The 17th Conference of the Parties of the United Nations Framework Convention on Climate Change concluded in the early morning hours of Sunday December 11, after more than two weeks of intense negotiations in Durban, South Africa. I've returned to Washington and I can report that we made some very significant progress. Though I'm steeped in the climate negotiations, I know how hard it can be to make sense of the various accords and agreements and how they can help us meet the climate challenge. So let me explain why what the Durban negotiations actually constitute an important step forward. (1) For the first time, we agreed that by 2020, all countries will be covered under the same legal regime. This is a breakthrough in climate negotiations. For the past 20 years, there has been a kind of firewall between developed and developing countries, most vividly embodied by the Kyoto Protocol, where all real obligations for reducing emissions apply to developed countries. If that ever made sense, it sure doesn't make sense now at a time when China is already far larger than the United States in emissions and will be more than twice our size in this decade, and where nearly all the global growth in emissions going forward will come from developing countries. The United States has been pushing consistently, since the start of the Obama Administration, for a global accord that would cover all the major players, whether developed or developing. The so-called "Durban Platform" does that, calling for a new legal instrument "applicable to all Parties." It thus sets us on a path toward a very different kind of global agreement, whose obligations will extend to countries responsible for the vast majority of global emissions. By contrast, Kyoto in its first period (2008-2012) has applied to countries with less than 30 percent of global emissions, and in its upcoming second period will cover countries (mostly in Europe) that account for less than 15 percent of global emissions. You can't address climate change with an agreement that leaves 85 percent of global emissions on the sidelines. The Durban Platform did not seem in the cards when the conference started. But several factors combined to make it happen. First, the European Union held strong to its position that it would agree to a second Kyoto period (something developing countries very much wanted) only if others committed to negotiate a legal instrument; second, small island states, facing what they see as an existential threat, spoke with a compelling voice in demanding ambitious action; third, the United States insisted, as it has done since 2009, that any language calling for a legal outcome had to apply to developing countries, especially the majors; and fourth, the major developing countries -- China, India, Brazil, South Africa -- showed new flexibility in accepting such language in a period from 2020 forward. The road to the "Durban Platform" was anything but smooth, but, helped by a final "huddle" on the floor of the Plenary session at 4 a.m. Sunday, with the United States proposing the language that broke the final logjam, the deal got done. Under the Durban Platform, a new legal agreement is to be negotiated by the end of 2015, and will start to be implemented from 2020, after it has been approved in an adequate number of countries. (2) We made good progress in carrying forward the agreements reached last year in Cancun for countries to reduce their emissions between now and 2020 and to build key institutions of an international climate regime. Cancun wasn't a legally binding agreement, but it was enormously important nonetheless. Under it, all major players pledged to take actions to reduce their emissions, to set up a transparency regime so that all countries could have confidence that others were acting, and to set up important institutions such as a Green Climate Fund, a Climate Technology Center and Network to help disseminate green technologies, and a new Adaptation Committee. The challenge in Durban was to start making these elements operational, and this challenge was largely met. We wrote the guidelines for the new transparency regime; we approved the instrument setting up the Green Climate Fund; and we took the next steps forward on technology and adaptation, among other things. These steps will help build an international climate infrastructure, and will be crucial for driving mitigation action and supporting adaptation over the coming years. (3) Answering a red herring: we are not putting off action until 2020. I've heard some people question whether the dates embedded in Durban Platform mean that we've put off "real" action on climate until 2020. The answer is emphatically no. Look at what will be on our plates in the immediate term. First, under Cancun, all the major players pledged to implement targets or actions to reduce emissions between now and 2020. These are serious promises, so the first focus of pledging countries will be to take real action at home -- now. Second, we have to do the important, on-the-ground work of setting up the Cancun institutions discussed above. Third, donor countries agreed in Copenhagen and again in Cancun to a goal of mobilizing $100 billion a year from public and private sources by 2020, assuming adequate mitigation and transparency by developing countries. Developing and implementing a plan to do this -- one that will inevitably depend heavily on using public measures to attract private investors -- will be a major undertaking in this decade. Fourth, while all this work to make the Cancun agreements operational is going on, we will need to get going on a parallel track of work toward negotiation of the new Durban Platform agreement by 2015. In short, the idea that Durban will result in real action being put off misconceives what we have just agreed to and the full-out effort required in the here and now. So -- this coming year promises to be an important one, as we continue moving aggressively to set up the Cancun institutions and as we begin to grapple with what a new legal instrument, genuinely applying to all parties, should look like. We're in a much better place right now than most people thought possible two weeks ago. Editor's Note: This entry appeared first on the The Huffington Post.