Shift in Earth's Orbit Transformed 'Green Sahara' into Planet's Largest Desert
Changes in the Earth’s tilt cause changes in weather patterns. Such a change is believed to have made the “Green Sahara” go dry. A change in the Earth’s orbit, many scientists believe, transformed the “Green Sahara” into what is now the largest desert on the planet. While scientists are still trying to find out if the slow shift in orbit had rapid or gradual environmental consequences, they say Earth’s orbit will continue to change today and into the future.
The Sahara, the world's largest desert, was once fertile grassland. This fact has been common knowledge in the scientific community for some time, but scientists are still grappling with historic data to determine whether that transition took place abruptly or gradually. At the European Geosciences Union General Assembly held in Vienna, Austria earlier this year, researchers presented new evidence showing that the eastern region of the Sahara desert, particularly the area near Lake Yoa in Chad, dried up slowly and progressively since the mid-Holocene period.
Francus explained that abrupt climate changes have been documented in many places on Earth at various times in the past. One example he cited is the Younger Dryas, one of the most famous examples of abrupt climate change that occurred between (approximately) 12,800 and 11,500 years ago. According to the National Oceanic and Atmospheric Administration, the end of this period was particularly abrupt when, for example, in Greenland, temperatures increased 18 degrees Fahrenheit in about a decade.
“Many scientists think that abrupt climate changes are possible in the future, but the nature, direction and intensity of these changes will most probably be region-dependent,” Francus said. Francus also noted that there are some models that cannot predict an abrupt climate shift at all. Some scientists feel that there is not enough knowledge to understand the processes driving these changes primarily because it is difficult to model the soil moisture and cover.
