Landmark discovery reveals region’s pivotal role in global climate evolution and early human migration
Rana Azeem TN Media Riyadh: In a groundbreaking discovery, scientists have unveiled compelling evidence of recurring humid periods that dramatically shaped the Arabian Peninsula’s climate over the past eight million years. The study, published in the prestigious journal Nature, was conducted under the Green Arabia Project and spearheaded by the Saudi Heritage Commission, marking a major advancement in understanding the region’s environmental history.
The research presents one of the longest and most accurately dated cave records ever documented from central Arabia. It involved the analysis of 22 speleothems—mineral formations found in caves—sourced from seven cave systems, with the oldest dating back 7.44 million years. These formations provide direct evidence of past periods of substantial rainfall and verdant landscapes, a stark contrast to the arid conditions that dominate the region today.
The study identified several distinct humid phases, particularly during the late Miocene, early Pliocene, and middle Pleistocene, during which rivers, lakes, and thriving ecosystems flourished across central Arabia. These wetter climates supported an array of water-dependent fauna, including now-extinct species such as crocodiles, hippopotamuses, and elephants—once roaming freely in a region now defined by deserts.
Crucially, these green corridors also likely served as key migration routes for early humans and mammals, connecting Africa with Eurasia. Fossil evidence from the Baynunah Formation and the Nefud Desert reinforces this theory, positioning the Arabian Peninsula as a vital crossroads in ancient biogeographic exchange.
Over time, however, these wet periods grew increasingly brief and less intense, reflecting a broader trend toward progressive aridification. This shift coincided with major global climate events, including Northern Hemisphere glaciation and the weakening of monsoon systems. After the mid-Pleistocene transition (around 700,000 years ago), rainfall became irregular and insufficient to sustain the once-lush environments.
Advanced isotopic analysis of the cave deposits revealed a marked decline in monsoon-fed moisture from the south, gradually replaced by limited winter rainfall from the north, signaling a significant reorganization of global atmospheric circulation patterns.
The research, carried out in the Duhool Al-Samman region northeast of Riyadh, underscores the climatic volatility of the Arabian Peninsula and its historical role in shaping ecosystems, migration pathways, and human evolution.
This milestone study not only redefines Arabia’s environmental legacy but also offers critical insights into the region’s sensitivity to global climate change, providing valuable context for understanding future environmental transformations.
