scholarly journals Earth's water reservoirs in a changing climate

2020 ◽  
Vol 476 (2236) ◽  
pp. 20190458 ◽  
Author(s):  
Graeme L. Stephens ◽  
Julia M. Slingo ◽  
Eric Rignot ◽  
John T. Reager ◽  
Maria Z. Hakuba ◽  
...  
Keyword(s):  
Sea Level ◽  
Hydrological Cycle ◽  
Water Cycle ◽  
Water Reservoirs ◽  
Future Evolution ◽  
Quantitative Understanding ◽  
Global Mean Sea Level ◽  
Earth’S Climate ◽  
The Many ◽  
Different Sources

Progress towards achieving a quantitative understanding of the exchanges of water between Earth's main water reservoirs is reviewed with emphasis on advances accrued from the latest advances in Earth Observation from space. These exchanges of water between the reservoirs are a result of processes that are at the core of important physical Earth-system feedbacks, which fundamentally control the response of Earth's climate to the greenhouse gas forcing it is now experiencing, and are therefore vital to understanding the future evolution of Earth's climate. The changing nature of global mean sea level (GMSL) is the context for discussion of these exchanges. Different sources of satellite observations that are used to quantify ice mass loss and water storage over continents, how water can be tracked to its source using water isotope information and how the waters in different reservoirs influence the fluxes of water between reservoirs are described. The profound influence of Earth's hydrological cycle, including human influences on it, on the rate of GMSL rise is emphasized. The many intricate ways water cycle processes influence water exchanges between reservoirs and thus sea-level rise, including disproportionate influences by the tiniest water reservoirs, are emphasized.

How Salty Is the Global Ocean: Weighting It All or Tasting It a Sip at a Time?

2020 ◽  
Author(s):  
Rui Ponte ◽  
Qiang Sun ◽  
Chao Liu ◽  
Xinfeng Liang
Keyword(s):  
Sea Ice ◽  
Sea Level ◽  
Hydrological Cycle ◽  
Global Ocean ◽  
Data Quality Control ◽  
Argo Data ◽  
Terrestrial Water ◽  
Control Procedures ◽  
Global Mean Sea Level

<div class="page" title="Page 1"> <div class="section"> <div class="layoutArea"> <div class="column"> <p>Global ocean mean salinity <em>S </em>is a key indicator of the Earth's hydrological cycle and the exchanges of freshwater between the terrestrial water and ice reservoirs and the ocean. We explore two different ways of determining how salty the ocean is: (1) use in situ salinity measurements to taste the ocean a sip at a time and obtain a sample average; (2) use space gravimetry to weigh the whole ocean including sea-ice, and then separate sea-ice effects to infer changes in liquid freshwater content and thus <em>S</em>. Focusing on the 2005-2019 period, we assess monthly series of <em>S </em>derived from five different in situ gridded products, based mostly but not exclusively on Argo data, versus a series obtained from GRACE and GRACE Follow-On data and available sea ice mass estimates.</p> <p>There is little consistency in <em>S </em>series from the two methods for all time scales examined (seasonal, interannual, long-term trend). In situ series show larger variability, particularly at the longest scales, and are somewhat incoherent with the GRACE-derived series. In addition, there are wide spread differences among all the in situ <em>S </em>series, which denote their considerable sensitivity to choice of data, quality control procedures, and mapping methods. Results also suggest that in situ <em>S </em>values are prone to systematic biases, with most series showing increases after around 2014 that are equivalent to a drop in barystatic sea level of tens of centimeters! Estimates derived from GRACE are much smaller in magnitude and consistent with contributions of freshwater to the global mean sea level budgets, and they are thus more reliable than in situ-based <em>S </em>estimates. The existence of GRACE-derived estimates can serve as a consistency check on in situ measurements, revealing potential unknown biases and providing a way to cross-calibrate the latter data.</p> </div> </div> </div> </div>

scholarly journals Coevolution of Hydrological Cycle Components under Climate Change: The Case of the Garonne River in France

Water ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1870 ◽  
Author(s):  
Youen Grusson ◽  
François Anctil ◽  
Sabine Sauvage ◽  
José Miguel Sánchez Pérez
Keyword(s):  
Climate Change ◽  
Hydrological Cycle ◽  
Water Cycle ◽  
Swat Model ◽  
Green Water ◽  
Climatic Data ◽  
Strong Impact ◽  
Catchment Scale ◽  
Garonne River ◽  
The Many

Climate change is suspected to impact water circulation within the hydrological cycle at catchment scale. A SWAT model approach to assess the evolution of the many hydrological components of the Garonne catchment (Southern France) is deployed in this study. Performance over the calibration period (2000–2010) are satisfactory, with Nash–Sutcliffe ranging from 0.55 to 0.94 or R2 from 0.86 to 0.98. Similar performance values are obtained in validation (1962–2000). Water cycle is first analyzed based on past observed climatic data (1962–2010) to understand its variations and geographical spread. Comparison is then conducted against the different trends obtained from a climate ensemble over 2010–2050. Results show a strong impact on green water, such as a reduction of the soil water content (SWC) and a substantial increase in evapotranspiration (ET) in winter. In summer, however, some part of the watershed faces lower ET fluxes because of a lack of SWC to answer the evapotranspiratory demand, highlighting possible future deficits of green water stocks. Blue water fluxes are found significantly decreasing during summer, when in winter, discharge in the higher part of the watershed is found increasing because of a lower snow stock associated to an increase of liquid precipitation, benefiting surface runoff.

scholarly journals Rationale for Monitoring Discharge on the Ground

2012 ◽  
Vol 13 (6) ◽  
pp. 1977-1986 ◽  
Author(s):  
Balázs M. Fekete ◽  
Ulrich Looser ◽  
Alain Pietroniro ◽  
Richard D. Robarts
Keyword(s):  
Remote Sensing ◽  
River Discharge ◽  
Hydrological Cycle ◽  
Water Cycle ◽  
In Situ Monitoring ◽  
Water Fluxes ◽  
Earth Observations ◽  
Discharge Monitoring ◽  
Earth’S Climate

Abstract The hydrological cycle is receiving increasing attention both as an essential natural resource for humans and ecosystems and as a critical component controlling the earth’s climate system. Better understanding of the water cycle and its interaction with changing climate will require improved monitoring of the various water fluxes and storages in hydrological processes. River discharge is a unique component reflecting an integrated hydrological signal over larger regions. Existing in situ monitoring solutions to monitor discharge are often considered too expensive and the difficulties in data sharing are viewed as insurmountable obstacles, which has led to growing interest in finding an alternative. This paper argues that in situ monitoring is far less expensive than claimed and the obstacles are not necessarily as insurmountable as often stated and a conscious effort to revitalize in situ monitoring will be needed. This paper demonstrates that there is no substitute for in situ discharge monitoring, but there should be a synergy between in situ monitoring and remote sensing since they are truly complementary. This paper primarily focuses on river discharge, but the conclusions are relevant for a host of other earth observations (particularly water quality) that would greatly benefit from a reconsidered balance between in situ and remote sensing observations.

scholarly journals Origin of interannual variability in global mean sea level

2020 ◽  
Vol 117 (25) ◽  
pp. 13983-13990
Author(s):  
Benjamin D. Hamlington ◽  
Christopher G. Piecuch ◽  
John T. Reager ◽  
Hrishi Chandanpurkar ◽  
Thomas Frederikse ◽  
...  
Keyword(s):  
Interannual Variability ◽  
Sea Level ◽  
Decadal Variability ◽  
Hydrological Cycle ◽  
Southern Oscillation ◽  
Heat Content ◽  
Scaling Analysis ◽  
Mean Sea Level ◽  
Global Mean Sea Level ◽  
Global Mean

The two dominant drivers of the global mean sea level (GMSL) variability at interannual timescales are steric changes due to changes in ocean heat content and barystatic changes due to the exchange of water mass between land and ocean. With Gravity Recovery and Climate Experiment (GRACE) satellites and Argo profiling floats, it has been possible to measure the relative steric and barystatic contributions to GMSL since 2004. While efforts to “close the GMSL budget” with satellite altimetry and other observing systems have been largely successful with regards to trends, the short time period covered by these records prohibits a full understanding of the drivers of interannual to decadal variability in GMSL. One particular area of focus is the link between variations in the El Niño−Southern Oscillation (ENSO) and GMSL. Recent literature disagrees on the relative importance of steric and barystatic contributions to interannual to decadal variability in GMSL. Here, we use a multivariate data analysis technique to estimate variability in barystatic and steric contributions to GMSL back to 1982. These independent estimates explain most of the observed interannual variability in satellite altimeter-measured GMSL. Both processes, which are highly correlated with ENSO variations, contribute about equally to observed interannual GMSL variability. A theoretical scaling analysis corroborates the observational results. The improved understanding of the origins of interannual variability in GMSL has important implications for our understanding of long-term trends in sea level, the hydrological cycle, and the planet’s radiation imbalance.

scholarly journals Comparison of Distributional Statistics of Aquarius and Argo Sea Surface Salinity Measurements

2016 ◽  
Vol 33 (1) ◽  
pp. 103-118 ◽  
Author(s):  
Elizabeth Mannshardt ◽  
Katarina Sucic ◽  
Montserrat Fuentes ◽  
Frederick M. Bingham
Keyword(s):  
Ocean Circulation ◽  
Hydrological Cycle ◽  
Water Cycle ◽  
Ocean Basin ◽  
Sea Surface ◽  
Sea Surface Salinity ◽  
Time And Space ◽  
Surface Salinity ◽  
Statistical Validation ◽  
Earth’S Climate

AbstractSalinity is an indicator of the interaction between ocean circulation and the global water cycle, which in turn affects the regulation of the earth’s climate. To thoroughly understand sea surface salinity’s connection to processes that define the hydrological cycle, such as surface forcing and ocean mixing, there is need for proper validation of remotely sensed salinity products with independent measurements, beyond central tendencies, across the entire distribution of salinity. Because of its fine spatial and temporal coverage, Aquarius presents an ideal measurement system for fully characterizing the distribution and properties of sea surface salinity. Using the first 33 months of Aquarius, version 3.0, level 2 sea surface salinity data, both central tendencies and distributional quantile characteristics across time and space are investigated, and a statistical validation of Aquarius measurements with Argo in situ observations is conducted. Several aspects are considered, including regional characteristics and temporal agreement, as well as seasonal differences by ocean basin and hemisphere. Regional studies examine the time and space scales of variability through time series comparisons and an analysis of quantile properties. Results indicate that there are significant differences between the tails of their respective distributions, especially the lower tail. The Aquarius data show longer, fatter lower tails, indicating higher probability to sample low-salinity events. There is also evidence of differences in measurement variation between Aquarius and Argo. These results are seen across seasons, ocean basins, hemispheres, and regions.

scholarly journals Closing the water cycle from observations across scales: Where do we stand?

2021 ◽  
pp. 1-95
Author(s):  
Wouter Dorigo ◽  
Stephan Dietrich ◽  
Filipe Aires ◽  
Luca Brocca ◽  
Sarah Carter ◽  
...  
Keyword(s):  
Hydrological Cycle ◽  
Water Cycle ◽  
Global Climate ◽  
Spatial Scales ◽  
Spatial And Temporal Scales ◽  
Mitigation And Adaptation ◽  
Consistent Assessment ◽  
Earth’S Climate ◽  
Improved Model

AbstractLife on Earth vitally depends on the availability of water. Human pressure on freshwater resources is increasing, as is human exposure to weather-related extremes (droughts, storms, floods) caused by climate change. Understanding these changes is pivotal for developing mitigation and adaptation strategies. The Global Climate Observing System (GCOS) defines a suite of Essential Climate Variables (ECVs), many related to the water cycle, required to systematically monitor the Earth's climate system. Since long-term observations of these ECVs are derived from different observation techniques, platforms, instruments, and retrieval algorithms, they often lack the accuracy, completeness, resolution, to consistently to characterize water cycle variability at multiple spatial and temporal scales.Here, we review the capability of ground-based and remotely sensed observations of water cycle ECVs to consistently observe the hydrological cycle. We evaluate the relevant land, atmosphere, and ocean water storages and the fluxes between them, including anthropogenic water use. Particularly, we assess how well they close on multiple temporal and spatial scales. On this basis, we discuss gaps in observation systems and formulate guidelines for future water cycle observation strategies. We conclude that, while long-term water-cycle monitoring has greatly advanced in the past, many observational gaps still need to be overcome to close the water budget and enable a comprehensive and consistent assessment across scales. Trends in water cycle components can only be observed with great uncertainty, mainly due to insufficient length and homogeneity. An advanced closure of the water cycle requires improved model-data synthesis capabilities, particularly at regional to local scales.

scholarly journals Snowfall-albedo feedbacks could have led to deglaciation of snowball Earth starting from mid-latitudes

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Philipp de Vrese ◽  
Tobias Stacke ◽  
Jeremy Caves Rugenstein ◽  
Jason Goodman ◽  
Victor Brovkin
Keyword(s):  
Carbon Dioxide ◽  
Atmospheric Carbon Dioxide ◽  
Climate Models ◽  
Hydrological Cycle ◽  
High Surface ◽  
Dust Deposition ◽  
Carbon Dioxide Concentrations ◽  
Maximum Temperatures ◽  
Carbon Dioxide Levels ◽  
Earth’S Climate

AbstractSimple and complex climate models suggest a hard snowball – a completely ice-covered planet – is one of the steady-states of Earth’s climate. However, a seemingly insurmountable challenge to the hard-snowball hypothesis lies in the difficulty in explaining how the planet could have exited the glaciated state within a realistic range of atmospheric carbon dioxide concentrations. Here, we use simulations with the Earth system model MPI-ESM to demonstrate that terminal deglaciation could have been triggered by high dust deposition fluxes. In these simulations, deglaciation is not initiated in the tropics, where a strong hydrological cycle constantly regenerates fresh snow at the surface, which limits the dust accumulation and snow aging, resulting in a high surface albedo. Instead, comparatively low precipitation rates in the mid-latitudes in combination with high maximum temperatures facilitate lower albedos and snow dynamics that – for extreme dust fluxes – trigger deglaciation even at present-day carbon dioxide levels.

scholarly journals Twenty-first century response of Petermann Glacier, northwest Greenland to ice shelf loss

2020 ◽  
pp. 1-11
Author(s):  
Emily A. Hill ◽  
G. Hilmar Gudmundsson ◽  
J. Rachel Carr ◽  
Chris R. Stokes ◽  
Helen M. King
Keyword(s):  
Sea Level ◽  
First Century ◽  
Ice Shelf ◽  
Ice Shelves ◽  
Sea Levels ◽  
Grounding Line ◽  
Global Mean Sea Level ◽  
Near Future ◽  
Global Mean ◽  
Large Sections

Abstract Ice shelves restrain flow from the Greenland and Antarctic ice sheets. Climate-ocean warming could force thinning or collapse of floating ice shelves and subsequently accelerate flow, increase ice discharge and raise global mean sea levels. Petermann Glacier (PG), northwest Greenland, recently lost large sections of its ice shelf, but its response to total ice shelf loss in the future remains uncertain. Here, we use the ice flow model Úa to assess the sensitivity of PG to changes in ice shelf extent, and to estimate the resultant loss of grounded ice and contribution to sea level rise. Our results have shown that under several scenarios of ice shelf thinning and retreat, removal of the shelf will not contribute substantially to global mean sea level (<1 mm). We hypothesize that grounded ice loss was limited by the stabilization of the grounding line at a topographic high ~12 km inland of its current grounding line position. Further inland, the likelihood of a narrow fjord that slopes seawards suggests that PG is likely to remain insensitive to terminus changes in the near future.

3. Note on Solar Radiation

1888 ◽  
Vol 14 ◽  
pp. 118-121
Author(s):  
John Aitken
Keyword(s):  
Solar Radiation ◽  
The Sun ◽  
Geological History ◽  
Conservation Of Energy ◽  
Vast Amount ◽  
Chemical Theory ◽  
Energy Theory ◽  
The Many ◽  
Different Sources

In the many theories that have been advanced to explain the comparative constancy of solar radiation in long past ages as evidenced by geological history, it has been generally assumed that the temperature of the sun has not varied much, and to account for its not falling in temperature a number of theories have been advanced, all suggesting different sources from which it may have received the energy which it radiates as heat. Since the chemical theory was shown to be insufficient to account for the vast amount of heat radiated, other theories, such as the meteoric theory and the conservation of energy theory, have been advanced.

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