140 research outputs found
When Will Arctic Sea Ice Be Gone?
No full textThe Arctic sea ice is the ice that is floating on the Arctic Ocean. In recent decades, this pack ice has been disappearing very rapidly. So the question arises when the Arctic sea ice will be completely gone. DIRK NOTZ has examined this using the Arctic summer sea ice in September as example. As he explains in this video, his research group combined satellite observations with model simulations and found a clear linear correlation between the loss of Arctic sea ice and carbon dioxide emissions. For each ton of CO2 we emit, we make about three square meters of Arctic sea ice disappear. From this linear relationship the researchers could extrapolate the amount of carbon dioxide that can still be emitted before the Arctic sea ice is completely gone in summers. For the first time, these findings present very intuitive numbers that make clear the impact every individual has on the global warming
A short history of climate change
No full textThe flux of energy through the climate system determines the living conditions of our planet. In this contribution, I outline the main processes regulating this flux of energy, how these processes have changed throughout Earth history, and how today they are changing by human activities, in particular by activities related to energy production. The changes in the climate state of our planet, which have been ongoing ever since the formation of the Earth some 5 billion years ago, have shaped the world we live in today. Yet, today’s climate change is special in two overarching ways. First, it is the first time that a major climate change is globally affecting a civilisation that is perfectly adapted to thousands of years of stable climate conditions. Second, today’s climate change is occurring at a rate much faster than preceding natural climate changes. In combination, these two factors make today’s climate change a unique challenge to humankind, with direct consequences of future energy production as outlined in the other contributions to this volume
In-ice temperature and conductivity profile measurements on MOSAiC with the salt harp sensor - raw data
No full textSea ice buoy saltharp was deployed at the MOSAiC LM-site from mid January to August 2022. It measured autonomously and non-destructively the temperature and conductivity between horizontal wire pairs, from which we retrieve solid fraction and sea ice bulk salinity profiles. This dataset contains the raw data of saltharp as it was received onshore via satellite link. The saltharp had severe technical problems, making most of the data unusable. A processed data set will exclude these values. Definitely wrong ones have already been replaced here with -999. as NaN indicator. Further information on the data format and the measurement record are collected in the attached protocol documents
In-ice light and temperature profile measurements on MOSAiC with the light harp sensor - raw data
No full textSea ice buoy lightharp was deployed at the MOSAiC LM-site from mid January to August 2022. It measured autonomously and non-destructively the up- and downwelling light field in the ice. This dataset contains the raw data of buoy lightharp as it was received onshore via satellite link. Further information on the data format and the measurement record are collected in the attached protocol documents
Sea ice in coupled climate models
No full textWe give an overview of the representation of sea ice in coupled climate models. Such representation is based on the conservation of heat, mass, and momentum to represent the interaction between sea ice and the oceanic and atmospheric forcing. We introduce the underlying physical laws and discuss their numerical implementation. We also briefly describe the coupling of sea ice to the other components of climate models and discuss a few aspects related to the evaluation of the sea ice model component. © 2019 Elsevier Ltd. All rights reserved
The future of ice sheets and sea ice: Between reversible retreat and unstoppable loss
No full textWe discuss the existence of cryospheric “tipping points” in the Earth's climate system. Such critical thresholds have been suggested to exist for the disappearance of Arctic sea ice and the retreat of ice sheets: Once these ice masses have shrunk below an anticipated critical extent, the ice–albedo feedback might lead to the irreversible and unstoppable loss of the remaining ice. We here give an overview of our current understanding of such threshold behavior. By using conceptual arguments, we review the recent findings that such a tipping point probably does not exist for the loss of Arctic summer sea ice. Hence, in a cooler climate, sea ice could recover rapidly from the loss it has experienced in recent years. In addition, we discuss why this recent rapid retreat of Arctic summer sea ice might largely be a consequence of a slow shift in ice-thickness distribution, which will lead to strongly increased year-to-year variability of the Arctic summer sea-ice extent. This variability will render seasonal forecasts of the Arctic summer sea-ice extent increasingly difficult. We also discuss why, in contrast to Arctic summer sea ice, a tipping point is more likely to exist for the loss of the Greenland ice sheet and the West Antarctic ice sheet
Challenges in simulating sea ice in Earth System Models
No full textSea ice is a key element of the Earth's climate system, and also of significant ecological, geo‐political, and economic importance. Understanding the ongoing changes of the Earth's sea‐ice cover is therefore not only scientifically interesting in itself, but also crucial for a large number of different stakeholders. Without such understanding, a reliable projection of possible future changes will be impossible. A main focus of ongoing sea‐ice research is therefore aimed at identifying the factors that modulate the ice's variability on seasonal and longer time scales. For such efforts, coupled Climate Models or Earth System Models are used. To give trustworthy results, these models must be able to realistically simulate the mechanical and thermodynamic interaction of sea ice with the atmosphere and the ocean, which determine the resulting sea‐ice thickness distribution. While the representation of such air–ice–sea interaction has seen some major advances in the most complex sea‐ice models during the past decade, a number of fundamental processes of air–ice–sea interaction are still only crudely understood and currently not realistically represented in models. This article provides a succinct description of these processes and discusses necessary research directions for their improved representation in models
Atmospheric dynamics: Arctic winds of change
No full textThe Earth's climate evolves in response to both externally forced changes and internal variability. Now research suggests that both drivers combine to set the pace of Arctic warming caused by large-scale sea-ice los
A transforming Arctic: Unraveling Climate Change Impacts on Sea-Ice Evolution and Oceanic pCO2
No full textThe Arctic undergoes profound transformations due to global warming, with climate change impacts varying at regional levels. While many changes, such as declining sea ice and alterations in ocean biochemistry, are often discussed based on the pan-Arctic average, their local implications and intensity variations across regions have been largely overlooked, despite their importance for stakeholders. This thesis aims to help shift the perspective towards understanding regional changes in the Arctic by investigating two crucial indicators affected by a warming climate: Arctic sea-ice coverage and surface ocean partial pressure of carbon dioxide (pCO2 ). The first is of interest to a variety of stakeholders, particularly to those interested in changes along the coast–ice transition zone, such as the shipping industry and indigenous people. The latter is a key factor in the exchange of CO2 between ocean and atmosphere and is, therefore, decisive for the acidification of the oceans. The sensitivity of sea-ice area to near-surface air temperature changes, i. e. how strongly sea-ice area diminishes for a given rise in temperature, exhibits a high seasonal dependence, characterized by significant variability in summer and low variability in winter. This study reveals that the transition between summer and winter, along with the observed low variability in winter, can be attributed to the geographic blocking of the sea-ice edge by surrounding land masses. By quantifying the timing of the blocking, the analysis links the timing changes to rising global temperatures. The findings indicate that as the timing shifts and the season during which the ice edge is blocked shortens (by around 7 days per tenth degree of global warming on average), adjacent seasons will experience heightened sensitivity in sea-ice area. Particularly, sensitivities in areas along the coasts of the high Arctic Ocean will undergo a sudden change in the future. Expanding the sensitivity analysis to a regional scale, the study provides new perspectives on how the sea ice in individual Arctic regions responds to global warming, anticipating future changes. The East Siberian Sea, the Chukchi Sea, and the Laptev Sea are identified as regions likely to lose their summer sea ice first. The Barents Sea is projected to become the first region to lose its remaining winter sea ice, ultimately becoming ice-free year-round.
Shifting focus to surface ocean pCO2, two data products estimating surface ocean pCO2 to fill the sparse observations in the Arctic are used to investigate the evolution of surface ocean pCO2 in the Arctic domain. Both products reveal consistent increases in most regions over the last two decades. However, substantial differences in the magnitudes of inter- and intra-annual changes are observed between the two datasets. Separating the spatial and temporal variability in the pCO2 via EOF analysis reveals the dominant drivers of changes in the pCO2 in different domains of the Arctic. The study identifies sub-Arctic domain changes primarily related to the seasonal solar irradiance cycle, while high Arctic pCO2 changes are dominated by changes in sea-ice cover. Examining seasonality, shifts and changes in intra-annual amplitude are noted already in the historical record, particularly north of Canada, indicating potential impact on ecosystems. This thesis underscores the necessity of taking a regional perspective on Arctic climate change. By systematically analyzing and quantifying the blocking effect for the first time, it provides a foundation for understanding sea-ice area changes in the high Arctic, benefiting stakeholders interested in Arctic Ocean transformations, particularly in coastal regions. Additionally, the pCO2 analysis offers insights into the drivers of pCO2 in the Arctic Ocean, serving as a benchmark to enhance future data products, crucial for investigating regional changes in the Arctic surface ocean carbon cycle. These findings contribute to the groundwork for future research in the Arctic.Die Arktis ist aufgrund der globalen Erwärmung tiefgreifenden Veränderungen unterworfen, wobei sich die Auswirkungen des Klimawandels je nach Region stark unterscheiden. Während viele Veränderungen, wie der Rückgang des Meereises und Veränderungen in der Meeres-Biochemie, oft auf pan-arktischer Ebene diskutiert werden, blieben ihre lokalen Auswirkungen und Unterschiede in deren Intensität zwischen den Regionen lange Zeit weitgehend unbeachtet, obwohl sie für verschiedene Interessensgruppen von großer Bedeutung sind. Diese Dissertation soll dazu beitragen, den Fokus auf das Verständnis regionaler Änderungen in der Arktis zu verlagern, indem sie zwei wesentliche Indikatoren untersucht, die von einem wärmeren Klima betroffen sind: die Meereisbedeckung der Arktis und der Partialdruck von Kohlendioxid (pCO2 ) an der Meeresoberfläche. Erstere ist von Interesse für eine Vielzahl von Interessensgruppen, insbesondere für diejenigen, die an Veränderungen entlang der Küsten-Eis-Übergangszone interessiert sind, wie z. B. die Schifffahrtsindustrie und indigene Bevölkerungsgruppen. Letztere ist ein Schlüsselfaktor für den Austausch von CO2 zwischen Ozean und Atmosphäre und entsprechend maßgeblich entscheidend für die Versauerung der Ozeane. Die Sensitivität der Meereisfläche gegenüber Veränderungen in der oberflächennahen Lufttemperatur, d. h. wie stark sich die Meereisfläche bei gegebenem Temperaturanstieg verringert, zeigt eine hohe saisonale Abhängigkeit, die durch starke Variabilität im Sommer und geringe Variabilität im Winter gekennzeichnet ist. Diese Studie zeigt, dass der Übergang zwischen Sommer und Winter sowie die geringe Variabilität im Winter auf das Blockieren des Meereises durch umliegende Landmassen zurückzuführen ist. Dies wird in der Arbeit als “geographic muting” oder auch “geographic blocking” bezeichnet. Durch die Quantifizierung des Zeitpunkts dieses Blocking-Effekts wird eine klare Relation zwischen dem Timing dem globalen Temperaturanstieg festgestellt. Die Ergebnisse deuten darauf hin, dass mit der Verschiebung des Timings und der Verkürzung der Saison, über welche das Meereis blockiert ist, (im Durchschnitt etwa 7 Tage pro Zehntelgrad globaler Erwärmung) benachbarte Jahreszeiten eine erhöhte Sensitivität der Meereisfläche zeigen werden. Insbesondere Sensitivitäten in küstennahen Regionen werden zukünftig einer plötzlichen Verände rung unterliegen. Durch Ausweiten der Sensitivitätsanalyse auf regionale Ebene zeigt die Studie neue Perspektiven auf, wie das Meereis in einzelnen Regionen der Arktis auf die globale Erwärmung reagiert, und antizipiert zukünftige Änderungen. Die Ost-Sibirische See, die Tschuktschensee und die Laptewsee werden als Regionen identifiziert, die mit großer Wahrscheinlichkeit zuerst ihr Sommer-Meereis verlieren werden. Die Barentssee wird dagegen voraussichtlich die erste Region sein, die ihr verbleibendes Winter-Meereis verliert und letztendlich das ganze Jahr über eisfrei sein wird. Bei der anschließenden Betrachtung des oberflächennahen Partialdrucks von Kohlendioxid (pCO2 ) werden zwei Datensätze verwendet, welche pCO2 aus lückenhaften Beobachtungen schätzen, um die Entwicklung des pCO2 in der Arktis zu untersuchen. Beide Datensätze zeigen über die letzten zwei Jahrzehnte eine konsistente Zunahme des pCO2 für die meisten Regionen. Dabei werden jedoch erhebliche Unterschiede im Ausmaß der zwischenjährlichen und innerjährlichen Veränderungen zwischen den beiden Datensätzen beobachtet. Indem räumliche und zeitliche Variabilität im pCO2 mittels EOF-Analyse separiert werden, lassen sich die dominierenden Treiber jener Veränderungen identifizieren. Die Studie zeigt, dass Veränderungen im subarktischen Bereich hauptsächlich dem saisonalen Zyklus der Sonneneinstrahlung zugeordnet werden können, während in der hohen Arktis Prozesse dominieren, die mit Änderungen in der Meereisbedeckung in Verbindung stehen. Bei der Untersuchung der Saisonalität, lassen sich Hinweise auf Verschiebungen und Änderungen in der saisonalen Amplitude bereits in den historischen Daten feststellen (insbesondere nördlich von Kanada), was potenzielle Auswirkungen auf die dortigen Ökosysteme vermuten lässt. Diese Dissertation unterstreicht die Notwendigkeit, eine regionale Perspektive auf den arktischen Klimawandel einzunehmen. Indem der Blocking-Effekt erstmals systematisch analysiert und quantifiziert wird, legt diese Arbeit die Grundlage für das Verständnis von Veränderungen in der Meereisfläche in der hohen Arktis und dürfte somit von Nutzen für Interessengruppen sein, für welche die Transformationen des Arktischen Ozeans, insbesondere in Küstenregionen, von Bedeutung sind. Darüber hinaus bietet die pCO2-Analyse Einblicke in die Treiber des pCO2 im Arktischen Ozean und dient somit auch der Verbesserung zukünftiger Datensätze, die für die Untersuchung regionaler Veränderungen im Kohlenstoffkreislauf der arktischen Meeresoberfläche entscheidend sind. Diese Erkenntnisse tragen zur Grundlagenforschung für zukünftige Studien in der Arktis bei
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