位于阿曼和迪拜酋长国边界的鲁卜哈利沙漠 Rub' al Khali desert on the border of Oman and the Emirate of Dubai (© Daniel Schoenen/Offset by Shutterstock)

位于阿曼和迪拜酋长国边界的鲁卜哈利沙漠 Rub' al Khali desert on the border of Oman and the Emirate of Dubai (© Daniel Schoenen/Offset by Shutterstock)

Signs of life in the 'Empty Quarter'

An unlikely tree stands amid the seemingly endless dunes of the Rub' al Khali desert in the Arabian Peninsula. The Rub' al Khali, meaning the 'Empty Quarter,' is a vast sea of sand. Spreading across 250,000 square miles, it's the largest contiguous sand desert in the world, covering most of southeastern Saudi Arabia, with smaller portions in Yemen, Oman, and the United Arab Emirates. One of the driest places on Earth, almost no one lives in Rub' al Khali, and much of the desert remains unexplored. Some of the dunes tower more than 800 feet, and the depressions in between—called sabkhas—can be so soft that vehicles, camels, and people can easily become stuck.

The Rub' al Khali wasn't always so forbiddingly dry. At various times between 2,000 and 6,000 years ago, 'cataclysmic rainfall,' like modern-day monsoons, formed shallow lakes in the spaces between the dunes. Most of these lakes were temporary, but some lasted hundreds of years and supported a variety of plants and animals, even large creatures like hippopotamuses, water buffalo, and long-horned cattle. Rain isn't unheard of today, either. In May 2018, Cyclone Mekunu brought enough rain to once again form lakes in the Rub' al Khali, reportedly the first time that had happened in about 20 years—it was the rare occasion when the 'Empty Quarter' wasn't looking so empty after all.

“空旷地区”的生命迹象

阿拉伯半岛的鲁布阿勒哈利沙漠看似无边无际的沙丘中矗立着一棵不太可能的树。“鲁布”阿勒哈利，意思是“空区”，是一片广阔的沙海。它横跨250000平方英里，是世界上最大的连片沙漠，覆盖沙特阿拉伯东南部大部分地区，也门、阿曼和阿拉伯联合酋长国的面积较小。作为地球上最干燥的地方之一，鲁巴勒哈利几乎无人居住，而大部分沙漠仍未被勘探。有些沙丘高达800英尺以上，中间的洼地称为沙布喀，非常柔软，车辆、骆驼和人很容易被卡住。

阿勒哈利河并不总是那么干燥。在2000年至6000年前的不同时期，“灾难性降雨”就像现代季风一样，在沙丘之间形成了浅湖。这些湖泊大多是临时性的，但也有一些持续了数百年，供养着各种动植物，甚至还有河马、水牛和长角牛等大型动物。今天下雨也并非闻所未闻。2018年5月，梅库努气旋带来了足够的雨水，再次在鲁布阿勒哈利形成湖泊，据报道这是大约20年来首次发生，这是罕见的“空旷区”看起来不再那么空旷的情况。