Raising the pH of the ocean to reduce carbon in the air, and robots that can landscape   First up on this week’s show, Contributing Correspondent Warren Cornwall discusses research into making oceans more alkaline as a way to increase carbon capture and slow climate change. But there are a few open questions with this strategy: Could enough material be dumped in the ocean to slow climate change? Would mining that material release a lot of carbon? And, would either the mining or ocean changes have big impacts on ecosystems or human health?   Next, we hear from Ryan Luke Johns, a recent Ph.D. graduate from ETH Zürich, about why we want robots building big rocky structures from found materials: It reduces energy costs and waste associated with construction, and it would allow us to build things remotely on Mars.   This week’s episode was produced with help from Podigy.   About the Science Podcast   Authors: Sarah Crespi; Warren Cornwall   Episode page: https://www.science.org/doi/10.1126/science.z66mytn