The oceans are rising faster than at any point in the last 28 centuries, and human emissions¹ of greenhouse gases are primarily responsible, scientists reported Monday.

科学家本周一表示，海平面目前上升的速度比过去28个世纪中的任何时候都要快，而罪魁祸首就是人类排放的温室气体。

They added that the flooding that is starting to make life miserable² in many coastal³ towns — like Miami Beach; Norfolk, Va.; and Charleston, S.C. — was largely a consequence⁴ of those emissions, and that it is likely to grow worse in coming years.

他们还表示，洪水正在让很多沿海城镇的生活苦不堪言——比如迈阿密海滩、弗吉尼亚州的诺福克，还有南卡罗来纳州的查尔斯顿——这主要是人为排放导致的，而且情况很可能在未来的年份里恶化。

The scientists confirmed previous estimates, but with a larger data set, that if global emissions continue at a high rate over the next few decades, the ocean could rise as much as three or four feet by 2100, as ocean water expands and the great ice sheets in Greenland and Antarctica begin to collapse⁵.

科学家们证实了先前的估算，但现在他们采用了一个更大的数据库。这种估算认为，如果全球温室气体排放的速率继续在未来的几十年中保持在较高水平，那么随着海水膨胀、格陵兰岛和南极洲的巨大冰盖崩塌，海平面可能会到2100年上升多达3到4英尺。

Experts say the situation will grow far worse in the 22nd century and beyond, likely requiring the abandonment of many of the world’s coastal cities.

专家们称，这种情况将自22世纪起严重恶化，世界各地的人们可能会被迫放弃很多沿海城市。

“I think we can definitely be confident that sea-level rise is going to continue to accelerate if there’s further warming, which inevitably⁶ there will be,” said Stefan Rahmstorf, a professor of ocean physics at the Potsdam Institute for Climate Impact Research in Germany and co-author of a paper released Monday by the Proceedings⁷ of the National Academy of Sciences.

“我认为，我们绝对可以相信，如果出现进一步升温，海平面上升的速率将会继续加快，而进一步升温在所难免，”德国波茨坦气候影响研究所(Potsdam Institute for Climate Impact Research)的海洋物理学教授斯特凡·拉姆斯托夫(Stefan Rahmstorf)说。他是《美国国家科学院院刊》(The Proceedings of the National Academy of Sciences)本周刊登的一篇相关论文的合著者。

“Ice simply melts faster when the temperatures get higher,” Dr. Rahmstorf added. “That’s just basic physics.”

“随着温度的升高，冰融化的速度就会加快，”拉姆斯托夫博士说。“这是简单的物理现象。”

In a report issued at the same time as the scientific paper, a climate research and communications organization in Princeton, N.J., Climate Central, used the new findings to calculate that roughly three-quarters of the tidal floods now occurring in towns along the American East Coast would not be happening in the absence of sea-level rise caused by human emissions.

这篇科学论文问世的同时，新泽西州普林斯顿的气候研究与沟通机构气候中心(Climate Central)也发表了一篇报告。文中使用这些新的结论来计算潮汐洪水，发现如果没有人为排放造成的海平面上升，美国东海岸城镇目前的潮汐洪水中，大约有四分之三都不会发生。

The lead author of that report, Benjamin H. Strauss, said the same was likely to be true on a global scale, in any coastal community that has seen an increase of saltwater flooding in recent decades.

该报告的第一作者本杰明·H·施特劳斯(Benjamin H. Strauss)表示，在全球范围内，情况很可能也是一样的，很多海岸社区近几十年经历了潮汐洪水的增多。

Local factors do come into play, though: Communities on land that is sinking, as in the Chesapeake Bay region of the United States, are being hit especially hard by the rising sea level.

不过，其中也有局地因素在起作用：一些陆地区域正在下沉，比如在美国的切萨皮克湾地区，对于他们来说，海平面上升的打击尤为严重。

Tidal floods are occurring more frequently, and are becoming a strain in many towns by killing⁸ lawns and trees, polluting supplies of fresh water, blocking streets in the middle of sunny afternoons and sometimes stranding⁹ entire island communities for hours by covering the roads to the mainland.

潮汐洪水出现得更加频繁，正在成为很多城镇的心腹之患。它们危害草坪和树木，污染淡水供应，在阳光明媚的下午造成街道阻塞，海水漫过陆上道路，有时会让整个岛屿社区瘫痪好几个小时。

“I think we need a new way to think about most coastal flooding,” Dr. Strauss said in an interview. “It’s not the tide. It’s not the wind. It’s us. That’s true for most of the coastal floods we now experience.”

“我认为，对于多数的沿海洪水，我们需要采取新的思考方式，”斯特劳斯博士在接受采访时说。“原因不是海潮，也不是风，而是我们。对于目前的大多数沿海洪水来说，这就是事实。”

The new research was led by Robert E. Kopp, an earth scientist at Rutgers University who has won respect from his colleagues by bringing elaborate statistical¹⁰ techniques to bear on longstanding problems, like understanding the history of global sea level.

这项新的研究由罗格斯大学(Rutgers University)的地球科学家罗伯特·E·科普(Robert E. Kopp)牵头进行。他将精密的统计学技术应用于一些长期存在的问题，比如怎样了解全球海平面的历史，赢得了同行的敬重。

Scientists already knew that the sea level rose drastically at the end of the last ice age, by almost 400 feet, causing shorelines to retreat by up to 100 miles in places. They also knew that the sea level had basically stabilized¹¹, like the rest of the climate, over the past several thousand years, the period when human civilization arose and spread across the earth.

科学家们已经知道，海平面在最后一个冰河时代结束时大幅上升了近400英尺（约合120米），造成有些地方的海岸线向陆地推进了至多100英里（约合160公里）。他们也知道，在过去几千年中，海平面就像其他气候元素一样，基本趋于稳定。人类文明在这期间崛起，蔓延到地球各处。

There were small variations of climate and sea level over that period, and several recent papers have tried to clarify these. The new paper confirms a central finding of the earlier research, that the sharp increase of sea level in the 20th century was unprecedented¹² over thousands of years, but does so with a larger data set that may add to the confidence scientists place in the results.

在此期间，气候和海平面出现过一些微小的变化，最近刊出的几篇论文试图在这些方面做出清晰的解释。这篇新的论文证实了早前研究的一个核心发现，即海平面在20世纪的急剧上升是几千年来前所未有的，但是文中采用了一个更大的数据库来证实这个发现，可能会增加科学家给这一结论的置信度。

The paper confirms that the ocean is exquisitely¹³ sensitive to small variations in the earth’s temperature — a portentous¹⁴ finding, given that human emissions are inducing a large temperature rise.

该论文确认，海洋对地球温度的微小变化非常敏感——鉴于人类排放在导致温度大幅上升，这个发现令人担忧。

The researchers found that when the average global temperature fell by a third of a degree Fahrenheit¹⁵ in the Middle Ages, for instance, ice started to build up on land, and the volume of ocean water contracted, causing the average surface of the ocean to fall by about three inches over 400 years. When the climate warmed slightly, that trend reversed.

例如，研究人员得出结论，在中世纪，全球平均气温下降了0.2摄氏度，陆冰开始增加，海水总量减少，导致海平面在400年的时间里平均下降了大约8厘米。当气候略微转暖时，这一趋势便出现逆转。

“Physics tells us that sea-level change and temperature change should go hand in hand,” Dr. Kopp said. “This new geological record confirms it.”

“物理学告诉我们，海平面变化和温度变化是同进同退的，”科普博士说。“新的地质记录证实了这个说法。”

In the 19th century, as the Industrial Revolution took hold, the oceans began to rise, and have gone up by about eight inches since 1880. That may sound small, but the increase has caused extensive erosion worldwide, and governments are spending billions of dollars to try to shore up beaches and other coastal defenses.

19世纪工业革命开始兴起，海平面也开始上升，自1880年以来已经上升了约20厘米。这个幅度听上去可能不大，但却在世界各地引发了广泛侵蚀，各国政府花费了数以亿计的资金来加固海滩，强化其他沿海防御措施。

Largely because of human emissions, global temperatures have jumped by about 1.8 degrees Fahrenheit since the 19th century. Land ice has started to melt all over the planet, and seawater is expanding as it absorbs heat. The seas are rising at what appears to be an accelerating pace, lately reaching a rate of about a foot per century.

自19世纪以来，全球气温大幅上升了约1摄氏度，这主要是人为排放造成的。全球各地的陆冰开始融化，海水吸收热量后膨胀。海平面日益上升，而且节奏似乎正在不断加快，近期达到了每世纪约30厘米的速度。

One of the authors of the new paper, Dr. Rahmstorf, had previously¹⁷ published estimates suggesting the seas could rise as much as five or six feet by 2100. But with the improved calculations from the new paper, his latest upper estimate is three to four feet.

这篇新论文的作者之一拉姆斯托夫之前曾发表估算文章，其中表示，到2100年时，海平面会上涨至多五六英尺，但依据这篇新的论文，他估计上限会在三到四英尺之间。

That means Dr. Rahmstorf’s estimate is now more consistent with calculations issued in 2013 by the Intergovernmental Panel on Climate Change, a United Nations body that periodically reviews and summarizes climate research. The panel found that continued high emissions might produce a sea rise of 1.7 to 3.2 feet over the 21st century.

这意味着，拉姆斯托夫现在的估计和政府间气候变化专门委员会（ Intergovernmental Panel on Climate Change，简称IPCC）2013年发布的计算结果更趋一致。IPCC是联合国机构，定期回顾和总结气候研究。它发现，持续的高排放可能会导致海平面在21世纪上升53厘米到92厘米。

Dr. Rahmstorf said, however, that the rise would eventually exceed three feet — the only question is how long it will take. The recent climate agreement negotiated in Paris, if acted upon, will bring emissions down enough to slow the rate of sea-level rise in coming centuries, but scientists say the deal was not remotely ambitious enough to forestall¹⁸ a significant melting of the Antarctic and Greenland ice sheets.

不过，拉姆斯托夫称，上升幅度最终会超过3英尺——唯一的问题是这需要多长的时间。如果按照最近在巴黎达成的气候协议采取行动，把排放量降至足够低的程度，那么未来几个世纪的海平面上升速率就会放缓。但科学家们表示，这份协议远不足以阻止南极和格陵兰冰盖融化。

On a geologic¹⁶ time scale, the recent, human-induced planetary warming has been quite sudden, and the huge ice sheets have only just started to respond.

从地质时间的尺度来看，近来人类活动引起的地球变暖现象是相当突然的，巨大的冰盖这才刚刚开始有所反应。

The upper estimate of three to four feet of sea-level rise in the 21st century rules out any large contribution from Antarctica in the near term, but that finding is tentative, given that the ice covering the western part of that continent is already showing signs of instability. And recent studies suggest that the destruction of large parts of the Antarctic ice sheet may have become inevitable¹⁹, even though that could take hundreds or thousands of years to play out.

在估计21世纪海平面的上升上限为3到4英尺时，科学家排除了南极冰会在近期大幅融化的情景。但这只是个假设，覆盖在南极大陆西部的冰已经显示了不稳定迹象。近期的研究表明，南极大片地区的冰盖遭到破坏或许已经成为必然，尽管这一过程可能要延续数百或数千年的时间。

“Sea level is going to continue going up for many centuries,” Dr. Rahmstorf said.

“海平面将持续上升很多个世纪，”拉姆斯托夫说。