Trends of halocarbons in the Himalayan atmosphere and implications

: Halocarbons are the primary driver behind ozone depletion and global warming. There is a vast observation gap in the Himalayan region. We report the field observations of thirty-four halocarbons at Nepal Climate Laboratory-Pyramid station and near the Mt. Qomolangma (Everest) base camp in the high Himalayas, including their atmospheric abundance and related changes over time. The dominant ozone depleting substances (ODSs) exhibited a declining trend, reflecting the effectiveness of the Montreal Protocol. However, a larger increase in HFCs and a higher abundance of unregulated chlorocarbons (e. g., CH3Cl) in this region compared to the global and North-Hemisphere values were found. It underscores that more attention is needed, not only for knowing where and how much HFCs and unregulated chlorocarbons are being emitted, but also for understanding its complicated role in climate change.