>> Zoë Schlanger Published: 20 May 2021 09:04 AM BdST Updated: 20 May 2021 09:04 AM BdST Razed glossy buckthorn, an invasive shrub that chokes native species, in Acadia National Park in Maine on May 14, 2021. The New York Times For more than a century, the core mission of the National Park Service has been preserving the natural heritage of the United States. But now, as the planet warms, transforming ecosystems, the agency is conceding that its traditional goal of absolute conservation is no longer viable in many cases. "); } Late last month the service published an 80-page document that lays out new guidance for park managers in the era of climate change. The document, along with two peer-reviewed papers, is essentially a tool kit for the new world. It aims to help park ecologists and managers confront the fact that, increasingly, they must now actively choose what to save, what to shepherd through radical environmental transformation and what will vanish forever.