Rewetting Arctic peatlands could flip northern farmland from a carbon source into a climate ally. Credit: Shutterstock In their natural condition, peatlands rank among the planet's most important carbon reservoirs. The soil is saturated with water and contains very little oxygen, which slows the breakdown of dead plants. Instead of fully decomposing, plant material builds up layer upon layer over thousands of years, forming deep deposits of peat that lock away carbon for the long term. That