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.

For the rest of this week’s science and research articles, see the list below. And reply to this email with questions or subjects you’d like our science editors to explore.

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The Los Angeles Department of Water and Power’s Pine Tree Wind Farm and Solar Power Plant in Tehachapi, Calif., 115 miles from LA. Irfan Khan / Los Angeles Times via Getty Images

The US needs a macrogrid to move electricity from areas that make it to areas that need it

James D. McCalley, Iowa State University

The US electricity grid is actually five regional grids, and it's hard to share power between them. A macrogrid could bridge the gaps, making electricity cheaper and more reliable.

Ghost forest panorama in coastal North Carolina. Emily Ury

Sea level rise is killing trees along the Atlantic coast, creating ‘ghost forests’ that are visible from space

Emily Ury, Duke University

As sea levels rise along the Atlantic coast, saltwater is intruding inland, killing trees and turning coastal forests into marshes. Should scientists try to slow the process, or work with it?

A sign shows the way to a recovery area to monitor any immediate side effects from the COVID-19 vaccine on Dec. 17, 2020, in Reno, Nevada. Patrick T. Fallon /AFP via Getty Images

What COVID-19 vaccine side effects might I expect?

Matthew Woodruff, Emory University

Many people never experience the least bit of discomfort from the COVID-19 vaccines, but mild side effects are common. They include swelling in the affected arm, nausea and chills.

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