Global warming lifts capacity of air to hold water, behind rain fury and floods

The unparalleled levels of rainfall this year across the country, one of the impacts of global warming according to experts, also draw into an associated issue which is the 'unchecked' temperatures in the Himalayan region, where floods wreaked havoc recently.

Akshay Deoras, a meteorologist and research scientist from the National Centre for Atmospheric Science and the University of Reading, the UK, explains that during break-monsoon conditions, an increased capacity of the air to hold moisture due to global warming leads to amplified rainfall during favorable weather situations.

Experts underscore that while favourable conditions may have contributed to heavy rainfall, climate change significantly amplifies the intensity of such events. The recent flash floods and landslides in Uttarakhand and Himachal Pradesh, which resulted in loss of lives and extensive damage, stand as stark examples of the consequences.

“The escalating prevalence of extreme weather events is an unprecedented development, with these occurrences increasing at an alarming rate. The monsoon of 2023 serves as a striking illustration of how unchecked global warming can impact the Himalayan region, as emphasised in a report compiled by Climate Trends,” said another expert.

A professor from Garhwal University in Srinagar, Uttarakhand, highlights the vulnerability of the Shivalik range in the Himalayas due to its composition of debris, sandstone, and shale rock. This geological structure renders it susceptible to heavy rainfall, deforestation, and unregulated construction, all of which escalate the risk of erosion.

The monsoon season of 2023 has delivered unparalleled levels of rainfall across multiple regions in India. From July to August, an extraordinary deluge was witnessed, shattering previous records. While some areas grappled with excessive downpours, others faced prolonged dry conditions.

The downpour records were shattered in Delhi, Chandigarh, Uttarakhand and Himachal Pradesh, whereas several regions experienced a shortage in rainfall.

Global scientists uniformly attribute this anomaly to the changing dynamics of weather patterns caused by global warming. The resulting need for adopting new mechanisms to understand weather patterns is evident.

“The shift in understanding has brought about a significant alteration in meteorological norms, leading to this exceptional weather scenario. In contrast to concerns about a "below normal" monsoon in an El Nino year, the month of July witnessed a 15 per cent surge in rainfall, surpassing the expected norms,” said a scientist.

The seasonal forecast by the India Meteorological Department (IMD) indicated normal monsoon conditions, with anticipated levels ranging between 96 per cent to 104 per cent of the Long Period Average (LPA).

The influence of El Nino, a significant driver of the monsoon, can lead to subpar rainfall in India. Yet, other factors, such as a positive Indian Ocean Dipole (IOD) and snow cover across the Eurasian region, also play roles in shaping the summer monsoon. A positive IOD can translate into above average rainfall, while the extent of Eurasian snow cover inversely affects Indian summer monsoon rainfall.

June saw the development of a weak El Nino condition, marked by above average sea surface temperatures across the equatorial Pacific Ocean. Forecasts suggest a continued intensification of El Nino through the fall, with a peak in winter at moderate-to-strong levels.

The warming of the atmosphere, land, and oceans accelerates moisture retention in the atmosphere. This heightened moisture content leads to increased evaporation from the Earth's surface, augmenting the air's capacity to hold water.

Consequently, this results in heavier and more frequent rainfall, often over smaller areas in shorter periods, scientists pointed out.

Notably, India's monsoon rainfall patterns have witnessed a climatic shift in recent decades. Instead of evenly spread moderate rains, prolonged dry spells interspersed with intense rainfall have become common, leading to both floods and droughts in the same season and occasionally even in the same region. This pattern manifested during the current year, according to another expert