What happens in India doesn't stay in India. Why this deadly heat wave has a wide reach

Our planet is changing. So is our journalism. This story is part of a CBC News initiative entitled "Our Changing Planet" to show and explain the effects of climate change. Keep up with the latest news on our Climate and Environment page.

On December 29, 1972, mathematician and meteorologist Edward Lorenz presented a talk at the 139th meeting of the American Association for the Advancement of Science in Washington, D.C. The title being: "Predictability: Does the Flap of a Butterfly's Wings in Brazil Set Off a Tornado in Texas?" 

Though Lorenz was trying to detail the difficulty of weather forecasting, since then, the so-called "butterfly effect" has been used in movies — most notably Jurassic Park — and television to describe chaos theory, or how one small thing may influence something completely unrelated.

While the flap of a butterfly's wings won't necessarily influence the weather thousands of kilometres away, in the face of our rapidly warming planet, there are plenty of reminders concerning our interconnectivity.

Over the past week, stories have splashed across our computer and television screens about the crushing heat wave that has descended across most of India, and for good reason.

India is no stranger to heat waves. Year after year, the country experiences days of intense heat ahead of its monsoon season that brings much-needed rains for crops. 

But this spring has been much different.

Temperatures have soared to near 50 C across almost the entire country of more than 1.3 billion people.

"This heat wave is quite unusual. March has been the hottest in 122 years, pretty much the hottest year ever since we began recording temperatures," Aditi Mukherji, a principal researcher at the International Water Management Institute out of New Delhi told CBC News in an email. "Heat waves are common in India, but never so early. Then, heat waves are [normally] localized, but this time, it is widespread almost all across [the country]."

While it's not yet clear exactly what factors have played a role in this historic heat wave, scientists believe that it's been affected by climate change.

"This is what we expect from climate change," said Raghu Murtugudde, a visiting research scientist at the University of Maryland's Earth System Science Interdisciplinary Center. "The thing to notice is that if you look at the Middle East, Mediterranean region, that has warmed a lot since about 1990. And that wind that blows from that direction over to India, is now warmer by a lot." 

That's not to say there isn't some natural variability that's playing a role. Currently, there is a La Niña event occurring. La Niña is part of a natural cycle called the El Niño-Southern Oscillation,or ENSO, where colder waters persist in part of the Pacific Ocean (the opposite, El Niño, means there is warmer water). This can affect weather patterns around the world.

"La Niña sets up a pressure pattern that brings the cold way, way down into peninsular India," Murtugudde said. "We had a colder than normal winter, as we expect from La Niña. Now we are having much warmer than normal spring because that warm air is funnelling straight down all the way into peninsular India."

Then there's the saying: What happens in the Arctic doesn't stay in the Arctic.