<p>Dear Director of the US Fish and Wildlife Service Director:</p><p>While governments and international organizations debate the political intricacies of carbon emissions, Earth's oceans continue to absorb massive quantities of carbon dioxide, resulting in increasingly acidic waters. This process, known as ocean acidification, threatens marine ecosystems throughout the world.</p><p>As a global problem, ocean acidification demands a global solution. Your organization, however, enjoys a unique position to grant immediate respite to marine life through the designation of additional Marine Protected Areas (MPAs). A number of statutes—including the Endangered Species Act (1973), the Fish and Wildlife Coordination Act (1934) and the Wilderness Act (1964)—endow the U.S. Fish and Wildlife Service with the authority and flexibility to create new federal MPAs. In these protected zones, marine ecosystems have proven more resilient against global threats, such as warming seas and ocean acidification.</p><p>MPAs are not a panacea for ocean acidification, but as part of a coordinated response including local organizations and the international community, they do offer a short-term plan to reverse current trends. In the past, MPAs have also demonstrated unanticipated practical benefits, such as fish spillover and larval drift, helping to replenish fish stocks well beyond the area's designated boundaries. Additionally, these zones could help raise public awareness around the issue of acidification—the "hidden side" of the world's carbon crisis.</p><p>Given the imminence of ocean acidification, we cannot afford to wait for international consensus on carbon emissions. Additional MPAs offer an immediate and practical first step, and I hope your agency will exercise its legal authority to protect Earth's oceans and all who depend on them.</p>