在2015年12月大会召开之前，这190个国家中已有187个做出行动承诺。这些计划为减少温室气体排放形成了一个持久的长期框架，并为各国将全球气温上升控制在两摄氏度以下的共同努力奠定了基础。

究竟如何切实实现我们的未来低碳目标呢？可以从小事做起。各国政府都已承诺做好自己的工作，但它们的行动可能会比较缓慢。国家政策需要时间才能通过立法和实施程序。但是较小的实体 ―― 城市、各州、企业和院校 ―― 则可以更加迅速地行动，而且它们已经完成了许多工作。

市长们齐心协力

世界各地的城市已经开始采取行动。在美国，有117名市长签署了《市长契约》(Compact of Mayors)，承诺推行标准化政策，计量温室气体排放量，并向公众报告减少各城市碳足迹的努力的成效。美国的市长们通过诸如“C40城市气候领袖集团”(C40 Cities Climate Leadership Group)等组织与世界各地的同行们进行交流。洛杉矶(Los Angeles)、墨西哥城(Mexico City)、新德里(New Delhi)、北京和里约热内卢(Rio de Janeiro)都有类似的污染问题，它们也共享解决方案。

控制在两摄氏度以下

这里说的是摄氏度。“地方性全球气候问题领袖谅解备忘录”( Subnational Global Climate Leadership Memorandum of Understanding)，也称为“低于2摄氏度谅解备忘录”(Under 2 MOU)，是从美国的加利福尼亚(California)与德国的巴登-符腾堡(Baden-Württemberg)这两个州之间的伙伴合作开始的。后来不断扩展包括了世界其他的国家和地区。美国的一些州，如俄勒冈州(Oregon)、佛蒙特州(Vermont)、华盛顿州(Washington)、明尼苏达州(Minnesota)、新罕布什尔州(New Hampshire)和纽约州(New York)也都已经签署了协议，保证到2050年将温室气体排放量减少到1990年水平以下的80％至95％，并在相互分享技术和科研成果。签约方还承诺增加零排放车辆的数量并减少其他污染物 ―― 以及报告所取得的成效。

公司企业采取气候行动（#ActOnClimate）

154家美国公司 ―― 包括那些大公司如苹果公司(Apple)、嘉吉公司(Cargill)、可口可乐(Coca-Cola)、脸书(Facebook)、谷歌(Google)、利伐-斯特劳斯(Levi Strauss)、麦当劳(McDonald’s)、微软(Microsoft)和沃尔玛(Wal-Mart) ―― 都在2015年就“美国企业采取气候行动”（American Business Act on Climate）做出承诺，减少排放、增加低碳投资、增加清洁能源的使用并在可持续商业实践方面引领前行。

• 苹果公司在美国的业务已经在100％地使用可再生能源运营。 自2011年以来，该公司已将其全球各生产设施的二氧化碳排放量减少了48%。
• 嘉吉公司在10年的时间里将能源效率提高了16％，并已设定2020年的新目标，例如将可再生能源占能源使用总量的比例从14％提高到18%。该公司也在努力阻止在具生态价值的土地上进行砍伐。
• 麦当劳集团承诺，到2020年它所使用的棕榈油、纤维、牛肉和咖啡产品都将是100%以环境可持续性方式生产的。该公司还在努力提高能源效率及使用可再生能源。
• 沃尔玛在美国的商店和设施都有实地太阳能项目，并将到2020年增加一倍。它还要求供应商在跟踪和减少温室气体排放数量方面提高透明度。

作出承诺的企业在美国所有50个州及世界各地运营。这些公司总共雇用了近一千一百万员工，拥有超过4.2万亿美元的年收入，它们加在一起的总市值超过7万亿美元。

高校加入行动行列

在通往零排放前景的道路上一路领先的是美国的学院和大学，其中311所院校已加入了“美国大学采取气候行动承诺”(American Colleges Act on Climate Pledge)。

加州大学(University of California)所有10个分校以及加州州立大学(California State University)的23个分校都已签署了这一承诺，其中许多学校已经提前达到零排放目标，这要归功于整个大学系统内的可持续性政策。（请见英文报道）

加州大学欧文分校(UC Irvine)还开设了有关环境可持续性发展的领导力课程。加州大学戴维斯分校(UC Davis)已与中国合作，加速零排放汽车的开发（请见英文报道）。而麻省理工学院(Massachusetts Institute of Technology)、斯坦福大学(Stanford)、哈佛大学(Harvard)、耶鲁大学(Yale)以及纽约州立大学(State University of New York)的48个分校也都在加快使用清洁能源及采取可持续性举措。

The agreement recently adopted by more than 190 countries at the U.N. climate conference in Paris is the most ambitious climate pact yet.

Action pledges came from 187 of those 190 countries before the December 2015 conference. The various plans built a durable, long-term framework to reduce greenhouse gases and laid a foundation for countries to work together to hold the rise in global temperature to below 2 degrees Celsius.

How will our low-carbon future be achieved, in real terms? It will start small. National governments are committed to do their parts, but they can be slow. Their policies take time to move through the lawmaking and implementation processes. But smaller entities — cities, states, businesses and colleges — can move more quickly and are already getting things done.

Mayors unite

Cities around the world are already acting. In the United States, 117 mayors have signed aCompact of Mayors pledge to implement standardized policies, measure greenhouse gas emissions and report publicly on efforts to lower their cities’ carbon footprints. U.S. mayors talk with their counterparts around the world through organizations such as the C40 Cities Climate Leadership Group. Los Angeles, Mexico City, New Delhi, Beijing and Rio de Janeiro share similar pollution problems, and they also share solutions.

Keep it under 2

Degrees Celsius, that is. The Subnational Global Climate Leadership Memorandum of Understanding, also called the Under 2 MOU, started as a partnership between the states of California, in the USA, and Baden-Württemberg, in Germany. It expanded to include other states and regions across the globe. Oregon, Vermont, Washington, Minnesota, New Hampshire and New York are among the U.S. states that have signed the agreement to cut greenhouse gas emissions 80 to 95 percent below 1990 levels by 2050 and to share technology and scientific research. Signatories also commit to increase the number of zero-emissions vehicles and reduce other pollutants — and report their results.

Businesses #ActOnClimate

High-powered corporations — including Apple, Cargill, Coca-Cola, Facebook, Google, Levi Strauss, McDonald’s, Microsoft and Wal-Mart — are among 154 American companies who took the American Business Act on Climate Pledge in 2015. They are reducing emissions, increasing low-carbon investments, stepping up clean-energy use and becoming leaders in sustainable business practices.

• Apple’s U.S. operations already run on 100 percent renewable energy. Since 2011, the company has reduced carbon emissions from its global facilities by 48 percent.
• Cargill improved energy efficiency by 16 percent in 10 years and has set new goals through 2020, such as boosting renewable energy from 14 to 18 percent of total energy use. It is also working to stop deforestation of ecologically valuable lands.
• McDonald’s pledges that by 2020, 100 percent of its palm oil, fiber, beef and coffee supplies will be produced in environmentally sustainable ways. The company also aims to increase energy efficiency and renewable energy sources.
• Wal-Mart has on-site solar energy projects at its U.S. stores and facilities and will double the number by 2020. It asks suppliers for transparency in tracking and reducing greenhouse gas emissions.

Pledging companies operate in all 50 U.S. states and around the world. In all, they employ nearly 11 million people, have more than $4.2 trillion in annual revenue, and have a combined market capitalization exceeding $7 trillion.

Higher ed is on board

Leading the way to a zero emissions future are U.S. colleges and universities, 311 of which joined the American Colleges Act on Climate Pledge.

All 10 University of California campuses and all 23 California State University campuses signed on, many of which are ahead of their deadlines in meeting zero-emissions goals, thanks to the universitywide sustainability policy.

UC Irvine even offers a curriculum on environmental-sustainability leadership. UC Davis haspartnered with China to put zero emission vehicles on a fast track. And the Massachusetts Institute of Technology, Stanford, Harvard, Yale and 48 State University of New York campuses are among schools accelerating their use of clean energy and sustainability practices.