursday, Gore said, “Listening to what President Trump has said out of his own mouth when he publicly asks foreign governments to dig up dirt on one of his principal political opponents, that is an impeachable offense.”

“It’s probably still unlikely the Republican Senate would convict, but I don’t think it’s any longer possible to say that’s a certainty by any means,” he added. “Of course most people have assumed that the Republican controlled Senate would never convict and remove. I don’t know, the evidence still matters.”

Gore was Vice President to former President Bill Clinton during the last impeachment inquiry into a President.

The impeachment inquiry began after a whistleblower filed a complaint that Trump pressured Ukrainian President Volodymyr Zelensky to investigate Hunter Biden and his father former Vice President Joe Biden, a political rival and a front runner in the 2020 presidential race. (There has been no evidence of wrongdoing by either Biden.) On Sept. 24, House Speaker Nancy Pelosi announced the House would pursue a formal impeachment inquiry into the President. Every member of the Democratic presidential primary supports the impeachment inquiry, and the topic was the first issue discussed in Tuesday’s Democratic debate. Trump has maintained that his phone call with Zelensky was “perfect” and there was “no quid pro quo” with Ukraine.

Gore, a longtime advocate about the dangers of climate change, urged voters to vote out Trump and other Republican policy makers who oppose regulation to combat global warming. “In order to fix the climate crisis, we have to solve the democracy crisis,” he said.

At the TIME 100 Health Summit, Gore also spoke about the affect climate change has already had on the health of humans around the planet, highlighting recent deaths from heat stress and tropical diseases that become endemic as environments grow wetter and warmer. According to Gore, about 9 million people die every year worldwide from air pollution caused from burning fossil fuels.

“When you burn, coal or gas or oil, we’re putting 142 million tons of man made global warming pollution into the sky everyday,” he said. “We’re using it as an open sewer basically.” Gore added that those pollutants trap as much accumulated heat every day as 500,000 Hiroshima class atomic bombs would release.

The former Vice President also stressed the need for policy changes, and praised Scandinavian countries and some U.S. states like California and New York for leading by example.

“The green economy in the U.S. is now many times larger already than the fossil fuel economy,” he said, adding that the fastest-growing job in the U.S. is solar panel installer. “We are now in the early stages of a sustainability revolution.”

He in turn criticized the Trump Administration’s rollback of regulations intended to curb climate change. “It’s dangerous and shameful what we’ve done,” he said.

“It is not fair to put the burden on individuals to solve this climate crisis… as important as it is to change your lightbulbs to LEDs, it’s way more important to change your governments policies,” Gore said.

He stressed that Americans need to vote out politicians in both parties who oppose climate-focused policies, and said the issue is becoming increasingly nonpartisan because Americans themselves are already seeing the effects of climate change. “If you care about this climate crisis, make sure that this election next year is a wave election in favor of saving the climate,” he said.

Gore said in the last nine years, the U.S. has seen 18 “once in a thousand year” storms that have been caused by climate change, and said more than two-thirds of all water born diseases in the U.S. come after these storms.

He put it simply: “The most powerful advocate of all is mother nature.”

Write to Madeleine Carlisle at madeleine.carlisle@time.com.