( CNN ) -- Twenty years ago last month , the North American Free Trade Agreement was born . The goal of NAFTA was straightforward -- to encourage the free movement of goods and capital between the U.S. , Mexico and Canada . Few points in history have been as important in forging bonds between our three countries . While NAFTA is a relatively new pact that ties our nations , there are some things that go back far longer that bind us . Like the annual monarch butterfly migration , which started long before the trades , borders or foreign affairs were even an issue . There 's no record telling us when monarch butterflies first began their journeys of up to 2,800 miles between southern Canada , the northern U.S. , and central Mexico . It 's easy to assume that an end date for the migrations is just as elusive , but reality tells a different story . In January , we got grim news from the central mountains of Mexico , the southernmost destination for migrating monarchs and sanctuary for their winter hibernation . According to surveys carried out by World Wildlife Fund , together with Mexico 's National Commission on Protected Areas and other partners , the entire hibernating population of monarch butterflies in the 2013-2014 season occupied an area of forest not much bigger than a football field -- a mere 1.6 acres . This is a 44 % drop from the previous season , and a continuation of the freefall migrating monarchs have taken since data collection began two decades ago . 2013 was the worst year for these butterflies in recorded history . Now people are talking about the migration disappearing altogether . There are several reasons for the decline , including extreme climate events in the U.S. and Canada as well as deforestation in Mexico . Yet the biggest culprit is likely the widespread extermination of milkweed , a flowering plant critical to monarch butterfly reproduction and development . Across much of the monarch 's range , particularly in the midwestern U.S. , milkweed has fallen victim en masse to changing land use and the advent of herbicide-resistant crops . In short , the cupboard is bare for monarch caterpillars , and as a result one of North America 's most dazzling natural wonders is on the brink of vanishing entirely . If you 've been fortunate enough to witness any part of the monarch spectacle , you understand why we ca n't let this happen . Whether a blanket of orange against a deep blue sky ; a forest draped from root to leaf in dormant monarchs ; or a single butterfly fluttering past you en route to join the masses , there is nothing quite like it . The proverbial silver lining to this dark news on migratory monarch numbers is that it may have come at an opportune time . Next Wednesday , February 19 , U.S. President Obama will meet with Canadian Prime Minister Stephen Harper and Mexican President PeÃ±a Nieto at the North American Leaders ' Summit in Toluca , Mexico . Toluca is just a short distance from the monarch 's hibernation sites . During the summit , the butterflies will still be in nearby forests , poised to emerge from a four-month siesta that began in early winter . White House officials have said the three leaders will discuss `` a range of issues important to the daily lives of all of North America 's people . '' What is n't clear is whether the plight of the monarchs will make the agenda , and if the three countries bound by an age-old butterfly migration will together show resolve in making sure this unique connection is n't permanently severed . Whether monarchs flying south from Ontario , across America 's heartland to converge on the oyamel fir trees of the Sierra Madre ; gray whales hugging the California coast as they migrate from Baja to the Beaufort Sea and back again ; or pronghorn antelope clinging to strongholds from the Northern Great Plains to the Sonoran Desert , the natural bonds connecting the U.S. , Mexico and Canada stretch back millennia and transcend anything that can be traded or written on paper . They are bonds to take pride in , that unite the countries of North America in unexpected , beautiful ways . Something we simply can not let disappear . The summit in Toluca may be the last hope we have of saving the monarch migration . President PeÃ±a Nieto himself has been committed to the conservation of the monarch sanctuaries of Estado de Mexico since he served as governor there from 2005 to 2011 . He knows firsthand the significant efforts and sacrifices of Mexico 's local indigenous communities , authorities and civil society organizations to protect the sanctuaries . He also knows the important contribution the butterflies bring to local social and economic well-being . Only a joint effort from all three countries will turn the tide in favor of the monarch . Our leaders must re-energize efforts to conserve the monarch butterfly , like those under the North American Agreement on Environmental Cooperation that was born alongside NAFTA . This plan must include concrete actions to halt destruction of milkweed in the U.S. and Canada , restore monarch habitat in all three countries , and strengthen law enforcement in Mexico to stop deforestation . If together we could pull off something as big and ambitious as NAFTA , solving the monarch crisis must be within our means . We urge our heads-of-state , on behalf of all the people of North America , to use this opportunity to commit to the long-term preservation of one of our most ancient and spectacular bonds . The opinions expressed in this commentary are solely those of Carter Roberts and Omar Vidal .
President Obama and his counterparts from Canada and Mexico will be at summit . Carter Roberts , Omar Vidal : They should discuss plight of these butterflies . 2013 was the worst year for these butterflies in recorded history , they said . Roberts , Vidal : They 're a special to North America , we should stop their decline .