Increased Tropical Cyclones due to global climate change

By Irshad A Khan

The cyclone – Nisarga hitting west coast of India from Gujarat to Maharashtra in the early hours of June 3 is too quick an extreme event after the recent devastation caused by the Amphan in Orissa and West Bengal on May 21. Mumbai never had a cyclone for the last more than 130 years and thus is not ready to face this calamity though cyclones in the eastern coast are not infrequent.

The overall frequency and severity of the cyclones and hurricanes world over has increased during the last 30-40 years. The main cause of these extreme sea level events is climate change resulting in melting of ice and glaciers, ocean level rise and warming of seawater. 

The Inter-Government Panel on Climate Change (IPCC) has recently brought out a “Special Report on the Ocean and Cryospehere in a Chaniging Climate” (2019). According to this report global warming has resulted in widespread shrinking of cryosphere with mass loss from ice sheets and glaciers and reductions in snow cover over Arctic sea ice extent and thickness and increased temperature of permafrosts. Also, it is certain that the global ocean has warmed unabated since 1970. It is a scientific fact that global mean sea level rise is accelerating in recent decades. Increases in tropical cyclone winds and rainfall, and increases in extreme waves, combined relative sea level rise, exacerbate extreme sea level events and coastal hazards.

Anthropogenic climate change has increased precipitation, winds and sea level events associated with some tropical cyclones, which has increased intensity of multiple extreme events and associated cascading impacts. IPCC report  further highlights that extreme sea level events that are historically rare (once per century in the recent past) are projected to occur frequently at least once a year at many locations by 2050 especially in tropical regions. The average intensity of tropical cyclones and the accompanying precipitation rates are also projected to increase for a 2°C global temperature rise. Rising sea levels will contribute to higher extreme sea level events associated with tropical cyclone. Coastal hazards will be exacerbated by an increase in average intensity, magnitude of storm scourge and precipitation rates of tropical cyclones.

Nisarga cyclone can be easily attributed to the climate change impact as Mumbai did not have a cyclone for more than a century. In 2014 Cyclone Nilofar was the first severe tropical cyclone recorded in the Arabian Sea in post-monsoon cyclone season. It did not make land fall but produced heavy rainfall on the Western Indian Coast. It was attributed to anthropogenic global warming which has been shown to have increased the probability of post-monsoon tropical cyclone over the Arabian Sea. Cyclone Nisarga is a pre-monsoon or monsoon cyclone.

Amphan over the Bay of Bengal and Nisarga cyclones over the Arabian sea respectively causing tremendous destruction on India’s east and west coasts are a result of climate change. All Indian coastal areas are highly vulnerable and have future risks of cyclone related hazards including flooding and destruction of crops and other property and even in extreme cases submergence of part of coastal areas. These threats are caused by global problems and can only be managed through a globally agreed and financed climate change mitigation and adaptation action. When will the international community awake to the climate change catastrophe in offing and will seriously implement Paris Climate Agreement?