Last week the hottest in recorded world history, U.N. agency says

Last week was the hottest ever recorded across the world — and an oncoming El Niño is likely to keep upward pressure on global temperatures, the World Meteorological Organization said Monday.

Global average surface temperatures were not the only records broken last week, the United Nations' weather and climate agency said, citing preliminary data. It noted sea surface temperatures also hit "unprecedented" highs and that Antarctic sea ice coverage is at a record low.

The WMO said climate change and the developing El Niño are expected to push land and ocean temperatures higher. But that El Niño system has yet to take full effect, meaning temperature records are likely to be reached again later this year.

"The scientific community is struggling to a certain extent to keep up," Michael Sparrow, head of the WMO's world climate research department, said in a press call. "It's very concerning."

Mean temperatures reached as high as 17.24 degrees Celsius (63.03 degrees Fahrenheit) globally on Friday, according to the Japanese government's JRA-3Q dataset, the WMO said.

The U.N. agency said that finding backed up observations from the European Union's Copernicus ECMWF ERA5 and the National Oceanic and Atmospheric Administration.

Those early results point to the first week of July being the hottest since modern instruments began measuring global temperatures. It follows record high temperatures in June, which were 0.5 degrees C above the 1991 through 2020 average.

The high ocean temperatures in the North Atlantic are "unprecedented and of great concern" given the region's role in driving extreme weather events, Sparrow said in a statement. A warmer Atlantic could contribute to more hurricanes and tropical cyclones, as well as heavier rains and drought in West Africa, he said.

The hotter temperatures in the North Atlantic, however, are not likely due to El Niño. The oceans absorb more than 90 percent heat from human-produced greenhouse gases that drive climate change, Sparrow noted.

But the development of the El Niño system will likely raise ocean temperatures, which is "worrying news for the planet," Christopher Hewitt, WMO director of climate services, said in a statement.

Zia Weise contributed to this report.