Jeff Berardelli is WFLA’s Chief Meteorologist and Climate Specialist

TAMPA, Fla. (WFLA) — September was so unusually warm around the Globe, that climate scientists are “gobsmacked” by the record-shattering heat. Many of the World’s leading climate scientists are simply at a loss for words to convey to the public just how extraordinary the spike was.

When the September numbers landed, one by one, scientists flocked to social media to try and convey the significance of what they were seeing. September 2023 was around 1 degree Fahrenheit above the previous record hottest September — a huge leap when you’re talking about the average temperature of the whole planet.

Given how far out of bounds this September was compared to September just a few decades ago, I asked climate and energy researcher Leon Simons to calculate how rare September 2023’s warmth was relative to our past climate just a few decades ago in the 1980s and 1990s.

The answer is astonishing: A once-in-400 billion-year occurrence.

To put the rarity of this event into perspective let’s compare it to something we can relate to — the PowerBall — which is valued at $1.4 billion currently. Your chances of winning that are 1-in-292 million.

That means your chance of winning the PowerBall is almost 1,400 times better than September 2023’s likelihood of being as hot as it was.

Now, if that seems impossible, you are on to something.

The way we calculate the odds of a rare heat event occurring is based on historical temperature data. Historical being the keyword, but there is no historical precedent in our record for how warm the Earth is now. That’s because our climate has changed dramatically in the past few decades due to the heat-trapping effect of substantial greenhouse gas emissions from the burning of fossil fuels.

So statistically, it makes the possibility of achieving today’s heat impossible in the pre-heated climate of a century ago — and virtually impossible even in the semi-heated climate of a few decades ago. That’s why statistical analysis generates numbers like 1-in-400 billion. It means September heat like this past month simply wasn’t possible in the 1980s and 1990s.

In the below graph In the below image – from the European Copernicus Climate Change Service (the same agency that runs the famous European Weather Model) — you can see September global temperatures going back to 1940 from various tracking agencies like NOAA and NASA relative to the late 1800s.

This September was a remarkable 3.25 degrees Fahrenheit (1.75 degrees Celsius) warmer than a typical September around 1900. This departure at least temporarily eclipses the Paris goal of staying below 1.5 degrees C of warming.

The spike is an outlier, even among outliers. And you can visually see why it would have been impossible to generate from any historical statistical analysis.

Below is another image from Copernicus. This time temperatures that are above the 1991-2020 average are in the color red and below-average temperatures are in the blue. This gradual upward trend from cooler blue to warmer red is very well understood. It’s almost entirely due to human-caused climate change.

But what unnerves some scientists is that 2023 leaps out of the graph on the far right at 1.67 degrees Fahrenheit (.93 degrees C) above the recent normal.

Scientists say there’s nothing wrong with the data. All of the agencies that monitor global temperatures show similar numbers. It’s correct and consistent with similar unusual spikes every month this summer.

It’s not even surprising that temperatures significantly spiked this summer — scientists expected it with the intensification of El Niño. But the degree of the leap is what is both unsettling and confounding, as leading global climate scientist Prof. Stefan Rahmstorf explains in this post on X.

Let’s be clear. Scientists do understand “much” of the reason we are seeing such a hot few months. Over the longer term, it’s mainly due to climate change as discussed above. But there are other shorter-term factors.

The biggest one this year is the switch from three years of La Niña in the Tropical Pacific Ocean to a now intensifying El Niño. La Niña is the cool phase of a natural climate oscillation, which traps heat in the depths of the Pacific Ocean. El Niño is the warm phase, which releases that heat into the climate system.

Beyond the La Niña to El Niño transition, there are some other smaller factors. Many scientists point to the reduction of aerosol pollution which typically blocks the sun and reduces Earth’s heating. As the pollution is cleaned up, more sun reaches the surface and thus heats the climate. Along with that, there is likely some reduced cloud cover as well.

Next, there was an eruption of a large underwater volcano called Hunga Tonga last year which released a large amount of water vapor into the Stratosphere. Some contend it is warming the Earth, but studies show the effect is rather modest.

Lastly, Global sea ice is at a record low. This is in part caused by the warm global temperatures but also helps increase temperatures even more due to less reflection of sunlight back into space.

So for all these reasons, scientists understand why we’ve seen a big spike this year. But the magnitude remains a mystery. Something seems to be missing and you can bet there will be numerous studies in the coming months and years to figure it out.

With all that said, these fluctuations in month-to-month or year-to-year surface temperature are probably not quite as important as they may seem. This is a fact that top climate scientist Dr. Michael Mann often stresses.

What’s more important, he says, is the warming rate of the ocean, because it’s not subject to herky-jerky changes like the atmosphere. In the oceans, we see a steady climb with little evidence of acceleration. The graph below is from NOAA showing the much less ‘herky-jerky’ climb of ocean heat.

Here’s something else I noticed this morning when digging into this data and it takes us back to the traditional temperature record again (not ocean heat).

When you look closely at the surface temperature record below, you will notice something similar happened during the last strong El Niño in 2016. Below is another graph of monthly global temperature departures from the 1981-2010 normal.

Notice how the temperature leaped from 2015 to 2016, just like it has leaped from 2022 to 2023. In both instances the leap is shocking, but in both instances, it happened during El Niño years.

This year is a larger leap, but I’d argue some of that is due to a transition from away from three years of cool La Niña. That’s rare and the transition to the warm phase is quite a jolt as the deep oceans release years of pent-up heat.

Monthly global temperature departures from the 1981-2010 normal. Credit: Copernicus
Monthly global temperature departures from the 1981-2010 normal. Credit: Copernicus

My analysis is in good company. Dr Michael Mann also made note of the 2015-2016 leap today on X/Twitter:

None of this is meant to minimize the seriousness of this year’s intense spike in temperature or the main culprit behind most of our warming — namely human-caused climate change. But it does help put what appears to be shocking climate events into some perspective.

Zooming out, the past few month’s extreme warmth and the corresponding climate disasters that went along with it, are alarming because it is a window into the extent of climate extremes a typical summer will feature in just a decade from now. More heat = more energy = more extremes. It’s just that simple.

In other words, by the early 2030s, every year will be as warm as this year is, without El Niño, due simply to manmade greenhouse warming. That’s a fact and can not be changed. Years with El Niño a decade from now will be much hotter than this year.

However, in the longer term, humanity has a real chance to arrest warming by significantly slowing our rate of burning of fossil fuels. We know how to fix it, we have the tools and it’s less expensive than the cost of escalating climate breakdown.

The decision is up to us to collectively conquer climate change — or not.

If we choose not to, our children will bear the burden of a climate that will make this year seem tame — like the good olé days — with extremes that far outpace anything we have experienced this year.

The ball is in our court.