Convection in the Greenland Sea : Model and Observations

The Meridional overturning circulation (MOC) is one crucial component in Earth's climate system, redistributing heat round the globe. The abyssal limb of the MOC is fed by the deep water formation near the poles. A basic requirement for any successful climate model simulation is the ability to reproduce this circulation correctly. The deep water formation itself, convection, occurs on smaller scales than the climate model grid size. Therefore the convection process needs to be parameterized. It is, however, somewhat unclear how well the parameterizations which are developed for turbulence can reproduce the deep convection and associated water mass transformations. The convection in the Greenland Sea was studied with 1-D turbulence model GOTM and with data from three Argo floats. The model was run over the winter 2010-2011 with ERA-Interim and NCEP/NCAR atmospheric forcings and with three different mixing parameterizations, k-e, k-kL (Mellor-Yamada) and KPP. Furthermore, the effects of mesoscale spatial variations in the atmospheric forcing data were tested by running the model with forcings taken along the floats' paths (Lagrangian approach) and from the floats' median locations (Eulerian approach). The convection was found to happen by gradual mixed layer deepening. It caused salinity decrease in the Recirculating Atlantic Water (RAW) layer just below the surface while in the deeper layers salinity and density increase was clearly visible. A slight temperature decrease was observed in whole water column above the convection depth. Atmospheric forcing had the strongest effect on the model results. ERA-interim forcing produced model output closer to the observations, but the convection begun too early with both forcings and both generated too low temperatures in the end. The salinity increase at mid-depths was controlled mainly by the RAW layer, but also atmospheric freshwater flux was found to affect the end result. Furthermore, NCEP/NCAR freshwater flux was found to be large enough (negative) to become a clear secondary driving factor for the convection. The results show that mixing parameterization mainly alters the timing of convection. KPP parameterization produced clearly too fast convection while k-e parameterization produced output which was closest to the observations. The results using Lagrangian and Eulerian approaches were ambiguous in the sense that neither of them was systematically closer to the observations. This could be explained by the errors in the reanalyzes arising from their grid size. More conclusive results could be produced with the aid of finer scale atmospheric data. The results, however, clearly indicate that atmospheric variability in scales of 100 km produces quantifiable differences in the results

Connecting ocean heat transport changes from the mid-latitudes to the Arctic Ocean

Under greenhouse warming, climate models simulate a weakening of the Atlantic Meridional Overturning Circulation and the associated ocean heat transport at midlatitudes but an increase in the ocean heat transport to the Arctic Ocean. These opposing trends lead to what could appear to be a discrepancy in the reported ocean contribution to Arctic amplification. This study clarifies how ocean heat transport affects Arctic climate under strong greenhouse warming using a set of the 21st century simulations performed within the Coupled Model Intercomparison Project. The results suggest that a future reduction in subpolar ocean heat loss enhances ocean heat transport to the Arctic Ocean, driving an increase in Arctic Ocean heat content and contributing to the intermodel spread in Arctic amplification. The results caution against extrapolating the forced oceanic signal from the midlatitudes to the Arctic.publishedVersio

Rapid and agile ocean forecasting with surrogate modelling

Marine safety and security, including military situational awareness, create a need for short-term ocean forecasts of the ocean state. At present, such forecasts are done using numerical models on high performance computers. These models, although robust, often provide information at relatively coarse resolution for local/regional application, are difficult to deploy rapidly, and require connection between the data centre and user in the field. However, the rapid development of data-driven methods has opened a possibility for statistical emulators that can be trained with numerical model data to produce similar information but can be evaluated on a laptop computer in the field in a matter of seconds. To this end, we demonstrate creating an emulator to predict thermocline depth, an important parameter for sonar weather, up to 10 days in advance in the Archipelago Sea, Baltic Sea. We find that for this purpose, multiple linear regression produces the best results as more complex architectures suffered from limited training data or limited memory in the training phase.This publication is part of the implementation of research funding of the Scientific Advisory Board for Defence (MATINE). (www.defmin.fi/matine) The content is the responsibility of the producers of the information and does not necessarily represent the view of the Defence Ministry

Added value of a regional coupled model: the case study for marine heatwaves in the Caribbean

There is an urgent need to improve capacity to predict marine heatwaves given their substantial negative impacts on marine ecosystems. Here we present the added value of a regional climate simulation, performed with the regional Coupled-Ocean–Atmosphere-Wave-Sediment Transport model COAWST, centered over the Caribbean – one of the first of its kind on a climatological scale. We show its added value with regards to temporal distribution of marine heatwaves, compared with state-of-the-art global models. In this region, global models tend to simulate too few heatwaves that last too long compared to the observation-based dataset of CoralTemp. The regional climate model agrees more favourably with the CoralTemp dataset, particularly in winter. While examining potential mechanisms behind the differences we find that the more realistic representation of marine heatwaves in the regional model arises from the sea surface temperatures ability to increase/decrease more quickly in the regional model than in the global model. The reason for this is two fold. Firstly, the regional model has a shallower mixed layer than the global model which results in a lower heat capacity that allows its sea surface temperatures to warm and cool more quickly. The second reason is found during days when marine heatwaves are increasing in intensity. During these days, reduced wind speeds leads to less latent heat release and a faster warming surface, more so in the regional model than in the global models.publishedVersio

Co-feeding of live feed and inert diet from first-feeding affects Artemia lipid digestibility and retention in Senegalese sole (Solea senegalensis) larvae

The present study intended to evaluate the effects of early introduction of inert diet in lipid digestibility and metabolism of sole, while larval feed intake, growth and survival were also monitored. Solea senegalensis larvae were reared on a standard live feed regime (ST) and co-feeding regime with inert diet (Art R). Trials using sole larvae fed with Artemia enriched with two different lipid emulsions, containing glycerol tri [1-14C] oleate (TAG) and L-3-phosphatidylcholine-1,2-di-[1-14C] oleoyl (PL), were performed at 9 and 17 days after hatching (DAH) to study lipid utilization. Co-feeding did not affect sole survival rates (ST 59.1 ± 15.9 %; Art R 69.56 ± 9.3 %), but was reflected in significantly smaller final weight at 16 DAH (ST 0.71 ± 0.20; Art R 0.48 ± 0.14 mg). Higher feed intake was observed in sole larvae fed on Artemia enriched with labeled PL at 9 DAH but not at 17 DAH. At 17 DAH, the smaller larvae (Art R treatment) ingested proportionally more Artemia in weight percentage, independently of enrichment. At 9 DAH lipid digestibility was equal among treatments and higher than 90%, while at 17 DAH it was higher in ST treatment (around 73 %) compared to the Art R group (around 66 %). Lipid retention efficiency at 9 DAH was higher in the Art R treatment, reaching values of 50 %, while these values almost duplicated at 17 DAH, ranging up to 80 % in both treatments without significant differences. These results show that co-feeding of live feed and inert diet from first-feeding in Senegalese sole has a toll in terms of growth and lipid digestibility but does not seem to compromise lipid metabolic utilization

Evaluation of global ocean–sea-ice model simulations based on the experimental protocols of the Ocean Model Intercomparison Project phase 2 (OMIP-2)

We present a new framework for global ocean- sea-ice model simulations based on phase 2 of the Ocean Model Intercomparison Project (OMIP-2), making use of the surface dataset based on the Japanese 55-year atmospheric reanalysis for driving ocean-sea-ice models (JRA55-do).We motivate the use of OMIP-2 over the framework for the first phase of OMIP (OMIP-1), previously referred to as the Coordinated Ocean-ice Reference Experiments (COREs), via the evaluation of OMIP-1 and OMIP-2 simulations from 11 state-of-the-science global ocean-sea-ice models. In the present evaluation, multi-model ensemble means and spreads are calculated separately for the OMIP-1 and OMIP-2 simulations and overall performance is assessed considering metrics commonly used by ocean modelers. Both OMIP-1 and OMIP-2 multi-model ensemble ranges capture observations in more than 80% of the time and region for most metrics, with the multi-model ensemble spread greatly exceeding the difference between the means of the two datasets. Many features, including some climatologically relevant ocean circulation indices, are very similar between OMIP-1 and OMIP- 2 simulations, and yet we could also identify key qualitative improvements in transitioning from OMIP-1 to OMIP- 2. For example, the sea surface temperatures of the OMIP- 2 simulations reproduce the observed global warming during the 1980s and 1990s, as well as the warming slowdown in the 2000s and the more recent accelerated warming, which were absent in OMIP-1, noting that the last feature is part of the design of OMIP-2 because OMIP-1 forcing stopped in 2009. A negative bias in the sea-ice concentration in summer of both hemispheres in OMIP-1 is significantly reduced in OMIP-2. The overall reproducibility of both seasonal and interannual variations in sea surface temperature and sea surface height (dynamic sea level) is improved in OMIP-2. These improvements represent a new capability of the OMIP-2 framework for evaluating processlevel responses using simulation results. Regarding the sensitivity of individual models to the change in forcing, the models show well-ordered responses for the metrics that are directly forced, while they show less organized responses for those that require complex model adjustments. Many of the remaining common model biases may be attributed either to errors in representing important processes in ocean-sea-ice models, some of which are expected to be reduced by using finer horizontal and/or vertical resolutions, or to shared biases and limitations in the atmospheric forcing. In particular, further efforts are warranted to resolve remaining issues in OMIP-2 such as the warm bias in the upper layer, the mismatch between the observed and simulated variability of heat content and thermosteric sea level before 1990s, and the erroneous representation of deep and bottom water formations and circulations. We suggest that such problems can be resolved through collaboration between those developing models (including parameterizations) and forcing datasets. Overall, the present assessment justifies our recommendation that future model development and analysis studies use the OMIP-2 framework

Evaluation of global ocean–sea-ice model simulations based on the experimental protocols of the Ocean Model Intercomparison Project phase 2 (OMIP-2)

We present a new framework for global ocean–sea-ice model simulations based on phase 2 of the Ocean Model Intercomparison Project (OMIP-2), making use of the surface dataset based on the Japanese 55-year atmospheric reanalysis for driving ocean–sea-ice models (JRA55-do). We motivate the use of OMIP-2 over the framework for the first phase of OMIP (OMIP-1), previously referred to as the Coordinated Ocean–ice Reference Experiments (COREs), via the evaluation of OMIP-1 and OMIP-2 simulations from 11 state-of-the-science global ocean–sea-ice models. In the present evaluation, multi-model ensemble means and spreads are calculated separately for the OMIP-1 and OMIP-2 simulations and overall performance is assessed considering metrics commonly used by ocean modelers. Both OMIP-1 and OMIP-2 multi-model ensemble ranges capture observations in more than 80 % of the time and region for most metrics, with the multi-model ensemble spread greatly exceeding the difference between the means of the two datasets. Many features, including some climatologically relevant ocean circulation indices, are very similar between OMIP-1 and OMIP-2 simulations, and yet we could also identify key qualitative improvements in transitioning from OMIP-1 to OMIP-2. For example, the sea surface temperatures of the OMIP-2 simulations reproduce the observed global warming during the 1980s and 1990s, as well as the warming slowdown in the 2000s and the more recent accelerated warming, which were absent in OMIP-1, noting that the last feature is part of the design of OMIP-2 because OMIP-1 forcing stopped in 2009. A negative bias in the sea-ice concentration in summer of both hemispheres in OMIP-1 is significantly reduced in OMIP-2. The overall reproducibility of both seasonal and interannual variations in sea surface temperature and sea surface height (dynamic sea level) is improved in OMIP-2. These improvements represent a new capability of the OMIP-2 framework for evaluating process-level responses using simulation results. Regarding the sensitivity of individual models to the change in forcing, the models show well-ordered responses for the metrics that are directly forced, while they show less organized responses for those that require complex model adjustments. Many of the remaining common model biases may be attributed either to errors in representing important processes in ocean–sea-ice models, some of which are expected to be reduced by using finer horizontal and/or vertical resolutions, or to shared biases and limitations in the atmospheric forcing. In particular, further efforts are warranted to resolve remaining issues in OMIP-2 such as the warm bias in the upper layer, the mismatch between the observed and simulated variability of heat content and thermosteric sea level before 1990s, and the erroneous representation of deep and bottom water formations and circulations. We suggest that such problems can be resolved through collaboration between those developing models (including parameterizations) and forcing datasets. Overall, the present assessment justifies our recommendation that future model development and analysis studies use the OMIP-2 framework.This research has been supported by the Integrated Research Program for Advancing Climate Models (TOUGOU) of the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan (grant nos. JPMXD0717935457 and JPMXD0717935561), the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) (grant no. 274762653), the Helmholtz Climate Initiative REKLIM (Regional Climate Change) and European Union's Horizon 2020 Research & Innovation program (grant nos. 727862 and 800154), the Research Council of Norway (EVA (grant no. 229771) and INES (grant no. 270061)), the US National Science Foundation (NSF) (grant no. 1852977), the National Natural Science Foundation of China (grant nos. 41931183 and 41976026), NOAA's Science Collaboration Program and administered by UCAR's Cooperative Programs for the Advancement of Earth System Science (CPAESS) (grant nos. NA16NWS4620043 and NA18NWS4620043B), and NOAA (grant no. NA18OAR4320123).Peer ReviewedPostprint (published version

Kerrostalon ulkovaippakorjauksen rakenneratkaisut

Insinöörityö tehtiin Insinööritoimisto Konstru Oy:lle. Yrityksen suunnitteluprojekteista suuri osa liittyy julkisivujen ja parvekkeiden betonirakenteiden korjaukseen. Insinöörityön tavoite on laatia korjaussuunnitelma Helsingin keskustassa sijaitsevan kerrostalon julkisivujen ja parvekkeiden betonirakenteille. Korjaussuunnitelmassa tavoitellaan rakenteille pitkää käyttöikää ennakoimalla tulevia vaurioita, jotta rakennuksen vaativan sijainnin takia vaurioita ei tarvitse korjata uudelleen lähitulevaisuudessa. Insinöörityön alkuosa koostuu teoreettisesta vaurioiden ja niiden syntymekanismien sekä korjaustapojen tutkimisesta. Työn keskimmäinen osa sisältää yleistietoa kyseessä olevasta kohteesta ja siinä olevista vaurioista. Loppuosassa keskitytään teoria- ja kuntotutkimustietojen avulla valittuun korjaustapaan. Insinöörityön tuloksena on kohteelle toteutettu korjaussuunnitelma, joka on yrityksen salassa pidettävää tietoa, mutta sen pääpiirteet esitetään työn loppuosassa. Korjaussuunnitelmassa valittiin korjaustavat rakenneosittain julkisivujen sekä parvekkeiden betonirakenteille ja hankittiin tietoa materiaalien käytöstä. Toteutettua korjaussuunnitelmaa ja uutta tietoa materiaaleista voidaan käyttää pohjana tulevissa vastaavanlaisissa projekteissa. Korjauksessa käytettyjen materiaalien työohjeita tullaan käyttämään jatkossa työselostuksien laatimiseen.The graduate study was carried out for Insinööritoimisto Konstru Oy. Most of the renovation projects that the company has, are associated with concrete structures on façades and balconies. The goal of this study was to develop repair work schedule for the facades and balconies of the building located in the centre of Helsinki. Repair work schedule aims to prolong the service life of the structures by predicting upcoming damages, to eliminate need for further repairs due to the challenging location of the building. The first part of the thesis is comprised of theoretical research of the damages and their causes and methods of renovation. Next, general information of the building and its current damages is provided. Finally, the thesis concentrates on the selected methods of renovation, which are based on the theoretical information and the information obtained during the condition survey. A repair work schedule was drawn up as a result of the thesis, however it is classified information and only for the use of the company. Nevertheless, the outlines of the repair work schedule are described in the last part of the thesis. The method of renovation was selected for every component individually in the repair work schedule, and new information of the use of materials was acquired. The executed repair work schedule and the new material information can be used as a basis in upcoming projects. The working instruction for the materials used, will be utilized in drawing up specifications in the future

"En ehkä kirjottaisi ansioluettelooni, että käytän nuuskaa muuten päivittäin" : laadullinen tutkimus liikuntapedagogiikan opiskelijoiden nuuskankäytöstä

Tutkimukseni tarkoituksena oli selvittää liikuntapedagogiikan opiskelijoiden nuuskankäytön syitä, sekä kuvailla heidän kokemuksiaan opiskelijayhteisön vaikutuksesta nuuskankäyttöön. Lisäksi tutkimuksessa selvitin opettajaksi opiskelevien näkemyksiä nuuskankäytön ja opettajan ammatin välisestä suhteesta. Tutkimusraportin kirjallisuuskatsauksessa käsittelen nuuskankäyttöä Suomessa, sen vaikutuksia terveydelle, nuuskankäytön syitä sekä keskeisiä terveyskäyttäytymisen teorioita ja malleja. Terveysuskomusmalli ja sosiaalis-kognitiivinen teoria soveltuivat mielestäni parhaiten kuvaamaan terveyskäyttäytymistä tässä kontekstissa. Toteutin tutkimuksen laadullisilla tutkimusmenetelmillä. Analyysimenetelmänä käytin teoriasidonnaista sisällönanalyysiä. Tutkimus tukeutuu fenomenologis-hermeneuttiseen tieteenfilosofiaan. Keräsin tutkimuksessa käytetyn aineiston teemahaastatteluin viideltä nuuskaa käyttävältä Jyväskylän yliopiston liikuntapedagogiikan pääaineopiskelijalta. Kaikki haastatellut edustivat eri vuosikursseja. Haastatelluista neljä oli miehiä ja yksi nainen. Haastattelut toteutettiin kasvotusten tai videopuheluyhteydellä ja tallensin keskustelut äänittämällä. Tutkimusaineistona käyttämäni litteroidut haastattelut sisälsivät yhteensä 44 sivua tekstiä fontilla Times New Roman, fonttikoolla 12 ja rivivälillä 1,5. Tutkimustulosten mukaan opiskelijat käyttävät nuuskaa pääasiassa rentoutumiskeinona, mielihyvähakuisesti ja päivittäisiin rutiineihin liittyneenä. Tutkimukseen osallistuneet eivät kokeneet nuuskankäytön juurikaan vaikuttaneen heidän terveyteensä. Liikunnanopettajaopiskelijat olivat tietoisia nuuskankäytön terveysriskeistä, mutta riskit eivät konkretisoidu heidän kokemuksissaan. Tutkimukseen osallistuneiden mielestä Liikunnalla käytetään nuuskaa suhteellisen vähän. Heidän mielestään nuuskankäyttöä kuitenkin lisää ympärillä näkyvä nuuskankäyttö. Ympäröivän yhteisön asenne nuuskankäyttöä kohtaan on pääasiassa salliva. Nuuskan saatavuutta myös helpottaa muiden käyttäjien tunteminen opiskelijoiden keskuudessa. Nuuskankäytön ja opettajana toimimisen välillä opiskelijat näkivät arvoristiriidan, jonka selvittämiseksi opiskelijat olivat valmiita lopettamaan käytön tai piilottelemaan omaa käyttöään oppilailta. Työn ja vapaa-ajan välille nähtiin tärkeänä vetää selkeä raja nuuskankäytön suhteen; koulussa nuuskankäyttö ei saa näkyä. Opiskelijat eivät olleet huolissaan terveysriskeistä, vaikka juuri näillä opiskelijoilla pitäisi olla hyvinkin tarkka ja ajantasainen tieto nuuskan terveysriskeistä. Ympäröivän opiskelijayhteisön koettiin vaikuttavan lisäävästi omaan nuuskankäyttöön. Nuuskankäyttö saatetaan nähdä yksilön omana asiana, johon vertaiset eivät halua puuttua. Opettajana toimiessaan nuuskankäyttö nähtiin ongelmallisena. Nuuskankäytön julkitulemisen riskeinä nähtiin auktoriteetin rapistuminen ja huonon esimerkin näyttäminen oppilaille.The purpose of my study was to find out the reasons of the use of moist snuff among sport pedagogy students, and to describe their experiences on the student community’s effect on their snuff dipping. Moreover, this study clarified teacher students’ views on the relationship between using snuff and the profession of a teacher. On the literary survey of this research report, I deal with snuff use in Finland, its effects on health, the reasons of use of snuff and the key theories and models of health behavior. To illustrate health behavior in this context, I found the health belief model and the social cognitive theory to be the most suitable ones. I carried out this study with qualitative research methods. I used the theory-guided content analysis as the analyzing method. The study is based on the hermeneutic-phenomenological scientific philosophy. I gathered the data used in this study by semi-structured interviews with five snuff using sport pedagogy students from the university of Jyväskylä. All interviewees represented different year classes. Four of the interviewees were male and one was female. The interviews were carried out face to face or via video call connection and I voice recorded the conversations. The transcriptions used as the data in this study consisted of total 44 pages of text in font Times New Roman, font size 12 and row spacing 1,5. According to the findings of this study, students dip snuff mainly in means to relax, seeking pleasure and associated with daily routines. Those participating this study, found the use of snuff hardly affecting their health. PE students were aware of the health risks related to the use of snuff, but they did not experience the risks to take shape. The participating students saw the use of snuff in their faculty to be relatively rare. Yet, they find the snuff dipping happening around them increasing their own use of snuff. The attitude of the surrounding community towards snuff use is mainly permissive. Knowing other users among the students also makes the availability of snuff easier. Students were ready to cease using snuff, or hide it from pupils, to solve a value conflict which they saw between using snuff and working as a teacher. It was felt important to draw a strict line between work and leisure concerning snuff use: snuff dipping must not be seen in school. The students were not worried about the health risks, even though exactly these students should have very specific and up-to-date knowledge on the health risks of using snuff. The surrounding student community was found increasing their own use of snuff. Snuff dipping might be seen as an individuals own issue, to which peers do not want to intervene. Snuff use as a teacher was seen problematic. Breaking as a snuff user, they saw the risks of crumbling their authority and setting a bad example for the pupils

The Arctic Ocean in a Fresh and Warm Future

The Arctic Ocean remains one of the least known ocean regions due to its remote location, year-round sea ice cover, and harsh weather conditions. Today, knowledge of the Arctic atmosphere-sea ice-ocean system increases in parallel with the need to understand this changing environment under anthropogenic greenhouse warming. Indeed, the Arctic is an area where the effects of anthropogenic greenhouse warming are already visible and among the strongest on Earth; the atmosphere and the ocean are warming, the sea ice cover is diminishing, and the freshwater input to the ocean through river inflow, precipitation, and ice melt is increasing. It is this rapidly changing, but poorly understood, Arctic climate system that motivates us to study its fate in a fresh and warm future. Our objective is to assess how the ocean circulation, the ocean heat content, and the ice cover respond to increasing freshwater input and overall greenhouse warming. We also ask whether changes in the ocean affect the atmosphere, i.e., is the atmospheric surface warming modified by the changing ocean? We choose to seek answers to these questions with a hierarchy of model simulations. We focus on the North Atlantic-Arctic sector and examine changes in the ocean circulation and ocean heat content under greenhouse warming. We use idealized model simulations to assess changes in freshwater forcing, and global climate model simulations to examine the changing ocean heat budget. With this hierarchy of models we build a comprehensive understanding of the changing high latitude climate system and compile this dissertation around three main scientific findings. First, we increase the Arctic river runoff in an idealized column model which represents the large scale average conditions of the Arctic ocean-sea ice-atmosphere system. A larger Arctic river runoff leads to a new equilibrium with a fresher surface and a warmer subsurface. Interestingly, even though the fresher surface leads to larger vertical density differences and suppresses vertical mixing, the vertical heat flux towards the surface remains close to constant. This is because stronger density and temperature differences balance the heat flux: even a relatively small amount of warm water carries a relatively large amount of heat. As a result changes in the sea ice thickness remain small. Second, we extend our focus to larger scales and increase river runoff in a global ocean-sea ice model. Again, we find a fresher surface and a warmer subsurface Arctic Ocean as a response to increasing Arctic river runoff. The model also simulates a slightly weaker flow of water between the Arctic Ocean and its surrounding ocean basins. However, the heat exchanges between the central Arctic Ocean and the lower latitude oceans remain relatively constant. In a wider North Atlantic perspective, the subpolar North Atlantic shows an opposite response to the Arctic Ocean. The river runoff that enters the Arctic Ocean flows south along the coasts of Greenland and through the Canadian Arctic Archipelago and mixes into the subpolar North Atlantic. The additional freshwater weakens the large scale horizontal and vertical density differences and the ocean flow that depends on these density differences. The weaker ocean circulation brings less warm waters to the subpolar North Atlantic and the ocean cools as a result. Third, we find that, as the ocean heat content increases under greenhouse warming, the rate of the increase only weakly depends on the latitude in climate models. Only the Arctic Ocean, the northern part of the Southern Ocean, and the mid-latitude North Atlantic are warming slightly faster than the global average. We find that this stronger warming is associated with changes in the surface heat fluxes between the atmosphere and the ocean. In contrast, the subpolar North Atlantic is warming slightly slower than the global average because of the weaker ocean circulation that transports less warm waters towards the north. In summary, under greenhouse warming the high latitude ocean freshens and warms. Freshening at northern high latitudes acts to weaken the vertical heat exchanges between surface and subsurface waters which warms the Arctic Ocean. However, freshening in the north also acts to slow down the ocean circulation in the subpolar North Atlantic which reduces the northward ocean heat transport and cools the ocean there. Greenhouse warming leads to ocean warming and most of the small differences in the rate of ocean warming from latitude to latitude can be explained by changes in surface heat fluxes