For each of the 7.2 billion people on the planet, there are hundreds of trees. These beloved cohabitants of Spaceship Earth give us breath, food, shelter and beauty. Their importance in ecological systems cannot be overstated. And many of them face novel threats as the human touch on the planet gets ever heavier. Join University of Maryland remote-sensing scientist Matthew Hansen, arborist Earl Eutsler, Deputy Director of Washington, DC’s Urban Forestry Administration, and science journalist Gabriel Popkin for a discussion about trees that will sweep from a global perspective on the state of trees in a climate-changing world, to a local effort to increase tree coverage in the District of Columbia, to a tale illustrating the diversity of challenges our arboreal partners face today.