Mika Rantanen
@mikarantane.bsky.social
Researcher at the Finnish Meteorological Institute. Climate change, extreme weather and attribution of extreme events. PhD in meteorology from the University of Helsinki.
Pinned
Mika Rantanen
@mikarantane.bsky.social
· Apr 28
Summer 2024 in northern Fennoscandia was very likely the warmest in 2000 years - npj Climate and Atmospheric Science
npj Climate and Atmospheric Science - Summer 2024 in northern Fennoscandia was very likely the warmest in 2000 years
doi.org
Excited to share that our new paper
“Summer 2024 in northern Fennoscandia was very likely the warmest in 2000 years”
has been published in npj Climate and Atmospheric Science!
See the open-access paper from doi.org/10.1038/s416...
Short thread 👇
“Summer 2024 in northern Fennoscandia was very likely the warmest in 2000 years”
has been published in npj Climate and Atmospheric Science!
See the open-access paper from doi.org/10.1038/s416...
Short thread 👇
Meanwhile in Helsinki (Kaisaniemi) Finland: the season's first snow finally arrived today. Approximately the same latitude and winter climate as Juneau, Alaska.
One of the latest first snows on record for Helsinki.
One of the latest first snows on record for Helsinki.
Will the snow ever stop in Juneau? The record snow depth keeps growing. Over 40" new snow in the last 4 days - and still snowing. Only April 1-4, 1963, had more in a 4-day period (45.9"). Still a few hours to go ...
December 31, 2025 at 8:33 AM
Meanwhile in Helsinki (Kaisaniemi) Finland: the season's first snow finally arrived today. Approximately the same latitude and winter climate as Juneau, Alaska.
One of the latest first snows on record for Helsinki.
One of the latest first snows on record for Helsinki.
As far as I know, here are all known cases of ≥ 31 m/s mean wind speed observations in Finnish sea areas:
31 m/s Valassaaret 1971
31 m/s Korsnäs 1975 (twice)
31 m/s Hanko 1995
32.5 m/s Kökar 2019
33.5 m/s Rauma 2024
31.4 m/s Rauma 2025 (yesterday)
31 m/s Valassaaret 1971
31 m/s Korsnäs 1975 (twice)
31 m/s Hanko 1995
32.5 m/s Kökar 2019
33.5 m/s Rauma 2024
31.4 m/s Rauma 2025 (yesterday)
December 28, 2025 at 1:33 PM
As far as I know, here are all known cases of ≥ 31 m/s mean wind speed observations in Finnish sea areas:
31 m/s Valassaaret 1971
31 m/s Korsnäs 1975 (twice)
31 m/s Hanko 1995
32.5 m/s Kökar 2019
33.5 m/s Rauma 2024
31.4 m/s Rauma 2025 (yesterday)
31 m/s Valassaaret 1971
31 m/s Korsnäs 1975 (twice)
31 m/s Hanko 1995
32.5 m/s Kökar 2019
33.5 m/s Rauma 2024
31.4 m/s Rauma 2025 (yesterday)
According to FMI wave buoy measurements, the significant wave height reached 11.1 meters last night in the Bothnian Sea.
If true, it would be the highest waves ever recorded in the Baltic Sea.
en.ilmatieteenlaitos.fi/wave-height?...
If true, it would be the highest waves ever recorded in the Baltic Sea.
en.ilmatieteenlaitos.fi/wave-height?...
December 28, 2025 at 6:40 AM
According to FMI wave buoy measurements, the significant wave height reached 11.1 meters last night in the Bothnian Sea.
If true, it would be the highest waves ever recorded in the Baltic Sea.
en.ilmatieteenlaitos.fi/wave-height?...
If true, it would be the highest waves ever recorded in the Baltic Sea.
en.ilmatieteenlaitos.fi/wave-height?...
Jo 100 000 sähkötöntä taloutta. #Hannesmyrsky sai siis nimensä myrskyjen "raskassarjalaisiin" ja lukema oikeuttaa pääsyn merkittävimpien myrskyjen listalle: www.ilmatieteenlaitos.fi/merkittavia-...
December 27, 2025 at 7:24 PM
Jo 100 000 sähkötöntä taloutta. #Hannesmyrsky sai siis nimensä myrskyjen "raskassarjalaisiin" ja lukema oikeuttaa pääsyn merkittävimpien myrskyjen listalle: www.ilmatieteenlaitos.fi/merkittavia-...
Kovin keskituuli toistaiseksi tuttuun tapaan Rauman Kylmäpihlajalla 31,4 m/s.
Vastaa ankaraa myrskyä, joka toistuu noin kerran 10 vuodessa. #Hannesmyrsky
Vastaa ankaraa myrskyä, joka toistuu noin kerran 10 vuodessa. #Hannesmyrsky
December 27, 2025 at 6:32 PM
Kovin keskituuli toistaiseksi tuttuun tapaan Rauman Kylmäpihlajalla 31,4 m/s.
Vastaa ankaraa myrskyä, joka toistuu noin kerran 10 vuodessa. #Hannesmyrsky
Vastaa ankaraa myrskyä, joka toistuu noin kerran 10 vuodessa. #Hannesmyrsky
Hirmumyrskyä tuntureilla. Saanalta viimeisin tuulihavainto tunti sitten 38 m/s (puuskat 44m/s).
Sen jälkeen tiedot puuttuvat. Ehkä laadunvarmistus luulee havaintoja virheellisiksi tai voimakas tuuli on rikkonut mittarin.
Sen jälkeen tiedot puuttuvat. Ehkä laadunvarmistus luulee havaintoja virheellisiksi tai voimakas tuuli on rikkonut mittarin.
December 27, 2025 at 1:35 PM
Hirmumyrskyä tuntureilla. Saanalta viimeisin tuulihavainto tunti sitten 38 m/s (puuskat 44m/s).
Sen jälkeen tiedot puuttuvat. Ehkä laadunvarmistus luulee havaintoja virheellisiksi tai voimakas tuuli on rikkonut mittarin.
Sen jälkeen tiedot puuttuvat. Ehkä laadunvarmistus luulee havaintoja virheellisiksi tai voimakas tuuli on rikkonut mittarin.
Boxing Day in Orimattila, Finland at 61°N latitude.
Wonderful weather, although at this far north you'd expect to have some snow at Christmas.
Wonderful weather, although at this far north you'd expect to have some snow at Christmas.
December 27, 2025 at 9:00 AM
Boxing Day in Orimattila, Finland at 61°N latitude.
Wonderful weather, although at this far north you'd expect to have some snow at Christmas.
Wonderful weather, although at this far north you'd expect to have some snow at Christmas.
The last week of 2025 will bring us the strongest windstorm of the year.
Forecasted maximum gusts of ~140 km/h (39 m/s) and the affected area are more or less similar to the recent extreme northerly windstorms in Finland (Aapeli 2019, Lyly 2024).
Forecasted maximum gusts of ~140 km/h (39 m/s) and the affected area are more or less similar to the recent extreme northerly windstorms in Finland (Aapeli 2019, Lyly 2024).
December 25, 2025 at 7:55 PM
The last week of 2025 will bring us the strongest windstorm of the year.
Forecasted maximum gusts of ~140 km/h (39 m/s) and the affected area are more or less similar to the recent extreme northerly windstorms in Finland (Aapeli 2019, Lyly 2024).
Forecasted maximum gusts of ~140 km/h (39 m/s) and the affected area are more or less similar to the recent extreme northerly windstorms in Finland (Aapeli 2019, Lyly 2024).
Reposted by Mika Rantanen
The administration of US President Donald Trump intends to dismantle the National Center for Atmospheric Research (NCAR), a world-leading Earth-science centre in Boulder, Colorado.
go.nature.com/4pjzUqB
go.nature.com/4pjzUqB
Trump team plans to break up ‘global mothership’ of climate science
Much of the National Center for Atmospheric Research’s non-climate portfolio will be dispersed, the White House says.
go.nature.com
December 17, 2025 at 7:51 PM
The administration of US President Donald Trump intends to dismantle the National Center for Atmospheric Research (NCAR), a world-leading Earth-science centre in Boulder, Colorado.
go.nature.com/4pjzUqB
go.nature.com/4pjzUqB
Reposted by Mika Rantanen
🌊📉 Sea surface temperatures have… come back down.
After the big global jump in 2023/24, SSTs are now back at below pre-jump levels in November (climatereanalyzer.org/clim/sst_dai...).
Climate surprise or expected? What role does climate variability play? Let’s try to unpack 👇
After the big global jump in 2023/24, SSTs are now back at below pre-jump levels in November (climatereanalyzer.org/clim/sst_dai...).
Climate surprise or expected? What role does climate variability play? Let’s try to unpack 👇
December 15, 2025 at 10:40 AM
🌊📉 Sea surface temperatures have… come back down.
After the big global jump in 2023/24, SSTs are now back at below pre-jump levels in November (climatereanalyzer.org/clim/sst_dai...).
Climate surprise or expected? What role does climate variability play? Let’s try to unpack 👇
After the big global jump in 2023/24, SSTs are now back at below pre-jump levels in November (climatereanalyzer.org/clim/sst_dai...).
Climate surprise or expected? What role does climate variability play? Let’s try to unpack 👇
Reposted by Mika Rantanen
The new GloSAT temperature dataset extends our observational estimates of global temperature change back to 1781
Blog: climatelabbook.substack.com/p/new-estima...
Paper by Morice et al.: essd.copernicus.org/articles/17/...
Blog: climatelabbook.substack.com/p/new-estima...
Paper by Morice et al.: essd.copernicus.org/articles/17/...
New estimates of surface temperature change since the late 18th century
Releasing an observation-based global temperature dataset extending back to 1781
climatelabbook.substack.com
December 15, 2025 at 2:10 PM
The new GloSAT temperature dataset extends our observational estimates of global temperature change back to 1781
Blog: climatelabbook.substack.com/p/new-estima...
Paper by Morice et al.: essd.copernicus.org/articles/17/...
Blog: climatelabbook.substack.com/p/new-estima...
Paper by Morice et al.: essd.copernicus.org/articles/17/...
Unfortunately it seems likely that southern Finland will see a widespread green Christmas this year. The largest temperature anomalies will occur just before the holidays.
Resembles a bit the situation in December 2020 when it was last time widely a snowless Christmas.
Resembles a bit the situation in December 2020 when it was last time widely a snowless Christmas.
December 15, 2025 at 7:24 AM
Unfortunately it seems likely that southern Finland will see a widespread green Christmas this year. The largest temperature anomalies will occur just before the holidays.
Resembles a bit the situation in December 2020 when it was last time widely a snowless Christmas.
Resembles a bit the situation in December 2020 when it was last time widely a snowless Christmas.
A rare phenomenon this morning in Helsinki ☀️
December 12, 2025 at 9:02 AM
A rare phenomenon this morning in Helsinki ☀️
Reposted by Mika Rantanen
#CopernicusClimate has released its first data from the Copernicus pan-Arctic Regional Reanalysis (CARRA2): 2.5 km pan‑Arctic coverage, 24 years of data in the Climate Data Store, more realistic physics & improved details for local extremes, lots of added details with respect to ERA5.
⬇️
⬇️
December 10, 2025 at 1:17 PM
#CopernicusClimate has released its first data from the Copernicus pan-Arctic Regional Reanalysis (CARRA2): 2.5 km pan‑Arctic coverage, 24 years of data in the Climate Data Store, more realistic physics & improved details for local extremes, lots of added details with respect to ERA5.
⬇️
⬇️
Reposted by Mika Rantanen
By the finest of margins, ERA5 shows a reversal of the daily-mean 10 hPa 60°N zonal-mean zonal winds on 28 November to –0.13 m/s.
That nominally ties with 28 Nov 1968 as the earliest major sudden stratospheric warming on record in ERA5 post-1958 (when stratospheric observations increased).
That nominally ties with 28 Nov 1968 as the earliest major sudden stratospheric warming on record in ERA5 post-1958 (when stratospheric observations increased).
December 8, 2025 at 8:13 PM
By the finest of margins, ERA5 shows a reversal of the daily-mean 10 hPa 60°N zonal-mean zonal winds on 28 November to –0.13 m/s.
That nominally ties with 28 Nov 1968 as the earliest major sudden stratospheric warming on record in ERA5 post-1958 (when stratospheric observations increased).
That nominally ties with 28 Nov 1968 as the earliest major sudden stratospheric warming on record in ERA5 post-1958 (when stratospheric observations increased).
Sunshine durations so far in December. Zero hours almost everywhere in Finland. No wonder if it's felt dark recently.
December 9, 2025 at 10:54 AM
Sunshine durations so far in December. Zero hours almost everywhere in Finland. No wonder if it's felt dark recently.
Reposted by Mika Rantanen
2025 is on course to be joint-second warmest year.
The #C3S Climate Bulletin reports that November was 1.54°C above pre-industrial levels, making it the third-warmest November on record. The 2023–2025 average is likely to be the first three-year average exceeding 1.5°C.
Find more info ⬇️
The #C3S Climate Bulletin reports that November was 1.54°C above pre-industrial levels, making it the third-warmest November on record. The 2023–2025 average is likely to be the first three-year average exceeding 1.5°C.
Find more info ⬇️
December 9, 2025 at 8:30 AM
2025 is on course to be joint-second warmest year.
The #C3S Climate Bulletin reports that November was 1.54°C above pre-industrial levels, making it the third-warmest November on record. The 2023–2025 average is likely to be the first three-year average exceeding 1.5°C.
Find more info ⬇️
The #C3S Climate Bulletin reports that November was 1.54°C above pre-industrial levels, making it the third-warmest November on record. The 2023–2025 average is likely to be the first three-year average exceeding 1.5°C.
Find more info ⬇️
New evidence suggests weather persistence is increasing in the northern mid– and high latitudes due to climate change.
So far, I’ve been skeptical as the signal seems small compared to natural variability, but maybe it’s time to update my thinking.
www.nature.com/articles/s43...
So far, I’ve been skeptical as the signal seems small compared to natural variability, but maybe it’s time to update my thinking.
www.nature.com/articles/s43...
Enhanced weather persistence due to amplified Arctic warming - Communications Earth & Environment
Weather persistence, in terms of duration of surface-air temperature anomalies across all weather types and seasons in Northern Hemisphere mid-latitudes, has increased in recent decades due to Arctic ...
www.nature.com
December 9, 2025 at 6:38 AM
New evidence suggests weather persistence is increasing in the northern mid– and high latitudes due to climate change.
So far, I’ve been skeptical as the signal seems small compared to natural variability, but maybe it’s time to update my thinking.
www.nature.com/articles/s43...
So far, I’ve been skeptical as the signal seems small compared to natural variability, but maybe it’s time to update my thinking.
www.nature.com/articles/s43...
This morning's ECMWF deterministic forecast simulates an extreme scenario: +11 °C in Finland in mid-December.
Most likely does not verify as such but gives perspective of what it possible in today's climate under the current large-scale weather pattern.
Most likely does not verify as such but gives perspective of what it possible in today's climate under the current large-scale weather pattern.
December 8, 2025 at 7:38 AM
This morning's ECMWF deterministic forecast simulates an extreme scenario: +11 °C in Finland in mid-December.
Most likely does not verify as such but gives perspective of what it possible in today's climate under the current large-scale weather pattern.
Most likely does not verify as such but gives perspective of what it possible in today's climate under the current large-scale weather pattern.
New ECMWF seasonal forecast came out two days ago, suggesting still NAO+ dominated late winter. The surprisingly high run-to-run consistency indicates a predictable signal that was "visible" to the model already in September. Perhaps originating from the tropics (i.e. ENSO)?
December 7, 2025 at 1:34 PM
New ECMWF seasonal forecast came out two days ago, suggesting still NAO+ dominated late winter. The surprisingly high run-to-run consistency indicates a predictable signal that was "visible" to the model already in September. Perhaps originating from the tropics (i.e. ENSO)?
Olin Asiastudio-podcastin vieraana juttelemassa mahdollisesta Atlantin kiertoliikkeen romahduksesta ja sen vaikutuksista. Paljon asiaa, eikä kaikkea tietenkään muistanut edes kertoa!
www.youtube.com/watch?v=lnRC...
www.youtube.com/watch?v=lnRC...
Golf-virta romahtaa: Helsinkiin 40 asteen pakkaset?
YouTube video by Asiastudiofi
www.youtube.com
December 4, 2025 at 7:03 AM
Olin Asiastudio-podcastin vieraana juttelemassa mahdollisesta Atlantin kiertoliikkeen romahduksesta ja sen vaikutuksista. Paljon asiaa, eikä kaikkea tietenkään muistanut edes kertoa!
www.youtube.com/watch?v=lnRC...
www.youtube.com/watch?v=lnRC...
Reposted by Mika Rantanen
Here are
the press release on the retraction of one our Nature papers
www.pik-potsdam.de/en/news/late...
some explanations
www.pik-potsdam.de/en/news/late...
the journal's comment
www.nature.com/articles/s41...
Please note:
The fact that climate change causes huge economic damages is not disputed..
the press release on the retraction of one our Nature papers
www.pik-potsdam.de/en/news/late...
some explanations
www.pik-potsdam.de/en/news/late...
the journal's comment
www.nature.com/articles/s41...
Please note:
The fact that climate change causes huge economic damages is not disputed..
Authors retract Nature study on economic damages from climate change, will resubmit for peer review
03.12.2025 - Following the publication of two critiques as “Matters Arising”, and in conversation with the journal Nature, the authors of the study “The economic commitment of climate change” at the P...
www.pik-potsdam.de
December 3, 2025 at 11:11 AM
Here are
the press release on the retraction of one our Nature papers
www.pik-potsdam.de/en/news/late...
some explanations
www.pik-potsdam.de/en/news/late...
the journal's comment
www.nature.com/articles/s41...
Please note:
The fact that climate change causes huge economic damages is not disputed..
the press release on the retraction of one our Nature papers
www.pik-potsdam.de/en/news/late...
some explanations
www.pik-potsdam.de/en/news/late...
the journal's comment
www.nature.com/articles/s41...
Please note:
The fact that climate change causes huge economic damages is not disputed..
Helsinki, Finland, is currently on track for the 2nd warmest calendar year on record, trailing only 2020 📈🌡️
To avoid this, December would need to be more than 2 °C colder than average, a scenario that seems unlikely at this point (based on sub-seasonal forecasts).
To avoid this, December would need to be more than 2 °C colder than average, a scenario that seems unlikely at this point (based on sub-seasonal forecasts).
December 1, 2025 at 1:43 PM
Helsinki, Finland, is currently on track for the 2nd warmest calendar year on record, trailing only 2020 📈🌡️
To avoid this, December would need to be more than 2 °C colder than average, a scenario that seems unlikely at this point (based on sub-seasonal forecasts).
To avoid this, December would need to be more than 2 °C colder than average, a scenario that seems unlikely at this point (based on sub-seasonal forecasts).
Reposted by Mika Rantanen
I've had the privilege of being Co-Editor-in-Chief of @rmets.org Weather since September 2020, first alongside @eddywx.bsky.social and then Regan Mudhar. Now please join me in welcoming Ben Maybee as the next Co-EiC! rmets.onlinelibrary.wiley.com/doi/10.1002/...
December 1, 2025 at 9:18 AM
I've had the privilege of being Co-Editor-in-Chief of @rmets.org Weather since September 2020, first alongside @eddywx.bsky.social and then Regan Mudhar. Now please join me in welcoming Ben Maybee as the next Co-EiC! rmets.onlinelibrary.wiley.com/doi/10.1002/...
The temperature anomaly difference between the south and north was exceptionally large in November: it was the first occurrence when the anomaly in Sodankylä was < -2 °C and in Helsinki > +2 °C during the same month!
Records kept since 1901.
Records kept since 1901.
December 1, 2025 at 10:35 AM
The temperature anomaly difference between the south and north was exceptionally large in November: it was the first occurrence when the anomaly in Sodankylä was < -2 °C and in Helsinki > +2 °C during the same month!
Records kept since 1901.
Records kept since 1901.