| 1. |
- Walker, Donald A., et al.
(author)
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Cumulative Effects of Rapid Land-Cover and Land-Use Changes on the Yamal Peninsula, Russia
- 2011
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In: Eurasian Arctic Land Cover and Land Use in a Changing Climate. - New York : Springer Netherlands. - 9789048191178 - 9789048191185 ; , s. 207-236
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Book chapter (other academic/artistic)abstract
- The Yamal Peninsula in northwest Siberia is undergoing some of the most rapid land-cover and land-use changes in the Arctic due to a combination of gas development, reindeer herding, and climate change. Unusual geological conditions (nutrient-poor sands, massive ground ice and extensive landslides) exacerbate the impacts. These changes will likely increase markedly as transportation corridors are built to transport the gas to market. Understanding the nature, extent, causes and consequences (i.e., the cumulative effects) of the past and ongoing rapid changes on the Yamal is important for effective, long-term decision-making and planning. The cumulative effects to vegetation are the focus of this chapter because the plants are a critical component of the Yamal landscape that support the indigenous Nenets people and their reindeer and also protect the underlying ice-rich permafrost from melting. We are using a combination of ground-based studies (a transect of live locations across the Yamal), remote-sensing studies, and analyses of Nenets land-use activities to develop vegetation-change models that can be used to help anticipate future states of the tundra and how those changes might affect traditional reindeer herding practices and the thermal state of the permafrost. This chapter provides an overview of the approach, some early results, and recommendations for expanding the concept of cumulative-effects analysis to include examining the simultaneous and interactive effects of multiple drivers of change.
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| 2. |
- Boyle, John F., et al.
(author)
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Modelling prehistoric land-use and carbon budgets: a critical review
- 2011
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In: The Holocene. - : SAGE Publications. - 0959-6836 .- 1477-0911. ; 21:5, s. 715-722
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Journal article (peer-reviewed)abstract
- An evaluation of modelled estimates for C release following early land clearance at the global level based on new model assumptions suggests that earlier studies may have underestimated its magnitude, chiefly because of underestimation of the mid-Holocene global population. Alternative information sources for population and land utilisation support both a greater total CO(2) release and a greater Neolithic contribution. Indeed, we show that the quantity of terrestrial C release due to early farming, even using the most conservative assumptions, greatly exceeds the net terrestrial C release estimated by inverse modelling of ice core data by Elsig et al. (Elsig J, Schmitt J, Leuenberger D, Schneider R, Eyer M, Leuenberger M et al. ( 2009) Stable isotope constraints on Holocene carbon cycle changes from an Antarctic ice core. Nature 461: 507-510), though uncertainty about past global population estimates precludes calculation of a precise value.
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| 3. |
- Büntgen, Ulf, et al.
(author)
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Cooling and societal change during the Late Antique Little Ice Age from 536 to around 660 AD
- 2016
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In: Nature Geoscience. - 1752-0894 .- 1752-0908. ; 9:3, s. 231-236
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Journal article (peer-reviewed)abstract
- Climatic changes during the first half of the Common Era have been suggested to play a role in societal reorganizations in Europe and Asia. In particular, the sixth century coincides with rising and falling civilizations, pandemics, human migration and political turmoil. Our understanding of the magnitude and spatial extent as well as the possible causes and concurrences of climate change during this period is, however, still limited. Here we use tree-ring chronologies from the Russian Altai and European Alps to reconstruct summer temperatures over the past two millennia. We find an unprecedented, long-lasting and spatially synchronized cooling following a cluster of large volcanic eruptions in 536, 540 and 547 AD, which was probably sustained by ocean and sea-ice feedbacks, as well as a solar minimum. We thus identify the interval from 536 to about 660 AD as the Late Antique Little Ice Age. Spanning most of the Northern Hemisphere, we suggest that this cold phase be considered as an additional environmental factor contributing to the establishment of the Justinian plague, transformation of the eastern Roman Empire and collapse of the Sasanian Empire, movements out of the Asian steppe and Arabian Peninsula, spread of Slavic-speaking peoples and political upheavals in China.
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| 4. |
- Büntgen, Ulf, et al.
(author)
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Reply to 'Limited Late Antique cooling'
- 2017
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In: Nature Geoscience. - : Springer Science and Business Media LLC. - 1752-0894 .- 1752-0908. ; 10:4, s. 243-243
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Journal article (other academic/artistic)
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| 5. |
- Fluet-Chouinard, Etienne, et al.
(author)
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Extensive global wetland loss over the past three centuries
- 2023
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In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 614:7947, s. 281-286
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Journal article (peer-reviewed)abstract
- Wetlands have long been drained for human use, thereby strongly affecting greenhouse gas fluxes, flood control, nutrient cycling and biodiversity1,2. Nevertheless, the global extent of natural wetland loss remains remarkably uncertain3. Here, we reconstruct the spatial distribution and timing of wetland loss through conversion to seven human land uses between 1700 and 2020, by combining national and subnational records of drainage and conversion with land-use maps and simulated wetland extents. We estimate that 3.4 million km2 (confidence interval 2.9–3.8) of inland wetlands have been lost since 1700, primarily for conversion to croplands. This net loss of 21% (confidence interval 16–23%) of global wetland area is lower than that suggested previously by extrapolations of data disproportionately from high-loss regions. Wetland loss has been concentrated in Europe, the United States and China, and rapidly expanded during the mid-twentieth century. Our reconstruction elucidates the timing and land-use drivers of global wetland losses, providing an improved historical baseline to guide assessment of wetland loss impact on Earth system processes, conservation planning to protect remaining wetlands and prioritization of sites for wetland restoration4.
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| 6. |
- Gaillard, Marie-José, et al.
(author)
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Has anthropogenic land-cover change been a significant climate forcing in the past? : An assessment for the Baltic Sea catchment area based on a literature review
- 2015
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In: Geophysical Research Abstracts.
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Conference paper (peer-reviewed)abstract
- We reviewed the recent published scientific literature on land cover-climate interactions at the global and regional spatial scales with the aim to assess whether it is convincingly demonstrated that anthropogenic land-cover change (ALCC) has been (over the last centuries and millennia) a significant climate forcing at the global scale, and more specifically at the scale of the Baltic Sea catchment area. The conclusions from this review are as follows: i) anthropogenic land-cover change (ALCC) is one of the few climate forcings for which the net direction of the climate response in the past is still not known. The uncertainty is due to the often counteracting temperature responses to the many biogeophysical effects, and to the biogeochemical vs biogeophysical effects; ii) there is no indication that deforestation in the Baltic Sea area since AD 1850 would have been a major cause of the recent climate warming in the region through a positive biogeochemical feedback; iii) several model studies suggest that boreal reforestation might not be an effective climate warming mitigation tool as it might lead to increased warming through biogeophysical processes; iv) palaeoecological studies indicate a major transformation of the landscape by anthropogenic activities in the southern zone of the study region occurring between 6000 and 3000/2500 calendar years before present (cal. BP) (1) ; v) the only modelling study so far of the biogeophysical effects of past ALCCs on regional climate in Europe suggests that a deforestation of the magnitude of that reconstructed for the past (between 6000 and 200 cal BP) can produce changes in winter and summer temperatures of +/- 1, the sign of the change depending on the season and the region (2). Thus, if ALCC and their biogeophysical effects did matter in the past, they should matter today and in the future. A still prevailing idea is that planting trees will mitigate climate warming through biogeochemical effects. Therefore, there is still an urgent need to better understand the biogeophysical effects on regional and continental climate of afforestation in the hemiboreal and boreal regions, and their significance in relation to the biogeochemical effects.
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| 7. |
- Gaillard, Marie-José, 1953-, et al.
(author)
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Land cover-climate interactions in the past for the understanding of current and future climate change : the LANDCLIM project
- 2014
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In: Proceedings of the Global Land Project 2nd Open Science Meeting, Berlin,<em> </em>March 19<sup>th</sup> – 21<sup>st</sup>, 2014. - Amsterdam/Berlin/Sao Paulo : Global Land Project. ; , s. 229-230
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Conference paper (other academic/artistic)abstract
- The LANDCLIM (LAND cover – CLIMate interactions in NW Europe during the Holocene) project has the overall aim to quantify human-induced changes in regional vegetation/land-cover in northwestern and western Europe North of the Alps during the Holocene (the last 11 500 years) with the purpose to evaluate and further refine the dynamic vegetation model LPJGUESS and the regional climate model RCA3, and to assess the possible effects on the climate development of two historical processes, i.e. climate-driven changes in vegetation and human-induced changes in land cover, via the influence of forested versus non-forested land cover on shortwave albedo, energy and water fluxes. Accounting for land surface changes may be particularly important for regional climate modeling, as the biophysical feedbacks operate at this scale. The aims of the LANDCLIM project are achieved by applying a model-data comparison scheme. The REVEALS model is used to estimate land cover from pollen data for 10 plant functional types (PFTs) and 5 time windows of the Holocene - modern time, 200 BP, 500 BP, 3000 BP and 6000 BP. The REVEALS estimates are then compared to the LPJGUESS simulations of potential vegetation and with the ALCC scenarios of Kaplan et al. (KK10) and Klein-Goldewijk et al. (HYDE). The alternative descriptions of past land-cover are then used in the regional climate model RCA3 to study the effect of anthropogenic land-cover on climate. The model-simulated climate is finally compared to palaeoclimate proxies other than pollen. The REVEALS estimates demonstrate that the study region was characterized by larger areas of human-induced openland than pollen percentages suggest, and that these areas were already very large by 3000 BP. The KK10 scenarios were found to be closer to the REVEALS estimates than the HYDE scenarios. LPJGUESS simulates potential climate-induced vegetation. The results from the RCA3 runs at 200 BP and 6000 BP using the LPJGUESS and KK10 land-cover descriptions indicate that past human-induced deforestation did produce a decrease in summer temperatures of >0 - 1.5°C due to biogeophysical processes, and that the degree of decrease differed between regions; the effect of human-induced deforestation on winter temperatures was shown to be more complex. The positive property of forests as CO2 sinks is well known. But afforestation (i.e. planting forest) may also have the opposite effect of warming the climate through biogeophysical processes. Careful studies on land cover-climate interactions are essential to understand the net result of all possible processes related to anthropogenic land-cover change so that relevant landscape management can be implemented for mitigation of climate warming.
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| 8. |
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| 9. |
- Hamilton, Douglas S., et al.
(author)
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Impact of Changes to the Atmospheric Soluble Iron Deposition Flux on Ocean Biogeochemical Cycles in the Anthropocene
- 2020
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In: Global Biogeochemical Cycles. - 0886-6236. ; 34:3
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Journal article (peer-reviewed)abstract
- Iron can be a growth‐limiting nutrient for phytoplankton, modifying rates of net primary production, nitrogen fixation, and carbon export ‐ highlighting the importance of new iron inputs from the atmosphere. The bioavailable iron fraction depends on the emission source and the dissolution during transport. The impacts of anthropogenic combustion and land use change on emissions from industrial, domestic, shipping, desert, and wildfire sources suggest that Northern Hemisphere soluble iron deposition has likely been enhanced between 2% and 68% over the Industrial Era. If policy and climate follow the intermediate Representative Concentration Pathway 4.5 trajectory, then results suggest that Southern Ocean (>30°S) soluble iron deposition would be enhanced between 63% and 95% by 2100. Marine net primary productivity and carbon export within the open ocean are most sensitive to changes in soluble iron deposition in the Southern Hemisphere; this is predominantly driven by fire rather than dust iron sources. Changes in iron deposition cause large perturbations to the marine nitrogen cycle, up to 70% increase in denitrification and 15% increase in nitrogen fixation, but only modestly impacts the carbon cycle and atmospheric CO2 concentrations (1–3 ppm). Regionally, primary productivity increases due to increased iron deposition are often compensated by offsetting decreases downstream corresponding to equivalent changes in the rate of phytoplankton macronutrient uptake, particularly in the equatorial Pacific. These effects are weaker in the Southern Ocean, suggesting that changes in iron deposition in this region dominates the global carbon cycle and climate response.
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| 10. |
- Hantson, Stijn, et al.
(author)
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The status and challenge of global fire modelling
- 2016
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In: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 13:11, s. 3359-3375
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Journal article (peer-reviewed)abstract
- Biomass burning impacts vegetation dynamics, biogeochemical cycling, atmospheric chemistry, and climate, with sometimes deleterious socio-economic impacts. Under future climate projections it is often expected that the risk of wildfires will increase. Our ability to predict the magnitude and geographic pattern of future fire impacts rests on our ability to model fire regimes, using either well-founded empirical relationships or process-based models with good predictive skill. While a large variety of models exist today, it is still unclear which type of model or degree of complexity is required to model fire adequately at regional to global scales. This is the central question underpinning the creation of the Fire Model Intercomparison Project (FireMIP), an international initiative to compare and evaluate existing global fire models against benchmark data sets for present-day and historical conditions. In this paper we review how fires have been represented in fire-enabled dynamic global vegetation models (DGVMs) and give an overview of the current state of the art in fire-regime modelling. We indicate which challenges still remain in global fire modelling and stress the need for a comprehensive model evaluation and outline what lessons may be learned from FireMIP.
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