Behind David Milarch’s desk in a large warehouse in rural Michigan grows the future of climate change solutions. Thousands of sequoias, coastal redwoods, oaks and a hundred other tree species form the Archangel Ancient Tree Archive (AATA), a living library of the world’s mightiest trees. These are not just any saplings — they all are descendants of so-called champion trees. …At 75, David Milarch is trying to save the world’s last old-growth forests from extinction — by using their DNA to help reverse climate change. …Cloning these giants is challenging. It involves scaling the trees to the high points where the newest growth sprouts, snipping off the most vital tips, and then coaxing them to root in a mix of soil and specialized hormones. While arborists believed it was impossible to clone redwoods older than 80 years because of their diminished vitality, Milarch proved them wrong.