It just wouldn’t be an energy debate without a few sparks.

In front of a sold-out crowd at UCLA, four experts debated the future of energy and the environment at Powering Earth 2050: Is California’s 100% Renewable Strategy Globally Viable? The Feb. 23 event marked the latest installment of the Oppenheim Lecture Series, which is produced by the UCLA Institute for the Environment and Sustainability (IOES).

Science writer Oliver Morton moderated a group that included Ken Caldeira and Mark Jacobson from Stanford University, Dale Bryk from the National Resources Defense Council and Michael Shellenberger of the Breakthrough Institute.

While the experts agreed on the need to reduce greenhouse gas emissions, they sharply divided on how to achieve that goal. Jacobson and Bryk argued for a move toward renewable-only sources, such as solar and wind power. Caldeira and Shellenberger, on the other hand, supported more inclusive approaches that would not eliminate the use of nuclear power and cleaner fossil fuels.

Global warming and climate change are huge challenges that require every tool in the shed, Caldeira said. He likened removing some options to entering a boxing ring with one hand tied behind our backs.

Meanwhile, Shellenberger argued for continued use of nuclear power, noting that California’s single remaining nuclear plant can produce as much energy as all of its solar facilities combined. In one of the most provocative comments of the evening, he compared nuclear opposition to anti-vaccine activism, calling them both “irrational.”

Read a complete wrapup of the discussion on the IoES website. You can also watch a replay of the event below.