Jens Hesselbjerg Christensen

Jens Hesselbjerg Christensen
University of Copenhagen · Niels Bohr Institute

Professor

About

259
Publications
67,086
Reads
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21,884
Citations
Introduction
More than 10 years as head of climate research at DMI until I moved to University. Former Director of Centre for Regional Change in the Earth System and CLA or LA on WG-I contributions to the IPCC reports TAR, AR4 and AR5, RE on AR6. I have acted as a member of the WCRP - JSC since 2015 Lead scientist on regional climate change detection and attribution - climate predictions and regional projections and I spend most of my scientific career developing, refining and applying the HIRHAM RCM
Additional affiliations
September 2017 - present
Norce Research
Position
  • Professor
March 2017 - present
University of Copenhagen
Position
  • Professor
January 2015 - February 2017
Danish Meteorological Institute
Position
  • Research Leader
Education
January 1986 - July 1990
University of Copenhagen
Field of study
  • astrophysics

Publications

Publications (259)
Article
Full-text available
The continuous change in observed key indicators such as increasing nitrogen deposition, temperatures and precipitation will have marked but uncertain consequences for the ecosystem carbon (C) sink-source functioning of the Arctic. Here, we use multiple in-situ data streams measured by the Greenland Ecosystem Monitoring programme in tight connectio...
Article
Full-text available
Plain Language Summary Northern European winters differ. Some are mild and moist with prevailing westerly winds and some are cold and dry, dominated by the Siberian air masses from East. When the Northern European winters are mild, the winter in Greenland is cold, and vice versa. This is the North Atlantic Oscillation (NAO) and its companion, the E...
Article
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It is well established that using kilometer scale grid resolution for simulations of weather systems in weather and climate models enhances their realism. This study explores heavy- and extreme-precipitation characteristics over the Nordic region generated by the regional climate model HARMONIE-Climate (HCLIM). Two model setups of HCLIM are used: E...
Article
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Using a sub-selection of regional climate models at 0.11° ( $$\approx$$ ≈ 12 km) grid resolution from the EURO-CORDEX ensemble, we investigate how the spatial extent of areas associated with the most intensive daily precipitation events changes as a consequence of global warming. We address this by analysing three different warming levels: 1 °C, 2...
Preprint
Full-text available
Various methods are available for assessing uncertainties in climate impact studies. Among such methods, model weighting by expert elicitation is a practical way to provide a weighted ensemble of models for specific real-world impacts. The aim is to decrease the influence of improbable models in the results and easing the decision-making process. I...
Preprint
Full-text available
It is well established that using km scale grid resolution for simulations of weather systems in weather and climate models enhances their realism. This study explores heavy and extreme precipitation characteristics over the Nordic region generated by the regional climate model, HARMONIE-Climate (HCLIM). Two model setups of HCLIM are used: ERA-Inte...
Article
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European climate is associated with variability and changes in the mid-latitude atmospheric circulation. In this study, we aim to investigate potential future change in circulation over Europe by using the EURO-CORDEX regional climate projections at 0.11° grid mesh. In particular, we analyze future change in 500-hPa geopotential height (Gph), 500-h...
Article
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Global warming is likely to cause a progressive drought increase in some regions, but how population and natural resources will be affected is still underexplored. This study focuses on global population and land-use (forests, croplands, pastures) exposure to meteorological drought hazard in the 21st century, expressed as frequency and severity...
Article
Climate models are fundamental to understanding climate change and anticipating its risks. They provide the basis for predicting impacts, guiding adaptation decisions and setting mitigation targets. Society now needs more detailed and precise information to enable robust decision-making in the face of rapidly amplifying climate change and for achie...
Technical Report
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For this volume, a survey was conducted among WMO Members in 2018 to judge the level of service provision in each area, the extent to which users and providers collaborate and the status of urban services currently provided. The common hazards that require Integrated Urban Services are identified as heavy rainfall, flooding, windstorms, tropical st...
Article
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Recent assessments from the Intergovernmental Panel on Climate Change (IPCC) imply that global mean sea level is unlikely to rise more than about 1.1 m within this century but will increase further beyond 2100. Even within the most intensive future anthropogenic greenhouse gas emission scenarios, higher levels are assessed to be unlikely. However,...
Article
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Severe precipitation events occur rarely and are often localised in space and of short duration, but they are important for societal managing of infrastructure. Therefore, there is a demand for estimating future changes in the statistics of the occurrence of these rare events. These are often projected using data from regional climate model (RCM) s...
Chapter
This chapter describes a new World Meteorological Organisation (WMO) approach to the provision of science-based services to assist the planning of safe, healthy, resilient and climate-friendly cities. The approach is outlined in full in the WMO Guidance on Integrated Urban Hydrometeorological, Climate and Environmental Services. Volume I, Concepts...
Preprint
Full-text available
Recent assessments from the Intergovernmental Panel on Climate Change implies that global mean sea level is unlikely to rise more than about 1.1 m within this century, but with further increase beyond 2100, even within the most intensive future anthropogenic carbon dioxide emission scenarios. However, some studies conclude that considerably greater...
Preprint
Full-text available
Severe precipitation events occur rarely and are often localized in space and of short duration; but they are important for societal managing of infrastructure. Therefore, there is a demand for estimating future changes in the statistics of these rare events. These are usually projected using Regional Climate Model (RCM) scenario simulations combin...
Article
Full-text available
Abrupt climate change is a striking feature of many climate records, particularly the warming events in Greenland ice cores. These abrupt and high-amplitude events were tightly coupled to rapid sea-ice retreat in the North Atlantic and Nordic Seas, and observational evidence shows they had global repercussions. In the present-day Arctic, sea-ice lo...
Article
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Two questions motivated this study: 1) Will meteorological droughts become more frequent and severe during the 21 st century? 2) Given the projected global temperature rise, to what extent does the inclusion of temperature (in addition to precipitation) in drought indicators, play a role in future meteorological droughts? To answer, we analyzed the...
Article
Full-text available
The European CORDEX (EURO-CORDEX) initiative is a large voluntary effort that seeks to advance regional climate and Earth system science in Europe. As part of the World Climate Research Programme (WCRP) - Coordinated Regional Downscaling Experiment (CORDEX), it shares the broader goals of providing a model evaluation and climate projection framewor...
Article
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The potential link between decreasing Barents-Kara sea ice and cold winters in Europe is investigated using the 1 enhanced resolution (horizontal atmospheric resolution of ∼80 km) global, coupled climate model EC-Earth. Nudging sea ice 2 only in the Barents and Kara Seas, five configurations of sea ice covers are used to assess the importance of th...
Article
Hurricanes are the most destructive natural disasters in the United States. The record of economic damage from hurricanes shows a steep positive trend dominated by increases in wealth. It is necessary to account for temporal changes in exposed wealth, in a process called normalization, before we can compare the destructiveness of recorded damaging...
Article
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2018: Arctic researchers have just witnessed another extreme summer—but in a new sense of the word. Although public interest has long been focused on general warming trends and trends towards a lower sea ice cover in the Arctic Ocean, this summer saw the realization of another predicted trend: that of increasing precipitation during the winter mont...
Article
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10 How climate change will unfold in the years to come is a central topic in today's environmental debate, in particular at 11 the regional level. While projections using large ensembles of global climate models consistently indicate a future 12 decrease in summer precipitation over southern Europe and an increase over northern Europe, individual m...
Article
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Observed and model‐projected sea ice loss enhances warming in the Arctic. We investigate to what extent warming on Greenland can be attributed to changes in the sea ice cover in different parts of the Arctic. Using Climate Model Intercomparison Project phase 5 model projections of the future, we perform multilinear regressions to separate the simul...
Article
Climate change in Greenland is interfering with environmental and human systems at an accelerating rate. Climate-related effects are particularly observable in the Greenlandic tourism sector-which is a designated future key industry. Responding to these changes requires planned efforts for the various tourist seasons. To date, studies investigating...
Article
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Wine production is climate dependent and highly sensitive to weather variability, which makes the sector a good indicator of ongoing and future climate change impacts. Under high-end climate change (HECC), temperatures in Scotland are projected to increase significantly by the end of the twenty-first century. This raises the possibility of future t...
Article
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Climate models have been making significant progress encompassing an increasing number of complex feedback mechanisms from natural ecosystems. Permafrost thaw and subsequent induced greenhouse gas emissions, however, remain a challenge for climate models at large. Deducing permafrost conditions and associated greenhouse gas emissions from parameter...
Article
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The ability of state-of-the-art regional climate models (RCMs) to simulate the trends of intense cyclone activity in the Arctic is assessed based on an ensemble of 13 simulations from 11 models from the Arctic-CORDEX initiative. Some models employ large-scale spectral nudging techniques. Cyclone characteristics simulated by the ensemble in winter a...
Article
Full-text available
The regional manifestation of climate change projections for Europe consistently indicates a future decrease in summer precipitation over southern Europe and an increase over northern Europe. However, individual models substantially modulate these overarching precipitation change signals. Despite considerable model improvements as well as increasin...
Article
Climate adaptation in Greenland is dependent on high-resolution climate simulations and associated uncertainty estimates. A single high-resolution climate simulation is generally insufficient to quantify the uncertainty of a given scenario projection. For Greenland this becomes a critical issue due to a lack of high-resolution climate experiments f...
Article
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Using regional climate-model runs with a horizontal resolution of 5.5 km for two future scenarios and two time slices (representative concentration pathway [RCP] 4.5 and 8.5; 2031-2050 and 2081-2100) relative to a historical period (1991-2010), we study the climate change for the Qeqqata municipality in general and for Kangerlussuaq in particular....
Article
The challenge of meeting the UNFCCC CoP21 goal of keeping global warming ‘well below 2 °C and to pursue efforts towards 1.5 °C’ (‘the 2–1.5 °C target’) calls for research efforts to better understand the opportunities and constraints for fundamental transformations in global systems dynamics which currently drive the unsustainable and inequitable u...
Article
Full-text available
The ability of state-of-the-art regional climate models to simulate cyclone activity in the Arctic is assessed based on an ensemble of 13 simulations from 11 models from the Arctic-CORDEX initiative. Some models employ large-scale spectral nudging techniques. Cyclone characteristics simulated by the ensemble are compared with the results forced by...
Article
Full-text available
Multi-model ensembles are widely analyzed to estimate the range of future regional climate change projections. For an ensemble of climate models, the result is often portrayed by showing maps of the geographical distribution of the multi-model mean results and associated uncertainties represented by model spread at the grid point scale. Here we use...
Article
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Surface mass balance (SMB) is the builder of the Greenland ice sheet and the driver of ice dynamics. Quantifying the past, present and future state of SMB is important to understand the drivers and climatic processes that control SMB, and to both initialize and run ice sheet models which will help clarify sea level rise, and how likely changes in i...
Technical Report
Full-text available
The report provides an overview over the ice‐metocean environment and the operating conditions in Northeast Greenland and the offshore licensing blocks.
Poster
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The ability to simulate regional precipitation realistically by climate models is essential to understand and adapt to climate change. Due to the complexity of associated processes, particularly at unresolved temporal and spatial scales this continues to be a major challenge. As a result, climate simulations of precipitation often exhibit substanti...
Article
Full-text available
The ability to simulate regional precipitation realistically by climate models is essential to understand and adapt to climate change. Due to the complexity of associated processes, particularly at unresolved temporal and spatial scales this continues to be a major challenge. As a result, climate simulations of precipitation often exhibit substanti...
Article
This paper assesses how various sources of uncertainty propagate through the uncertainty cascade from emission scenarios through climate models and hydrological models to impacts with particular focus on groundwater aspects for a number of coordinated studies in Denmark. We find results similar to surface water studies showing that climate model un...
Article
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The land surface-atmosphere interaction is described differently in large scale surface schemes of regional climate models and small scale spatially distributed hydrological models. In particular, the hydrological models include the influence of shallow groundwater on evapotranspiration during dry periods where soils are depleted and groundwater is...
Conference Paper
The complexity of precipitation processes makes it difficult for climate models to reliably simulate precipitation, particularly at sub-grid scales, where the important processes are associated with detailed land-atmosphere feedbacks like the vertical circulations driven by latent heat that affect convective precipitation systems. As a result clima...
Article
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Dynamical downscaling (DDS) is performed using regional climate models (RCMs) with global atmospheric states as the input, but there is no consensus among researchers on how to define and estimate the resolvable scale of the various climatic variables obtained by DDS. Sources of RCM uncertainties, including both internal model and intermodel variab...
Article
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In this Climate Research (CR) Special, the Centre for Regional Change in the Earth System (CRES) brings together scientific expertise (ranging from climate to social sciences) with practitioners and stakeholders to present thematic research addressing gaps in (1) our understanding of climate-system behaviour at a regional scale and in particular at...
Article
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With the help of a simulation using the global circulation model (GCM) EC-Earth, downscaled over Europe with the regional model DMI-HIRHAM5 at a 25 km grid point distance, we investigated regional climate change corresponding to 6°C of global warming to investigate whether regional climate change generally scales with global temperature even for ve...
Article
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AbstractResearch on regional climate modeling has remarkably expanded during the last few years in terms of the research groups, the sophistication of regional climate models and the number of new studies. Not least, the models used by the community are refined with additional complexity and resolution, which promotes new insights. The Third Intern...
Article
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Freshwater runoff to fjords with marine-terminating glaciers along the Greenland Ice Sheet margin has an impact on fjord circulation and potentially ice sheet mass balance through increasing heat transport to the glacier front. Here, the authors use the high-resolution (5.5 km) HIRHAM5 regional climate model, allowing high detail in topography and...
Article
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To improve our understanding of the impacts of feedback between the atmosphere and the terrestrial water cycle including groundwater and to improve the integration of water resource management modelling for climate adaption we have developed a dynamically coupled climate-hydrological modelling system. The OpenMI modelling interface is used to coupl...
Article
Full-text available
A major challenge in the emerging research field of coupling of existing regional climate models (RCMs) and hydrology/land-surface models is the computational interaction between the models. Here we present results from a full two-way coupling of the HIRHAM RCM over a 4000 km × 2800 km domain at 11 km resolution and the combined MIKE SHE-SWET hydro...
Conference Paper
Full-text available
Observations and climate projections provide evidence that water resources are vulnerable and subject to a high potential impact by climate change with wide implications for human societies and ecosystems. An improved understanding of the hydrological feedback and interaction mechanisms between the atmosphere, the land-surface and the subsurface is...