Changes in precipitation in moderate or very high emissions scenario to impact 3-5 billion people: Study

The potential impact of climate change on global precipitation patterns can have far-reaching consequences on human populations, a new study showed. Around 266.52 million people, equivalent to 3.3 per cent of the world’s population, are expected to experience drier conditions, while a staggering 2.76 billion individuals, accounting for 34.7 per cent of the global population, will face wetter conditions under an intermediate greenhouse gas (GHG) emissions scenario, the authors of the report noted.

The projected consequences showed variations under different emissions scenarios. In the case of intermediate GHG emissions, around 38 per cent of the current global population, roughly 3 billion people, could be impacted by substantial changes in precipitation patterns by the end of the century, the researchers found. However, under a high GHG emissions scenario, this number skyrockets to 65.6 per cent, affecting approximately 5 billion people, they added. 

These changes in rainfall patterns will have significant implications for extreme weather events like floods and wildfires, the authors of the research paper highlighted. Regions experiencing robust wetting and drying trends cover a substantial portion of the Earth’s landmass, according to the study published in Nature Communications on January 11, 2024.

The analysts estimated that, by the year 2100, 35.5 per cent of the global population, equivalent to 3.26 billion people, may be affected by wetter conditions under a moderate emissions scenario, while 61.4 per cent, or about 4.64 billion people, could be impacted by drier conditions under a very high emissions scenario.

These changes in precipitation patterns are directly linked to climate change, which increases the likelihood of worsening droughts and floods in various parts of the world. Regions already grappling with the effects of climate change, such as Mediterranean Europe, North Africa, central America, the Caribbean, southern South America, eastern Brazil, the Amazon and Western Australia, are expected to experience significant drying trends. Meanwhile, densely populated areas including Asia, Northern Europe, northwestern United States and central Africa are projected to see substantial increases in precipitation.

The intermediate GHG emissions scenario, known as SSP2-4.5, involves maintaining current CO2 emissions levels until mid-century. The study used this scenario to estimate the extent to which the global population might be affected by long-term changes in precipitation patterns driven by human-induced global warming. The analysis drew upon multiple climate models to create an intermediate-to-high emissions envelope for its projections.

Furthermore, the study highlighted regional concerns, particularly in North India, where a decline in rainfall during the post-monsoon season and minimal winter snowfall have been observed. These changes are attributed to a decrease in the intensity of western disturbances, which has persisted in recent years due to evolving climate conditions. This pattern has continued into the post-monsoon and winter seasons of 2023, warranting close attention to the local impact of climate change.