The idea of becoming a grandparent is emotional for Bill Gates to even write about.

“I started looking at the world through a new lens recently — when my older daughter gave me the incredible news that I’ll become a grandfather next year,” Gates wrote in a letter published overnight on his personal blog, Gates Notes.

Gates’ 26-year-old daughter, Jennifer, and her husband, Nayel Nassar, are expecting their first baby in 2023.

“Simply typing that phrase, ‘I’ll become a grandfather next year,’ makes me emotional,” wrote the 67-year-old billionaire philanthropist, who earned his fortune from co-founding Microsoft in the 1970s. “And the thought gives a new dimension to my work. When I think about the world my grandchild will be born into, I’m more inspired than ever to help everyone’s children and grandchildren have a chance to survive and thrive.”

Gates goes on to summarize the work his namesake philanthropic organization, the Gates Foundation, is doing for children living in global poverty, to improve education, pandemic preparedness, and the fights against polio and AIDS.

Gates also talks about the work he is doing to combat climate change, both through the Gates Foundation by supporting early stage climate companies with his investment firm, Breakthrough Energy Ventures.

Current leaders’ response to climate change will impact future generations, which is the first point Gates makes in the section of his letter where he addresses climate change.

“I can sum up the solution to climate change in two sentences: We need to eliminate global emissions of greenhouse gases by 2050,” Gates writes. “Extreme weather is already causing more suffering, and if we don’t get to net-zero emissions, our grandchildren will grow up in a world that is dramatically worse off.”

The implications are enormous — and so is the challenge.

“Getting to zero will be the hardest thing humans have ever done,” Gates writes. “We need to revolutionize the entire physical economy — how we make things, move around, produce electricity, grow food, and stay warm and cool — in less than three decades.”

Gates got started in working on climate change when he learned about the struggles of small farmers in countries where his namesake philanthropic organization was doing work. The Gates Foundation funds climate adaptation work, helping people adjust to the implications of a warming world, where there is no profit to be made by a commercial enterprise.

“It starts from the idea that the poorest are suffering the most from climate change, but businesses don’t have a natural incentive to make tools that help them,” Gates writes.

“A seed company can earn profits from, say, a new type of tomato that’s a nicer shade of red and doesn’t bruise easily, but it has no incentive to make better strains of cassava that (a) survive floods and droughts and (b) are cheap enough for the world’s low-income farmers,” Gates writes. “The foundation’s role is to make sure that the poorest benefit from the same innovative skills that benefit richer countries.”

Not all of Gates’ climate work is philanthropic. Breakthrough Energy Ventures funds early stage companies that are working to build and grow companies to decarbonize various sectors of the economy. Building for-profit companies to address a problem that impacts the well-being of the global population may come across as unsavory from Gates, who already has a fortune to his name — $103.6 billion according to Forbes as of Monday.

But Gates says decarbonizing global industry is too large a problem even for his deep pockets.

“Philanthropy alone can’t eliminate greenhouse gases. Only markets and governments can achieve that kind of pace and scale,” Gates said. Any profits Gates makes on investments he makes in Breakthrough Energy companies will go back into climate work or into the philanthropic foundation, he said.

Plus, if companies working to address climate change can be self-sustaining, that will encourage other investors to put money into them.

“Companies need to be profitable so they can grow, keep running, and prove that there’s a market for their products,” Gates writes. “The profit incentive will attract other innovators, creating competition that will drive down the prices of zero-emissions inventions and have a meaningful impact on emissions from buildings.”

“We are still moving in the wrong direction,” António Guterres said Monday. “The global emissions gap is growing. The 1.5-degree goal is gasping for breath. National climate plans are falling woefully short.”

Despite the bleakness of the current climate moment, Gates is optimistic about the rising investment in decarbonization technologies.

“We’re much further along than I would have predicted a few years ago on getting companies to invest in zero-carbon breakthroughs,” Gates writes.

Public money for climate research and development has gone up by one-third since the 2015 Paris climate accord, and in the United States, laws passed this year will put $500 billion toward moving the U.S. energy infrastructure away from fossil fuel-based sources, according to Gates.

Private money is also going into climate technologies at a good clip. Venture capital firms have put $70 billion in clean energy startups in the past two years, Gates writes.