"Ecologists Seek Wider Monitoring Network Amid El Niño Stress"
El Niño
periodic warming of central and eastern Pacific sea surface temperatures disrupting global weather patterns
Walker Circulation
east-west atmospheric circulation loop over the tropical Pacific driven by sea-temperature gradients
El Niño is the periodic weakening of trade winds over the tropical Pacific that flattens the west-east sea-temperature gradient and disrupts the Walker Circulation, the atmospheric loop that normally pulls monsoon moisture towards India. Strong El Niño years have historically coincided with some of India's worst droughts, including 1972, 2002 and 2009. The Walker Circulation's strength is not the only factor at play. The Indian Ocean Dipole (IOD), the difference in sea surface temperature between the western Indian Ocean and the eastern Indian Ocean near Indonesia, can offset or worsen El Niño's effect on the monsoon depending on its phase, which is why monsoon outcomes in El Niño years have not always been uniformly poor.
Even when the rainfall deficit is similar across regions, the resulting water stress on the ground is not. Water stress depends on local soil moisture, groundwater recharge, vegetation cover and the scale of human demand on a river or aquifer, not on rainfall shortfall alone. This is why two forests or two wetlands facing the same seasonal deficit can show very different levels of ecological strain, and why uniform, rainfall-based assessments of drought risk miss the ground reality.
A severe El Niño does not automatically produce an ecological collapse. It is more accurate to see it as a stress multiplier that can push an already weakened system past a threshold beyond which recovery becomes difficult. A forest with declining groundwater, a wetland already shrunk by encroachment, or a coral reef already weakened by past bleaching is far more vulnerable to the same degree of warming or dryness than a healthier system nearby. Identifying which ecosystems are close to such a threshold, rather than treating all of them as equally at risk, is the central argument for micro-monitoring.
India's weather forecasting capacity, built around continuous satellite observation of the atmosphere, has made alerts for cyclones, heavy rainfall and heat waves increasingly reliable. Ecological monitoring needs a similar but more localised architecture, because ecosystem stress is shaped by ground-level conditions that satellites alone cannot fully capture. …
In the South Atlantic and South-Eastern Pacific regions in tropical latitudes, cyclone does not originate. What is the reason?
With reference to 'Indian Ocean Dipole (IOD)' sometimes mentioned in the news while forecasting Indian monsoon, which of the following statements is/are correct?
1.IOD phenomenon is characterised by a difference in sea surface temperature between tropical Western Indian Ocean and tropical Eastern Pacific Ocean.
2.An IOD phenomenon can influence an El Nino's impact on the monsoon.
Select the correct answer using the code given below:
Consider the following statements about El Niño: 1. It is associated with a weakening of trade winds over the tropical Pacific Ocean. 2. It strengthens the Walker Circulation, thereby enhancing monsoon rainfall over India. Which of the statements given above is/are correct?
Consider the following statements regarding the Indian Ocean Dipole (IOD): 1. It refers to the difference in sea surface temperature between the western and eastern Indian Ocean. 2. A positive phase of the IOD can offset the adverse impact of El Niño on the Indian monsoon. Which of the statements given above is/are correct?
Coral bleaching, used as an indicator of marine ecosystem stress, is primarily caused by which of the following?
Consider the following years: 1. 1972, 2. 1983, 3. 2002, 4. 2009. How many of the above years witnessed a major drought in India associated with a strong El Niño event?
Match List I (Ecosystem) with List II (Ground-level monitoring approach used to track El Niño-driven stress): List I:
A.Glacial lakes,
B.Forests,
C.Coral reefs. List II:
1.Soil moisture and vegetation-stress tracking,
2.Thermal-stress monitoring for bleaching,
3.Water-level and snow-depth sensors. Select the correct answer using the code given below:
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