The U.S. already produces 21% of its electricity from renewable sources. But the cheapest path to 50% in the next 15 years isn’t by simply plugging more solar, wind and hydro power into the existing grid. Moving electricity very nimbly – for instance, shuttling excess wind energy from the Midwest to cities on the East Coast at peak hours – requires an overlay of high-voltage transmission lines, says Iowa State electrical engineering professor James D. McCalley. He explains why a “macrogrid” is the most cost-effective way to build a high-renewables grid.

A research team of ecologists investigating how rising seas were affecting plants and soils in coastal North Carolina were shocked to find that more than 10% of forested wetland in a wildlife refuge had been lost over the past 35 years. The forest appears unable to adapt to the wetter, saltier conditions, a trend that is occurring from Florida to Maine, researcher Emily Ury writes. Scientists call the resulting huge bare swaths “ghost forests.”

Many of us are hearing and sharing stories about the side effects from the COVID-19 vaccine, which vary widely. Immunologist Matthew Woodruff writes that vaccine designers walk a line between wanting to kick a person’s immune system into gear with adjuvants, while minimizing side effects. But the bottom line is that, in general, side effects are a good thing – the vaccine is training your immune system to respond to a pathogen.

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