| 1. |
- Power, M. J., et al.
(författare)
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Changes in fire regimes since the Last Glacial Maximum : an assessment based on a global synthesis and analysis of charcoal data
- 2008
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Ingår i: Climate Dynamics. - : Springer Science and Business Media LLC. - 0930-7575 .- 1432-0894. ; 30:7-8, s. 887-907
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Tidskriftsartikel (refereegranskat)abstract
- Fire activity has varied globally and continuously since the last glacial maximum (LGM) in response to long-term changes in global climate and shorter-term regional changes in climate, vegetation, and human land use. We have synthesized sedimentary charcoal records of biomass burning since the LGM and present global maps showing changes in fire activity for time slices during the past 21,000 years (as differences in charcoal accumulation values compared to pre-industrial). There is strong broad-scale coherence in fire activity after the LGM, but spatial heterogeneity in the signals increases thereafter. In North America, Europe and southern South America, charcoal records indicate less-than-present fire activity during the deglacial period, from 21,000 to ∼11,000 cal yr BP. In contrast, the tropical latitudes of South America and Africa show greater-than-present fire activity from ∼19,000 to ∼17,000 cal yr BP and most sites from Indochina and Australia show greater-than-present fire activity from 16,000 to ∼13,000 cal yr BP. Many sites indicate greater-than-present or near-present activity during the Holocene with the exception of eastern North America and eastern Asia from 8,000 to ∼3,000 cal yr BP, Indonesia and Australia from 11,000 to 4,000 cal yr BP, and southern South America from 6,000 to 3,000 cal yr BP where fire activity was less than present. Regional coherence in the patterns of change in fire activity was evident throughout the post-glacial period. These complex patterns can largely be explained in terms of large-scale climate controls modulated by local changes in vegetation and fuel load.
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| 2. |
- Schuur, E. A. G., et al.
(författare)
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Expert assessment of vulnerability of permafrost carbon to climate change
- 2013
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Ingår i: Climatic Change. - : Springer Science and Business Media LLC. - 0165-0009 .- 1573-1480. ; 119:2, s. 359-374
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Tidskriftsartikel (refereegranskat)abstract
- Approximately 1700 Pg of soil carbon (C) are stored in the northern circumpolar permafrost zone, more than twice as much C than in the atmosphere. The overall amount, rate, and form of C released to the atmosphere in a warmer world will influence the strength of the permafrost C feedback to climate change. We used a survey to quantify variability in the perception of the vulnerability of permafrost C to climate change. Experts were asked to provide quantitative estimates of permafrost change in response to four scenarios of warming. For the highest warming scenario (RCP 8.5), experts hypothesized that C release from permafrost zone soils could be 19-45 Pg C by 2040, 162-288 Pg C by 2100, and 381-616 Pg C by 2300 in CO2 equivalent using 100-year CH4 global warming potential (GWP). These values become 50 % larger using 20-year CH4 GWP, with a third to a half of expected climate forcing coming from CH4 even though CH4 was only 2.3 % of the expected C release. Experts projected that two-thirds of this release could be avoided under the lowest warming scenario (RCP 2.6). These results highlight the potential risk from permafrost thaw and serve to frame a hypothesis about the magnitude of this feedback to climate change. However, the level of emissions proposed here are unlikely to overshadow the impact of fossil fuel burning, which will continue to be the main source of C emissions and climate forcing.
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| 3. |
- Loisel, J., et al.
(författare)
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Expert assessment of future vulnerability of the global peatland carbon sink
- 2021
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Ingår i: Nature Climate Change. - : Springer Science and Business Media LLC. - 1758-678X .- 1758-6798. ; 11:1, s. 70-77
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Tidskriftsartikel (refereegranskat)abstract
- Peatlands are impacted by climate and land-use changes, with feedback to warming by acting as either sources or sinks of carbon. Expert elicitation combined with literature review reveals key drivers of change that alter peatland carbon dynamics, with implications for improving models. The carbon balance of peatlands is predicted to shift from a sink to a source this century. However, peatland ecosystems are still omitted from the main Earth system models that are used for future climate change projections, and they are not considered in integrated assessment models that are used in impact and mitigation studies. By using evidence synthesized from the literature and an expert elicitation, we define and quantify the leading drivers of change that have impacted peatland carbon stocks during the Holocene and predict their effect during this century and in the far future. We also identify uncertainties and knowledge gaps in the scientific community and provide insight towards better integration of peatlands into modelling frameworks. Given the importance of the contribution by peatlands to the global carbon cycle, this study shows that peatland science is a critical research area and that we still have a long way to go to fully understand the peatland-carbon-climate nexus.
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| 4. |
- Treat, C. C., et al.
(författare)
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Effects of permafrost aggradation on peat properties as determined from a pan-Arctic synthesis of plant macrofossils
- 2016
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Ingår i: Journal of Geophysical Research - Biogeosciences. - 2169-8953 .- 2169-8961. ; 121:1, s. 78-94
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Tidskriftsartikel (refereegranskat)abstract
- Permafrost dynamics play an important role in high-latitude peatland carbon balance and are key to understanding the future response of soil carbon stocks. Permafrost aggradation can control the magnitude of the carbon feedback in peatlands through effects on peat properties. We compiled peatland plant macrofossil records for the northern permafrost zone (515 cores from 280 sites) and classified samples by vegetation type and environmental class (fen, bog, tundra and boreal permafrost, and thawed permafrost). We examined differences in peat properties (bulk density, carbon (C), nitrogen (N) and organic matter content, and C/N ratio) and C accumulation rates among vegetation types and environmental classes. Consequences of permafrost aggradation differed between boreal and tundra biomes, including differences in vegetation composition, C/N ratios, and N content. The vegetation composition of tundra permafrost peatlands was similar to permafrost-free fens, while boreal permafrost peatlands more closely resembled permafrost-free bogs. Nitrogen content in boreal permafrost and thawed permafrost peatlands was significantly lower than in permafrost-free bogs despite similar vegetation types (0.9% versus 1.5% N). Median long-term C accumulation rates were higher in fens (23g C m(-2)yr(-1)) than in permafrost-free bogs (18g C m(-2)yr(-1)) and were lowest in boreal permafrost peatlands (14g C m(-2)yr(-1)). The plant macrofossil record demonstrated transitions from fens to bogs to permafrost peatlands, bogs to fens, permafrost aggradation within fens, and permafrost thaw and reaggradation. Using data synthesis, we have identified predominant peatland successional pathways, changes in vegetation type, peat properties, and C accumulation rates associated with permafrost aggradation.
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| 5. |
- Gallego-Sala, Angela V., et al.
(författare)
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Latitudinal limits to the predicted increase of the peatland carbon sink with warming
- 2018
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Ingår i: Nature Climate Change. - : Springer Science and Business Media LLC. - 1758-678X .- 1758-6798. ; 8:10, s. 907-
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Tidskriftsartikel (refereegranskat)abstract
- The carbon sink potential of peatlands depends on the balance of carbon uptake by plants and microbial decomposition. The rates of both these processes will increase with warming but it remains unclear which will dominate the global peatland response. Here we examine the global relationship between peatland carbon accumulation rates during the last millennium and planetary-scale climate space. A positive relationship is found between carbon accumulation and cumulative photosynthetically active radiation during the growing season for mid- to high-latitude peatlands in both hemispheres. However, this relationship reverses at lower latitudes, suggesting that carbon accumulation is lower under the warmest climate regimes. Projections under Representative Concentration Pathway (RCP)2.6 and RCP8.5 scenarios indicate that the present-day global sink will increase slightly until around AD 2100 but decline thereafter. Peatlands will remain a carbon sink in the future, but their response to warming switches from a negative to a positive climate feedback (decreased carbon sink with warming) at the end of the twenty-first century.
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| 6. |
- Hugelius, Gustaf, et al.
(författare)
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Estimated stocks of circumpolar permafrost carbon with quantified uncertainty ranges and identified data gaps
- 2014
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 11:23, s. 6573-6593
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Tidskriftsartikel (refereegranskat)abstract
- Soils and other unconsolidated deposits in the northern circumpolar permafrost region store large amounts of soil organic carbon (SOC). This SOC is potentially vulnerable to remobilization following soil warming and permafrost thaw, but SOC stock estimates were poorly constrained and quantitative error estimates were lacking. This study presents revised estimates of permafrost SOC stocks, including quantitative uncertainty estimates, in the 0-3m depth range in soils as well as for sediments deeper than 3m in deltaic deposits of major rivers and in the Yedoma region of Siberia and Alaska. Revised estimates are based on significantly larger databases compared to previous studies. Despite this there is evidence of significant remaining regional data gaps. Estimates remain particularly poorly constrained for soils in the High Arctic region and physiographic regions with thin sedimentary overburden (mountains, highlands and plateaus) as well as for deposits below 3mdepth in deltas and the Yedoma region. While some components of the revised SOC stocks are similar in magnitude to those previously reported for this region, there are substantial differences in other components, including the fraction of perennially frozen SOC. Upscaled based on regional soil maps, estimated permafrost region SOC stocks are 217 +/- 12 and 472 +/- 27 Pg for the 0-0.3 and 0-1 m soil depths, respectively (+/- 95% confidence intervals). Storage of SOC in 0-3m of soils is estimated to 1035 +/- 150 Pg. Of this, 34 +/- 16 PgC is stored in poorly developed soils of the High Arctic. Based on generalized calculations, storage of SOC below 3m of surface soils in deltaic alluvium of major Arctic rivers is estimated as 91 +/- 52 Pg. In the Yedoma region, estimated SOC stocks below 3mdepth are 181 +/- 54 Pg, of which 74 +/- 20 Pg is stored in intact Yedoma (late Pleistocene ice-and organic-rich silty sediments) with the remainder in refrozen thermokarst deposits. Total estimated SOC storage for the permafrost region is similar to 1300 Pg with an uncertainty range of similar to 1100 to 1500 Pg. Of this, similar to 500 Pg is in non-permafrost soils, seasonally thawed in the active layer or in deeper taliks, while similar to 800 Pg is perennially frozen. This represents a substantial similar to 300 Pg lowering of the estimated perennially frozen SOC stock compared to previous estimates.
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| 7. |
- Sim, Thomas G., et al.
(författare)
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Regional variability in peatland burning at mid-to high-latitudes during the Holocene
- 2023
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Ingår i: Quaternary Science Reviews. - : Elsevier. - 0277-3791 .- 1873-457X. ; 305
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Tidskriftsartikel (refereegranskat)abstract
- Northern peatlands store globally-important amounts of carbon in the form of partly decomposed plant detritus. Drying associated with climate and land-use change may lead to increased fire frequency and severity in peatlands and the rapid loss of carbon to the atmosphere. However, our understanding of the patterns and drivers of peatland burning on an appropriate decadal to millennial timescale relies heavily on individual site-based reconstructions. For the first time, we synthesise peatland macrocharcoal re-cords from across North America, Europe, and Patagonia to reveal regional variation in peatland burning during the Holocene. We used an existing database of proximal sedimentary charcoal to represent regional burning trends in the wider landscape for each region. Long-term trends in peatland burning appear to be largely climate driven, with human activities likely having an increasing influence in the late Holocene. Warmer conditions during the Holocene Thermal Maximum (similar to 9e6 cal. ka BP) were associated with greater peatland burning in North America's Atlantic coast, southern Scandinavia and the Baltics, and Patagonia. Since the Little Ice Age, peatland burning has declined across North America and in some areas of Europe. This decline is mirrored by a decrease in wider landscape burning in some, but not all sub-regions, linked to fire-suppression policies, and landscape fragmentation caused by agricultural expansion. Peatlands demonstrate lower susceptibility to burning than the wider landscape in several instances, probably because of autogenic processes that maintain high levels of near-surface wetness even during drought. Nonetheless, widespread drying and degradation of peatlands, particularly in Europe, has likely increased their vulnerability to burning in recent centuries. Consequently, peatland restoration efforts are important to mitigate the risk of peatland fire under a changing climate. Finally, we make recommendations for future research to improve our understanding of the controls on peatland fires.(c) 2023 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
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| 8. |
- Stauffer, Flurin, et al.
(författare)
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Soft Electronic Strain Sensor with Chipless Wireless Readout: Toward Real-Time Monitoring of Bladder Volume
- 2018
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Ingår i: Advanced Materials Technologies. - : WILEY. - 2365-709X. ; 3:6
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Tidskriftsartikel (refereegranskat)abstract
- Sensing mechanical tissue deformation in vivo can provide detailed information on organ functionality and tissue states. To bridge the huge mechanical mismatch between conventional electronics and biological tissues, stretchable electronic systems have recently been developed for interfacing tissues in healthcare applications. A major challenge for wireless electronic implants is that they typically require microchips, which adds complexity and may compromise long-term stability. Here, a chipless wireless strain sensor technology based on a novel soft conductor with high cyclic stability is reported. The composite material consists of gold-coated titanium dioxide nanowires embedded in a soft silicone elastomer. The implantable strain sensor is based on an resonant circuit which consists of a stretchable plate capacitor and a coil for inductive readout of its resonance frequency. Successful continuous wireless readout during 50% strain cycles is demonstrated. The sensor element has a Youngs modulus of 260 kPa, similar to that of the bladder in order to not impair physiological bladder expansion. A proof-of-principle measurement on an ex vivo porcine bladder is presented, which shows the feasibility of the presented materials and devices for continuous, wireless strain monitoring of various tissues and organs in vivo.
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