Causal Pathways connecting Indian summer monsoon to the Arctic sea ice decline

The Indian Summer Monsoon (ISM) is one of the most energetic components of the Earth system observed during the boreal summer. As a crucial freshwater source and a lifeline for billions, the ISM has been extensively studied to understand its variability and improve its predictability. However, accurately predicting the ISM remains challenging due to the shifting dynamics of established drivers and the increased influence of emerging teleconnection patterns. In recent years, the Arctic region, a hotspot of climate change, has emerged as a driver of global climate, with its influence hypothesized to extend from the mid-latitudes to the tropics. The strength of the large-scale ISM circulation has been found to influence summer Arctic sea ice through the monsoon-desert mechanism. Understanding and quantifying the two-way interactions between Arctic and ISM systems is crucial, as these teleconnections may help improve the predictions of extreme weather events and seasonal forecasts. Although a few studies have focused on quantifying the association between Arctic sea ice and the Indian Summer Monsoon, the causal mechanisms are yet to be fully explored. Traditional statistical methods for analyzing climate variability have primarily relied on correlations and composite analysis, which have several limitations. This study quantifies the Arctic-ISM teleconnections using a causal inference approach. This technique allows us to evaluate the importance and magnitude of tropical and extratropical drivers of ISM circulation and seasonal variability while controlling for confounding mechanisms. Furthermore, we examine the role of state dependencies, such as the phase of ENSO in modulating the strength of these causal pathways.