Hottest summer: Why 11 states and Union Territories in India saw record temperatures in June-August

During June-August, over 3.8 billion people — 48 percent of the global population — experienced at least 30 days of CSI level 3 or higher. A CSI level 3 indicates that human-caused climate change made those temperatures at least three times more likely. (Photo Ben Brooks via Wikimedia Commons)

The heat is on. It started with a scorching June, the hottest ever. Then scientists confirmed that July 2023 was the Earth’s hottest month on record. Now, according to a Climate Central report, released on September 7, the planet has had its hottest northern hemisphere summer on record, caused by human-driven climate change.

In this period, approximately 7.95 billion people – 98 percent of the entire human population – experienced temperatures that were made at least two times more likely by heat-trapping carbon pollution in Earth’s atmosphere. In all, 180 countries and 22 territories were impacted.

“Virtually no one on Earth escaped the influence of global warming during the past three months,” said Dr Andrew Pershing, Climate Central's vice president for science. “In every country we could analyse, including the southern hemisphere where this is the coolest time of year, we saw temperatures that would be difficult – and in some cases nearly impossible – without human-caused climate change. Carbon pollution is clearly responsible for this season's record-setting heat.”

Also read: India's climate ambitions are slipping

Deep impact

The Climate Shift Index (CSI), Climate Central’s temperature attribution system, maps the influence of climate change on temperatures across the globe, every day. For this particular analysis, it reviewed local, daily temperatures around the world with and without current levels of carbon pollution.

It found that from June to August 2023, over 3.8 billion people — 48 percent of the global population — experienced at least 30 days during June-August with a CSI level 3 or higher. A CSI level 3 indicates that human-caused climate change made those temperatures at least three times more likely. Global exposure peaked on August 16, when 4.2 billion people worldwide experienced extreme heat at CSI level 3 or higher.

What’s also concerning is the inequitable impact of climate change. According to the report, 79 countries experienced at least half of all June-August days at CSI level 3 or higher. But more than half of these (49) were UN-designated least developed countries and small island developing states, which together account for approximately only 7 percent of cumulative historical greenhouse gas emissions.

In fact, as per the report, countries with lowest emissions experienced approximately three to four times more June-August days with very strong climate fingerprints than the G20 countries.

Cause and effect

It resulted in record-shattering temperatures and dangerous heat waves in many parts of the world. As per the report, heat waves are the deadliest weather-related hazards, and their rising global frequency and intensity is consistent with well-established scientific understanding of the consequences of carbon pollution—mainly from burning coal, oil, and natural gas.

In India, 11 states and Union Territories (Kerala, Puducherry, Andaman and Nicobar, Meghalaya, Goa, Karnataka, Mizoram, Manipur, Tripura, Nagaland, and Tamil Nadu) recorded a hotter summer. At least half of all their June-August days were CSI level 3 or higher. Three of these - Kerala, Puducherry, and Andaman and Nicobar - experienced at least 60 days (about two months) at CSI level 3 or higher.

Eleven regions also experienced average temperatures that were 1 degree Celsius or more above the long-term average (1991-2020). They included Andhra Pradesh, Bihar, Chhattisgarh, Jharkhand, Karnataka, Kerala, Odisha, Sikkim, Telangana, Tripura and West Bengal.

It also caused wildfires in North America, Europe, and Africa. Record-breaking summer heat also occurred in the ocean, increasing the risk of rapidly intensifying tropical cyclones like Hurricane Idalia and coral bleaching events like those impacting Florida and the Caribbean.