PRINCETON, NJ: In a prelude to COP28, a report by Climate Central scientists estimate that the global average temperature between November 1, 2022 and October 31, 2023 was 1.32°C above the pre-industrial baseline – the hottest 12 months in recorded history.

The Paris Agreement goal is to keep global warming under 2.0˚C and preferably 1.5˚C.

Using its Climate Shift Index (CSI), a daily local temperature attribution system, scientists have produced data for 175 countries, 154 states or provinces and 920 major cities.

The CSI scale is centered on zero. A level of 1 means that climate change is detectable with the temperature anomaly at least 1.5x more likely.

In the past 12 months, the country with the highest average CSI was Jamaica with a level of 4.5 out of a maximum of 5. On an average day a person experienced extreme temperatures made more than four times more likely by human-caused climate change.

Two other countries, Guatemala (4.4) and Rwanda (4.1), also had 12-month average CSI values above 4.

The scientists also analyzed extreme temperatures in 700 cities of at least one million people around the world.

Houston, Texas topped the list with a 22-day streak of extreme heat. Twelve U.S. cities in Texas, Florida, Louisiana, Arizona and Nevada experienced periods of five or more days with an average CSI of 5, meaning that climate change boosted the likelihood of extreme temperatures by at least a factor of five.

Since October 2022, 7.3 billion people worldwide endured at least 10 days of temperatures with a CSI of 3 or higher and 5.8 billion experienced a similar index for more than a month.

Over the same period 90 percent of people worldwide and 49 percent in the U.S. experienced at least 10 days of temperatures caused by climate change and 1.9 billion had heat waves lasting at least five days.

Climate Central says its findings confirm that less-developed countries and small island nations have an inequitable exposure to climate-driven heat while one in four people on Earth face extreme, persistent, and dangerous heat waves driven by burning coal, oil, and natural gas.

Human-induced climate change impacted large parts of South America: the heat-boosted drought in Argentina led to an estimated 3.0 GDP reduction, while in the Amazon River region, the water level reached its lowest point ever recorded, affecting water and food distribution to half a million people in October alone.

In the Panama Canal, which facilitates an estimated 5.0 percent of global trade, a two-year drought disrupted volumes for months.

Human-induced climate change also increases the severity and frequency of extreme rainfall and, consequently, of fatal flooding events.

Over the past year, thousands have been killed and millions have been displaced around the world: in New Zealand during Cyclone Gabrielle; in Malawi, Mozambique, and Madagascar during Cyclone Freddy; in China during Typhoon Haikui; and in Libya, Greece, Bulgaria and Turkey during Storm Daniel — Africa’s deadliest storm ever, with over 4,000 victims.

A recent investigation shows that extreme weather killed at least 15,700 people in Africa by November this year. In April, unprecedented flooding in Rwanda and the Democratic Republic of the Congo killed over 400 people; by September, flooding washed away farmlands in Ghana and displaced nearly 26,000 people - most of whom are women and children.

Meanwhile, the drought in the Horn of Africa, intensified by climate-fueled heat, continues to claim new victims, having left over 23 million people acutely food insecure while displacing another 2.7 million.

In the U.S., 24 extreme weather events killed at least 383 people. In what is now considered the deadliest U.S. fire of the century, 93 people died in Hawaii. In Canada, one person out of every 200 was forced to evacuate their homes due to wildfires that burned over 45 million acres and lasted for months.

Heat waves that approached the human survivability threshold stretched from East and South Asia to Europe and North Africa, killing at least 264 people in India and over 2,000 people in Spain, at a time when parts of the country also faced their driest period in 500 years.

In Italy, as temperatures surpassed 40°C in August and September, hospitals were unable to accommodate the number of people seeking care for heat-related illnesses, with COVID-era admission levels reported in emergency units.

“While the last year has set records, it is also not surprising - we are in the midst of a warming trend fueled by carbon pollution,” says the report. “As long as humanity continues to burn coal, oil, and natural gas, temperatures will rise and [the] impacts will accelerate and spread.”

Climate Central is a nonprofit organization that analyzes and reports on climate science and how it affects people’s lives. https://www.climatecentral.org/