By Krishna AchutaRao, Professor, Centre for Atmospheric Sciences, Affiliate Faculty, School of Public Policy, Indian Institute of Technology Delhi, India

Recent years have seen dramatic increases in extreme weather and climate events across the world. Such events include heat waves, droughts, tropical cyclones, extreme rainfall and floods. These increases have been predicted to occur by climate scientists warning about the consequences of climate change brought on by human activities. The science of event attribution has enabled scientists to quantify the contribution of climate change in making such events more extreme than they would have been without human activities. As a climate scientist who has worked to improve our understanding of the climate system, I have watched with alarm how dramatically climate change has unfolded.

Uncertainty is Not Your Friend

There have always been uncertainties in estimates of future climate change. While not the only source of uncertainty, our incomplete understanding of the climate system is the primary reason as far as climate scientists are concerned. Lately, we are seeing that some variable of consequence or other has completely overshot the uncertainty range we had predicted just a couple of years ago and in a direction with adverse consequences for the climate and society. The dramatic increases in sea surface temperatures in parts of the Atlantic Ocean or the large decreases in sea-ice extent around Antarctica in the last couple of years have led to concerns that what we know less than we thought we did, and that the climate system is perhaps more sensitive to our activities than we had estimated.

What Does it Mean to Forecast?

Our plans for adaptation to climate change seem to hinge on mitigating disaster risk by forecasting weather and climate hazards well enough in advance. One such hazard in India is heatwaves for which many Heat Action Plans are in place. India is no stranger to hot summers and heatwaves have occurred here well before human-caused climate change happened. A recent study by Arulalan et al. (2023) suggests that the future heatwaves over India will be more widespread geographically and last for longer durations – perhaps as long as a couple of months. The last couple of years have witnessed heatwaves across the Indian subcontinent and Southeast Asia that have lasted for weeks. If future summer seasons are essentially one long heatwave, what is the value added from forecasting?

Acting in the Face of Uncertainty

Science is currently better at forecasting temperatures than heavy rainfall or flooding and we will always be chasing the better forecast to take better actions. But knowing that we will never be able to make a perfect forecast, what is a good enough forecast to act? The answer to this question could benefit adaptation actions. The details of everyday weather forecasting cannot become our strategy guiding adaptation actions. We need to take a longer-term view of the changing statistics of weather to inform our decisions that reduce exposure and vulnerability.

Reference: Arulalan T, AchutaRao, K. & Sagar, A.D. “Climate science to inform adaptation policy: Heat waves over India in the 1.5°C and 2°C warmer worlds.” Climatic Change 176, 64 (2023). https://doi.org/10.1007/s10584-023-03527-y

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