Kerala should be ready for more extreme weather in the near future, says climate scientist

Kerala once again is in the throes of flooding and landslips triggered by extreme rainfall events wh

Kerala once again is in the throes of flooding and landslips triggered by extreme rainfall events which often lead to loss of lives and damage to property. As the resurgent rain has brought back memories of the worst floods in Kerala, P.S. Biju, a climate scientist of India Meteorological Department (IMD), Thiruvananthapuram, who won the best scientist award in atmospheric science in 2022 instituted by the Ministry of Earth Sciences, speaks about the challenges faced by the State. Excerpts:

Climatology will not speak reality, but climate change is a reality. As Mark Twain said, “Climate is what we expect and weather is what we get”. Obviously, the number of severe weather incidences is on a steady increase in Kerala. The monsoon data of the last 120 years (1901-2020) clearly indicate that there has been a rise in temperature in this millennium (2000-2020) by more than 0.5 degree Celsius in all observatories in Kerala. However, the monsoon was deficient in the last 120 years in the State for only 17 years.

There is always an 85% chance of Kerala getting a normal monsoon every year. But severe weather incidences such heavy rainfall days and thunderstorm activity have increased as a result of climate change. The fact is that if we analyse the data between 1991 to 2020 (30 years) and 1901-2010 (110 years), it can be seen that many places in Wayanad, Kasaragod, Idukki, Thrissur, Kozhikode, Ernakulam, and Kannur, the frequency of heavy rainfall has been increasing.

It is true that the extreme rainfall events have increased significantly in August of late. But four years are a shorter period in climate science to reach a conclusion. However, the change I noticed during the past few years is that there was a rising trend in heat influx during the months of June and July. This is expected to draw more moisture to the atmosphere, leading to the formation of convective clouds which ultimately leads to severe weather incidents.

Also read:Deep convection behind rise in rainfall intensity, says Cusat study

Thunderstorm activities are reported during the monsoon as well, but not with severe lightning as in summer or Thulavarsham. In the coming years as well, thunderstorm days during the southwest monsoon may increase. Usually, during the active spell of monsoon, stratus clouds dominate over cumulonimbus clouds. That is why thunderstorm days are fewer in monsoon. But, nowadays, the presence of frequent convective clouds (cumulonimbus or thunderclouds) is also reported in the monsoon season, which is also one of the main reasons for extreme rainfall events.

Now we have more than 100 automatic weather stations (AWS) in Kerala, the first State to achieve this in India. As I said earlier, we need the data from a relatively longer period to make such an assessment. However, stations such as Vythiri, Hosdurg, Kudulu, Peermade, Kunnamkulam, Kodungallur, Koyilandy, Kuttiyadi, Neryamangalam, Piravom, Aluva, Irikkur, Ayyankunnu and so on are the heavy rainfall belts. But more studies need to be done in the coming years to make a real assessment.