How does the slowdown in Atlantic circulation system impact Kerala's monsoon

What if waves stop crashing on shores or seas fall silent like lakes? It's never a good sign for life on earth. Called the collapse of the ocean current system. scientists say the phenomenon could result in climate catastrophes.

In October last year, a group of 40 scientists wrote an open letter to the Nordic Council of Ministers (the official body for inter-governmental cooperation in the region) warning about the impending danger of a collapse of the ocean current system in the Atlantic Ocean that is directly linked to life and biodiversity in the landmasses flanking it in the American and European continents and indirectly to those of the rest of the world.

Why is AMOC now the hot topic
The study warns of the chances of a collapse of the Atlantic Meridional Overturning Circulation (AMOC) in 2025 itself. AMOC is the northward flow of warm, saline water in the upper layers of the Atlantic and a southward flow of colder, deep waters that are part of the thermohaline circulation. It's a process in which deep-ocean currents are driven by differences in the water density, which is controlled by temperature (thermo) and salinity (haline). Prof Peter Ditlevsen, at the University of Copenhagen in Denmark, who led the study says that it would be a disastrous change as the AMOC has not collapsed for 12,000 years.

Many scientists who have conducted studies on the subject maintain that the risks hinted are being underestimated and are wary about policymakers conveniently turning a blind eye to the scientific evidence of the growing threats. However, researchers are equivocal about how immediate or late the threat of an AMOC shutdown is.

National Centre for Polar and Ocean Research (NCPOR) Director Dr Thamban Meloth reaffirms the AMOC slowdown and highlights the possible climate threats. There is scientific evidence of a 15 per cent slowdown in AMOC, and if the current trend persists, there are chances of its collapse.

But Meloth says the claims about how sooner or later it can happen are controversial because the mathematical modelling used in the study is based on data from only the past 50 years. He does not entirely bank on the notion that AMOC is about to stop suddenly.

In the AMOC system, the ocean current carrying warm saline water reaches the polar region and expends the heat in the atmosphere and the coastal area. The cold environment of the ice-capped poles makes the ocean cold, and the salinity helps the water sink, triggering the overturning circulation. The current then carries the cold water to the tropical region making the places around it cooler.

This leads to the balancing of climate and temperature of places around it. However, the melting of ice in the polar region causes excess flow of fresh water into the ocean decreasing the salinity of water in the oceanic region there. This slows down the sinking of the water, which ultimately thwarts the overturning circulation system. It's believed that this may this may eventually lead to its stop. The prediction of the time frame for a complete halt is based on mathematical modelling.

Mathematical modelling presents ideal situations and according to Meloth, only some such modelling is useful. "In nature, there are several additional factors which determine the climatic phenomena. Therefore, the AMOC slowdown is real and its collapse is impending, but when it will happen - whether in 2050 or in 2100 - is unclear. That is why I think the proposition is controversial," he says.

How AMOC is going to impact Kerala's monsoon
AMOC is part of the interconnected system of ocean currents, which includes the Gulf Stream.  The collapse or the slowdown of AMOC will eventually affect the climate pattern across the world. The Gulf Stream, a strong ocean current, brings warm water from the Gulf of Mexico into the Atlantic Ocean. AMOC slowdown or the shutdown will disarray the whole cycle. Meanwhile, the eventual Gulf Stream collapse will throw the tropical monsoon haywire.

The monsoon trough, which is directed northwards from the south, giving its first rain to the Kerala coast and southern region of India, may get redirected in the reverse north-south pattern, leaving southern India bereft of rain in monsoon. The state which relies on an agro-based economy will have a tough time.

What are the governments doing?
From the Paris Agreement, adopted by 196 countries to European Green Deal approved in 2020, all major climate pacts factor in all the climate emergencies and relevant protocols that are urgent. But, it is the cost factor that is stopping governments from fully implementing the clauses in them. Governments cite various reasons from inflation to their own development goals to back off from implementing the temperature parameter (aiming to keep global warming significantly below 2°C, while striving to limit it to 1.5°C). At the same time, the rationale behind rich nations, who have exhausted their natural resources, asking the poor or developing countries to stop fossil fuel-based industries, is persistently questioned.

Developing nations like India and China say they need more time as they are just growing up. But the question still remains: "Who is responsible." Policymakers across the globe are not keen to address these as they are answerable to the next election, not future generations. Except for some pro-people European countries, no one is taking any major step in this direction.

What lessons do we learn from Los Angeles wildfires?
Bush fires are common in the Pacific Palisades area. But dryness brought in by the climate-change-induced drought has been increasing over the years. This has had devastating effects during the wildfires in LA. In Kerala, heat waves, which were once reported only in Palakkad, are now experienced across Kerala. Here too wildfires are increasingly being reported. During heat waves, the moisture in trees and leaves diminishes and the chances of a fire breakout is high. Cases of lightning strikes are also on the rise.

Climate adaptation is the key
We have already witnessed the temperature touching 1.5 degrees C; the rise to 2 degrees C may soon happen as the chances of all nations coming together to contain global warming seem bleak. What is most feasible in this context is climate adaptation. Resilient infrastructure like strong flood-resistant buildings, green energy options, disaster preparedness, early warning systems can ensure more climate adaptation.

Melting of ice and sea level rise is a fact. Arctic ice and Antarctic ice are melting at an alarmingly fast. It's estimated that by 2100 the sea level will rise by half a metre. That means the sea will come 100 to 200 metres into the coastal land. For India with a coastline of more than 7,000 km, this rise will severely impact coastal cities.

The Indian government is investing heavily in the early warning system for sea incursion, swell waves, heavy rain, cyclones and so on which can save a number of lives and improve the weather prediction. Then there is Mission Mausam, which aims to improve weather and climate services, ensuring timely and precise observation, modelling, and forecasting information for multiple sectors, including agriculture, disaster management, and rural development.

The project involves infrastructure development with installation of more Doppler Weather Radars (DWRs), Automatic Weather Stations (AWS), rain gauges and so on across the country. It also looks at augmenting high-performance computing systems for advanced climate modelling and partnering with global bodies like the World Meteorological Organization (WMO) to enhance forecasting techniques. The early warning system can help improve water management, agricultural adaptation, restoration of natural buffers like mangroves.

Irrespective of whether governments take any measures or not, the public can and must take small steps. Unless we bring about small changes like shifting to the public transport system or switching to greener options, life will be difficult for the generations to come.

What if the world remains insensitive?
The Arctic is warming up four times faster than the global average. The dynamic nature of climate that balances the different climatic patterns across the globe is maintained by the difference in the oceanic conditions between the tropic and the polar regions. If that is stopped it can impact the climate adversely. When huge changes happen in the Arctic region, the rest of the world feels the heat.

But people don't bother much about the Arctic events as they are far away. If we keep neglecting the climate threats climate will become more and more unpredictable; there could be more flooding, waterlogging in the urban regions, extreme precipitation, heat waves, sea incursions, cyclones and so on. So, adaptation is the key.

Government measures are not enough, we must be mentally, physically and policy-wise prepared for it. Climate change is the truth and we are going through it. If climate change was part of intellectual discussions before, it's today's reality.

We do a lot for the greener energy options - but that is not enough. It is the adaptation strategy, that we should be focussing on. Otherwise, we will be stuck in the climate trauma.