Welcome to already the 3rd edition of our “Climate Figure of the Day” series! Every day, I’ll be sharing a climate or climate change related figure. It might be a graph, a map, or another visual. It might be my own creation or sourced elsewhere. The figures will be posted on Twitter/X.com too, under the hashtag #ClimateFigureOfTheDay. While Twitter gives you a snapshot, here on my website, every now and then, I might delve a bit deeper into the details. Want to stay updated? Be sure to follow me on Twitter/X.com here.
The first ice day at Helsinki-Vantaa airport yesterday! Relatively early, especially compared to the current trendline. Ice days seem to come later and later with a slight upward trend, however, there is still large annual variability.
Cold days can occur even in a warming climate. It’s just that the temperature distribution is shifting to the warmer side: warm extremes happen more frequently and become more extreme. Cold extremes become more rare.
For millennia after the last Ice Age, Earth’s global temperature and climate remained relatively stable. Society and civilization have adapted to this rather stable climate. However, the sharp incline since the Industrial Revolution is alarming. Under current policies, we could see a 2°C rise by 2050 and even more by 2100. This may not sound like much, but consider that during the last ice age, the global temperature was 4-5°C cooler globally than it is nowadays. Now imagine this same difference, but with an earth 4-5°C warmer than the current one.
Yes, the earth has been warmer before. However, climate change in the past happened over longer timescales, with the species alive having more time to adapt. The rate of change is extreme and, very importantly: the earth has not been this warm since the start of human civilisation. The Roman Warm Period and Medieval Warm Period were mostly warmer regionally, not globally. We have no reason to assume our species can trive in a much warmer global climate.
More than half of humanity’s CO2 emissions have taken place over the last 30 years. A rapid decline in emissions is vital to avoid further warming of the globe.
The warmer the atmosphere, the more water vapor it can hold. Similar weather systems will now lead to more precipitation than it would on a cooler earth.
Global ocean temperatures remain in unprecedented regions for the time of year. It takes about 3000 times more energy to raise the temperature of water by 1°C than it does for air. This means the oceans can hold a lot of heat. As the oceans warm up, they can eventually release some of that heat back into the atmosphere, leading to an increase in air temperatures as well.
Another way to visualize the September global temperature record. We surpassed the previous record by nearly 0.5°C. That might not sound like a lot, but on a global scale, that is an enormous margin. See the figure below to understand how much of a record shattering event this was.
One of the main differences between natural climate variability and human-induced climate change, is the fact that this man-made warming is occurring at a much faster rate.
Since 20,000 years ago, the Earth has gradually warmed as it transformed from a glacial period to an interglacial. A bit less than 10,000 years ago, the climate stabilized and remained similar, on a global level, for thousands of years. Now, in a timeframe of just 150 years, we already warmed the globe with more than 1°C. And the end is not yet in sight.
With every tenth of a degree of warming, we will see more extreme weather, more frequently.
The snow season in Helsinki is getting shorter. Part of the reason is the fact that the first snow comes later and later. The first snow comes about 3.5 days later per decade; in recent years the first snow sometimes even arrived first in January. In the past, November generally was the month marking the first snow cover.
Another series of measurements, another confirmation of an insanely warm September month on a global scale. By far the warmest on record.
The last 365 days on earth make up the warmest year on record globally. We’re reaching new terrain.
September 2023 compared to an older climatological period (1951-1980). Too often, the fact that our current climatological norm (1991-2020) has already warmed significantly, is overlooked. Here’s how warm September in the Arctic looked, compared to a typical period in the previous century. Another example of Arctic Amplification.
The Arctic warms much faster than the rest of the world, a process known as Arctic Amplification. We can also see that in the temperature data of September:
First frost after summer was measured in Helsinki’s city center! Compared to the long term trend, this year’s frost was slightly on the early side. Compared to long term trends however, it is rather ordinary, as the first frost most commonly shows up in late September to October, sometimes (but rarely) first in November.
From 1844, there’s a slight upward trend in the timing of the first frost, although the trend is not statistically significant. Contrast that with data since 1970, where the first frost is arriving an average of 2.3 days later per decade—a significant shift.
Following the record high global average September temperature, Europe also broke it’s September temperature record. September 2023 was a staggering 2.51°C above the 1991-2020 average—clearly outdistancing the previous European record with a 1.09°C gap. The margins of the records we see nowadays are statistically speaking truly staggering. This is not just record breaking, this is record shattering.
A very warm world. This (mostly red) map, showing temperature anomalies compared to the (already warmed) 1991-2020 baseline, shows the distribution of September warmth around the world. Remarkably, Svalbard is one fo the few cooler-than-average places.
In terms of global temperature, September absolutely shattered previous records. The temperature anomaly for this September was twice as high as the anomaly of the previous record-holder from 2020.
The average surface air temperature of 16.38°C was 0.93°C above the 1991-2020 average—a baseline that itself has seen significant warming compared to earlier decades.
With regard to global temperatures, these numbers are absolutely ludicrous.
For a change, an unusually cold month on Svalbard, defying the warming trend. Svalbard is one of the fastest warming places on earth. But during the past month, it was one of the few places on the planet that was cooler than average.
Compared to the previous century however, the month was not that cold, as the month has warmed by about 3 degrees since the 1970’s.
September was extremely warm in Helsinki. The previous record was broken by almost a full degree. Since the late 1800’s, Helsinki has warmed with about 0.13°C per decade. Since 1970, the month of September has warmed with approximately 0.55°C per decade.
In the Netherlands, it was the 2nd warmest September ever recorded—17.5°C, significantly above the 1991-2020 climatological average of 14.7°C. The all-time record-holder remains September 2006 with 17.9°C.
Regionally, a record-long September heatwave even took place in the country during the past month.
For earlier Climate Figures of The Day, I refer you to these links below: