Last month was the hottest June ever recorded on Earth

Rebecca Hersher

Last month was the hottest June on record going back 174 years, according to the National Oceanic and Atmospheric Administration. It's the latest temperature record to fall this summer, as the El Niño climate pattern exacerbates the effects of human-caused climate change.

The average global temperature in June 2023 was slightly hotter than the previous record June, which occurred in 2020.

Millions of people around the world suffered as a result, as heat waves hit every continent. In the U.S., record-breaking heat gripped much of the country including the Northeast, Texas, the Plains and Puerto Rico in June, and another round of deadly heat is affecting people across the southern half of the country this week.

Every June for the last 47 years has been hotter than the twentieth century average for the month, a stark reminder that greenhouse gas emissions, largely from burning fossil fuels, are causing steady and devastating warming worldwide.

The El Niño climate pattern, which officially began last month, is one reason temperatures are so hot right now. The cyclic pattern causes hotter than normal water in the Pacific Ocean, and the extra heat alters weather around the world and raises global temperatures. Usually, the hottest years on record occur when El Niño is active.

But the main driver of record-breaking heat is human-caused climate change. This June is just the latest reminder that heat-trapping greenhouse gasses continue to accumulate in the atmosphere and disrupt the planet's climate. The last eight years were the hottest ever recorded, and forecasters say the next five years will be the hottest on record.

Oceans are trending even hotter than the planet as a whole. This June was the hottest month ever recorded for the world's oceans. One of many hotspots is in the Gulf of Mexico, where water temperatures in some areas hovered around 90 degrees Fahrenheit this week. That's dangerously hot for some marine species, including coral.

Oceans have absorbed more than 90% of the extra heat in the atmosphere generated by human-caused warming.

Many parts of the U.S. are continuing to see dangerously high temperatures in July. Heat waves are the deadliest weather-related disasters in the U.S., and are especially dangerous for people who live or work outside, and for people with cardiovascular or respiratory diseases. Officials recommend learning the signs of heatstroke and other heat-related illnesses, staying hydrated and taking time to adjust when outside temperatures are high.