Research area 1 did fundamental research on the dynamics of the atmosphere and oceans and their influence on climate. They applied and developed theory and conceptual models to gain insight into the underlying mechanisms that govern the oceanic and atmospheric circulation. This understanding was then used to interpret simulations using complex global climate models aimed at understand past and present climates as well as to predict future climate change.

Low pressure system over Iceland. Photo: NASA

Winds, waves and currents within Earth’s fluid envelope play a central role in climate. Such motions transport heat around the globe exerting a fundamental control on the global temperature distribution. The atmospheric circulation also plays a key role in shaping the global distributions of humidity and precipitation and of minor constituents such as CO2, aerosols, and ozone. These constituents can absorb and reflect solar and thermal radiation, profoundly influencing local and global temperatures. The ocean circulation, on the other hand, transports salt and biogeochemical properties such as dissolved inorganic carbon and nutrients, which play a crucial role for the Earth's marine ecosystems and the concentration of CO2 in the atmosphere.

The Bolin Centre’s Research Area 1 conducted fundamental research into the nature and impact of large-scale wind patterns in the atmosphere and currents in the ocean. Research methods ranged from complex global climate models to simple conceptual models and theory and observational analyses. Some work tackled global questions such as how, where and when surface water in the oceans sinks to the deep oceans, while other work took a more regional focus on areas of special interest such as the Baltic Sea. The research activities spanned time periods ranging from studies of the Eocene warm climate about 50 million years ago, to the glacial cycles of the last million years, and to the prediction of future climate change and impacts as a result of warmth-producing gasses from human activities.

Research area 2 investigated the role of clouds, turbulence and aerosols in the climate system and developed approaches for representing them in large-scale models. They used experimental data from detailed laboratory experiments, extensive field campaigns and long-term observations, in combination with models ranging from molecular-scale to fully coupled Earth system models.

Photo: Martin Jakobsson

Many atmospheric processes of large importance for the global climate occur on size and time scales that are so small that they are not directly resolved in global Earth System Models. Examples of such phenomena are processes related to atmospheric aerosols,clouds and turbulent flows. This research area brought together scientists working on a detailed understanding of these processes, on developing approaches for representing them in large-scale models and on investigating their role in the climate system. The tools used in this research area spanned from detailed laboratory experiments to long-term field observations, extensive field campaigns, and from molecular-scale models to fully coupled Earth System Models.

Water circulation at or near Earth’s surface occurs by rainfall, evapotranspiration, surface water and groundwater flows. Frozen water forms snow cover, glaciers, ice sheets and permafrost. Research area 3 studied couplings between water in all physical states and climate systems. This included effects of natural or man-made changes in land cover, vegetation and water flow paths. They also explored the effects of climate change on water-borne flows of substances including contaminants.

Waterfall, Brecon Beacon Wales. Photo: Karin Jonsell

Water and climate are closely interlinked. This is manifested through the highly heterogeneous terrestrial water cycle, and its water exchanges with the atmosphere and the oceans through precipitation, evapotranspiration, surface water flows and groundwater flows. This research area studied the mutual feedback between climate and water circulation in the crust and its hydrological basins and at different timescales and spatial scales. Reflections and projections of climate-driven changes in coupled surface water-groundwater systems, sediments, the terrestrial cryosphere and ecosystems were considered.

In addition to climate change, terrestrial hydrology changes have also other drivers, such as changes in land use, vegetation and water use, which to large extent are related to human activities, and directly affect evapotranspiration, regional climate and atmospheric circulation. The research area furthermore explored how hydro-climatic changes can influence travel times, transport and attenuation of different water-borne substances including contaminants in various hydrological, geological and environmental reservoirs.

Research area 4 studied interactions between climate and carbon-nutrient cycles through Earth system modeling, experimental, and observational studies. Questions included: How much carbon dioxide and methane will be released from thawing permafrost on land and under the sea? How efficiently are carbon and nutrients used at the organism level to the global scale and across environmental and climatic gradients?

Icebreaker Oden. Photo: Björn Eriksson

Studies of biogeochemical cycles from microscales to global scales are an important part of climate research and have both strong legacy and presence in the Bolin Centre. The processes and rates of biogeochemical cycling are affected by climate change, and involve interactions between and within the different components of the Earth system. These interactions are generally nonlinear, but climate models that include the dynamics of the carbon cycle suggest that the overall effect of carbon-climate interactions is generally a positive feedback. An important aspect of climate research is thus to identify potential biogeochemical feedbacks and assess if such feedbacks could produce large and undesired responses to perturbations resulting from human activities.

Rresearch within the Bolin Centre addresses these key aspects using field, experimental, and modelling studies. Only few mechanisms in the Earth system may cause a net redistribution of carbon from land and ocean to the atmosphere on the centennial time scale. The key candidate is a positive feedback to climate warming on permafrost thawing, carbon release and greenhouse gas additions to the atmosphere. A particular focus of biogeochemical research within the Bolin Centre is therefore the study of the fate of the large amount of organic carbon and methane stored in terrestrial and sub-sea permafrost.

This work was addressed through large-scale collaborative research expeditions on the Siberian Arctic shelf, microbial process regulation studies, and studies of soil organic matter dynamics. Another focal area was the study of climate-forcing aerosols and their emissions using observational-based inverse approaches. Future aspects of the research will include intensified modeling activities with the purpose to attempt reliable projections of future climate changes. These models will account explicitly for the feedbacks between climate and the processes that determine the atmospheric concentrations of greenhouse gases, reactive gases and aerosol particles.

Research area 5 reconstructed past climate evolution by investigating natural records such as marine, lake and terrestrial sediment cores, ice cores, cave deposits, tree rings, landforms and historical documents. By developing appropriate statistical methods and comparing with climate model simulations, they aimed to better understand and interpret past climate variability on historical and millennial time scales.

Sediment Inspection, Thailand. Photo: Ludvig LöwemarkPhoto: Ludvig Löwemark

This research area brought together physical geographers, geologists, climate modelers, statisticians, historians and other scientists to study climate variability since the last ice age and into the Quaternary. Past climate evolution is seen from archives such as ocean, lake and terrestrial sediment cores, landforms, ice cores, cave deposits, tree rings, and historical documents. Through the analysis of proxies in these archives they could acquire information about past climate variability. This data could then be analysed statistically to produce quantitative climate reconstructions. Meanwhile, climate models were applied to simulate past climate and explore the mechanisms of climate change and climate variability, which gave confidence in their ability to project future climate change.

To appreciate the full range of Earth's climate variability it is necessary to look far back into geologic time where we find intervals when the world has been much warmer and colder than today. Research area 6's mission was to reconstruct and interpret past climate variations on long timescales by comparing computer simulations and data from natural archives such as rocks, sediments and fossils. This helped them place limits on natural climate variability and better understand the Earth system.

Svalbard. Photo: Love Dalén

To understand the full range of climate variability on Earth it is necessary to look far back into geologic time where external forcings at tectonic (slow acting over millions of years) and orbital (rhythmic fluctuations over thousands of years) have left imprints of environmental change in a variety of Earth materials. By reconstructing ancient climates using these ‘natural archives’ and running computer models, it is possible to gain insight into the workings of the climate system, which may help us place limits on natural climate variability and anticipate possible future climate change.

Research area 6 was a meeting place for Bolin Centre scientists interested in climate variability over such long timescales, with a focus on the pre-Quaternary. The main activities were reconstruction and numerical modeling of:

• the long-term evolution of climate parameters, including, oceans, atmosphere, ice-sheets, biota, weathering and carbon cycling, as far back as the Neoproterozoic (ca. 1000–540 million years ago), and
• shorter lived ‘events’ and ‘perturbations’ including warmings, coolings and extinctions with an emphasis on climate forces and feedbacks on millennial to hundreds of thousands of year time scales.

Participants in research area 6 represented a wide spectrum of field, laboratory and computer-based disciplines, ranging from sedimentology, micropaleontology, palynology, paleobotany, geomorphology, geochronolgy, geochemistry, paleoceanography, marine geophysics and metamorphic petrology to theory and large-scale modeling of ocean and atmosphere circulation, and ice sheet dynamics.

Using the Bolin Centre platform they aimed to integrate research area 6's combined observational and theoretical expertise to enhance understanding of:

• glacial-interglacial ocean circulation regimes, sea ice history, subsea permafrost, and marine archives,
• timing, forcing, magnitude, frequency and feedback mechanisms of glaciation, deglaciation and the prominent late Cenozoic coolings,
• the carbon cycle and its interaction with atmospheric circulation,
• long-term peatland and permafrost dynamics and methane release
• climate/biosphere interaction and paleoecology
• Mesozoic and Cenozoic greenhouse to icehouse climate switching.

The combined effects of changes in climate, land-use and water-use may heavily influence natural resources in terrestrial and marine environments in the coming decades. To meet these challenges, research area 7 brought together natural and social scientists to do coordinated research on ecosystems. They focused on multi-scale processes of climate, biodiversity, ecosystem services and adaptive governance across landscape.

Photo: Sara Cousins

Climate is an important regulator of the distribution and function of the world’s ecosystems. Besides the human induced climate change other kinds of anthropogenic activities impact terrestrial, limnic and marine environments across the earth. Thus, to understand the effects of climate change we need to study the integrated effects of changes in climate, land-use, water-use and other human induced changes.

Research area 7 gathered natural and social scientists to study the effects of climate change on ecosystems, including its abiotic and biotic components and integrated effects on human well-being like using the ecosystem services concept. The focus was both on fundamental questions of how natural and anthropogenic processes at multiple scales play out in the landscape and on how society can respond to this for example by adaptive governance. They were interested in climate and climate change projections on various relevant scales for different processes and for land-use, water-use and natural resource management and governance.

Research area 8 investigateed how climate influences ecological and evolutionary processes in natural populations. Field observations and experiments were used to examine effects on abundance and distribution of single species, as well as how climate affect interactions between species, community structure and ecosystem functioning. They also used this information to develop methods to mitigate negative effects of climate change on biodiversity.

Photo: Christer Wiklund