Kirsti Jylhä

Finnish Meteorological Institute · Weather and Climate Change Impact Research

Severe heat waves lasting for weeks and expanding over hundreds of kilometres in horizontal scale have many harmful impacts on health, ecosystems, societies, and economy. Under the ongoing climate change heat waves are becoming even longer and hotter, and as proactive adaptation, the development of early warning services is essential. Weather forec...

As the incidence of extended hot summers in the Nordic climate increases due to climate change, non-mechanically cooled apartments face high risks of overheating. Hence, this study aimed to investigate the temporal effects of heatwaves on indoor temperatures and examine the correlation between outdoor weather conditions and indoor temperature level...

Plain Language Summary Sea levels in the Baltic Sea can vary a lot. In winter, powerful storms can lead to storm surges that seriously affect coastal towns. Our research studied storm paths and sea level observations. We found that multiple consecutive storms within a week raise sea levels in the Baltic Sea more than when only one storm passes the...

European heatwaves at the 0.5, 1.0, 1.5 and 2.0 $$^\circ$$ ∘ C global warming levels above the pre-industrial temperature are examined using bias-corrected daily-mean temperature data from 60 simulations performed with 25 global climate models (GCMs). A heatwave event is defined here to consist of at least three consecutive days above the 90th perc...

European heatwaves at the 0.5, 1.0, 1.5 and 2.0°C global warming levels are examined using bias-corrected daily-mean temperature data from 60 simulations performed with 25 global climate models (GCMs). A heatwave event is defined to consist of at least three consecutive days above the 90th percentile of summer daily-mean temperatures and the event...

Convective sea‐effect snowfall, in the form of snowbands, is observed over the northern Baltic Sea annually. Quasi‐stationary snowbands may last up to several days over the sea and, depending on the wind direction, move towards the coast. This study provides climatology of spatial and temporal occurrence of snowbands in Finland for a 48‐year period...

The buildings’ HVAC system design and indoor conditions are affected by climate change. This study aimed to investigate the effects of climate change on office buildings’ cooling system design and indoor temperature conditions in the Nordic cold climate. Thus, two types of mechanical cooling systems, the all-air (ventilative) and the air-water (rad...

The KUITTI project assessed the direct and indirect cost of climate change risks for Finland while distinguishing proactive and reactive adaptation. It also reviewed the availability of data necessary for assessing the economic effects of climate change and adaptation in Fin-land, and provided an outlook of innovation needs and options which serve...

A natural hazard is a naturally occurring extreme event that has a negative effect on people and society or the environment. Natural hazards may have severe implications for human life and can potentially generate economic losses and damage ecosystems. A better understanding of their major causes, probability of occurrence, and consequences enables...

Simultaneous heavy precipitation with high sea level can lead to more severe flooding than if the hazards occur individually. In recent years, the significance of compound flooding has gained attention in many coastal areas, but studies on compound flooding in Finland are still lacking. In this paper, we investigate the co-occurrence of heavy preci...

The global average air temperature is increasing as a manifestation of climate change and more intense and frequent heatwaves are expected to be associated with this rise worldwide, including northern Europe. Summertime indoor conditions in residential buildings and the health of occupants are influenced by climate change, particularly if no mechan...

A natural hazard is a naturally occurring extreme event with a negative effect on people and society or the environment. Natural hazards may have severe implications for human life and they can potentially generate economic losses and damage ecosystems. A better understanding of their major causes, probability of occurrence, and consequences enable...

Urbanization and ongoing climate change increase the exposure of the populations to heat stress, and the urban heat island (UHI) effect may magnify heat-related mortality, especially during heatwaves. We studied temperature-related mortality in the city of Helsinki—with urban and suburban land uses—and in the surrounding Helsinki-Uusimaa hospital d...

Extreme precipitation events (EPEs) have a major impact across Arctic Fennoscandia (AF). Here we examine the spatial variability of seasonal 50-year trends in three EPEs across AF for 1968–2017, using daily precipitation data from 46 meteorological stations, and analyse how these are related to contemporaneous changes in the principal atmospheric c...

The formation of convective sea-effect snowfall (i.e., snow bands) is triggered by cold air outbreaks over a relatively warm and open sea. Snow bands can produce intense snowfall which can last for several days over the sea and potentially move towards the coast depending on wind direction. We defined the meteorological conditions which statistical...

In this work, the climatic impacts of modifying urban surface characteristics are examined for the medium-sized city of Vantaa, Finland, in the current climate and in a projected future climate of 2040–2069. In simulations with the SURFEX air-surface interaction model with a horizontal resolution of 500 m, the fraction of green spaces and relativel...

We studied interannual variability and changes over time in selected climate indices in the reindeer management area (RMA) in northern Finland. We present together the knowledge possessed by reindeer herders with information from meteorological measurements over three decades. The practitioner knowledge was gathered via a survey questionnaire addre...

The general objective of EXWE was to give better estimates of probabilities of extreme geophysical events that affect the design principles of nuclear power plants (NPPs) and may pose external threats to the plants. Extreme incidents in weather, sea level events and space weather, as well as atmospheric dispersion were considered. Various observati...

Extremity of precipitation climate can be evaluated by the intensity of both wet and dry extremes. Here we illustrate the tendency towards more extreme precipitation climate during the 21st century in a multi-model ensemble of 32 climate model simulations from the Coupled Model Intercomparison Project Phase 5. We compare the projected changes in tw...

Snow conditions in high‐latitude regions are changing in response to climate warming, and these changes are likely to accelerate as the warming proceeds. Here, we analyse daily gridded snow depth, temperature and precipitation data from Finland over the period 1961–2014 to discover the ongoing changes in monthly average snow depths (SN) and several...

A sea-effect snowfall accumulated a national record-breaking snowdrift of 73 cm in Merikarvia, on the west coast of Finland, in less than one day on 8 January 2016. A good understanding of such heavy sea-effect snowfalls in the present climate is essential if we want to assess the probability of their occurrence and intensity in the future. Since v...

The effects of climate change on freezing rain in Europe under medium (RCP4.5) and strong (RCP8.5) future emission scenarios were assessed using seven regional climate model simulations conducted within the World Climate Research Project's COordinated Regional climate Downscaling Experiment over the European Domain (EURO-CORDEX). A precipitation-ty...

Major nuclear accidents are typically low-probability–high-consequence events. This paper focuses on weather and sea-level events that might affect the safety of nuclear power plants (NPPs). Flooding risks at Finnish NPP sites have been re-evaluated based on investigations of long-term changes and short-term variations in sea level, which has led t...

The commentators regard a categorical truncation of supersaturations with respect to ice in climate model output as an inappropriate solution to the supersaturation issue. This view is supported by observational evidence from the East Antarctic Plateau. We accept this criticism to a certain degree. Even so, it is necessary to make a clear distincti...

Arctic Fennoscandia has undergone significant climate change over recent decades. Reanalysis datasets allow us to understand the atmospheric processes driving such changes. Here we evaluate four reanalyses against observations of near-surface air temperature (SAT) and precipitation (PPN) from 35 meteorological stations across the region for the 35-...

The aim of this study was to assess regional differences in temperature-mortality relationships across 21 hospital districts in Finland. The temperature dependence of the daily number of all-cause, all-aged deaths during 2000-2014 was studied in each hospital district by using daily mean temperatures, spatially averaged across each hospital distric...

Arctic Fennoscandia has undergone significant climate change over recent decades. Reanalysis data sets allow us to understand the atmospheric processes driving such changes. Here we evaluate four reanalyses against observations of near‐surface air temperature (SAT) and precipitation (PPN) from 35 meteorological stations across the region for the 35...

Climate change is expected to increase heat-related and decrease cold-related mortality. The extent of acclimatization of the population to gradually-changing thermal conditions is not well understood. We aimed to define the relationship between mortality and temperature extremes in different age groups in the Helsinki-Uusimaa hospital district in...

In 17 out of the 29 CMIP5 climate models examined in this work, near-surface air relative humidity (RH) frequently exceeded 100 % with respect to ice in polar areas in winter. The degree of supersaturation varied considerably across the models, and the same evidently applies to the causes of the phenomenon. Consultations with the modelling groups r...

A new national daily snowfall record was measured in Finland on 8 January 2016 when it snowed 73 cm (31 mm as liquid water) in less than a day in Merikarvia on the western coast of Finland. The area of the most intense snowfall was very small, which is common in convective precipitation. In this work we used hourly weather radar images to identify...

Highlights - Embedding scenarios of global change in local and regional contexts can support the identification of local adaptation challenges. - Comparability across local studies of adaptation challenges can be facilitated by using the Shared Socioeconomic Pathways (SSPs) from the global scenario framework developed by the climate research commun...

We studied climate trends and the occurrence of rare and extreme temperature and precipitation events in northern Fennoscandia in 1914–2013. Weather data were derived from nine observation stations located in Finland, Norway, Sweden and Russia. The results showed that spring and autumn temperatures and to a lesser extent summer temperatures increas...

A method for estimating the occurrence of freezing rain (FZRA) in gridded atmospheric data sets was evaluated, calibrated against SYNOP weather station observations, and applied to the ERA-Interim reanalysis for climatological studies of the phenomenon. The algorithm, originally developed at the Finnish Meteorological Institute for detecting the pr...

A case study of a new national snowfall record which was measured on the 8 th of January 2016 when it snowed up to 73 cm (31 mm) in less than a day in Merikarvia, on the western coast of Finland. The heavy snowfall area was very small, which is common in convective precipitation. The background to this case is a well known lake-effect (here sea-eff...

A method for estimating the occurrence of freezing rain (FZRA) in gridded atmospheric datasets was evaluated, calibrated against SYNOP weather station observations, and applied to the ERA-Interim reanalysis for climatological studies of the phenomenon. The algorithm, originally developed for detecting the precipitation type in numerical weather pre...

Long-term time series of key climate variables with a relevant spatiotemporal resolution are essential for environmental science. Moreover, such spatially continuous data, based on weather observations, are commonly used in, e.g., downscaling and bias correcting of climate model simulations. Here we conducted a comprehensive spatial interpolation s...

Climate change projections for Finland have been calculated from simulations performed with 28 recent-generation (CMIP5) global climate models. During the next few decades, projected changes are fairly similar under all four RCP forcing scenarios examined. Conversely, in the second half of this cen-tury, the evolution of climate is highly dependent...

A worldwide online survey about user awareness of reanalyses and climate services was conducted in the period November 2013 to February 2014 by the CORE-CLIMAX project. The 2578 respondents were mostly users of global reanalyses (particularly ECMWF, NCEP, NASA and JMA reanalyses). They answered queries arranged in 11 sections by choosing from pre-p...

We studied regional effects of alternative climate change and management scenarios on timber production, its economic profitability (net present value (NPV), with 2% interest rate), and carbon stocks over a 90 year simulation period in Norway spruce (Picea abies (L.) Karst.) forests located in southern, central, and northern Finland. We also compar...

In this work, it was studied the need to adapt the choice of main Finnish boreal tree species in forest regeneration under the projected climate change. The forest ecosystem model (SIMA) was used to simulate the volume growth of young Norway spruce, Scots pine and silver birch stands under the current and gradually changing climate throughout Finla...

Dynamic building energy simulations need hourly weather data as input. The same high temporal resolution is required for assessments of future heating and cooling energy demand. The data presented in this article concern current typical values and estimated future changes in outdoor air temperature, wind speed, relative humidity and global, diffuse...

A web-based survey to assess the benefits and gaps in reanalyses as part of growing climate services was carried out in 2013–2014. The survey elicited responses from about 2500 users of climate information. One of the eleven survey points specifically addressed the observations used in reanalysis, with a multiple-choice question "Have you used rean...

We assessed the energy demand of a typical detached house in Finland in the observed recent and anticipated future climatic conditions. Hourly test reference weather data sets spanning a whole year (2030, 2050 and 2100) were used as input to a dynamic building energy simulation tool. The annual energy demand for heating of spaces and ventilation su...

We studied the effects of climate change and forest management scenarios on net climate impacts (radiative forcing) of production and utilization of energy biomass, in a Norway spruce forest area over an 80-year simulation period in Finnish boreal conditions. A stable age-class distribution was used in model-based analyses in order to identify pure...

The timing of springtime end of snowmelt (snow-off date) in northern Eurasia in version 5.4 of the ECHAM5 atmospheric general circulation model (GCM) is evaluated through comparison with a snow-off date data set based on space-borne microwave radiometer measurements and with Russian snow course data. ECHAM5 reproduces well the observed gross geogra...

The timing of springtime end of snowmelt (snow-off date) in northern Eurasia in version 5.4 of the ECHAM5 atmospheric general circulation model (GCM) is evaluated through comparison with a snow-off date data set based on space-borne microwave radiometer measurements and with Russian snow course data. ECHAM5 reproduces well the observed gross geogra...

A multiple regression model was applied to estimate the future number of forest fire danger days (FDDs) in boreal climate conditions in Finland. The model used anomalies of June−August mean temperature and precipitation as predictors. Joint probability distribution functions (PDFs) created during the ENSEMBLES project for the SRES A1B scenario were...

We project changes in the annual maximum ice extent and the maximum coastal fast ice thickness in the Baltic Sea during the ongoing century. The influence of future warming on the ice conditions was assessed using the November-March Baltic coastal mean temperature as a predictor for the annual maximum ice extent (MIB), and the local freezing degree...

Climate variability and temporal trends in the period 1990-2010 around the Valkea-Kotinen environmental monitoring area were compared both with earlier observations and with climate model projections for the 2040s and 2080s. The focus was on climatic variables relevant for aquatic and terrestrial ecosystems, i.e., air temperature, precipitation, sn...

As both global (GCM) and regional (RCM) climate models have their own advantages, the most comprehensive picture of changes in precipitation and their uncertainty ranges can be achieved by comparing the results of both model categories. Here we have evaluated seasonal changes in indices representing excess or scarcity of precipitation in Europe on...

In spite of the relatively humid climate of Northern Europe, prolonged meteorological dry spells do occasionally cause problems for the water supply in different sectors of society. During recent decades, total annual precipitation has increased in the region, especially during winter. A linear change in total precipitation does not necessarily ind...

We analyzed the effects of management on the economic profitability of forest biomass production and car-bon neutrality of bioenergy use in Norway spruce (Picea abies L. Karst) stands under the changing climate. We employed a forest ecosystem model and life cycle assessment tool. In particular, we studied the effects of thinning, nitrogen fertiliza...

Precipitation cleanses the air by capturing airborne pollutants and depositing them onto the ground. The efficiency of this process may be expressed by the so-called scavenging coefficient A. It depends on the size distribution of the bydrometeors and is thereby related to the radar reflectivity factor Z and to the precipitation rate R. The greates...

Carter, Timothy R., Bärlund, Ilona, Fronzek, Stefan, Kankaanpää, Susanna, Kaivo-oja, Jari, Luukkanen, Jyrki, Wilenius, Markku, Tuomenvirta, Heikki, Jylhä, Kirsti, Kahma, Kimmo, Johansson, Milla, Boman, Hanna, Launiainen, Jouko, Laurila, Tuomas, Lindfors, Virpi, Tuovinen, Juha-Pekka, Aurela, Mika, Syri, Sanna, Forsius, Martin & Karvosenoja, Niko (20...

At a global level, it is estimated that nearly two-thirds of ecosystem services have been degraded in just fifty years. The additional stresses imposed by climate change will require extraordinary adaptation. This paper synthesises main result of a large Finnish project studying the vulnerability of key ecosystem services to climate change and the...