Hello fellow scientists!Thanks to your active collaboration,our study the world's largest uncontrolled experiment.crossed a historic milestone on May 9,2013,Ahead of schedule,the concentration of carbon dioxide gas in the Earth's atmosphere has reached 400 parts per million.This is a big change from a hundred years ago,when the concentration was just 300 ppm.below which it had stayed for more than 800,00 years.

科学家们你们好!正由于你们的积极合作 我们的研究，世界上最大的不受控实验，在2013年5月9日跨过了一个新的里程碑，我们提前将地球大气中二氧化碳浓度，提高到了百万分之四百。和一百年前相比 这是个极大的变化，当时二氧化碳浓度仅为300ppm，80万年以来这个数字一直保持在300之下。

We've used the most effective methods to increase the levels of CO2 in our atmosphere.burning coal,oil and natural gas,chopping down forests,and surprisingly making cement.In some respects 400 ppm is just an arbitrary figure.an attractively round number like the four-minute mile.or the 7 billion mark for world population.but it indicates that we have reached a new phase of our experiment.

我们采用了最有效的方法来提高大气中的二氧化碳浓度：燃烧煤炭 油和天然气 砍伐森林，还有更令人惊讶的 制造水泥。在某些方面 400ppm只是一个任意设定的数字，一个吸引人的约整数 正如每英里四分钟(速度)，或者是地球人口70亿大关。但这意味着我们已经达到了实验的新一个阶段。

Each day forward,we go deeper into territory uncharted in human history!After 400ppm who knows what will happen?Actually,our preliminary results give us a pretty good idea.

日复一日 我们向人类历史的未知地域探得越深!400ppm过后 谁知道会发生什么呢?实际上 我们的初步结果已带来了比较明确的思路。

We've seen more and bigger floods,fires,droughts,and storms,Melting ice caps and rising sea levels.You may already have experienced some of these yourself,and you can expect more in the future,Please publicize our experiment and tell your friends,family and politicians how important their contributions have been.

我们已经目睹了更凶猛更频繁的洪水 大火和风暴。冰盖在融化 海平面在上升。你可能也已经亲身经历了当中的某些事情，在未来 你可以指望经历更多这样的事，请帮忙宣传我们的实验 并且告诉你的朋友 家人，以及政客们他们对实验的贡献有多重要。

After all,it is people-like you and me and major corporations-with access to cars,air conditioning supermarkets,and so on who are responsible for the large majority of today's greenhouse gas emissions.

毕竟 是人类 如你我 还有那些大公司。通过开车 开空调 去超市购物等等，是这些人对今日排放的大部分温室气体负有责任。

This global experiment can't continue without your participation.So remember,the next time you let your car idle,leave the Ac on when you're not home.or forget to eat the food you bought...yor're part of something big.

这项全球性的实验不能没有你的参与，所以请牢记 下次你让自己车闲置无用时，或是在不在家时开着空调，要么忘记吃自己带的食物，你就是那大计划的一部分。