2023-10-12 オークリッジ国立研究所(ORNL)
◆気象変動を理解し、気候変動がこの不安定性にどの程度寄与するかを明らかにすることが重要です。研究は、海洋と大気の要因、特にエルニーニョ・サザンオシレーション（ENSO）や気象パターンの影響を分析し、気候要因の影響が21世紀に増加していることを示しています。気候変動が降水量の増加に寄与する可能性もあるが、詳細な調査が必要です。
＜関連情報＞
- https://www.ornl.gov/news/new-study-reveals-influence-natural-climate-drivers-extreme-monsoons-pakistan
- https://www.nature.com/articles/s41612-023-00462-8
パキスタンの異常モンスーンにおける自然変動の影響 The influence of natural variability on extreme monsoons in Pakistan
Moetasim Ashfaq,Nathaniel Johnson,Fred Kucharski,Noah S. Diffenbaugh,Muhammad Adnan Abid,Matthew F. Horan,Deepti Singh,Salil Mahajan,Subimal Ghosh,Auroop R. Ganguly,Katherine J. Evans & Shafiqul Islam
npj Climate and Atmospheric Science Published:21 September 2023
DOI:https://doi.org/10.1038/s41612-023-00462-8
Abstract
The monsoons in Pakistan have been exceptionally harsh in recent decades, resulting in extraordinary drought conditions and record flooding events. The changing characteristics of extreme events are widely attributed to climate change. However, given this region’s long history of floods and droughts, the role of natural climate variability cannot be rejected without a careful diagnosis. Here, we examine how oceanic and atmospheric variability has contributed to unusual precipitation distributions in West South Asia. Variations in sea surface temperatures in the tropical Pacific and northern Arabian Sea, and internal atmospheric variability related to the circumglobal teleconnection pattern and the subtropical westerly jet stream, explain more than 70% of monthly summer precipitation variability in the 21st century. Several of these forcings have co-occurred with record strength during episodes of extreme monsoons, which have exacerbated the overall effect. Climate change may have contributed to increased variability and the in-phase co-occurrences of the identified mechanisms, but further research is required to confirm any such connection.
