India has recently witnessed its highest October temperature since 1901 as temperatures hit the next level. The average of the mean temperatures of the country for the month of October 2024 was 26.92°C which is 1.23°C above from the normal average of 25.69°C, according to IMD. This is very uncharacteristic of what is obtained under normal climatic conditions for the past hundred years.
And it wasn’t just the high day time temperatures that were recorded; the nights were also rather warm. Mean minimum temperature for the particular month was 21.85°C while the normal mean minimum temperature is 20.01°C. It is shocking having realized that these night temperatures have been rising, and this means there is a general rise of temperatures all over the country.
Specific causes of such a high degree of warmth included, lack of proper Western Disturbances over Northwest India. WDs are also, non-tropical storms which develop over the Mediterranean Sea and are associated with cooler temperatures. Their lack this year resulted in nearly 75% deficiency of rainfall in Northwest India that has already increased heat.
Furthermore, it is evident that low pressure systems at the Bay of Bengal were active during that time of year thus brought about easterly warm winds. Originally, fresh north-westerly winds are expected to provide cooler temperatures but these were weaker this year. Another factor that contributed to fairly high degree of temperature was that the southwest monsoon which is expected to begins its withdrawal towards the end of September did not begin withdrawal until mid-October.
As we enter November, the IMD has predicted above normal maximum and minimum temperatures over most of the regions of India. This means that the kind of warm experienced in the month of October is likely to be experienced further without any symptoms of winter in the offing. The IMD does not treat November as a winter month; rather, winter in India is reckoned from the beginning of January and ends in February.
This has been due to persistent neutral ENSO events in the equatorial Pacific Ocean that has helped delay the start of cooler climate. ENSO conditions are becoming characterized by La Niña slowly and hence warmer weather may be observed later in the year but not now.
The southern peninsula however, is expected to see above normal rainfall, which is due to the active northeast storm. This will afford little consolation to areas such as Tamil Nadu, Puducherry, Coastal Andhra Pradesh, Rayalaseema, Kerala, Mahe and South Interior Karnataka. The other parts of the nation especially the north-west are expected to remain warm with little rains.
The consequences of this rather longer period of warmth are enormous. The discovery also reveals that in warmer homes, more power is used for cooling which impacts the resource use and emissions in the nation. It also brings an effect on agriculture as crops goes through heat stress and produce lower yield. Also, heat stress impact can be reflected on general health of socio-demographic vulnerable groups like the elderly and patients with pre-existing conditions.
Therefore owing to India’s warmest October since 1901 and no winter in November there is more to it – the climate change & the weather. The impacts become manifested in terms of increased temperatures and changes in precipitation while, potentially severe implications are considered in the future. There is a need to demonstrate the undesirable impacts and apprise policy makers, scientists and the affected communities on the imperative need to avoid these impacts and transition to climate smart practices.
The El Niño-Southern Oscillation (ENSO)
El Niño - Southern Oscillation (ENSO) is a climatic event that involves changes in temperature of sea surface and oscillation in pressures in central and eastern Pacific at the equatorial line. ENSO has significant results on climate weather involving rainfall, temperatures, and storm. It consists of three phases.
Phases of ENSO
1. El Niño
El Niño is the warm phase of ENSO and is characterized by high temperature of sea surface in the central and eastern Pacific. This phase starts and ends randomly within two to seven years and could take several months. In El Niño the trade winds that blow from east to west across the Pacific weaken or even reverse direction, allowing warm water to accumulate along the coast of South America.
The effects of El Niño are multifaceted: Temporal and spatial distribution of rainfall over the globe is highly influenced by El Niño. In the America, it is linked with higher rainfall and possibilities for floods in South and Central America particularly to the west flank of the region. On the other hand, other areas in East Asia, Australia, and Indonesia and Southeast Asia are exposed to comparatively low levels of precipitation and high temperatures that raise chances of dry spells and bush fires during certain months in a year. The changes are also seen in the aquatic climate whereby temperature changes might have an impact on the fisheries and the coral reef.
2. La Niña
La Niña is the cool phase of ENSO where seas surface temperatures is cooler than average in the central and eastern parts of the Pacific Ocean. La Niña season is characterized by an increase in strength of the trade winds that force warm water toward the central and western Pacific coast and allowing colder water to upwell to the coast of South America.
While El Niño brings warm temperatures, above average precipitation and dry soils to many regions of the globe, La Niña mostly has the opposite impact. In the Americas for instance, La Niña causes lower water temperatures, thus brings rise to less precipitation, and hence likely to cause dryness and frequent droughts throughout the south-western area of United States. However, other areas such as Australia or parts of South East Asia might receive relatively heavy down pourage and that too may result in flooding. La Niña can also intensify the Atlantic hurricane season; there will be more frequent storms and storm intensity will be higher.
3. Neutral
The Neutral phase of ENSO happens when the surface temperature in the central and eastern Pacific is close to normal, and trade winds are moderate. In the case of Neutral, conditions of ENSO remain inconsequential to world weather patterns, and the climate in other regions prevails to be balanced.
Mechanisms and Impact
ENSO impacts on the global climate are more so determined by the ocean temperatures and the basic atmospheric pressures. Such interactions are capable of resulting in large differences when it comes to weather for agriculture use, water supplies, and other ecosystems, globally.
Climate and Ecosystem Impacts
ENSO’s impacts are many and varied and affect climate and ecosystems. During the El Niño periods tropical precipitations rises causes flood, landslides and affects crops in some areas. On the other hand, drought situation in other regions leads to water rationing, yieldage decrease and launching of maximal fires. It also causes contrariwise impacts, and La Niña is said to increase the occurrence of cyclones and hurricanes experienced on earth.
ENSO has quite a strong impact on marine ecosystems. During El Niño, warmer waters cause changes in the nutrient distribution causing decline in fisheries production for cold water dependent species. Coral reefs can experience bleaching events due to elevated temperatures, causing long-term damage to these vital ecosystems. Marine life is also affected since cooler waters define the existence and amount of every species that is present in the water.
Western Disturbances
Western Disturbances are significant meteorological phenomena that play a crucial role in shaping the weather patterns of South Asia, particularly India, Pakistan, and Nepal. These disturbances are extra-tropical storms that develop over the Mediterranean Sea and then migrate towards the Indian subcontinent.
Formation and Movement
The storm system known as the Western Disturbances evolves out of the contact of cold air from the polar region with a comparatively warmer air mass from the subtropical zone. This interaction forms low pressure centres which are sub-tropical style, which travels along the westerly subtropical jet stream. These systems as they move from the Mediterranean region, they pickup moisture from the Mediterranean sea, Caspian sea and the Persian gulf.
In the Indian subcontinent, the Western Disturbances are generally experienced in the northern part of the region of Punjab, Haryana, Himachal Pradesh, Uttarakhand and, Jammu, and Kashmir. These disturbances happen mainly in the period between November and March as the colder months but they may also be observed in other months as well at times.
Weather Impact
Western Disturbances have impacts on the climate of the areas they impact. The arrival of these systems leads to a variety of weather phenomena, including:
- Rainfall: During winter, western disturbances cause much needed winter precipitation on the northern plain and the western Himalayas. This precipitation is important for the Rabi crop season because it is raining well for crops such as wheat, barley and mustard.
- Snowfall: In the higher reaches of the western Himalayas WD causes heavy snowfall which is important for replenishing of glaciers and to maintaining the water supplying to rivers like Indus and Ganges.
- Temperature Variations: The system brings about the Western Disturbances and during this the temperatures dropping as the event carries along cold air masses. This brings cold waves and frosty conditions in the affected regions of the country deliberately because the damage that comes with it afterwards is worth it.
- Cloudy Skies: Higher cloud frequency is another meteorological characteristic associated with WDs and consists of overcast and comparatively low visibility.
Agricultural and hydrological importance
The precipitation in the form of rain and snow produced by the WDs is essential both for the agricultural and water resource demands of the area. This leads to the replenishment of water needs during the Rabi crops, which are important within the agricultural sector in the northern states. Also, fresh snow in the Himalayan range is accumulated on the glaciers and thus helps maintain supply of water in some of the important rivers during the summer season.