I‘ve spent much of the last 25 years thinking and lobbying about climate change and trying to get it on the agenda. This town hall impressed me. While there were differences, all the candidates seemed well-informed about the issue and backed policies that make sense.

It was clear that Senator Amy Klobuchar had thought about the climate crisis from many angles. She seemed much more detail-oriented than Senator Kamala Harris. Less charismatic though. How do you trade off expertise against personality?

Less specific and less clear than Klobuchar was Joe Biden, though he was still well informed. He emphasized the need to involve the rest of the world – and that without them, even if the US goes net zero, the world will still have a crisis. Good point. He talked about his experience in working with foreign leaders and the need for diplomacy – again, good point. He said he’d go to Brazil to talk with President Jair Bolsonaro right away.

Again, that makes sense.

Bernie Sanders, like Biden, stressed the need for diplomacy and involving the rest of the world. Sanders was very emphatic about the priority of climate change and the need to preserve the planet. Although he was rather vague about where exactly his famous $16 trillion will come from, he did list some plausible sources. And he sees nuclear energy as expensive and risky, which is accurate. Sanders also suggested that his administration would compensate people who work in fossil fuels and lose their jobs by paying them incomes for five years. That seems fair and is also good politics.

Senator Elizabeth Warren was very coherent – as usual. She supports a carbon tax and moving away from nuclear and spoke of a need for carbon-based border adjustment taxes – no one else did.

Like Sanders, Warren was very aware of the need to provide for those who lose jobs in fossil fuels. Her suggestion was to employ them in infrastructure investment.

She wants to get to zero carbon in new buildings by 2028, in new cars by 2030 and power generation by 2035. This is probably just about feasible and the right way to tackle the problem. Warren also reacted well to a question about the impact of CO2 on the oceans. No one else spoke of the impact of climate on the oceans, but it’s a big issue.

Senator Cory Booker, who spoke last, came across as having thought about the issues more than most. His statement that if we want to get off carbon as early as 2030 then we have to continue using nuclear energy was potentially controversial to a Democratic audience, but is also probably true, so I give him high marks for this. He also seemed more aware than others of the climate-agriculture connection and the need to bring factory farming under control.

No doubt some policies would be more effective than others, but nevertheless having a town hall devoted to climate change makes the 2020 presidential elections more advanced than previous years.

Geoffrey Heal, the Donald C. Waite III Professor of Social Enterprise and a Chazen Senior Scholar at Columbia Business School, is the author of "Endangered Economies -- How the Neglect of Nature Threatens Our Prosperity."