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Posts by Mika Rantanen

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Opinion: The AMOC is weakening – time to take the evidence seriously Abstract. The Atlantic Meridional Overturning Circulation (AMOC) is a critical component of the climate system. Climate models have long predicted a slowing of the AMOC due to anthropogenic forcing, w...

We have a new preprint out for open review at Ocean Science, which discusses the evidence for the #AMOC already slowing. 🌊
If you have any comments, counter-arguments, or things we may have missed - please post them there! (Or here.)
Thanks!
egusphere.copernicus.org/preprints/20...

9 hours ago 80 28 0 1
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Svalbard is thawing in April, and it’s not supposed to. 2026 ground temperatures at 0.2m depth in Svalbard spiking to 0°C in April, far exceeding the 1998-2025 median and maximum

11 hours ago 82 39 3 3
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Yes, I am amazed by the persistence of the northerly winds.. Next 10 days do not show much tailwinds to the migratory birds at least for Lahti region.

14 hours ago 1 0 0 0
ECMWF forecast for Sunday 06 UTC showing strong windstorm over eastern Finland with snowfall and strong winds.

ECMWF forecast for Sunday 06 UTC showing strong windstorm over eastern Finland with snowfall and strong winds.

The boring weather pattern will end this weekend. The low pressure on Sat-Sun looks especially problematic, with all that snow and strong winds.

Although this spring has so far been free of cold spells, there’s never a spring without at least one return of winter!

15 hours ago 31 3 2 2
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Joo, minustakin ehkä vähän harhaanjohtavaa, ettei selvästi sanottu että yksittäisen vuoden ylitys on eri asia kuin mitä Pariisin sopimus on tarkoitettu. Tuosta voi saada käsityksen että alempi raja on nyt saavutettu.

1 day ago 0 0 0 0
Accumulated precipitation in Helsinki Kaisaniemi since January 1st, 2026. The value in 2026 is outside the 1845–2025 max/min values.

Accumulated precipitation in Helsinki Kaisaniemi since January 1st, 2026. The value in 2026 is outside the 1845–2025 max/min values.

Here we are: the cumulative precipitation in Helsinki Kaisaniemi this year is currently the lowest on record.

Helsinki Kaisaniemi is the oldest weather station in Finland. Records have been kept since 1845.

1 day ago 31 11 1 0

Merkittävä asia, joskin on huomattava se, että kyseessä on yksittäisen vuoden ylitys El Niñon boostaamana. Pitkäaikainen ilmastonmuutos on tällä hetkellä noin 1,4 asteessa (joka sekin on paljon!)

1 day ago 17 1 2 0

On myös niin, että ilmastotutkimuksista kertoviin iltapäivälehtiin liittyy paljon skandaalinhakuista liioittelua :)

1 day ago 0 0 0 0
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”Ei voi puhua jääkaudesta” – professori kertoo, miten merivirtojen hidastuminen vaikuttaa Suomeen Golf-virta on osa Pohjois-Atlantin merivirtojen kiertoliikettä eli Amocia, jonka mahdollisesta romahtamisesta on ristiriitaista tutkimustietoa.

Syvällisempi juttu viimeaikaisista AMOCin heikkenemiseen liittyvistä uhkakuvista. Tällaisia haastatteluja enemmän, kiitos!

yle.fi/a/74-2022126...

2 days ago 74 10 6 0

Yep, from tree-rings.

2 days ago 1 0 0 0
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Volcano eruptions. It's discussed in the paper:

2 days ago 2 0 1 0
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New open-access study: summer 2024 in the northern extra-tropics was the warmest in 2000 years.

The warmest reconstructed summer (246 CE) was 1.5 °C colder than 2024.

Helama (2026): link.springer.com/article/10.1...

2 days ago 46 21 2 0
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Suurin sadevajaus vallitsee Pohjois-Karjalan seudulla.

Ääriesimerkki on Tohmajärvi Kemie, jossa vuoden 2026 sademäärä menee täysin omia polkujaan verrattuna pitkän ajan klimatologiaan. Kuluvan vuoden sademäärä on 28 mm edellisen *ennätyksen* alapuolella ja noin 100 mm normaalia alempana.

2 days ago 33 3 0 0
Stacked bar chart showing probabilities of four weather regimes (positive NAO, Atlantic Ridge, negative NAO and Scandi Blocking) plus No Regime

Stacked bar chart showing probabilities of four weather regimes (positive NAO, Atlantic Ridge, negative NAO and Scandi Blocking) plus No Regime

I've implemented a North Atlantic weather regime classification following the same method we introduced for North America, yielding NAO+, Atlantic Ridge, NAO– and Scandinavian Blocking (plus No Regime = nearer climatology than any regime). simonleewx.com/ecmwf_north_...

2 days ago 25 1 2 0
No evidence for attributing nearly four-fold Arctic Amplification to internal variability | ESS Open Archive The Arctic has been warming nearly four times faster than the rest of the planet over the past decades. Zhou et al. [1] argue that only threefold Arctic amplification is due to external forcing, and t...

The debate continues...

essopenarchive.org/doi/full/10....

4 days ago 4 0 0 0
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Communicating changes in the intensity of UK heatwaves Communicating how a global warming of ‘just’ 1°C affects people is challenging. The hottest UK summer days have warmed more than 3 times faster than the rate of global warming in the past century, ca...

Communicating changes in the intensity of UK heatwaves

Global warming of ‘just’ 1°C does not necessarily sound like a problem. But in the UK, the hottest summer days are warming much faster than typical summer days, changing our experience of heatwaves

rmets.onlinelibrary.wiley.com/doi/full/10....

4 days ago 112 55 7 1

Hienoa nähdä että Bluesky-palvelu alkaa löytyä myös toimittajien uutisiin: yle.fi/a/74-20221188.

Pieni korjaus uutiseen: siitä ei selviä että kyse on nimenomaan maan itäosan sademäärästä, ei koko Suomen.

4 days ago 29 1 1 0
Sea surface temperature anomaly in the Nino3.4 region.

Sea surface temperature anomaly in the Nino3.4 region.

Niño3.4 region warming rapidly...

The latest daily value in the NOAA OISST dataset is already > 0.5 °C, which is the typical threshold for an El Niño event.

However, for official El Niño, this threshold must be met for several consecutive months.

Figure from cyclonicwx.com/sst/

5 days ago 40 12 0 0
Science | AAAS

Breaking: New study using observational constraints projects that the Atlantic Ocean circulation #AMOC will weaken ~50% by 2100, even for medium emissions and without Greenland melting. 🌊
More realistic models means stronger weakening - not entirely unexpected.
www.science.org/doi/10.1126/...

6 days ago 434 288 9 45

Yleisesti ottaen talvet ovat Suomessa siis muuttumassa lauhemmiksi ja märemmiksi. Siltä osin kuin Järvi-Suomen kuivuus liittyy korkeapaineiseen (ja kylmään) viime talveen, en pitäisi sitä ilmastonmuutoksen pahentamana.

Päinvaistoin, 50 vuotta sitten vastaava talvi olisi voinut olla vielä kuivempi.

6 days ago 14 0 0 0
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Päivittäinen lumensyvyys ja sen klimatologia Suomen itäosassa.

Päivittäinen lumensyvyys ja sen klimatologia Suomen itäosassa.

Ilmaston lämmetessä talvisateet lisääntyvät ja ovatkin jo lisääntyneet, kuten kuvan trendistä näkyy. Nykyinen vuosi onkin sitten selvä poikkeus pitkällä aikavälillä.

Vähäisistä sademääristä johtuen talvesta tuli vähäluminen, ja lumet myös sulivat kuukausi normaalia aiemmin.

6 days ago 21 2 1 0
Aikasarjagraafi maan itäosan sademääristä aikavälillä 1.1.–14.4. vuosina 1961–2026.

Aikasarjagraafi maan itäosan sademääristä aikavälillä 1.1.–14.4. vuosina 1961–2026.

Varsinkin maan itäosaa kurittaa kuivuus. Tämän vuoden sademäärä 66 mm on alle puolet normaalista, ja vuosien 1961-2026 havaintoaikasarjassa ennätysalhainen määrä.

Mediassa on arveltu tilanteen linkittyvän ilmastonmuutokseen.

6 days ago 44 10 1 1
This cloud-free satellite image, acquired on 11 April 2026 by one of the Copernicus Sentinel-3 satellites, shows widespread snow cover across Norway’s mountainous spine, northern Sweden, and Finland. The Norwegian fjords appear as dark, narrow inlets cutting through bright snow-covered terrain, while the Gulf of Bothnia and the broader Baltic Sea display deep blue waters, with residual ice visible along the northern shores. Southern Sweden and Finland show more exposed land, with muted brown and green tones indicating early snowmelt.

This cloud-free satellite image, acquired on 11 April 2026 by one of the Copernicus Sentinel-3 satellites, shows widespread snow cover across Norway’s mountainous spine, northern Sweden, and Finland. The Norwegian fjords appear as dark, narrow inlets cutting through bright snow-covered terrain, while the Gulf of Bothnia and the broader Baltic Sea display deep blue waters, with residual ice visible along the northern shores. Southern Sweden and Finland show more exposed land, with muted brown and green tones indicating early snowmelt.

What a beauty 😍 - A cloud-free Scandinavia! My home 💙

Credit: European Union, Copernicus Sentinel-3 imagery

1 week ago 39 5 1 1
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Here are some drought indices from Syke's hydrological model: wwwi2.ymparisto.fi/i2/drought/s...

A standardized runoff index from past 30 days and forecast for May. Looking really dry. The early spring melted the snow we had really early, and now our large lakes will be really low.

1 week ago 24 6 1 0
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Relative humidity values below 10% are so rare that FMI’s automatic quality control flags them as erroneous. Therefore they do not appear in the measurements.

www.ilmatieteenlaitos.fi/saa/juuka?pa...

1 week ago 12 1 2 0
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Lämmin sää jatkuu – kuivuuteen ei ole odotettavissa laaja-alaista Ajankohtaan nähden selvästi korkeammat päivälämpötilat ovat saaneet lumipeitteen hupenemaan pohjoisessa paikoin poikkeuksellisen aikaisin.

Warm weather will continue, no widespread relief from the drought

Relative humidity has dropped down to 10% at some stations. Wildfire warning is in effect across southern and central Finland.

Finnish press release about the situation: www.ilmatieteenlaitos.fi/tiedote/0ZZc...

1 week ago 37 8 1 0
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I'd say random! Since 1961 the precipitation has increased but the current year is a deviation from the trend.

1 week ago 5 1 0 1

Yes, thanks for pointing that out. My datasets only cover the meteorological part.

1 week ago 1 0 1 0
Cumulative precipitation plot for Helsinki Kaisaniemi for 1 Jan to 31 May. The 2026 value is highlighted with a red line.

Cumulative precipitation plot for Helsinki Kaisaniemi for 1 Jan to 31 May. The 2026 value is highlighted with a red line.

Southern and eastern Finland is suffering from a meteorological drought (lack of precipitation).

Helsinki Kaisaniemi has received only 60.6 mm of precipitation so far this year, ranking it to the 2nd lowest in the year-to-date statistics. Only the year 1980 was drier.

1 week ago 42 14 2 0
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How confident should we be in a prediction of El Niño? Seasonal forecasts are fuelling headlines about El Niño, but uncertainty remains. This blog explains what the signals mean, where confidence is growing, and why caution is still essential.

How confident should we be in a prediction of El Niño?
By Tim Stockdale (ECMWF)

www.ecmwf.int/en/about/med...

1 week ago 33 11 0 0
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