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Mika Rantanen

@mikarantane.bsky.social

6.7K followers 490 following 750 posts

Researcher in Weather and Climate Change Impact Research in Finnish Meteorological Institute. PhD in meteorology.

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Mika Rantanen @mikarantane.bsky.social · Apr 28

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 - 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

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Reposted by Mika Rantanen

Sam Burgess @oceanterra.org · 5h

The @copernicusecmwf.bsky.social climate monitoring application #Climate Pulse has been updated. Same climate monitoring data with new features and better layout. 🌏🌊⚒️🧪

User feedback always welcome so let us know what you would like to see updated in the next version:

pulse.climate.copernicus.eu

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Reposted by Mika Rantanen

Communications Earth & Environment @commsearth.nature.com · 22h

🌊The unprecedented June 2023 marine heatwave in north-western Europe had a 10% annual likelihood, with climate change accelerating the risk of similar events.

👉Read more here:
www.nature.com/articles/s43...

Recent European marine heatwaves are unprecedented but not unexpected - Communications Earth & Environment

The unprecedented June 2023 marine heatwave in north-western Europe had a 10% annual likelihood, with climate change accelerating the risk of similar events, according to ensemble climate model simulations.

www.nature.com

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Mika Rantanen @mikarantane.bsky.social · 1d

As far as I can tell, the "more frequent and intense" refers here to simulations without sea level rise. The simulations are run with constant CO₂ levels, so they do not take into account the warming climate. (as pointed out also by one reviewer)

Bjerknes Center for Climate Research (BCCR) @bjerknes.uib.no · 1d

Rising sea levels are making extreme winter cold events MORE frequent and intense in East Asia. Yes, you read that right. New paper in Nature Communications reveals a fascinating connection. (1/4) 🧪🌊

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Reposted by Mika Rantanen

Ilmatieteen laitos - Finnish Meteorological Institute @ilmatieteenlaitos.fi · 2d

Ovatko sään ääri-ilmiöt haitanneet elämääsi? Vastaa kyselyyn!

Keräämme tietoa sään ääri-ilmiöiden koetuista haittavaikutuksista ja selvitämme, minkälaista tietoa tarvittaisiin niihin varautumiseksi.

Kyselyyn pääset tästä linkistä 🔽

link.webropolsurveys.com/Participatio...

📸 Jukka Salmi / Plugi.

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Reposted by Mika Rantanen

Met Office - weather and climate @metoffice.gov.uk · 3d

Storm Amy has been record breaking ⚠️

An air pressure of 947.9 hPa was recorded at Baltasound, Shetland, provisionally setting a new UK lowest pressure record for October.

Northern Ireland provisionally recorded its strongest October wind gust on record, with a gust of 92 mph at Magilligan.

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Reposted by Mika Rantanen

Ruth Mottram @ruthmottram.bsky.social · 5d

🚨New paper 🚨@natgeosci.nature.com Greenlandification of Antarctica - comment by me + colleagues @dmidk.bsky.social @eo4cryo.bsky.social + @universityofleeds.bsky.social showing how Antarctica increasingly resembles Greenland- drawing on a mass of work from @esaclimate.bsky.social

rdcu.be/eJiqJ

The Greenlandification of Antarctica

Nature Geoscience - Climate and ice sheet processes in Antarctica increasingly reflect those observed earlier in Greenland. Applying process insights from Greenland can improve projections of...

rdcu.be

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Reposted by Mika Rantanen

Frans-Jan Parmentier @thissideofthearctic.org · 5d

Storm Amy is litterally giving Norway the finger, according to this weekend's forecast. 🌬️

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Mika Rantanen @mikarantane.bsky.social · 5d

The rapid deepening of Storm Amy has begun.

Over the next hours, the storm will travel across the jet stream and move to the left exit region of the jet stream where the most explosive deepening will take place.

Satellite image of Storm Amy, overlaid with MSLP contours at 6 UTC. Screenshot from Eumetrain.

MSLP and jet stream at 18 UTC in Europe. The figure is from https://www.atmos.albany.edu/student/abentley/realtime/standard.php?domain=europe&variable=mslp_jet.

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Reposted by Mika Rantanen

Jens Terhaar @polarocean.bsky.social · 6d

Future atmospheric and ocean warming over the 21st century might be larger than previously expected based on a new study by @linusvogt.bsky.social

Linus & I developed the idea during Linus research visit with me at @whoi.edu and turned it then into this paper:

esd.copernicus.org/articles/16/...

Increased future ocean heat uptake constrained by Antarctic sea ice extent

Abstract. The ocean takes up over 90 % of the excess heat stored in the Earth system as a result of anthropogenic climate change, which has led to sea level rise and an intensification of marine extre...

esd.copernicus.org

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Reposted by Mika Rantanen

Dr. Crystal A. Kolden @pyrogeog.bsky.social · 5d

Published today: our new paper showing a 44-year trend of increasing global wildfire disasters (fatalities and economic losses) due to climate change-induced extreme weather. www.science.org/doi/10.1126/...

Climate-linked escalation of societally disastrous wildfires

Climate change and land mismanagement are creating increasingly fire-prone built and natural environments. However, despite worsening fire seasons, evidence is lacking globally for trends in socially ...

www.science.org

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Mika Rantanen @mikarantane.bsky.social · 7d

Finland's regionally averaged temperature in September was the 3rd highest on record, but here you can see how Septembers 2023–2025 surpass all previous years since 1900.

A graph showing September mean temperature in Finland in 1900–2025

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Reposted by Mika Rantanen

Simon Lee @simonleewx.com · 7d

Per the Met Office forecast charts, the system deepens by 43 hPa between 00Z Friday and 00Z Saturday. Adjusting for an approx midpoint latitude of 55°N makes this 1.89 times the required 'bomb cyclone' rate.

Met Office - weather and climate @metoffice.gov.uk · 7d

#StormAmy has been named and is forecast to bring strong winds and heavy rain to the UK later on Friday and into Saturday #WeatherAware

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Mika Rantanen @mikarantane.bsky.social · 7d

Those estimates were based on climate change information from CMIP6 models, but the experimental observation-based method that only takes into account the change in mean temperature (not in variability), generally agree with PR ~50 and ΔI ~2 °C.

Probability ratio and change in intensity in September 2025 temperature in Sodankylä Tähtelä, based on climate change information from observation-based datasets.

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Mika Rantanen @mikarantane.bsky.social · 7d

With our statistical attribution, we can estimate that September this warm in Sodankylä occurs every ~90 years in today's climate. In the climate of 1900, the event is almost impossible (~4700 years).

So we estimate that the month was ~50 times more likely and 1.9 °C warmer due to climate change.

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Mika Rantanen @mikarantane.bsky.social · 7d

September 2025 featured very optimal large-scale circulation for persistent warmth in northern Fennoscandia.

The ridge was situated east of Fennoscandia with low pressure anomaly over the North Atlantic. This favoured southerly flow that kept temperatures above freezing almost the whole month.

500 hPa geopotential height and anomaly from NCEP/NCAR reanalysis for 1-28 September 2025.

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Mika Rantanen @mikarantane.bsky.social · 7d

Breaking: September 2025 was record-warm in Finnish Lapland, for the third time in a row.

Monthly mean temperature in Sodankylä Tähtelä was 11.0 °C, exceeding the previous record of 10.3 °C set in 2024 (which itself had exceeded the previous record of 10.0 °C set in 2023 and 1934).

Time series of September monthly mean temperatures in Sodankylä Tähtelä in 1901–2025.

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Reposted by Mika Rantanen

Antje Weisheimer @antjeweisheimer.bsky.social · 7d

Are you interested in seasonal forecasts and how they have advanced over the past two decades?
Chris O’Reilly (Univ. of Reading) led a new paper on exactly this: rmets.onlinelibrary.wiley.com/doi/10.1002/...

Evaluating seasonal forecast improvements over the past two decades

We have analysed the performance of operational seasonal forecasting models since their inception. Clear improvements are measured through the different model eras, particularly in the Tropics. For t....

rmets.onlinelibrary.wiley.com

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Reposted by Mika Rantanen

Philippe Papin @pppapin.bsky.social · 8d

And with the 15z advisories -- #Hurricane #Imdelda & #Humberto are just 479 miles apart.

This might be the closest two simultaneous hurricanes have ever been in the Atlantic basin in the satellite era (since ~1975).

Close enough for their outer sfc circulations to interact as well.

Great Circle Distance tool calculator available here -- https://www.nhc.noaa.gov/gccalc.shtml

Weathernerds image of the 06 UTC GFS forecast valid 15 UTC today showing 10 m winds (shaded), direction (barbs), and sea-level pressure (black contours).

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Mika Rantanen @mikarantane.bsky.social · 8d

Quite worrying solutions recently in the global weather models regarding Humberto's post-tropical intensification. The system is forecast to deepen explosively while arriving Europe.

The northern British Isles might be hit hard. 👀

Peak wind gust in the ECMWF model in NW Europe.

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Mika Rantanen @mikarantane.bsky.social · 13d

The highlight of this week was meeting with @mattpriestley.bsky.social here in Helsinki and his seminar about constraining future windstorm trends for Europe. Very interesting work!

Photo of the seminar room and the front slide of the presentation.

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Mika Rantanen @mikarantane.bsky.social · 13d

Blocking high in action. The newest ECMWF forecast keeps Finland completely dry for the next 10 days.

Accumulated rainfall until 5 October shows zero rain for Finland. The forecast is based on ECMWF forecast from 25 Sep 2025 00UTC.

Forecast mean sea level pressure anomaly on Tue 30 Sep in Europe. Positive values in northern Europe indicates high pressure -dominated weather type.

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Mika Rantanen @mikarantane.bsky.social · 15d

That is a prominent signal for blocking predicted by ECMWF for the rest of the month.

It will likely lock in a record-warm September for much of Fennoscandia, the third year in a row.

5-day EPS forecast for 500 hPa geopotential height anomaly for Europe. The chart shows Scandinavian blocking, so positive anomaly values over Scandinavia.

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Mika Rantanen @mikarantane.bsky.social · 16d

Okay, that would be great! Fingers crossed 🤞

Mika Rantanen @mikarantane.bsky.social · 16d

Yes, for GFS many of the variables load extremely slowly. It's a pity ☹️

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Mika Rantanen @mikarantane.bsky.social · 16d

Windy day ahead tomorrow. One major factor is the powerful jet stream that facilitates cyclogenesis. Not so often we'll have 90 m/s wind speeds above us.

Forecast 300 hPa wind speeds from GFS model.

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