The world’s thickest continuous loess record retrieved from the southern margin of the Taklimakan Desert has provided evidence that global cooling could be a key factor in climate changes in inland Asia since ~3.6 Ma, according to
a recent study published in Proceedings of the National Academy of Sciences of the United States of America.
“MLA is a key source of global atmospheric dust, which is strongly influenced by westerlies-controlled climate and has a great potential impact on oceanic biogeochemical activity. But the evolution of westerlies, MLA aridity, and dust flux in this region over time remains unclear,” said FANG Xiaomin.
The 3.6-million-year-old eolian dust accumulation in the region indicates that MLA had a dry climate, desert area, and stable land surface, which are correlated with aridity and changes in the westerlies. More specifically, based on Fang’s research, MLA experienced long-term stepwise drying at ~2.7 Ma, 1.1 Ma, and 0.5 Ma, coeval with a dominant periodicity shift from 41-ka cyclicity to 100-ka cyclicity between 1.1 Ma and 0.5 Ma.
These features match well with global ice volume variability both in time and frequency, added Fang, which signals the existence of global cooling-forced aridity and westerlies climate changes in these timescales.
To understand the interactions among westerlies, MLA climate changes and global cooling, Fang and his colleagues designed a numerical model and found that global cooling would dry the MLA and intensify westerlies, which in turn would reinforce cooling by facilitating dust emission and transport.
“There could be positive linkages and feedback among dust emission, marine biogeochemical activity, atmospheric CO2, and global cooling,” said FANG.“This finding could provide the basis for further study of the dynamics of Earth’s climate system and improve predictions for the future.”
Editor’s note: This study is supported by Pan-TPE, a TPE-related science project.
