“It has been observed that since 2001, places in northern India, especially in Rajasthan, are witnessing a rising temperature trend every year. The main reason is the excessive … emission of carbon dioxide.” — Laxman Singh Rathore, the director general of the India Meteorological Department.
The reduction in India’s monsoon rains is a big deal. It generates systemic drought, creates a prevalence for heatwaves, and locally amplifies the impacts of human-caused climate change. For three years now, the Indian monsoon has been delayed. India is experiencing its worst heatwaves ever recorded and water shortages across the country are growing dire. The monsoonal rains are coming, again late. And people across India — residents as well as weather and climate experts — are beginning to wonder if the endemic drought and heat stress will ever end.
Historically, there was only one climate condition known to bring about a delay in India’s Monsoon — El Nino. And last year, a strong El Nino is thought to have contributed both to the Monsoon’s late arrival and to a very severe drought that is now gripping the state. What the 2015 El Nino cannot also account for is the 2014 delay and weakening of monsoonal rains. And during 2016, as India’s monsoon has again been held back by 1-2 weeks, and El Nino is now but a memory, it’s beginning to become quite clear that there’s something else involved in the weakening of India’s annual rains.
Indian Monsoon Delayed Third Year in a Row
(Onset of the Indian Monsoon has been delayed for three years in a row now. A condition likely caused by a human-forced warming of the world and one that is worsening an extreme drought and heatwave situation across the country. Image source: The India Meteorological Department.)
As of today, the eastern edge of the Southeast Asian monsoon had only advanced to the middle of Myanmar. This late progress is two weeks behind the typical advance of the monsoon in this part of the world at this time of year. Further west, the monsoon has extended somewhat futher — only trailing the typical monsoon’s advance by 5 days along the western coast of India.
With La Nina blooming in the Eastern Pacific, there’s no other climatological excuse for this delay. The El Nino influence is mostly gone. And all that’s left is a global climate context in which temperatures have now risen to around 1.3 C hotter than 1880s averages.
Climate Change is Likely Cause
Scientific studies modeling the impacts of human-forced warming have long found that heating the Earth atmosphere resulted in an eventual delay and weakening of the Indian monsoon. A study published last year in Geoscience Frontiers continued this line of study. Global Circulation Model (GCM) runs found that the Indian monsoon was expected to be delayed by 15 days on average during the 21st Century due to human caused climate change. That the amount of precipitation provided by the monsoon would be reduced by about 70 percent. And that the eastern section of the monsoon would tend to be subject to greater delays than the west.
(Extreme heat in the range of 45 to 51 degrees Celsius [113 to 124 degrees Fahrenheit] is expected to continue to impact a broad region of Northern India and Eastern Pakistan tomorrow. These temperatures are in record ranges and threaten to again break the all-time hottest temperatures ever recorded in India this week. By now, the onset of monsoonal rains should be taking the edge off a good portion of this heat. But a monsoon apparently delayed by a human forced warming of the world still holds back its cooling loads of moisture. Image source: Earth Nullschool.)
Delays in the Indian Monsoon result in a loss of precipitation due to the fact that the duration of the event is greatly reduced. Rainfall has to therefore be more intense over a shorter period of time in order to make up for losses. Increasing drought prevalence results in further moisture losses due to a kind of atmospheric heat and dryness barrier that tends to sap storms of precipitation even as they start to form. The net result for India is a prediction of severe moisture loss due to human-caused climate change.
This year’s India monsoonal delay — as with the delay during 2014 — falls into that pattern. And the massive drought that India is now experiencing as a result appears to be emerging from a set of atmospheric conditions that are consistent with human-caused climate change. India’s risk for continued drought and increasingly extreme heatwaves over the coming years is therefore on the rise. And it is yet to be seen if this year’s monsoon will deliver the hoped-for and desperately-needed relief. Already, the rain-bearing storm system is lagging. And that’s not a good sign.