scholarly journals Deglaciation-enhanced mantle CO2 fluxes at Yellowstone imply positive climate feedback

2021 ◽  
Author(s):  
Fiona Clerc ◽  
Mark Behn ◽  
Brent Minchew
Keyword(s):  
Co2 Flux ◽  
Climate Feedback ◽  
Mantle Melting ◽  
West Antarctica ◽  
Positive Feedbacks ◽  
Active Systems ◽  
Ice Cap ◽  
Volatile Release ◽  
Show Evidence ◽  
Positive Climate

The generation of mantle melts in response to decompression by glacial unloading has been linked to enhanced volcanic activity and volatile release in Iceland and in global eruptive records. However, it is unclear whether this process is also important in magmatically-active systems that do not show evidence of enhanced eruption rates. For example, the deglaciation of the Yellowstone ice cap did not observably enhance volcanism, yet Yellowstone may still have released large volumes of CO2 to the surface due to the crystallization of melts at depth. Here we develop models to simulate mantle melt production and volatile release associated with the deglaciation of Yellowstone and Iceland. In agreement with previous work, we find mantle melt production in Iceland is enhanced 33-fold during deglaciation, generating an additional 3728 km3 of melt and releasing an additional 31–51 Gt of CO2. Beneath Yellowstone, we find mantle melt production is comparably enhanced 19-fold during deglaciation, generating an additional 815 km3 of melt, though thicker lithosphere may prevent the transport of this melt to the surface. These melts segregate an additional 135–230 Gt of CO2 from the mantle, representing a ~23–39% increase of the global volcanic CO2 flux (if degassed during deglaciation). Our results suggest deglaciation-enhanced mantle melting is important in continental settings with partially molten mantle (potentially Greenland and West Antarctica) and may result in positive feedbacks between deglaciation and climate warming.

The changing effects of Alaska’s boreal forests on the climate systemThis article is one of a selection of papers from The Dynamics of Change in Alaska’s Boreal Forests: Resilience and Vulnerability in Response to Climate Warming.

2010 ◽  
Vol 40 (7) ◽  
pp. 1336-1346 ◽  
Author(s):  
E.S. Euskirchen ◽  
A.D. McGuire ◽  
F.S. Chapin ◽  
T.S. Rupp
Keyword(s):  
Boreal Forests ◽  
Regional Scale ◽  
Terrestrial Ecosystems ◽  
Climate System ◽  
Climate Feedbacks ◽  
Regional Warming ◽  
Positive Feedbacks ◽  
Forest Resilience ◽  
And Function ◽  
Positive Climate

In the boreal forests of Alaska, recent changes in climate have influenced the exchange of trace gases, water, and energy between these forests and the atmosphere. These changes in the structure and function of boreal forests can then feed back to impact regional and global climates. In this manuscript, we examine the type and magnitude of the climate feedbacks from boreal forests in Alaska. Research generally suggests that the net effect of a warming climate is a positive regional feedback to warming. Currently, the primary positive climate feedbacks are likely related to decreases in surface albedo due to decreases in snow cover. Fewer negative feedbacks have been identified, and they may not be large enough to counterbalance the large positive feedbacks. These positive feedbacks are most pronounced at the regional scale and reduce the resilience of the boreal vegetation – climate system by amplifying the rate of regional warming. Given the recent warming in this region, the large variety of associated mechanisms that can alter terrestrial ecosystems and influence the climate system, and a reduction in the boreal forest resilience, there is a strong need to continue to quantify and evaluate the feedback pathways.

Eocene and Oligocene volcanism at Mount Petras, Marie Byrd Land: implications for middle Cenozoic ice sheet reconstructions in West Antarctica

2000 ◽  
Vol 12 (4) ◽  
pp. 477-491 ◽  
Author(s):  
T.I. Wilch ◽  
W.C. McIntosh
Keyword(s):  
Ice Sheet ◽  
Late Eocene ◽  
West Antarctica ◽  
Tuff Cone ◽  
Ice Cap ◽  
West Antarctic ◽  
Strombolian Eruptions ◽  
Intermittent Contact ◽  
External Water ◽  
Latest Eocene

Evidence for one late Eocene and four middle Oligocene eruptions of Mount Petras, Marie Byrd Land provides new insights into reconstructions of middle Tertiary ice sheet configurations, surface topography, and volcanism in West Antarctica. The interpretation presented here of the volcanic record at Mount Petras, based on detailed analyses of lithofacies, petrography, 40Ar/39Ar geochronology, and geochemistry, is significantly different from previous interpretations based on reconnaissance studies. A massive, 25 m thick, mugearite lava near the summit of Mount Petras is 40Ar/39Ar dated to 36.11 ± 0.22 Ma (2 σ uncertainty), indicating an onset of Cenozoic alkaline volcanism in the Marie Byrd Land Volcanic Province in latest Eocene time. Middle Oligocene (29-27 Ma) hawaiite volcaniclastic lithofacies at Mount Petras are interpreted as products of mixed magmatic (Strombolian style) and phreatomagmatic (Surtseyan style) subaerial eruptions. The four hawaiite outcrop areas exhibit characteristics of near-vent tuff cone environments. The near-vent deposits are located at different elevations and positions on Mount Petras and suggest four separate eruptive centres, with eruptions dated to between 28.59 ± 0.22 Ma and 27.18 ± 0.23 Ma. The mixed Surtseyan and Strombolian eruptions imply local or intermittent contact with external water, which we infer was derived from melting of a thin, local ice cap or ice and snow on slopes. The 29-27 Ma volcanic deposits at Mount Petras provide the oldest terrestrial evidence for glacial ice in Marie Byrd Land. The 29-27 Ma tuff cone deposits overlie an erosional unconformity, with > 400 m of topographic relief. The relatively high relief pre-volcanic environment is suggestive of ongoing erosion and is inconsistent with previous interpretations of a regional, low relief, early Cenozoic West Antarctic Erosion Surface.

Overlooked volatile production from Arctic permafrost triggered by global warming

2020 ◽  
Author(s):  
Haiyan Li ◽  
Mari Mäki ◽  
Lukas Kohl ◽  
Minna Väliranta ◽  
Jaana Bäck ◽  
...  
Keyword(s):  
Active Layer ◽  
Climate Feedback ◽  
The Arctic ◽  
Future Evolution ◽  
Permafrost Thaw ◽  
Finnish Lapland ◽  
Volatile Release ◽  
Carbon Release ◽  
Thawing Permafrost ◽  
Volatile Production

<p>Permafrost thaw, as a consequence of climate warming, liberates large quantities of frozen organic carbon in the Arctic regions. The response of gaseous carbon release upon permafrost thaw might play a crucial role in the future evolution of atmosphere-land fluxes of biogenic gases such as volatile organic compounds (VOCs), a group of reactive gases and the dominant modulator of tropospheric oxidation capacities. Here, we examine the response of volatile release from Finnish Lapland permafrost soils to temperature increase in a series of laboratory incubation experiments. The experiments show that when the temperature rises from 0 °C to 15 °C, various VOC species are significantly emitted from the gradually thawing soils. The VOC fluxes from thawing permafrost are on average four times as high as those from active layer. Acetic acid and acetone dominate the total volatile emissions from both permafrost and active layer, with significant amounts of aromatics and terpenes detected as well. The emission rate and the composition of volatile release from thawing soils are highly responsive to temperature variations. As temperature increases, more less volatile compounds are released, i.e., sesquiterpenes and diterpenes. Collectively, these results demonstrate the highly overlooked volatile production from thawing permafrost, which will create a stronger permafrost carbon-climate feedback.</p>

scholarly journals The Nonlinear and Nonlocal Nature of Climate Feedbacks

2013 ◽  
Vol 26 (21) ◽  
pp. 8289-8304 ◽  
Author(s):  
Nicole Feldl ◽  
Gerard H. Roe
Keyword(s):  
Radiative Forcing ◽  
Global Climate ◽  
Regional Climate ◽  
Critical Role ◽  
Nonlinear Effects ◽  
Climate Feedback ◽  
Climate Response ◽  
Positive Feedbacks ◽  
Local Climate ◽  
Two Factors

Abstract The climate feedback framework partitions the radiative response to climate forcing into contributions from individual atmospheric processes. The goal of this study is to understand the closure of the energy budget in as much detail and precision as possible, within as clean an experimental setup as possible. Radiative kernels and radiative forcing are diagnosed for an aquaplanet simulation under perpetual equinox conditions. The role of the meridional structure of feedbacks, heat transport, and nonlinearities in controlling the local climate response is characterized. Results display a combination of positive subtropical feedbacks and polar amplified warming. These two factors imply a critical role for transport and nonlinear effects, with the latter acting to substantially reduce global climate sensitivity. At the hemispheric scale, a rich picture emerges: anomalous divergence of heat flux away from positive feedbacks in the subtropics; nonlinear interactions among and within clear-sky feedbacks, which reinforce the pattern of tropical cooling and high-latitude warming tendencies; and strong ice-line feedbacks that drive further amplification of polar warming. These results have implications for regional climate predictability, by providing an indication of how spatial patterns in feedbacks combine to affect both the local and nonlocal climate response, and how constraining uncertainty in those feedbacks may constrain the climate response.

scholarly journals Effects of temperature-dependent NO<sub>x</sub> emissions on continental ozone production

2017 ◽  
Author(s):  
Paul S. Romer ◽  
Kaitlin C. Duffey ◽  
Paul J. Wooldridge ◽  
Eric Edgerton ◽  
Karsten Baumann ◽  
...  
Keyword(s):  
Surface Ozone ◽  
Ozone Production ◽  
Climate Feedback ◽  
Nox Emissions ◽  
Southeast United States ◽  
Average Temperature ◽  
Ozone Concentrations ◽  
Effects Of Temperature ◽  
Positive Climate

Abstract. Surface ozone concentrations are observed to increase with rising temperatures, but the mechanisms responsible for this effect in rural and remote continental regions remain uncertain. Better understanding of the effects of temperature on ozone is crucial to understanding global air quality and how it may be affected by climate change. We combine measurements from a focused ground campaign in summer 2013 with a long-term record from a forested site in the rural southeast United States to examine how daily average temperature affects ozone production. We find that changes to local chemistry are key drivers of increased ozone concentrations on hotter days, with integrated daily ozone production increasing by 2.3 ppb C−1. Nearly half of this increase is attributable to temperature-driven increases in emissions of nitrogen oxides (NOx), most likely by soil microbes. The increase of soil NOx emissions with temperature suggests that ozone will continue to increase with temperature in the future, even as direct anthropogenic NOx emissions decrease dramatically. The links between temperature, soil NOx, and ozone form a positive climate feedback.

scholarly journals Till genesis and glacier motion inferred from sedimentological evidence associated with the surge-type glacier, Brúarjökull, Iceland

2005 ◽  
Vol 42 ◽  
pp. 14-22 ◽  
Author(s):  
Anna E. Nelson ◽  
Ian C. Willis ◽  
Colm Ó. Cofaigh
Keyword(s):  
Shear Stresses ◽  
Brittle Deformation ◽  
Outlet Glacier ◽  
Ice Cap ◽  
Show Evidence ◽  
Sediment Deformation ◽  
Basal Shear ◽  
Clay Lenses ◽  
Glacier Motion

AbstractA study employing macro- and micro-sedimentological techniques was conducted at three sites with recently deglaciated sediments in the proglacial area of Brúarjökull, a surge-type outlet glacier of the Vatnajökull ice cap, Iceland. Tills at these sites were likely deposited and deformed during the 1963/64 surge. At the height of the last surge, these sediments were beneath 90-120 m of ice, and associated basal shear stresses would have been 24-32 kPa. Tills associated with the surge at these sites formed by a combination of subglacial sediment deformation and lodgement and are thus regarded as ‘hybrid tills’. The tills show evidence of both ductile and brittle deformation. Discontinuous clay lenses within the tills, indicating local ice-bed decoupling and sliding, imply that subglacial water pressures were spatially and temporally variable during the surge. The thickness of the subglacial deforming-till layer was 50-90 cm.

scholarly journals Carbon–Concentration and Carbon–Climate Feedbacks in CMIP5 Earth System Models

2013 ◽  
Vol 26 (15) ◽  
pp. 5289-5314 ◽  
Author(s):  
Vivek K. Arora ◽  
George J. Boer ◽  
Pierre Friedlingstein ◽  
Michael Eby ◽  
Chris D. Jones ◽  
...  
Keyword(s):  
Carbon Concentration ◽  
Coupled Model ◽  
Co2 Flux ◽  
Co2 Concentration ◽  
Climate System ◽  
Climate Feedback ◽  
Earth System ◽  
System Models ◽  
Common Framework ◽  
Earth System Models

Abstract The magnitude and evolution of parameters that characterize feedbacks in the coupled carbon–climate system are compared across nine Earth system models (ESMs). The analysis is based on results from biogeochemically, radiatively, and fully coupled simulations in which CO2 increases at a rate of 1% yr−1. These simulations are part of phase 5 of the Coupled Model Intercomparison Project (CMIP5). The CO2 fluxes between the atmosphere and underlying land and ocean respond to changes in atmospheric CO2 concentration and to changes in temperature and other climate variables. The carbon–concentration and carbon–climate feedback parameters characterize the response of the CO2 flux between the atmosphere and the underlying surface to these changes. Feedback parameters are calculated using two different approaches. The two approaches are equivalent and either may be used to calculate the contribution of the feedback terms to diagnosed cumulative emissions. The contribution of carbon–concentration feedback to diagnosed cumulative emissions that are consistent with the 1% increasing CO2 concentration scenario is about 4.5 times larger than the carbon–climate feedback. Differences in the modeled responses of the carbon budget to changes in CO2 and temperature are seen to be 3–4 times larger for the land components compared to the ocean components of participating models. The feedback parameters depend on the state of the system as well the forcing scenario but nevertheless provide insight into the behavior of the coupled carbon–climate system and a useful common framework for comparing models.

scholarly journals Analysis of the first jökulhlaup at Blåmannsisen, northern Norway, and implications for future events

2005 ◽  
Vol 42 ◽  
pp. 35-41 ◽  
Author(s):  
Rune Verpe Engeset ◽  
Thomas Vikhamar Schuler ◽  
Miriam Jackson
Keyword(s):  
Water Levels ◽  
Pressure Measurements ◽  
Negative Mass ◽  
Overburden Pressure ◽  
Northern Norway ◽  
Ice Cap ◽  
Lake Volume ◽  
Show Evidence ◽  
Future Events ◽  
Hydropower Reservoir

AbstractThe first known jökulhlaup from the Blåmannsisen ice cap in northern Norway began on 6 September 2001. It lasted 35 hours and emptied the lake Øvre Messingmalmvatn (∼4.0 × 107m3). Before the event, the lake drained steadily via a rock spillway into Sweden. The water from the jökulhlaup drained into the hydropower reservoir Sisovatn, and so was financially beneficial to Norway. Glaciological data show evidence of glacier retreat and thinning during the last four decades. Glacier thickness decreased in the ablation zone, reducing ice-barrier stability. The lake drained at a water level 40 m below that required to equalize the ice overburden pressure. Measurements show an ice-barrier thinning of 3.5 m since the jökulhlaup occurred. Climate scenarios indicate future negative mass balance and further thinning. The lake volume was 82% full 2.5 years after the event, suggesting a probable repeat interval of 3 years. Future jökulhlaups may be triggered at lower water levels and produce lower discharges.

scholarly journals Climate-driven chemistry and aerosol feedbacks in CMIP6 Earth system models

2020 ◽  
Author(s):  
Gillian Thornhill ◽  
William Collins ◽  
Dirk Olivié ◽  
Alex Archibald ◽  
Susanne Bauer ◽  
...  
Keyword(s):  
Organic Aerosol ◽  
Methane Emissions ◽  
Climate Feedback ◽  
Earth System ◽  
Positive Feedbacks ◽  
System Models ◽  
State Variable ◽  
Biogenic Voc ◽  
Reactive Gases ◽  
Earth System Models

Abstract. Feedbacks play a fundamental role in determining the magnitude of the response of the climate system to external forcing, such as from anthropogenic emissions. The latest generation of Earth system models include aerosol and chemistry components that interact with each other and with the biosphere. These interactions introduce a complex web of feedbacks which it is important to understand and quantify. This paper addresses the multiple pathways for aerosol and chemical feedbacks in Earth system models. This is achieved by extending previous formalisms which include CO2 concentrations as a state variable to a formalism which in principle includes the concentrations of all climate-active atmospheric constituents. This framework is demonstrated by applying it to the Earth system models participating in CMIP6 with a focus on the non-CO2 reactive gases and aerosols (methane, ozone, sulphate aerosol, organic aerosol and dust). We find that the overall climate feedback through chemistry and aerosols is negative in the CMIP6 Earth system models due to increased negative forcing from aerosols with warmer temperatures. Through diagnosing changes in methane emissions and lifetime we find that if Earth system models were to allow methane to vary interactively, methane positive feedbacks (principally wetland methane emissions and biogenic VOC emissions) would offset much of the aerosol feedbacks.

scholarly journals A Recent Systematic Increase in Vapor Pressure Deficit over Tropical South America

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Armineh Barkhordarian ◽  
Sassan S. Saatchi ◽  
Ali Behrangi ◽  
Paul C. Loikith ◽  
Carlos R. Mechoso
Keyword(s):  
South America ◽  
Vapor Pressure ◽  
Vapor Pressure Deficit ◽  
Climate Feedback ◽  
Evaporative Fraction ◽  
Surface Energy Fluxes ◽  
Detection Analysis ◽  
Attribution Analysis ◽  
Positive Climate ◽  
Tropical South America

Abstract We show a recent increasing trend in Vapor Pressure Deficit (VPD) over tropical South America in dry months with values well beyond the range of trends due to natural variability of the climate system defined in both the undisturbed Preindustrial climate and the climate over 850–1850 perturbed with natural external forcing. This trend is systematic in the southeast Amazon but driven by episodic droughts (2005, 2010, 2015) in the northwest, with the highest recoded VPD since 1979 for the 2015 drought. The univariant detection analysis shows that the observed increase in VPD cannot be explained by greenhouse-gas-induced (GHG) radiative warming alone. The bivariate attribution analysis demonstrates that forcing by elevated GHG levels and biomass burning aerosols are attributed as key causes for the observed VPD increase. We further show that There is a negative trend in evaporative fraction in the southeast Amazon, where lack of atmospheric moisture, reduced precipitation together with higher incoming solar radiation (~7% decade−1 cloud-cover reduction) influences the partitioning of surface energy fluxes towards less evapotranspiration. The VPD increase combined with the decrease in evaporative fraction are the first indications of positive climate feedback mechanisms, which we show that will continue and intensify in the course of unfolding anthropogenic climate change.

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