The Arabian Desert, now the largest expanse of sand dunes on Earth, experienced periods of humidity millions of years ago, as evidenced by mineral formations in caves beneath the Arabian Peninsula. These speleothems, such as stalagmites and stalactites, provide evidence of repeated humid periods dating back nearly 8 million years. Through uranium dating techniques, researchers were able to precisely determine the ages of these speleothems, offering one of the oldest climate records for the region.
Some researchers believe that the existence of speleothems in caves is indicative of a once-green Arabia, which required rainwater, vegetation, and soil for their formation. By studying oxygen isotopes in the speleothems, the team could estimate the amount of rainfall that occurred during specific periods. These findings suggest that the Arabian Desert was not always as barren as it is today but went through cycles of wetter, more hospitable environments.
These humid periods in the Arabian Desert may have been influenced by slow, cyclical changes in Earth’s orbit, which altered the amount of sunlight reaching the planet over tens of thousands of years. Researchers suggest that a warmer North Atlantic during these periods shifted weather patterns, bringing monsoons to Arabia from the south. These monsoons led to the creation of lakes, rivers, and grasslands, attracting mammals and hominids to the region.
Archaeological evidence from the United Arab Emirates, such as 7-million-year-old fossils of hippos, elephants, and giraffes, challenges previous notions that the Arabian Peninsula was always a desert barrier. Researchers now believe that Arabia was a verdant crossroads between Africa and Asia, supporting a rich ecosystem that encouraged migrations of various species over time, including hominids.
The new research fills a gap in our understanding of Arabia’s climate history, according to experts not involved in the study. However, further research is needed to paint a complete picture of what the landscape looked like in the past and whether it could have served as a gateway for species, including hominids, to move between Africa and Asia. By investigating the ancient climate of Arabia, researchers hope to gain insights into how mammals survived and thrived in what is now a harsh desert environment.
