If the world doesn't drastically reduce its carbon emissions, some regions of India and Pakistan could become too hot for people to live there, says climate scientist Chandni Singh.

Already, the neighbouring countries are suffering from extreme, record-breaking heat that's causing people to die, melting pavement, sparking fires and crashing the electricity grid.

Last month, northwest and central India saw its highest temperatures since the country began keeping records 122 years ago, according to the Indian Meteorological Department. New Delhi had seven consecutive days over 40 C in April. 

It's so hot in Pakistan that the country went from winter to summer this year without the spring season for the first time in decades. Some parts of the country are expected to hit as high as 50 C later this week. 

Chandni Singh is a climate change researcher at the Indian Institute for Human Settlements in Bangalore and one of the lead authors of this year's Intergovernmental Panel on Climate Change report. She recently experienced the scorching heat first-hand when she visited her family in New Delhi. Here is part of her conversation with As It Happens guest host Helen Mann. 

Dr. Singh, you spent a week in Delhi when temperatures were in the mid-40s. What did it feel like for you to live under that heat?

As you can imagine, temperatures of 45 C and 46 C are really absolutely excruciating. I ended up having to be out in the hot sun from around noon to 3 p.m. and was just completely exhausted by the end of it, not only that day, but the next day as well.

But of course, I always think of people who don't have the ability to cool their homes or go back out of the sun really because of the livelihoods they are in. So I at least had the respite of a cool home and plenty of water, while many people don't have that.

Can you describe for us what it feels like to be in 45 C, 46 C heat?

While you're in it, I think it's just very hot. But for me personally, it's after the heat. 

So when it's cooled down in the evening, there's just immense fatigue that you feel, and almost you feel as if you've been dried out in a certain way. And no matter how much water you drink, you just continue to feel really dry and desiccated.

And you felt that into the next day, you said.

It actually took me two days to come back to normal. And this was when it was just four hours of exposure and a lot of water along the way. I was drinking water. I had my head covered to avoid direct sun on me. I had dark glasses. So, you know, in spite of all that, I was feeling this fatigue.