India heat wave: Climate change-fueled event topples monthly records

The heat wave still gripping parts of India and Pakistan set all-time monthly records this weekend and has yet to fully abate.

Why it matters: At least a billion people suffered through temperatures of 104°F (40°C) or higher from Thursday through Sunday, with many seeing highs of 110°F (43°C) and above.

• Heat waves are becoming more common, severe and longer as the world warms in response to human emissions of greenhouse gases.

By the numbers: According to Maximiliano Herrera, an expert on global temperature extremes, several monthly records fell in India and Pakistan on April 30 and May 1, while Pakistan likely experienced its hottest April on record.

• Banda, in Uttar Pradesh, reached 117.4°F (47.2°C) on Friday, setting an April record. Other such records were set Saturday in Gurgaon, Chandigarh and Dharamshala.
• On May 1, the temperature climbed further, to 121.1°F (49.5°C) at Nawabshah, Pakistan, which is likely the hottest temperature on record in the Northern Hemisphere so far this year.
• Jacobabad in Pakistan hit a punishing 120.2F (49.0°C) on April 30.
• Delhi saw temperatures exceed 110°F (43.3°C) for several days.

Threat level: Many in this region lack access to air conditioning, and heat-related illnesses spiked in India and Pakistan, according to news reports. Power outages related to the high electricity demand exacerbated the suffering.

Context: While India and Pakistan typically see heat waves in April and May, the severity of this event and the early arrival of the extreme heat this year are both unusual. March was India's warmest such month on record, and April will make the top five nationwide, while northwestern India may see its warmest April.

• Climate studies have shown clear causal links between the intensity of heat waves and human-caused climate change. A study that examined the deadly heat wave in the Pacific Northwest last year, for example, found that the sizzling temperatures would have been "virtually impossible" without climate change.

Between the lines: India's average temperature has risen by around 0.7°C, or 1.26°F, between 1901–2018, according to an IMD report, which tied this trend to human emissions of greenhouse gases.

• That report found that under a worst-case emissions scenario (which is no longer considered the likeliest outcome) extreme heat could increase by 50 to 70% by 2100.
• However, recent assessments from the U.N.'s top climate panel projected significant increases in heat waves globally even under more modest warming through 2100.
• "We have looked at data for seventy years and at the intensity, the number of heatwaves is directly in response to global warming," Roxy Mathew Koll, a climate expert at the Indian Institute of Tropical Meteorology, told Bloomberg.

What's next: Temperatures will start easing during the next few days but more extreme heat is expected until the monsoon season arrives between May and June.

Editor's note: This story has been corrected to show the temperature in Banda reached 117.4°F, not 117.4°C.