• The world's average temperature climbed to its highest level since records began on Tuesday, according to provisional data from U.S. researchers.
• Scientists warned Tuesday's temperature record was likely to be the first of many over the coming months, citing the combination of the climate crisis and the El Niño phenomenon.
• It follows a series of mind-bending extreme weather events across the globe in recent months.

The world's average temperature climbed to its highest level since records began, according to provisional data from U.S. researchers, underscoring the pressing need to slash greenhouse gas emissions fueling the climate emergency.

The planet's average daily temperature climbed to 17.18 degrees Celsius (62.9 degrees Fahrenheit) on Tuesday, according to the University of Maine's Climate Reanalyzer, an unofficial tool that is often used by climate scientists as a reference to the world's condition.

The milestone comes just one day after global average temperatures topped 17 degrees Celsius for the first time in 44 years, when the data was first collected. The previous record of 16.92 degrees Celsius had stood since Aug. 14, 2016 — the warmest year ever recorded.

"Monday, July 3rd was the hottest day ever recorded on Planet Earth. A record that lasted until … Tuesday, July 4th," said Bill McGuire, professor emeritus of geophysical and climate hazards at University College London, via Twitter.

"Totally unprecedented and terrifying," he added.

Scientists warned Tuesday's temperature record was likely to be the first of many over the coming months, citing the combination of the climate crisis and the El Niño phenomenon.

"Do you remember yesterday's global surface air temperature record? It just got shattered again," climate researcher Leon Simons also said via Twitter.

It follows a series of mind-bending extreme weather events across the globe in recent months, with climate-fueled heat waves recorded in China, the western Mediterranean, Mexico and the southern U.S.

Researchers have also recently sounded the alarm over rapidly rising temperatures on land and sea.

'An unfamiliar world'

"Global warming is leading us into an unfamiliar world," said Robert Rohde, a physicist and lead scientist at the nonprofit environmental data analysis group Berkeley Earth.

Citing the University of Maine's Climate Reanalyzer, Rohde said via Twitter on Tuesday that though the data only stretches back to 1979, other data sets looking further back show that the recent temperature record was warmer than any point since instrumental measurements began, "and probably for a long time before that as well."

The temperature record comes shortly after the U.N. weather agency declared the onset of El Niño.

The World Meteorological Organization on Tuesday said the return of the phenomenon paves the way for a likely spike in global temperatures and extreme weather conditions.

El Niño — or "the little boy" in Spanish — is widely recognized as the warming of the sea surface temperature, a naturally occurring climate pattern which happens on average every two to seven years.

The effects of El Niño tend to peak during December, but the impact typically takes time to spread across the globe. This lagged effect is why forecasters believe 2024 could be the first year that humanity surpasses 1.5 degrees Celsius above preindustrial levels.

The 1.5 degrees Celsius threshold is the aspirational global temperature limit set in the landmark 2015 Paris Agreement. Its importance is widely recognized because so-called tipping points become more likely beyond this level. Tipping points are thresholds at which small changes can lead to dramatic shifts in Earth's entire life-support system.