Climate change increased extreme monsoon rainfall, flooding highly vulnerable communities in Pakistan

Abstract

As a direct consequence of extreme monsoon rainfall throughout the summer 2022 season Pakistan experienced the worst flooding in its history. We employ a probabilistic event attribution methodology as well as a detailed assessment of the dynamics to understand the role of climate change in this event. Many of the available state-of-the-art climate models struggle to simulate these rainfall characteristics. Those that pass our evaluation test generally show a much smaller change in likelihood and intensity of extreme rainfall than the trend we found in the observations. This discrepancy suggests that long-term variability, or processes that our evaluation may not capture, can play an important role, rendering it infeasible to quantify the overall role of human-induced climate change. However, the majority of models and observations we have analysed show that intense rainfall has become heavier as Pakistan has warmed. Some of these models suggest climate change could have increased the rainfall intensity up to 50%. The devastating impacts were also driven by the proximity of human settlements, infrastructure (homes, buildings, bridges), and agricultural land to flood plains, inadequate infrastructure, limited ex-ante risk reduction capacity, an outdated river management system, underlying vulnerabilities driven by high poverty rates and socioeconomic factors (e.g. gender, age, income, and education), and ongoing political and economic instability. Both current conditions and the potential further increase in extreme peaks in rainfall over Pakistan in light of anthropogenic climate change, highlight the urgent need to reduce vulnerability to extreme weather in Pakistan.

The Pakistan Flood of August 2022: Causes and Implications

“…The 2022 flood event caused significant mortality (∼1,739 human lives) and ranks second after the major floods in 2010 (1,985 human lives) (Table 1, EMDAT). The flood inundation caused the formation of a massive lake in the Sindh and Balochistan provinces (L Otto et al., 2022; Mallapaty, 2022) (Figure 1). The densely populated area on the right bank of the Indus was submerged, and the event affected 33 million people across several considerably populated cities (Figure 1b).…”

“…In the third category, moisture convergence from the Arabian sea and the Bay of Bengal, together with upper atmospheric circulation like the jet stream, causes precipitation over Pakistan. In 2022, most depressions formed over the Bay of Bengal converged to the southern provinces without moving to the north or eastern sides of Pakistan (L Otto et al., 2022; PMD, 2022), which is in contrast to extreme precipitation during the 2010 event. Ullah et al.…”

“…The “monsterˮ flood of August 2022 in Pakistan, preceded by a devastating heat wave in May, has disproportionately impacted the country’s southern provinces (Bhutto, 2022; Jones, 2022; L Otto et al., 2022). The flood affected one‐third of the fifth largest populous country in the world, internally displacing about 32 million people and causing 1,486 deaths, which include 530 children (Bhutto, 2022; Khokhar, 2022; NDMA, 2022; UNICEF, 2022).…”

“…The flood affected one‐third of the fifth largest populous country in the world, internally displacing about 32 million people and causing 1,486 deaths, which include 530 children (Bhutto, 2022; Khokhar, 2022; NDMA, 2022; UNICEF, 2022). The economic losses are estimated to be over $30 billion (Bhutto, 2022; L Otto et al., 2022). In addition to the direct impacts, famine due to the widespread devastation of agricultural fields and possible disease outbreaks in temporary shelters are forthcoming (Baqir et al., 2012; Sarkar, 2022).…”

“…The 2022 Flood: Was It Unprecedented? Satellite-based (see Section 2 for details) flood-inundated areas show that the 2022 flood in Pakistan considerably affected the southern provinces, including Balochistan, Sindh, and Khyber Pakhtunkhwa(L Otto et al, 2022; …”