Heavy rains, accompanied by strong winds from thunderstorms, impact the lives of people in Manipur during this time of year. These storms result in overflowing drains, flooded roads, blown-off rooftops, crop damage, and electricity outages. A thunderstorm is a product of an unstable atmosphere. Under ripe conditions, such an atmosphere may produce an anvil-shaped tall convective cloud called cumulonimbus, from which most thunderstorms form. It has a distinct life cycle. Typically, we experience this cycle as a strong, descending, cool wind (downdraft), followed by a brief period of heavy rainfall, with or without thunder, lightning, or hail, before the rainfall abruptly ceases.
Although thunderstorms are short-lived events, their impact on our lives is significant. The outsized effect of a thunderstorm, given its brief duration, is attributed to its powerful downdraft, which can destroy weak and moderately strong structures. In addition, the resulting heavy deluge often leads to flash floods, catching many unprepared. Not to mention the hail that wreaks havoc on old and weakly built rooftops and standing spring crops, bringing hardship to people and farmers alike. Considering the toll that thunderstorms take on the lives and properties of the people, it would be wise to regard them as a potent hazard in the context of Manipur.
Climate change and thunderstorms.
Global warming influences the occurrence of thunderstorms through a series of interrelated processes. Current theories suggest that as the world warms due to the enhanced greenhouse effect, more water vapor enters the atmosphere due to increased evaporation rates.
Additionally, warm air can hold more water vapor, making it more buoyant. Since 1850 AD, global temperatures have risen by over 1°C, resulting in the current atmosphere holding about 7 per cent more water vapor. The increased moisture content of the atmosphere intensifies convectional clouds like cumulonimbus, as more water vapor rises and condenses into water droplets, producing taller clouds that sustain for longer periods. Tall clouds often give concentrated rainfall with stronger downdrafts. Any process that increases the moisture in the atmosphere thus has the potential to increase the severity of thunderstorms and, in turn, affect the pattern of heavy rain occurrence.
Observations made across different regions of the world, particularly in the tropics, support the fact that the severity of extreme precipitation has indeed changed over the last few decades in terms of both frequency and intensity. In fact, changes in the frequency and intensity of extreme rainfall events are considered some of the strongest indicators of climate change.
These trends are likely to continue in the future if global warming continues unabated. Quantifying the impact of ever-increasing water vapor input into the atmosphere from global warming is difficult. However, based on our understanding of the role water vapor plays in augmenting convection, we can hypothesize that the intensity and frequency of heavy rainfall that come with thunderstorms will increase. In areas where the total amount of annual rainfall remains unchanged, there may be a reduced number of rainy days. This is a precarious situation as intense rainfall can lead to floods in a limited number of days while the majority of days remain dry. The frequent occurrence of such conditions will undoubtedly have a negative impact on agriculture-based societies.
In summary, heavy precipitation events are sensitive to the increased water vapor content in the atmosphere. Changes in water vapor amount directly affect their intensity and frequency, although the rate may not always be directly proportional. A recent study published in the journal Nature predicts that if current greenhouse emissions trends continue with moderate restrictions, previously experienced extreme rainfall events will become 32% more frequent globally by 2100. However, this prediction is based on computer models that simulate the climate system and may not have immediate relevance to local planning due to the broad temporal and spatial resolution. Nevertheless, past experience suggests that we can expect more frequent intense precipitation in tropical regions compared to other latitudes due to higher atmospheric temperature and vapor content.
Manipur and Thunderstorms.
Thunderstorms frequently hit Manipur during the pre-monsoon months of March, April, and May. While both hill and valley regions face similar susceptibility to these extreme weather events, the flat terrain with its dense population and infrastructure concentration poses a heightened risk, leading to comparatively more adverse effects in the latter. The devastating impact of the recent thunderstorm seen across large swathes of the valley area is unprecedented and suggests an intensification of thunderstorms, either due to natural processes or global warming.
While it is difficult to attribute a single event like the recent storm to global warming alone, the scale and intensity of the storm bear the fingerprint of climate change. Regions within the meteorological tropics (around 30° in both hemispheres), such as Manipur, are predicted to witness a rise in the frequency of extreme precipitation events derived from convection in the future. It is vital to integrate this understanding and other climate-related issues into collective and individual decision-making processes to construct a society resilient to climate challenges.
Unfortunately, there is evidence that this is not happening in the state. Recent reports of thunderstorm-induced destruction in different parts of Manipur suggest that we have failed to adapt to climate hazards both at the institutional and household levels. If we persist with our current "business as usual" approach towards heavy rainfall events and other climate hazards, we will face even more damaging consequences in the future.
Every disaster presents an opportunity for the government to streamline its response mechanism by shedding bureaucratic formalities and rules that could impede timely aid delivery to those in need. While it's commendable that the state swiftly announced the allocation of a large sum of money in aid of thunderstorm-affected families, this response still follows standard procedures, which may delay actual assistance reaching the victims.
In disaster response, time is of the essence.An innovative approach could involve invoking the Essential Commodities Act, allowing the government to procure corrugated sheets readily available in the market. Instead of victims submitting applications and documents, a designated government official could directly visit the affected families with a truckload of corrugated sheets, providing immediate assistance on the spot. This approach embodies the principle of "government going to the victims, not the victims coming to the government" for assistance during and after a natural calamity.
