Shrinking snowpacks, anxious snow lovers Serreze, Mark
Science (American Association for the Advancement of Science),
11/2021, Letnik:
374, Številka:
6570
Journal Article
Recenzirano
A cold-weather enthusiast confronts connections between the cryosphere and human culture
This is the first textbook to address all the components of the Earth's cryosphere – all forms of snow and ice, both terrestrial and marine. It provides a concise but comprehensive summary of snow ...cover, glaciers, ice sheets, lake and river ice, permafrost, sea ice and icebergs – their past history and projected future state. It is designed for courses at upper undergraduate and graduate level in environmental science, geography, geology, glaciology, hydrology, water resource engineering and ocean sciences. It also provides a superb up-to-date summary for researchers of the cryosphere. The book includes an extensive bibliography, numerous figures and color plates, thematic boxes on selected topics and a glossary. The book builds on courses taught by the authors for many decades at the University of Colorado and the University of Alberta. Whilst there are many existing texts on individual components of the cryosphere, no other textbook covers the whole cryosphere.
In mountainous regions, climate change threatens cryospheric water resources, and understanding all components of the hydrological cycle is necessary for effective water resource management. Rock ...glaciers are climatically more resilient than glaciers and contain potentially hydrologically valuable ice volumes, and yet have received less attention, even though rock glacier hydrological importance may increase under future climate warming. In synthesising data from a range of global studies, we provide the first comprehensive evaluation of the hydrological role played by rock glaciers. We evaluate hydrological significance over a range of temporal and spatial scales, alongside the complex multiple hydrological processes with which rock glaciers can interact diurnally, seasonally, annually, decadally and both at local and regional extents. We report that although no global-extent, complete inventory for rock glaciers exists currently, recent research efforts have greatly elaborated spatial coverage. Using these research papers, we synthesise information on rock glacier spatial distribution, morphometric characteristics, surface and subsurface features, ice-storage and hydrological flow dynamics, water chemistry, and future resilience, from which we provide the first comprehensive evaluation of their hydrological contribution. We identify and discuss long-, intermediate- and short-term timescales for rock glacier storage, allowing a more balanced assessment of the contrasting perspectives regarding the relative significance of rock glacier-derived hydrological contributions compared to other water sources. We show that further empirical observations are required to gain a deeper hydrological understanding of rock glaciers, in terms of (i) their genesis and geomorphological dynamics (ii) total ice/water volume; (iii) water discharge; and (iv) water quality. Lastly, we hypothesise that at decadal and longer timescales, under future climate warming, degradation of ice within rock glaciers may represent an increasing hydrological contribution to downstream regions, and thus increased hydrological significance while rock glacier water stores persist.
Permafrost degradation is delivering bioavailable dissolved organic matter (DOM) and inorganic nutrients to surface water networks. While these permafrost subsidies represent a small portion of total ...fluvial DOM and nutrient fluxes, they could influence food webs and net ecosystem carbon balance via priming or nutrient effects that destabilize background DOM. We investigated how addition of biolabile carbon (acetate) and inorganic nutrients (nitrogen and phosphorus) affected DOM decomposition with 28‐day incubations. We incubated late‐summer stream water from 23 locations nested in seven northern or high‐altitude regions in Asia, Europe, and North America. DOM loss ranged from 3% to 52%, showing a variety of longitudinal patterns within stream networks. DOM optical properties varied widely, but DOM showed compositional similarity based on Fourier transform ion cyclotron resonance mass spectrometry (FT‐ICR MS) analysis. Addition of acetate and nutrients decreased bulk DOM mineralization (i.e., negative priming), with more negative effects on biodegradable DOM but neutral or positive effects on stable DOM. Unexpectedly, acetate and nutrients triggered breakdown of colored DOM (CDOM), with median decreases of 1.6% in the control and 22% in the amended treatment. Additionally, the uptake of added acetate was strongly limited by nutrient availability across sites. These findings suggest that biolabile DOM and nutrients released from degrading permafrost may decrease background DOM mineralization but alter stoichiometry and light conditions in receiving waterbodies. We conclude that priming and nutrient effects are coupled in northern aquatic ecosystems and that quantifying two‐way interactions between DOM properties and environmental conditions could resolve conflicting observations about the drivers of DOM in permafrost zone waterways.
Key Points
Dissolved organic matter (DOM) from diverse circumpolar regions showed compositional and optical commonalities
Added acetate and nutrients suppressed background DOM degradation but accelerated colored DOM breakdown
Disconnect between DOM composition and function indicates intrinsic and extrinsic conditions interact to regulate DOM dynamics
Annual forest area burned (AFAB) in the western United States (US) has increased as a positive exponential function of rising aridity in recent decades. This non‐linear response has important ...implications for AFAB in a changing climate, yet the cause of the exponential AFAB‐aridity relationship has not been given rigorous attention. We investigated the exponential AFAB‐aridity relationship in western US forests using a new 1984–2019 database of fire events and 2001–2020 satellite‐based records of daily fire growth. While forest‐fire frequency and duration grow linearly with aridity, the exponential AFAB‐aridity relationship results from the exponential growth rates of individual fires. Larger fires generally have more potential for growth due to more extensive firelines. Thus, forces that promote fire growth, such as aridification, have more potent effects on larger fires. As aridity increases linearly, the potential for growth of large fires accelerates, leading to exponential increases in AFAB.
Plain Language Summary
Though a natural phenomenon in the western United States (US), wildfires have burned over increasingly large forested areas as the climate has warmed and dried in recent decades, straining fire management and putting humans at risk. An important characteristic of the wildfire response to climate is that as fuels dry–mainly from low precipitation and heat–the amount of annual forest area burned increases exponentially. Although scientists frequently use this relationship to project wildfire responses to climate change, the cause of the exponential relationship has not been robustly investigated. We show here that the exponential response of annual burned area to fuel dryness is related to how individual wildfires spread. Fire growth is a dispersion phenomenon–similar to how the area of a circle increases exponentially as the radius grows incrementally, wildfires tend to grow at compounding rates; the larger a fire, the more potential it has for rapid growth. As western US forest fires have grown under climate change, larger fires have grown more rapidly than smaller fires and increases in annual forest‐fire area have therefore accelerated. Annual western US forest area burned will likely continue to increase due to warming and drying until fuel availability becomes a limiting factor.
Key Points
We developed a database of western United States wildfires and examined why annual forest area burned grows exponentially with aridity
Individual fires grow at compounding rates, so fire enlargement driven by aridification is most rapid among large fires
Approximately two‐thirds of the increase in 1984–2019 forest burned area is shaped by each year's largest 10% of forest fires
The Sentinel-1, -2, and -3 satellite missions can meet various observational needs for spatially explicit physical, biogeophysical, and biological variables of the ocean, cryosphere, and land ...research activities. The currently known observational requirements were extracted from documents produced by major international scientific projects and programs. The summarized observational needs were then cross-referenced with the capabilities of the planned sensors aboard of the first three Sentinels. A comparative analysis, also incorporating scientific challenges of the ESA Living Planet Programme and the Essential Climate Variables (ECVs), resulted in a preliminary scientific priority assessment of the reviewed environmental variables. Results of these activities, discussed and consolidated in March 2011 at the Sentinels for Science (SEN4SCI) scientific workshop, demonstrate the high potential of the Sentinel-1, -2, and -3 missions for systematic, long-term observations of the Earth system.
► GMES Sentinel-1, -2, and -3 were assessed for ocean, cryosphere, and land science. ► Analysis indicates high potential of the Sentinels to satisfy observational needs. ► The first Sentinel for Science (SEN4SCI) scientific workshop took place in May 2011. ► More than 180 scientists fully supported scientific exploitation of the Sentinels.
Mining stakes claim on salmon futures as glaciers retreat Moore, Jonathan W.; Pitman, Kara J.; Whited, Diane ...
Science (American Association for the Advancement of Science),
11/2023, Letnik:
382, Številka:
6673
Journal Article
Recenzirano
Future ecological value of emerging habitats must be considered as climate change transforms the planet
As climate change warms Earth, the melting cryosphere creates nascent ecosystems that have ...future value as habitat but that are also the frontlines for resource extraction (
1
). For example, glacier retreat uncovers rivers and valleys that go through rapid ecological succession to provide new habitats for important species, such as moose and Pacific salmon (
2
–
5
). However, mining companies are looking to retreating glaciers for newly exposed mineral deposits (
6
). This proglacial mining is a global pressure, from Greenland to Kyrgyzstan to western Canada (
6
). Yet environmental and mining policies might fail to consider the future ecological value and capacity of emerging habitats. We illustrate these issues below by exploring the overlap of glacial retreat, Pacific salmon future habitats, and mining pressures in western Canada and southern Alaska. Stewardship of glacierized landscapes, and other ecosystems that are being transformed by climate change, urgently need forward-looking science and environmental policy.
The Antarctic Peninsula (AP) is often described as a region with one of the largest warming trends on Earth since the 1950s, based on the temperature trend of 0.54°C/decade during 1951–2011 recorded ...at Faraday/Vernadsky station. Accordingly, most works describing the evolution of the natural systems in the AP region cite this extreme trend as the underlying cause of their observed changes. However, a recent analysis (Turner et al., 2016) has shown that the regionally stacked temperature record for the last three decades has shifted from a warming trend of 0.32°C/decade during 1979–1997 to a cooling trend of −0.47°C/decade during 1999–2014. While that study focuses on the period 1979–2014, averaging the data over the entire AP region, we here update and re-assess the spatially-distributed temperature trends and inter-decadal variability from 1950 to 2015, using data from ten stations distributed across the AP region. We show that Faraday/Vernadsky warming trend is an extreme case, circa twice those of the long-term records from other parts of the northern AP. Our results also indicate that the cooling initiated in 1998/1999 has been most significant in the N and NE of the AP and the South Shetland Islands (>0.5°C between the two last decades), modest in the Orkney Islands, and absent in the SW of the AP. This recent cooling has already impacted the cryosphere in the northern AP, including slow-down of glacier recession, a shift to surface mass gains of the peripheral glacier and a thinning of the active layer of permafrost in northern AP islands.
Display omitted
•We examine climate variability since the 1950s in the Antarctic Peninsula region.•This region is often cited among those with the fastest warming rates on Earth.•A re-assessment of climate data shows a cooling trend initiated around 1998/1999.•This recent cooling has already impacted the cryosphere in the northern AP.•Observed changes on glacial mass balances, snow cover and permafrost state
The rapid retreat and thinning of the Arctic sea ice cover over the past several decades is one of the most striking manifestations of global climate change. Previous research revealed that the ...observed downward trend in September ice extent exceeded simulated trends from most models participating in the World Climate Research Programme Coupled Model Intercomparison Project Phase 3 (CMIP3). We show here that as a group, simulated trends from the models contributing to CMIP5 are more consistent with observations over the satellite era (1979–2011). Trends from most ensemble members and models nevertheless remain smaller than the observed value. Pointing to strong impacts of internal climate variability, 16% of the ensemble member trends over the satellite era are statistically indistinguishable from zero. Results from the CMIP5 models do not appear to have appreciably reduced uncertainty as to when a seasonally ice‐free Arctic Ocean will be realized.
Key Points
CMIP5 models continue to underestimate rate of sea ice loss
CMIP5 models are more consistent with observations than CMIP3
CMIP5 suggests 60% of 1979‐2011 rate of decline is externally forced
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