A new weapon in the fight against climate change: 18-inch-tall redwood clones. The laboratory-produced trees are genetic duplicates of three giants that were cut down in northern California more than a century ago. Remarkably, shoots still emerge from the stumps, including one known as the Fieldbrook Stump, which measures 35 feet in diameter and is believed to be about 4,000 years old. The tree was about 40 stories high before it was felled. “This is a first step toward mass production,” says David Milarch, the co-founder of the nonprofit group spearheading the project, which is planting redwoods today (yep, it’s Earth Day) in Australia, New Zealand, Great Britain, Ireland, Canada, Germany, and the US. The group has developed several methods of producing genetic copies from cuttings, including placing branch tips less than an inch long in baby food jars containing nutrients and hormones.