“Climate progress is moving ahead even though we won’t meet our highest aspirations,” he said in a Bloomberg TV interview at the annual United Nations meeting in Dubai, citing the biggest-ever attendance and new food and health initiatives.

Keeping warming to 2C “isn’t that likely,” he said. “Fortunately, if you stay below 3C, a lot of the ill effects that people have heard about don’t happen unless you really are irresponsible and let it get up to the higher range.” 

A planet that warms by 3C from pre-industrial levels could regularly expose up to 50 million people to temperatures that are beyond human survivability, a 2018 study in Lancet Planetary Health showed.

New York City might experience three once-in-a-century flooding events every year while as many as 52 times more people would face dangerous heat in African cities. The amount of land destroyed by wildfires globally would double and the Amazon rainforest would turn into grassland.

In the Paris pact, nearly 200 countries agreed to limit global temperatures to well below 2 degrees, ideally to 1.5C, to avoid the worst impacts of climate change. But a recent report by the UN’s environment program shows the world is instead on track to warm up to 2.9C with current country-level emissions reduction plans.

Climate scientists consistently stress that there’s no safe level of global warming, pointing to how dangerous impacts are already playing out in every corner of the globe today when global average temperatures have risen 1.2C from the pre-industrial era. Just this year alone, the warmest on record, a string of brutal wildfires, floods and extreme heat have claimed lives and reshaped communities.

Gates cited nuclear fusion and fission as well as green steel as being among the solutions he’s optimistic about. The Microsoft Corp. co-founder, who invests in dozens of clean-technology companies through Breakthrough Energy Ventures, said that meetings on the sidelines of COP28 are crucial for startups to get exposure to large players in industries that need to decarbonize, such as cement. 

This year’s summit, hosted by the oil-rich United Arab Emirates, has faced controversy for its embrace of the fossil fuel industry. Sultan Al Jaber, the oil executive overseeing the talks, argues that they need to be engaged in the conversation. Those who want a quicker move away from dirty energy say the industry is doing far too little to shift to alternatives. 

“We have to outcompete fossil fuels,” Gates said. “To do that properly, they shouldn’t get subsidies and in fact a carbon tax over time should be put on.”