New Orleans , Louisiana ( CNN ) -- Copenhagen , Denmark , is 5,000 miles away from New Orleans , Louisiana . But representatives of the 192 nations gathering this week at the climate change conference need to keep the memory of a flooded New Orleans in mind . Two years ago this month , the Make It Right Foundation was launched to help the families of New Orleans ' Lower 9th Ward rebuild their lives and community . That was already two years after Katrina , and the once-vibrant neighborhood was still in ruins , failed by government and frustrated by a lack of progress . Working with the Lower 9th Ward community , with families who lost everything in Katrina , with cutting-edge architects and inventive builders , we learned some truths and made some discoveries we would like to share with the climate change negotiators in Copenhagen : . We need urgent action . Climate change is real and happening now . The world already is reeling from the consequences -- rising sea levels , more violent storms , more frequent flooding and prolonged droughts . Hurricane Katrina , the killer heat wave in Europe , China 's floods and the enduring drought in Australia are not anomalies , they are harbingers . It is not enough to attack what causes global warming ; we also must prepare to live with it . We must reduce carbon emissions and adapt to the changing climate . Even if greenhouse gas emissions stopped increasing today , the climate would continue to change for generations because of the gases that are already in the atmosphere . People will go home , even if home is in harm 's way . The pull of family , friends and happy memories proved irresistible for many in the Lower 9th Ward . The common history and culture of any community will keep people living in flood plains , along earthquake faults , and on shorelines , if those places are home . More people are moving into harm 's way . The number of people who live at the water 's edge will continue to grow . The Lower 9th Ward is not unique -- more than 50 percent of America 's population lives within 50 miles of a coast , according to the National Oceanic and Atmospheric Administration . The same percentage applies to the world 's population . In the United States , NOAA predicts the number will rise as high as 75 percent by 2050 or sooner . Governments were formed to protect their citizens -- and not just from armed marauders . Solutions exist to protect people and allow them to live safely in their homes . The consequences of climate change require every community to make changes that will increase safety and survivability . In post-Hurricane Katrina New Orleans , we are building affordable homes designed to use less energy , reduce carbon emissions and run on solar power , as well as weather the next storm . Our storm-resistant features include high foundations to keep homes well above base flood levels ; hurricane-resistant fabric to protect windows ; increased structural durability to withstand 130-mph or higher winds ; and access to the rooftop -- because so many of Katrina 's victims died trapped in their attics . This approach should be adopted by coastal-area builders around the globe . Government has a unique and powerful role to play . Individual actions add up , but they pale compared to the reach and resources of government . We saw firsthand after Katrina how deadly and devastating it can be for a government to fail its citizens . Today , we still see boarded-up houses , razed landscapes and blighted neighborhoods across New Orleans -- over four years after the Army Corps of Engineers-built levees failed . There are large-scale solutions that only governments can provide -- such as setting emissions standards and initiating adaptation measures . These options are available to the participants in Copenhagen . It is time for the world 's governments to step up . We are facing the most serious challenge to the health and well-being of the world since World War II . But instead of putting shoulders to the wheel , the leaders of the world are busy lowering expectations and tempering outcomes . Instead , we ask them to act with urgency to reduce greenhouse gas emissions and embrace solutions that will help our children survive and thrive in a changing climate . They have the power to put the planet on a smarter , safer path to a low-carbon future and to protect us and generations to come . We ask them to use it . To quote Richard B . Alley , a climate-change expert from Penn State University , `` This is real , this is real , this is real . So act now , the ball 's in your court . '' The opinions expressed in this commentary are solely those of Tom Darden .
Tom Darden directs foundation that helps New Orleans residents rebuild their community . He says Hurricane Katrina , flooded New Orleans offer lessons for Copenhagen meeting . Darden : World is reeling from global warming ; effects will continue and we must adapt . Solutions exist , but it 's time for the international community to step up , he says .