This post is without any links to the literature - it is largely from memory but if necessary can be tightened up considerably. Actually, I will count on Amber G to correct and go into depth on this if there is interest.
In terms of how geologists have divided up earth's 4+ billion year existence, Earth is currently situated in the Phanerozoic Eon, Cenozoic Era, Quaternary Period, Holocene Epoch and Meghalayan Age.
The Meghalayan age began 4.2 kilo years ago (i.e., around 2200 BC) and began with a 200 year drought in the northern hemisphere. The Meghalayan age is so named because the evidence found in stalagmites in Mawmluh Cave in Meghalaya. Stalagmites grow in geologically stable caves; mineral-rich water drips on to the floor of the cave, and evaporates leaving deposits of calcium carbonate and other minerals. The ratio of the oxygen 18 and oxygen 16 isotopes left in these deposits indicates how intense the rainfall was. The heavier isotope condenses out of the atmosphere first, and so the more the rainfall the lower the O18/O16 ratio. What the data shows is that there was an around 20% reduction in the monsoon rain for about 200 years. That this reduction was across the northern hemisphere is confirmed by many lines of evidence.
The above is as much of a fact as anything in geology can be.
This drought affected the agriculture of the civilizations Saraswati-Sindhu, Mesopotamia, Egypt and China, "decimated" is a word used. This is a matter of the archaeological and historical record.
What caused this 200 year drought? There we get into a less settled area of science - there were probably many contributing factors; but among them the weakening of the Atlantic Meridional Overturning Circulation (AMOC) is accepted as one of the factors.
The AMOC is the surface north to south ocean current on the surface and return circulation in the deep ocean that carries a petawatt or more from the equator to the poles. The Pacific Ocean for various reasons does not have the equivalent current. The AMOC is known to have a global influence on climate. The AMOC is also why the northern Atlantic countries are warmer than equivalent latitudes in the Pacific, and so the European and American climate scientists have a deep interest and concern about the stability of the AMOC, which (unjustifiably) might seem remote to people in Asia.
Now we enter the realm of computer modeling of the ocean and the climate. Up to about a decade ago, the ocean and climate models on super computers used a grid size of around 100 kilometers. This has now improved to grid sizes of 10 kilometers, which enables more oceanic phenomena (oceanic eddies) to be included in the models. With these finer resolution models, a team from the University at Utrecht found "that the AMOC is more sensitive, less stable, and more prone to abrupt transitions than previously estimated, especially when models include eddy‑resolving ocean dynamics and realistic meltwater inputs."
In particular, the resolution is fine enough to follow what happens to the Gulf Stream - which is part of the AMOC, it hugs the coast of the US until around Cape Hatteras in North Carolina after which it detaches from the coast and heads north east into the deep ocean. They found that as the AMOC weakens the separation point moves northwards, and when the AMOC approaches a tipping point then there is an abrupt northward jump of around 200 kilometers which precedes by about twenty-five years the total collapse of the AMOC.
As far as I know, the data that we have shows some weakening of the AMOC, but the duration of our data is too short to show a trend, it could be natural cyclic variation.
The big threat to the AMOC is considered to be the melting of the glaciers of Greenland. The fresh water released from there dilutes the salinity of the North Atlantic waters. It is the sinking of the denser higher salinity water in the Northern Atlantic all the way to near the ocean floor that is the engine of the AMOC -- there is no equivalent in the Pacific, where the currents remain closer to the surface.
---
Remember that a 10-fold increase in the surface resolution of a climate model means 100 times the grid areas; and then there is the resolution vertically through the atmosphere which is of a different scale. So it takes more and more computational power and improved algorithms to make a higher resolution model that teach us new things.
---
Now, climate science says that global warming is causing the Greenland Ice to melt at an increasing rate.
FWIW, global warming and increased melt of Greenland Ice are also facts.
----
Now, what should policy makers do about this? (trying to address Jay's question).
The policy makers in one country, even as large as India, cannot address the human causes of climate change on their own. However, even just the US-Israel-Iran war shows how vulnerable India is to the fossil fuel supply; and so renewables (solar, wind, biogas, etc.) and nuclear as the "fill-in-the-gaps-of-the-intermittency-of-solar-and-wind" makes a lot of sense just from a strategic point of view. It also makes sense from a economic point of view as the costs of the alternatives to fossil fuels continue their downward trends; and also from an ecological view (if you burn less fossil fuel, you have cleaner air, and less respiratory and other health problems and so on).
Also, in preparation for a possibly drier future, whether from weakening of the AMOC or other reasons, improving the catchment and retention of rainwater, recharging aquifers, changing the crop mix towards lower water use/higher temperature tolerant crops, and people's customary food habits, sewage water treatment and reuse, and so on make sense whatever you think about climate change, because even without any diminution of rainfall over the country and snowfall in the Himalayas, the availability of freshwater per capita is not going to improve, while the usage of water is going to climb with Vikasit Bharat. Being more efficient and frugal with water simply makes sense whatever your ideology is.
Perhaps for areas along the coast, desalination can help with urban water supplies.
Ideally, short term economic calculations of actors in a free market drive these changes naturally; and policy support by government can accelerate the trends. The point is that all these changes make sense whether or not you are a climate skeptic.
In any case, what is needed is a sense of importance and urgency in making these changes, so whatever the climate future, the people and economy, and the flora and the fauna of India are resilient and can adapt to the change.
.. as I recall someone said {I am recalling, my Telugu is a little rusty} in Osmania..
What can we do so that we do not lose our way of life and face mass problems. Planet Earth does not give a shit about one way or another.
)