Earthweek: a diary of the planet

For the week ending Friday, Feb 24.

Engineered trees

The first batch of trees genetically engineered to grow taller and capture more carbon dioxide from the atmosphere was planted on private land in southern Georgia in an attempt to sideline restrictions on such plantings. More will soon be planted on abandoned Pennsylvania coal mines. The Living Carbon startup of San Francisco added three genes to the poplars to make their photosynthesis more efficient, hoping they will turbocharge the rate the trees grow wood and suck carbon dioxide from the air. Their prospect of helping to remove greenhouse gas has supporters and critics.

Metallic core

Analysis of increasingly detailed seismic data around the world has allowed scientists to confirm the existence of a huge metallic structure at the heart of Earth’s inner core. The structure was measured by looking at seismic waves from 200 quakes with a magnitude greater than 6.0 as they bounced back and forth up to five times inside the Earth. The transition from the outer regions of the inner core to the newly confirmed inner metallic structure is gradual rather than a sharp boundary, scientists say in the journal Nature.

Empty canals

Gondolas and other boats in the Italian lagoon city of Venice have been lying on nearly dried-up canals this month because of a prolonged drought and a series of unusually low tides. While the popular tourist destination has regularly been swamped by high astronomical tides made worse by rising sea levels, experts say ultra-low ebb tides this winter point to the need to clean and dredge some of Venice’s inner canal network.

Humpback fighters

The recovery in recent years of the humpback whale population is resulting in more aggressive mating behavior among the previously gentler males. Australia’s east coast humpback population alone grew from 3,700 in 2007 to 27,000 whales in 2015. Monitoring has found that male humpbacks have increasingly turned to fighting among themselves for the right to breed.