Climate change has led to extreme weather events, like storms, droughts, heavy rainfall and flooding, happening more regularly. Apart from climate change-driven events, natural global weather patterns may compound the problems further by adding to the chaos. For many in India, this climate chaos has led to a compound disaster known as Concurrent Droughts and Heatwaves, or CDHW for short. These are periods where droughts, which are times of significantly reduced rainfall, coincide with extreme heat waves, making life tremendously difficult and often dangerous. Farmers wrestle with dry fields and wilted crops, and the situation spirals into a crisis as both water and food supplies dwindle quickly. But this troubling pattern isn’t just a local issue; it ties back to global weather phenomena that affect conditions in India.
A recent study conducted by scientists from the Indian Institute of Science (IISc) and Trinity College Dublin set out to understand how worldwide climate patterns can increase the likelihood of these concurrent disasters in India. While many people attribute the onset of extreme weather solely to human-made climate changes, this research delves into natural climate variations to see how they might contribute as well. This allows for a more comprehensive understanding of the climate changes at play.
The scientists studied large-scale weather trends, known as climate variability modes, which are naturally occurring climate patterns. These are immense fluctuations in atmospheric and oceanic conditions that can influence local weather thousands of miles away. Among the major players they're examining are phenomena like the El Niño-Southern Oscillation, Indian Ocean Dipole, North Atlantic Oscillation, and the Pacific Decadal Oscillation.
El Niño, for example, is a weather pattern that occurs in the Pacific Ocean. When El Niño happens, it brings warm sea surface temperatures that affect rainfall patterns across the globe. In India, this often means bad news: droughts follow El Niño events. Conversely, its opposite phase, known as La Niña, sometimes brings more rain but can still have regions paralleling drought, especially in areas like western and southern India.
The researchers gathered information by analysing weather and temperature data from 1951 to 2018. They paired this information with climate indices to look for connections between these global weather patterns and the local occurrences of extreme heat and dry spells. Essentially, they established a clear method of establishing connections drawn from this historical data.
To capture data accurately, they defined drought events using the Standardized Precipitation Index (SPI), which checks how much rainfall occurred in a period compared to the rainfall in the same period from a point in history. Similarly, they measured heat waves using the Standardized Heat Index (SHI), indicating when temperatures are excessively high. By looking for instances where both SPI and SHI indicated drought and heatwave conditions simultaneously, the team identified true cases of CDHW.
Following an El Niño event, the study found that drought conditions spread across India’s landscape. The scientists found evidence that the Indian Ocean Dipole also contributed to droughts, regardless of whether it was in a warm or cool phase. Surprisingly, they discovered that different regions of India are affected by these climate trends in unique ways, meaning that responses to heat and drought are not uniform across the country.
Moreover, they found that when El Niño, a positive Indian Ocean Dipole, a positive North Atlantic Oscillation, or a positive Pacific Decadal Oscillation were in play, the likelihood of concurrent heatwaves and droughts increased significantly. This reveals that these global climate patterns could be exacerbating the problem locally, creating a dangerous result for regions already grappling with the consequences of climate change.
Understanding these relationships could improve heatwave and drought forecasting, equipping communities with the necessary information and time to prepare. Additionally, recognising the influence of natural climate variability provides a vital piece of knowledge for developing effective climate adaptation strategies.
The study, however, adopted a simplified approach to defining concurrent events, which may not capture the full complexity of climate interactions. As a result, it does not completely address how droughts and heat waves might influence one another over time, potentially missing out on critical aspects of their relationship.
Nevertheless, the study could help develop detailed models that can help scientists understand the underlying causes of CDHW. In the future, a multivariable approach that considers various climatic elements like humidity and wind patterns will be necessary to create a broader picture of the dynamics at play. Also, as weather patterns continue to shift, ongoing studies will be pivotal in testing the general applicability of these findings across different regions and conditions.
As the world wrestles with the realities of climate change, understanding the patterns and interactions between different climate systems becomes imperative. This research offers invaluable insights into how global phenomena shape local weather, highlighting the need for continued exploration to enhance forecasting, resilience, and, ultimately, preparedness against nature's most extreme and unpredictable behaviours.
This research news was partly generated using artificial intelligence and edited by an editor at Research Matters