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Long-duration, sub-seasonal dry spells in combination with high temperature extremes during summer have led to extreme impacts on society and ecosystems in the past. Such events are expected to become more frequent due to increasing temperatures as a result of anthropogenic climate change. However, there is little information on how long-duration dry and hot spells are represented in global climate models (GCMs). In this study, we evaluate 33 CMIP5 (coupled model intercomparison project 5) GCMs in their representation of long-duration dry spells and temperatures during dry spells. We define a dry spell as a consecutive number of days with a daily precipitation of less than 1 mm. CMIP5 models tend to underestimate the persistence of dry spells in northern Europe, while a large variability exists between model estimates in central and southern Europe, where models have contrasting biases. Throughout Europe, we also find a large spread between models in their representation of temperature extremes during dry spells. In central and southern Europe this spread in temperature extremes between models is related to the representation of dry spells, where models that produce longer dry spells also produce higher temperatures, and vice versa. Our results indicate that this variability in model estimates is due to model differences and not internal variability. At latitudes between 50–60∘ N, the differences in the representation of persistent dry spells are strongly related to the representation of persistent anticyclonic systems, such as atmospheric blocking and subtropical ridges. Furthermore, models simulating a higher frequency of anticyclonic systems than ERA5 also simulate temperatures in dry spells that are between 1.4, and 2.8 K warmer than models with a lower frequency in these areas. Overall, there is a large spread between CMIP5 models in their representation of long-duration dry and hot events that is due to errors in the representation of large-scale anticyclonic

Background β-amyloid (Aβ) positron emission tomography (PET) imaging is currently the only Food and Drug Administration-approved method to support clinical diagnosis of Alzheimer’s disease (AD). However, numerous research studies support the use of cerebrospinal fluid (CSF) biomarkers, as a cost-efficient, quick and equally valid method to define AD pathology. Methods Using automated Elecsys® assays (Roche Diagnostics) for Aβ (1–42) (Aβ42), Aβ (1–40) (Aβ40), total tau (tTau) and phosphorylated tau (181P) (pTau), we examined CSF samples from 202 participants of the Australian Imaging, Biomarkers and Lifestyle (AIBL) study of ageing cohort, to demonstrate the concordance with pathological AD via PET imaging. Results Ratios Aβ42/Aβ40, tTau/Aβ42 and pTau/Aβ42 had higher receiver operator characteristic—area under the curve (all 0.94), and greater concordance with Aβ-PET (overall percentage agreement ~ 90%), compared with individual biomarkers. Conclusion Strong concordance between CSF biomarkers and Aβ-PET status was observed overall, including for cognitively normal participants, further strengthening the association between these markers of AD neuropathological burden for both developmental research studies and for use in clinical trials.

The India-UK Water Centre (IUKWC) promotes cooperation and collaboration between the complementary priorities of NERC-MoES water security research. This report assesses the significant issues for hydro-climatic modelling and service development in the mountain regions of northern India. It is the main output from an IUKWC Pump Priming Project that ran from March to August 2018 and has been produced by an author team of climate scientist, hydrologists and glaciologist from India and the UK. It is found that although state-ofthe-art weather forecasting, climate, hydrological and glacier models are being used there are still substantial prediction uncertainties on all prediction timescales. There is a lack of detailed understanding of regional meteorological and hydrological processes, which results in potential misrepresentation of them in the models. Large-scale drivers of regional climate variability in the region have been identified but questions remain about their relevance on different timescales, their interaction, and their representation in global weather forecasting and climate models. Improving short-term predictions and climate change projections requires more meteorological, hydrological and glaciological observations in the Himalayas, improvements in data sharing, as well as additional efforts to integrate meteorological and hydrological modelling. There is also a need for improved communication of predictions to users, which should include their uncertainties. The report is intended for workshop participants, India-UK Water Centre Open Network members and stakeholders.

The India-UK Water Centre (IUKWC) promotes cooperation and collaboration between the complementary priorities of NERC-MoES water security research. This report represents an overview of the participation, activities and conclusions at a Science Workshop held at the Wildlife Institute of India, Dehradun, Uttarakhand, India, between the 2nd and 4th of May 2018. It was convened by the India UK Water Centre and led by Dr Martin Widmann of the University of Birmingham, UK and Dr Shresth Tayal of The Energy and Resource Institute (TERI), India. This inter-disciplinary workshop aimed to foster the integration of weather forecast and climate models with glacio-hydrological models for the Himalayas, which is crucial for the improvement of short-, medium-, and long-term hydrological predictions for Himalayan basins. By bringing together scientist from India and the UK it led to a detailed understanding of the key challenges related to data scarcity, process understanding, development and validation of meteorological and hydrological models, and to downscaling and bias adjustment methods. Based on this, a number of specific steps forward were suggested, which partly can be implemented in the near future using inter-disciplinary and inter-institutional synergies, and partly require additional resources and longer implementation periods. The report is intended for the workshop participants, IUKWC Open Network members and stakeholders.

The India-UK Water Centre (IUKWC) promotes cooperation and collaboration between the complementary priorities of NERC-MoES water security research. This report assesses the significant issues for hydro-climatic modelling and service development in the mountain regions of northern India. It is the main output from an IUKWC Pump Priming Project that ran from March to August 2018 and has been produced by an author team of climate scientist, hydrologists and glaciologist from India and the UK. It is found that although state-ofthe-art weather forecasting, climate, hydrological and glacier models are being used there are still substantial prediction uncertainties on all prediction timescales. There is a lack of detailed understanding of regional meteorological and hydrological processes, which results in potential misrepresentation of them in the models. Large-scale drivers of regional climate variability in the region have been identified but questions remain about their relevance on different timescales, their interaction, and their representation in global weather forecasting and climate models. Improving short-term predictions and climate change projections requires more meteorological, hydrological and glaciological observations in the Himalayas, improvements in data sharing, as well as additional efforts to integrate meteorological and hydrological modelling. There is also a need for improved communication of predictions to users, which should include their uncertainties. The report is intended for workshop participants, India-UK Water Centre Open Network members and stakeholders.

The India-UK Water Centre (IUKWC) promotes cooperation and collaboration between the complementary priorities of NERC-MoES water security research. This report represents an overview of the participation, activities and conclusions at a Science Workshop held at the Wildlife Institute of India, Dehradun, Uttarakhand, India, between the 2nd and 4th of May 2018. It was convened by the India UK Water Centre and led by Dr Martin Widmann of the University of Birmingham, UK and Dr Shresth Tayal of The Energy and Resource Institute (TERI), India. This inter-disciplinary workshop aimed to foster the integration of weather forecast and climate models with glacio-hydrological models for the Himalayas, which is crucial for the improvement of short-, medium-, and long-term hydrological predictions for Himalayan basins. By bringing together scientist from India and the UK it led to a detailed understanding of the key challenges related to data scarcity, process understanding, development and validation of meteorological and hydrological models, and to downscaling and bias adjustment methods. Based on this, a number of specific steps forward were suggested, which partly can be implemented in the near future using inter-disciplinary and inter-institutional synergies, and partly require additional resources and longer implementation periods. The report is intended for the workshop participants, IUKWC Open Network members and stakeholders.

The India-UK Water Centre (IUKWC) promotes cooperation and collaboration between the complementary priorities of NERC-MoES water security research. This State of Science Brief was produced as an output from an India–UK Water Centre supported Pump Priming Project on Current Opportunities and Challenges in Developing Hydro-Climatic Services in the Himalayas undertaken in 2017.

The India-UK Water Centre (IUKWC) promotes cooperation and collaboration between the complementary priorities of NERC-MoES water security research. This State of Science Brief was produced as an output from an India–UK Water Centre supported Pump Priming Project on Current Opportunities and Challenges in Developing Hydro-Climatic Services in the Himalayas undertaken in 2017.

Water availability is fundamental to societies and ecosystems, but our understanding of variations in hydroclimate (including extreme events, flooding, and decadal periods of drought) is limited because of a paucity of modern instrumental observations that are distributed unevenly across the globe and only span parts of the 20th and 21st centuries. Such data coverage is insufficient for characterizing hydroclimate and its associated dynamics because of its multidecadal to centennial variability and highly regionalized spatial signature. High-resolution (seasonal to decadal) hydroclimatic proxies that span all or parts of the Common Era (CE) and paleoclimate simulations from climate models are therefore important tools for augmenting our understanding of hydroclimate variability. In particular, the comparison of the two sources of information is critical for addressing the uncertainties and limitations of both while enriching each of their interpretations. We review the principal proxy data available for hydroclimatic reconstructions over the CE and highlight the contemporary understanding of how these proxies are interpreted as hydroclimate indicators. We also review the available last-millennium simulations from fully coupled climate models and discuss several outstanding challenges associated with simulating hydroclimate variability and change over the CE. A specific review of simulated hydroclimatic changes forced by volcanic events is provided, as is a discussion of expected improvements in estimated radiative forcings, models, and their implementation in the future. Our review of hydroclimatic proxies and last-millennium model simulations is used as the basis for articulating a variety of considerations and best practices for how to perform proxy-model comparisons of CE hydroclimate. This discussion provides a framework for how best to evaluate hydroclimate variability and its associated dynamics using these comparisons and how they can better inform interpreta

Optimism can be seen as an enduring strength in marriage. It provides spouses with a broader and more flexible range of behavioral options and helps them to successfully navigate stressful situations. Optimism is characterized by a positive attitude toward the future and by positive expectations. While a positive attitude toward the future may benefit adaptation, merely holding positive expectations may lead to disappointment and inflexible responding to daily challenges. Using questionnaires and diaries from 103 couples, this study examines how spouses respond to situations where the partner prefers being alone at the end of a workday. We investigated whether and how optimism, and two components of positive expectations, the overall level of and the flexibility, shape these responses. Findings showed that perceived partner withdrawal was associated with less positive and more negative reported behaviors. Optimism buffered this effect above and beyond the effect of positive expectations. Expectation levels indicated no buffering and even a tendency to more negative and less positive reactions. Finally, and unexpectedly, expectation flexibility had no effect on partners’ reported negative behaviors, and was even associated with less positive reported responses to the partner’s withdrawal. Implications for the theoretical understanding of optimism and expectations, as well as for intervention, will be discussed.

To assess potential impacts of climate change for a specific location, one typically employs climate model simulations at the grid box corresponding to the same geographical location. But based on regional climate model simulations, we show that simulated climate might be systematically displaced compared to observations. In particular in the rain shadow of moutain ranges, a local grid box is therefore often not representative of observed climate: the simulated windward weather does not flow far enough across the mountains; local grid boxes experience the wrong airmasses and atmospheric circulation. In some cases, also the local climate change signal is deteriorated. Classical bias correction methods fail to correct these location errors. Often, however, a distant simulated time series is representative of the considered observed precipitation, such that a non-local bias correction is possible. These findings also clarify limitations of bias correcting global model errors, and of bias correction against station data.

The traditional objective of parental enrichment programs is to train parents’ abilities and specific competences, but these interventions pay less attention to the key aspect of parental identity. Parenting programs, moreover, are generally delivered to groups of parents, but scarce attention has been devoted to the use of the group as a specific tool of the intervention and as a factor promoting changes in participants’ relational functioning. The Groups for Family Enrichment (GFE; Iafrate & Rosnati, 2007, Iafrate, Donato & Bertoni, 2010), focus on parental identity in addition to parental skills and adopt a semistructured format to take advantage of the group setting. We will first introduce the characteristics of GFE, then we will describe an application of this intervention to a group of Italian parents, and finally we will present the results of a qualitative evaluation of such an intervention. Findings from process evaluation showed that participants actively contributed to the development of themes during the intervention. Result evaluation showed that recognition of key aspects of parental identity can be an important prerequisite to the acquisition of better parenting skills. Implications for parenting programs design are discussed.

Optimism can be seen as an enduring strength in marriage. It provides spouses with a broader and more flexible range of behavioral options and helps them to successfully navigate stressful situations. Optimism is characterized by a positive attitude toward the future and by positive expectations. While a positive attitude toward the future may benefit adaptation, merely holding positive expectations may lead to disappointment and inflexible responding to daily challenges. Using questionnaires and diaries from 103 couples, this study examines how spouses respond to situations where the partner prefers being alone at the end of a workday. We investigated whether and how optimism, and two components of positive expectations, the overall level of and the flexibility, shape these responses. Findings showed that perceived partner withdrawal was associated with less positive and more negative reported behaviors. Optimism buffered this effect above and beyond the effect of positive expectations. Expectation levels indicated no buffering and even a tendency to more negative and less positive reactions. Finally, and unexpectedly, expectation flexibility had no effect on partners’ reported negative behaviors, and was even associated with less positive reported responses to the partner’s withdrawal. Implications for the theoretical understanding of optimism and expectations, as well as for intervention, will be discussed.

To assess potential impacts of climate change for a specific location, one typically employs climate model simulations at the grid box corresponding to the same geographical location. But based on regional climate model simulations, we show that simulated climate might be systematically displaced compared to observations. In particular in the rain shadow of moutain ranges, a local grid box is therefore often not representative of observed climate: the simulated windward weather does not flow far enough across the mountains; local grid boxes experience the wrong airmasses and atmospheric circulation. In some cases, also the local climate change signal is deteriorated. Classical bias correction methods fail to correct these location errors. Often, however, a distant simulated time series is representative of the considered observed precipitation, such that a non-local bias correction is possible. These findings also clarify limitations of bias correcting global model errors, and of bias correction against station data.

To assess potential impacts of climate change for a specific location, one typically employs climate model simulations at the grid box corresponding to the same geographical location. But based on regional climate model simulations, we show that simulated climate might be systematically displaced compared to observations. In particular in the rain shadow of moutain ranges, a local grid box is therefore often not representative of observed climate: the simulated windward weather does not flow far enough across the mountains; local grid boxes experience the wrong airmasses and atmospheric circulation. In some cases, also the local climate change signal is deteriorated. Classical bias correction methods fail to correct these location errors. Often, however, a distant simulated time series is representative of the considered observed precipitation, such that a non-local bias correction is possible. These findings also clarify limitations of bias correcting global model errors, and of bias correction against station data.

Precipitation downscaling improves the coarse resolution and poor representation of precipitation in global climate models and helps end users to assess the likely hydrological impacts of climate change. This paper integrates perspectives from meteorologists, climatologists, statisticians, and hydrologists to identify generic end user (in particular, impact modeler) needs and to discuss downscaling capabilities and gaps. End users need a reliable representation of precipitation intensities and temporal and spatial variability, as well as physical consistency, independent of region and season. In addition to presenting dynamical downscaling, we review perfect prognosis statistical downscaling, model output statistics, and weather generators, focusing on recent developments to improve the representation of space-time variability. Furthermore, evaluation techniques to assess downscaling skill are presented. Downscaling adds considerable value to projections from global climate models. Remaining gaps are uncertainties arising from sparse data; representation of extreme summer precipitation, subdaily precipitation, and full precipitation fields on fine scales; capturing changes in small-scale processes and their feedback on large scales; and errors inherited from the driving global climate model.

Precipitation downscaling improves the coarse resolution and poor representation of precipitation in global climate models and helps end users to assess the likely hydrological impacts of climate change. This paper integrates perspectives from meteorologists, climatologists, statisticians, and hydrologists to identify generic end user (in particular, impact modeler) needs and to discuss downscaling capabilities and gaps. End users need a reliable representation of precipitation intensities and temporal and spatial variability, as well as physical consistency, independent of region and season. In addition to presenting dynamical downscaling, we review perfect prognosis statistical downscaling, model output statistics, and weather generators, focusing on recent developments to improve the representation of space-time variability. Furthermore, evaluation techniques to assess downscaling skill are presented. Downscaling adds considerable value to projections from global climate models. Remaining gaps are uncertainties arising from sparse data; representation of extreme summer precipitation, subdaily precipitation, and full precipitation fields on fine scales; capturing changes in small-scale processes and their feedback on large scales; and errors inherited from the driving global climate model.

Precipitation downscaling improves the coarse resolution and poor representation of precipitation in global climate models and helps end users to assess the likely hydrological impacts of climate change. This paper integrates perspectives from meteorologists, climatologists, statisticians, and hydrologists to identify generic end user (in particular, impact modeler) needs and to discuss downscaling capabilities and gaps. End users need a reliable representation of precipitation intensities and temporal and spatial variability, as well as physical consistency, independent of region and season. In addition to presenting dynamical downscaling, we review perfect prognosis statistical downscaling, model output statistics, and weather generators, focusing on recent developments to improve the representation of space-time variability. Furthermore, evaluation techniques to assess downscaling skill are presented. Downscaling adds considerable value to projections from global climate models. Remaining gaps are uncertainties arising from sparse data; representation of extreme summer precipitation, subdaily precipitation, and full precipitation fields on fine scales; capturing changes in small-scale processes and their feedback on large scales; and errors inherited from the driving global climate model.

Seasonal reconstructions of the Southern Hemisphere annular mode (SAM) index are derived to extend the record before the reanalysis period, using station sea level pressure (SLP) data as predictors. Two reconstructions using different predictands are obtained: one [Jones and Widmann (JW)] based on the first principal component (PC) of extratropical SLP and the other (Fogt) on the index of Marshall. A regional-based SAM index (Visbeck) is also considered.These predictands agree well post-1979; correlations decline in all seasons except austral summer for the full series starting in 1958. Predictand agreement is strongest in spring and summer; hence agreement between the reconstructions is highest in these seasons. The less zonally symmetric SAM structure in winter and spring influences the strength of the SAM signal over land areas, hence the number of stations included in the reconstructions. Reconstructions from 1865 were, therefore, derived in summer and autumn and from 1905 in winter and spring. This paper examines the skill of each reconstruction by comparison with observations and reanalysis data. Some of the individual peaks in the reconstructions, such as the most recent in austral summer, represent a full hemispheric SAM pattern, while others are caused by regional SLP anomalies over the locations of the predictors. The JW and Fogt reconstructions are of similar quality in summer and autumn, while in winter and spring the Marshall index is better reconstructed by Fogt than the PC index is by JW. In spring and autumn the SAM shows considerable variability prior to recent decades.

Seasonal reconstructions of the Southern Hemisphere annular mode (SAM) index are derived to extend the record before the reanalysis period, using station sea level pressure (SLP) data as predictors. Two reconstructions using different predictands are obtained: one [Jones and Widmann (JW)] based on the first principal component (PC) of extratropical SLP and the other (Fogt) on the index of Marshall. A regional-based SAM index (Visbeck) is also considered.These predictands agree well post-1979; correlations decline in all seasons except austral summer for the full series starting in 1958. Predictand agreement is strongest in spring and summer; hence agreement between the reconstructions is highest in these seasons. The less zonally symmetric SAM structure in winter and spring influences the strength of the SAM signal over land areas, hence the number of stations included in the reconstructions. Reconstructions from 1865 were, therefore, derived in summer and autumn and from 1905 in winter and spring. This paper examines the skill of each reconstruction by comparison with observations and reanalysis data. Some of the individual peaks in the reconstructions, such as the most recent in austral summer, represent a full hemispheric SAM pattern, while others are caused by regional SLP anomalies over the locations of the predictors. The JW and Fogt reconstructions are of similar quality in summer and autumn, while in winter and spring the Marshall index is better reconstructed by Fogt than the PC index is by JW. In spring and autumn the SAM shows considerable variability prior to recent decades.

Seasonal reconstructions of the Southern Hemisphere annular mode (SAM) index are derived to extend the record before the reanalysis period, using station sea level pressure (SLP) data as predictors. Two reconstructions using different predictands are obtained: one [Jones and Widmann (JW)] based on the first principal component (PC) of extratropical SLP and the other (Fogt) on the index of Marshall. A regional-based SAM index (Visbeck) is also considered.These predictands agree well post-1979; correlations decline in all seasons except austral summer for the full series starting in 1958. Predictand agreement is strongest in spring and summer; hence agreement between the reconstructions is highest in these seasons. The less zonally symmetric SAM structure in winter and spring influences the strength of the SAM signal over land areas, hence the number of stations included in the reconstructions. Reconstructions from 1865 were, therefore, derived in summer and autumn and from 1905 in winter and spring. This paper examines the skill of each reconstruction by comparison with observations and reanalysis data. Some of the individual peaks in the reconstructions, such as the most recent in austral summer, represent a full hemispheric SAM pattern, while others are caused by regional SLP anomalies over the locations of the predictors. The JW and Fogt reconstructions are of similar quality in summer and autumn, while in winter and spring the Marshall index is better reconstructed by Fogt than the PC index is by JW. In spring and autumn the SAM shows considerable variability prior to recent decades.

The Unites States' first space systems programs were initially developed to meet the requirements of strategic users. Since the 1991 Gulf War there has been a growing dependence on the capabilities and support delivered by these programs to meet the requirements of nonstrategic users. The current National Security Space (NSS) architecture makes it rather difficult for all but critical strategic users to fully capitalize on the available assets. Timelines that were once adequate to deliver strategic capabilities are now not sufficient to allow a broader range of users to realize the benefit from using the available space systems. In addition, nonstrategic users run into challenges when they attempt to change the tasking requirements that would enable them to receive associated products and services that are useful and timely. With the identified gaps in the current NSS environment, the Integrated Product Team (IPT), consisting of 10 active duty military students, sought solutions to make space more "Operationally Responsive" (ORS) to its customers by 2025. Due to limited time and assets, the IPT narrowed the focus of the project to the four Joint Publication (JP) 3-14 "Joint Doctrine for Space Operations" mission areas of Space Support, Space Control, Force Enhancement, and Force Application. During this project, the IPT defined ORS from its perspective, developed the requirements to meet the identified NSS gaps, selected the final alternatives to satisfy those requirements, and suggested an implementation plan. While in the architecture process, the IPT conducted an in-depth evaluation of the original alternatives based on Responsiveness, Risk, Capability, and Cost. After building a foundation for further analysis, a total of 16 alternatives were chosen for the final ORS architecture. The alternative that provided the most responsiveness was to create a Single Space Agency., The original document contains color images.

The Unites States' first space systems programs, to include launch, ground, and space segments and their associated infrastructure, were initially developed to meet the requirements of the strategic users. Since the 1991 Gulf War, there has been a growing dependence on the capabilities and support delivered by those programs to meet requirements of non-strategic users. The current National Security Space (NSS) architecture makes it rather difficult and challenging for all but critical strategic users to fully capitalize on the available assets. Timelines that were once adequate to deliver strategic capabilities are now not sufficient to allow a broader range of users to realize the benefit from using the available space systems. In addition, the non-strategic users run into challenges when they attempt to change the tasking requirements that would enable them to receive associated products / services that are useful and timely. With the identified gaps in the current NSS environment, the Integrated Product Team (IPT), consisting of ten active duty military students, sought solutions to make space more Operationally Responsive to its customers by 2025. Due to limited time and assets, the IPT narrowed the focus of the project to the four Joint Publication (JP) 3-14 Joint Doctrine for Space Operations mission areas of Space Support, Space Control, Force Enhancement, and Force Application. During this project, the IPT defined Operationally Responsive Space (ORS) from its perspective, developed the requirements to meet the identified NSS gaps, selected the final alternatives to satisfy those requirements, and suggested an implementation plan. While in the architecture process, the IPT conducted an in-depth evaluation of the original [61] alternatives based on Responsiveness, Risk, Capability, and Cost. After building a foundation for further analysis, a total of 16 alternatives were chosen for the final ORS architecture. The IPT's leading alternative that provided the mo

The Unites States' first space systems programs, to include launch, ground, and space segments and their associated infrastructure, were initially developed to meet the requirements of the strategic users. Since the 1991 Gulf War, there has been a growing dependence on the capabilities and support delivered by those programs to meet requirements of non-strategic users. The current National Security Space (NSS) architecture makes it rather difficult and challenging for all but critical strategic users to fully capitalize on the available assets. Timelines that were once adequate to deliver strategic capabilities are now not sufficient to allow a broader range of users to realize the benefit from using the available space systems. In addition, the non-strategic users run into challenges when they attempt to change the tasking requirements that would enable them to receive associated products / services that are useful and timely. With the identified gaps in the current NSS environment, the Integrated Product Team (IPT), consisting of ten active duty military students, sought solutions to make space more Operationally Responsive to its customers by 2025. Due to limited time and assets, the IPT narrowed the focus of the project to the four Joint Publication (JP) 3-14 Joint Doctrine for Space Operations mission areas of Space Support, Space Control, Force Enhancement, and Force Application. During this project, the IPT defined Operationally Responsive Space (ORS) from its perspective, developed the requirements to meet the identified NSS gaps, selected the final alternatives to satisfy those requirements, and suggested an implementation plan. While in the architecture process, the IPT conducted an in-depth evaluation of the original [61] alternatives based on Responsiveness, Risk, Capability, and Cost. After building a foundation for further analysis, a total of 16 alternatives were chosen for the final ORS architecture. The IPT's leading alternative that provided the mo

The last four interglacials (intervals during which global ice volume was similar to, or less than, that of our current warm stage) correspond to the warmest parts of the marine oxygen isotope stages marine isotopic age (MIS) 5, 7, 9, and 11. These interglacials followed the 100-kyr rhythm of eccentricity, but each had different insolation regimes, different durations, different ice volumes, and different sea-level heights. However, atmospheric greenhouse gas concentrations were similar and reached values, which, largely, were close to those of the current interglacial (Holocene or MIS 1) before the industrial revolution led to the artificial enrichment of the atmosphere's greenhouse gas concentrations via the burning of fossil fuels. This chapter summarizes the state of knowledge on each of the climatic warm intervals.

Water availability is fundamental to societies and ecosystems, but our understanding of variations in hydroclimate (including extreme events, flooding, and decadal periods of drought) is limited because of a paucity of modern instrumental observations that are distributed unevenly across the globe and only span parts of the 20th and 21st centuries. Such data coverage is insufficient for characterizing hydroclimate and its associated dynamics because of its multidecadal to centennial variability and highly regionalized spatial signature. High-resolution (seasonal to decadal) hydroclimatic proxies that span all or parts of the Common Era (CE) and paleoclimate simulations from climate models are therefore important tools for augmenting our understanding of hydroclimate variability. In particular, the comparison of the two sources of information is critical for addressing the uncertainties and limitations of both while enriching each of their interpretations. We review the principal proxy data available for hydroclimatic reconstructions over the CE and highlight the contemporary understanding of how these proxies are interpreted as hydroclimate indicators. We also review the available last-millennium simulations from fully coupled climate models and discuss several outstanding challenges associated with simulating hydroclimate variability and change over the CE. A specific review of simulated hydroclimatic changes forced by volcanic events is provided, as is a discussion of expected improvements in estimated radiative forcings, models, and their implementation in the future. Our review of hydroclimatic proxies and last-millennium model simulations is used as the basis for articulating a variety of considerations and best practices for how to perform proxy–model comparisons of CE hydroclimate. This discussion provides a framework for how best to evaluate hydroclimate variability and its associated dynamics using these comparisons and how they can better inform interpretatio

Water availability is fundamental to societies and ecosystems, but our understanding of variations in hydroclimate (including extreme events, flooding, and decadal periods of drought) is limited because of a paucity of modern instrumental observations that are distributed unevenly across the globe and only span parts of the 20th and 21st centuries. Such data coverage is insufficient for characterizing hydroclimate and its associated dynamics because of its multidecadal to centennial variability and highly regionalized spatial signature. High-resolution (seasonal to decadal) hydroclimatic proxies that span all or parts of the Common Era (CE) and paleoclimate simulations from climate models are therefore important tools for augmenting our understanding of hydroclimate variability. In particular, the comparison of the two sources of information is critical for addressing the uncertainties and limitations of both while enriching each of their interpretations. We review the principal proxy data available for hydroclimatic reconstructions over the CE and highlight the contemporary understanding of how these proxies are interpreted as hydroclimate indicators. We also review the available last-millennium simulations from fully coupled climate models and discuss several outstanding challenges associated with simulating hydroclimate variability and change over the CE. A specific review of simulated hydroclimatic changes forced by volcanic events is provided, as is a discussion of expected improvements in estimated radiative forcings, models, and their implementation in the future. Our review of hydroclimatic proxies and last-millennium model simulations is used as the basis for articulating a variety of considerations and best practices for how to perform proxy–model comparisons of CE hydroclimate. This discussion provides a framework for how best to evaluate hydroclimate variability and its associated dynamics using these comparisons and how they can better inform interpretatio