A month of sweltering conditions drove global ocean and air temperatures to their hottest August in at least 174 years of record-keeping.

Why it matters: The planet’s summer of sizzling milestones is a clear indication that 2023 will likely rank at the top of the list of warmest years.

The big picture: The planet has seen a steady onslaught of extreme weather and climate disasters this summer, from the deadly flooding in Greece and Libya to repeat and deadly heat waves in the U.S. and Europe.

There is now at least a 95% likelihood that 2023 will rank as a top-2 warmest year on record, NOAA stated Thursday. This is a new development, since previously its forecasters were zeroing in on a top-5 warmest year.
Outside climate scientists, including those at Berkeley Earth, have stated that not only will 2023 be the warmest year on record, it even has a 50% chance of meeting or beating the 1.5°C (2.7°F) guardrail contained in the Paris Agreement.
Yes, but: The agreement refers to a long-term, multi-decadal increase of 1.5°C or more, not just a single year.)

By the numbers: The August data, along with NOAA and NASA’s official word that the meteorological summer of June through August was the warmest on record, is replete with superlatives.

Not only were the planet’s oceans the hottest on record for August, but the margin of the record itself set a record for the largest monthly sea surface temperature anomaly, coming in at 1.03°C (1.85°F) above average.
August was the fifth straight month that saw oceans set a temperature record.
It was also the fourth straight month with the lowest sea ice extent on record in the Antarctic, a development that is raising alarm bells among ice researchers.
Partly connected to an El Niño event in the tropical Pacific Ocean, all that extra ocean heat has to go somewhere. It is leading to devastating precipitation extremes, rapidly intensifying hurricanes and marine and land heat waves and wildfires
Zoom in: Four continents were warmest on record in August: Asia, Africa, North America and South America, the NOAA found.

According to climate scientist Kevin Trenberth, the record warm oceans are adding a tremendous amount of extra water vapor to the atmosphere. A warmer environment holds more moisture, at about 7% more water-holding capacity per 1°C of warming,
This in turn traps more heat, since water vapor is a greenhouse gas, as part of a positive climate feedback.
What they’re saying: Deke Arndt, who directs NOAA’s National Centers for Environmental Information and has completed monthly global reports for more than a decade, said the statistics for August were especially significant.

“I’m rarely stunned by our findings,” he wrote on X, formerly known as Twitter. “Yesterday when the climate monitoring team briefed this, it took me five minutes just to process the magnitude.”
“It’s common to dismiss 174-yr record as blip in geological time. Fact is, they are the most important, vital 174 yrs in the history of humanity’s relationship with the Earth system, when almost everything we know about agriculture and infrastructure was found or refined,” he wrote.
Between the lines: These events are contributing to a new sense of urgency among activists and some policymakers to act more boldly to address climate change.

There’s an acknowledged need to cut greenhouse gas emissions, bolster financing of “clean” energy technologies, and set new emissions reduction targets.
What’s next: Clues as to the extent to which the extremes of 2023 will translate to policy outcomes may be seen at the U.N. Secretary-General’s climate summit in New York next week, as well as at the COP28 summit in Dubai late this year.

The bottom line: The pace and extent of future warming depends on cutting emissions of greenhouse gases in the near term, multiple climate-related research reports have emphasized recently.

“Global marine heat waves and a growing El Niño are driving additional warming this year, but as long as emissions continue driving a steady march of background warming, we expect further records to be broken in the years to come,” NOAA chief scientist Sarah Kapnick said in a statement.