#Rivers across the #Siberian #Arctic unearth the #patterns of #carbon #release from thawing #permafrost (Proc Natl Acad Sci USA, abstract)

[Source: Proceedings of the National Academy of Sciences of the United States of America, full page: (LINK). Abstract, edited.]

Rivers across the Siberian Arctic unearth the patterns of carbon release from thawing permafrost

Birgit Wild, August Andersson, Lisa Bröder, Jorien Vonk, Gustaf Hugelius, James W. McClelland, Wenjun Song, Peter A. Raymond, and Örjan Gustafsson

PNAS first published May 6, 2019 / DOI: https://doi.org/10.1073/pnas.1811797116

Edited by Mark H. Thiemens, University of California, San Diego, La Jolla, CA, and approved March 26, 2019 (received for review July 9, 2018)

 

Significance

High-latitude permafrost and peat deposits contain a large reservoir of dormant carbon that, upon warming, may partly degrade to CO2 and CH4 at site and may partly enter rivers. Given the scale and heterogeneity of the Siberian Arctic, continent-wide patterns of thaw and remobilization have been challenging to constrain. This study combines a decade-long observational record of 14C in organic carbon of four large Siberian rivers with an extensive 14C source fingerprint database into a statistical model to provide a quantitative partitioning of the fraction of fluvially mobilized organic carbon that specifically stems from permafrost and peat deposits, and separately for dissolved and particulate vectors, across the Siberian Arctic, revealing distinct spatial and seasonal system patterns in carbon remobilization.

 

Abstract

Climate warming is expected to mobilize northern permafrost and peat organic carbon (PP-C), yet magnitudes and system specifics of even current releases are poorly constrained. While part of the PP-C will degrade at point of thaw to CO2 and CH4 to directly amplify global warming, another part will enter the fluvial network, potentially providing a window to observe large-scale PP-C remobilization patterns. Here, we employ a decade-long, high-temporal resolution record of 14C in dissolved and particulate organic carbon (DOC and POC, respectively) to deconvolute PP-C release in the large drainage basins of rivers across Siberia: Ob, Yenisey, Lena, and Kolyma. The 14C-constrained estimate of export specifically from PP-C corresponds to only 17 ± 8% of total fluvial organic carbon and serves as a benchmark for monitoring changes to fluvial PP-C remobilization in a warming Arctic. Whereas DOC was dominated by recent organic carbon and poorly traced PP-C (12 ± 8%), POC carried a much stronger signature of PP-C (63 ± 10%) and represents the best window to detect spatial and temporal dynamics of PP-C release. Distinct seasonal patterns suggest that while DOC primarily stems from gradual leaching of surface soils, POC reflects abrupt collapse of deeper deposits. Higher dissolved PP-C export by Ob and Yenisey aligns with discontinuous permafrost that facilitates leaching, whereas higher particulate PP-C export by Lena and Kolyma likely echoes the thermokarst-induced collapse of Pleistocene deposits. Quantitative 14C-based fingerprinting of fluvial organic carbon thus provides an opportunity to elucidate large-scale dynamics of PP-C remobilization in response to Arctic warming.

carbon cycle – climate change – radiocarbon – peat – leaching

Keywords: Climate Change; Global Warming; Permafrost; Russia.

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Forty-six years of #Greenland #IceSheet #mass balance from 1972 to 2018 (Proc Natl Acad Sci USA, abstract)

[Source: Proceedings of the National Academy of Sciences of the United States of America, full page: (LINK). Abstract, edited.]

Forty-six years of Greenland Ice Sheet mass balance from 1972 to 2018

Jérémie Mouginot, Eric Rignot, Anders A. Bjørk, Michiel van den Broeke, Romain Millan, Mathieu Morlighem, Brice Noël, Bernd Scheuchl, and Michael Wood

PNAS first published April 22, 2019 / DOI: https://doi.org/10.1073/pnas.1904242116

Edited by Mark H. Thiemens, University of California, San Diego, La Jolla, CA, and approved March 20, 2019 (received for review July 31, 2018)

 

Significance

We reconstruct the mass balance of the Greenland Ice Sheet for the past 46 years by comparing glacier ice discharge into the ocean with interior accumulation of snowfall from regional atmospheric climate models over 260 drainage basins. The mass balance started to deviate from its natural range of variability in the 1980s. The mass loss has increased sixfold since the 1980s. Greenland has raised sea level by 13.7 mm since 1972, half during the last 8 years.

 

Abstract

We reconstruct the mass balance of the Greenland Ice Sheet using a comprehensive survey of thickness, surface elevation, velocity, and surface mass balance (SMB) of 260 glaciers from 1972 to 2018. We calculate mass discharge, D, into the ocean directly for 107 glaciers (85% of D) and indirectly for 110 glaciers (15%) using velocity-scaled reference fluxes. The decadal mass balance switched from a mass gain of +47 ± 21 Gt/y in 1972–1980 to a loss of 51 ± 17 Gt/y in 1980–1990. The mass loss increased from 41 ± 17 Gt/y in 1990–2000, to 187 ± 17 Gt/y in 2000–2010, to 286 ± 20 Gt/y in 2010–2018, or sixfold since the 1980s, or 80 ± 6 Gt/y per decade, on average. The acceleration in mass loss switched from positive in 2000–2010 to negative in 2010–2018 due to a series of cold summers, which illustrates the difficulty of extrapolating short records into longer-term trends. Cumulated since 1972, the largest contributions to global sea level rise are from northwest (4.4 ± 0.2 mm), southeast (3.0 ± 0.3 mm), and central west (2.0 ± 0.2 mm) Greenland, with a total 13.7 ± 1.1 mm for the ice sheet. The mass loss is controlled at 66 ± 8% by glacier dynamics (9.1 mm) and 34 ± 8% by SMB (4.6 mm). Even in years of high SMB, enhanced glacier discharge has remained sufficiently high above equilibrium to maintain an annual mass loss every year since 1998.

Greenland – glaciology – sea level – climate change – glaciers

Keywords: Climate Change; Global Warming; Greenland.

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#Globalwarming has increased global #economic #inequality (Proc Natl Acad Sci USA, abstract)

[Source: Proceedings of the National Academy of Sciences of the United States of America, full page: (LINK). Abstract, edited.]

Global warming has increased global economic inequality

Noah S. Diffenbaugh and Marshall Burke

PNAS first published April 22, 2019 / DOI: https://doi.org/10.1073/pnas.1816020116

Edited by Ottmar Edenhofer, Potsdam Institute for Climate Impact Research, Potsdam, Germany, and accepted by Editorial Board Member Hans J. Schellnhuber

March 22, 2019 (received for review September 16, 2018)

 

Significance

We find that global warming has very likely exacerbated global economic inequality, including ∼25% increase in population-weighted between-country inequality over the past half century. This increase results from the impact of warming on annual economic growth, which over the course of decades has accumulated robust and substantial declines in economic output in hotter, poorer countries—and increases in many cooler, wealthier countries—relative to a world without anthropogenic warming. Thus, the global warming caused by fossil fuel use has likely exacerbated the economic inequality associated with historical disparities in energy consumption. Our results suggest that low-carbon energy sources have the potential to provide a substantial secondary development benefit, in addition to the primary benefits of increased energy access.

 

Abstract

Understanding the causes of economic inequality is critical for achieving equitable economic development. To investigate whether global warming has affected the recent evolution of inequality, we combine counterfactual historical temperature trajectories from a suite of global climate models with extensively replicated empirical evidence of the relationship between historical temperature fluctuations and economic growth. Together, these allow us to generate probabilistic country-level estimates of the influence of anthropogenic climate forcing on historical economic output. We find very high likelihood that anthropogenic climate forcing has increased economic inequality between countries. For example, per capita gross domestic product (GDP) has been reduced 17–31% at the poorest four deciles of the population-weighted country-level per capita GDP distribution, yielding a ratio between the top and bottom deciles that is 25% larger than in a world without global warming. As a result, although between-country inequality has decreased over the past half century, there is ∼90% likelihood that global warming has slowed that decrease. The primary driver is the parabolic relationship between temperature and economic growth, with warming increasing growth in cool countries and decreasing growth in warm countries. Although there is uncertainty in whether historical warming has benefited some temperate, rich countries, for most poor countries there is >90% likelihood that per capita GDP is lower today than if global warming had not occurred. Thus, our results show that, in addition to not sharing equally in the direct benefits of fossil fuel use, many poor countries have been significantly harmed by the warming arising from wealthy countries’ energy consumption.

economic inequality – global warming – climate change attribution – CMIP5

Keywords: Climate Change; Global Warming; Society; Poverty.

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#Climatechange and #lung #health: #presidential #failure, professional responsibility (Thorax, summary)

[Source: Thorax, full page: (LINK). Summary, edited.]

Editorial

Climate change and lung health: presidential failure, professional responsibility

Nicholas S Hopkinson 1, Nicholas Hart 2, Gisli Jenkins 3, Margaret Rosenfeld 4, Alan Robert Smyth 5, Alexander J K Wilkinson 6, Naftali Kaminski 7

Author affiliations: {1} National Heart and Lung Institute, Royal Brompton and Harefield NHS Foundation Trust and Imperial College, London, UK; {2} Lane Fox Respiratory Service, Guy’s & St Thomas’ NHS Foundation Trust, London, UK; {3} Centre for Respiratory Research, University of Nottingham, Nottingham, UK; {4} Pulmonary Medicine, Seattle Children’s Hospital, Seattle, Washington, USA; {5} Division of Child Health, Obstetrics & Gynaecology, University of Nottingham, Nottingham, UK; {6} Respiratory Department, East and North Hertfordshire NHS Trust, Stevenage, UK; {7} Yale School of Medicine Shield Education Patient Care Research Internal Medicine, Yale School of Medicine Shield Education Patient Care Research, New Haven, Connecticut, USA

Correspondence to Dr Nicholas S Hopkinson, National Heart and Lung Institute, Royal Brompton and Harefield NHS Foundation Trust and Imperial College, London SW3 6NP, UK; n.hopkinson@ic.ac.uk

DOI: http://dx.doi.org/10.1136/thoraxjnl-2019-213184

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Ignorance, allied with power, is the most ferocious enemy justice can have. James Baldwin

On the eve of President Trump’s inauguration in 2017, we published an editorial setting out the threat that climate change poses to lung health. We urged the incoming President to face up to his responsibilities and take steps to address this growing existential threat.1 We drew a parallel with the actions of two conservative leaders in the 1980s, Ronald Reagan and Margaret Thatcher who, faced with unequivocal scientific evidence, led the decisive steps necessary to avert the destruction of the ozone layer.2 3 Rather than being contrary to his stated goals, acting on climate change, we wrote ‘is one way in which President Trump can make good on his promises to improve the wellbeing of Americans, increase America’s energy independence, and act with fiscal prudence. Investing in green infrastructure creates jobs. It reduces healthcare costs, as 1/4 – 1/3 of the costs of decarbonising come straight back as health economic gains’.4

(…)

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Copyright information:  © Author(s) (or their employer(s)) 2019. No commercial re-use. See rights and permissions. Published by BMJ.

Keywords: Climate Change; Global Warmings; Public Health; Society.

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#Global #expansion and redistribution of #Aedes-borne #virus transmission #risk with #climatechange (PLoS Negl Trop Dis., abstract)

[Source: PLoS Neglected Tropical Diseases, full page: (LINK). Abstract, edited.]

OPEN ACCESS /  PEER-REVIEWED / RESEARCH ARTICLE

Global expansion and redistribution of Aedes-borne virus transmission risk with climate change

Sadie J. Ryan  , Colin J. Carlson , Erin A. Mordecai, Leah R. Johnson

Published: March 28, 2019 / DOI: https://doi.org/10.1371/journal.pntd.0007213

 

Abstract

Forecasting the impacts of climate change on Aedes-borne viruses—especially dengue, chikungunya, and Zika—is a key component of public health preparedness. We apply an empirically parameterized model of viral transmission by the vectors Aedes aegypti and Ae. albopictus, as a function of temperature, to predict cumulative monthly global transmission risk in current climates, and compare them with projected risk in 2050 and 2080 based on general circulation models (GCMs). Our results show that if mosquito range shifts track optimal temperature ranges for transmission (21.3–34.0°C for Ae. aegypti; 19.9–29.4°C for Ae. albopictus), we can expect poleward shifts in Aedes-borne virus distributions. However, the differing thermal niches of the two vectors produce different patterns of shifts under climate change. More severe climate change scenarios produce larger population exposures to transmission by Ae. aegypti, but not by Ae. albopictus in the most extreme cases. Climate-driven risk of transmission from both mosquitoes will increase substantially, even in the short term, for most of Europe. In contrast, significant reductions in climate suitability are expected for Ae. albopictus, most noticeably in southeast Asia and west Africa. Within the next century, nearly a billion people are threatened with new exposure to virus transmission by both Aedesspp. in the worst-case scenario. As major net losses in year-round transmission risk are predicted for Ae. albopictus, we project a global shift towards more seasonal risk across regions. Many other complicating factors (like mosquito range limits and viral evolution) exist, but overall our results indicate that while climate change will lead to increased net and new exposures to Aedes-borne viruses, the most extreme increases in Ae. albopictus transmission are predicted to occur at intermediate climate change scenarios.

 

Author summary

The established scientific consensus indicates that climate change will severely exacerbate the risk and burden of Aedes-transmitted viruses, including dengue, chikungunya, Zika, and other significant threats to global health security. Here, we show more subtle impacts of climate change on transmission, caused primarily by differences between the more heat-tolerant Aedes aegypti and the more heat-limited Ae. albopictus. Within the next century, nearly a billion people could face their first exposure to viral transmission from either mosquito in the worst-case scenario, mainly in Europe and high-elevation tropical and subtropical regions. However, while year-round transmission potential from Ae. aegypti is likely to expand (particularly in south Asia and sub-Saharan Africa), Ae. albopictus transmission potential is likely to decline substantially in the tropics, marking a global shift towards seasonal risk as the tropics eventually become too hot for transmission by Ae. albopictus. Complete mitigation of climate change to a pre-industrial baseline may protect almost a billion people from arbovirus range expansions; however, middle-of-the-road mitigation could produce the greatest expansion in the potential for viral transmission by Ae. albopictus. In any scenario, mitigating climate change would shift the projected burden of both dengue and chikungunya (and potentially other Aedes transmitted viruses) from higher-income regions back onto the tropics, where transmission might otherwise begin to decline due to rising temperatures.

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Citation: Ryan SJ, Carlson CJ, Mordecai EA, Johnson LR (2019) Global expansion and redistribution of Aedes-borne virus transmission risk with climate change. PLoS Negl Trop Dis 13(3): e0007213. https://doi.org/10.1371/journal.pntd.0007213

Editor: Barbara A. Han, Cary Institute of Ecosystem Studies, UNITED STATES

Received: September 11, 2018; Accepted: February 4, 2019; Published: March 28, 2019

Copyright: © 2019 Ryan et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Data Availability: All relevant data are within the manuscript and its Supporting Information files.

Funding: This work was funded by the National Science Foundation (DEB-1518681 to SJR, LRJ, EAM, NSF DEB-1641145 to SJR, and DEB-1640780 to EAM), and CDC grant 1U01CK000510-01: Southeastern Regional Center of Excellence in Vector-Borne Diseases: the Gateway Program, to SJR. This publication was supported by the Cooperative Agreement Number above from the Centers for Disease Control and Prevention. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the Centers for Disease Control and Prevention. Support was also provided by the Stanford Woods Institute for the Environment (https:// woods.stanford.edu/research/environmental- venture-projects), and the Stanford Center for Innovation in Global Health (http://globalhealth. stanford.edu/research/seed-grants.html). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing interests: The authors have declared that no competing interests exist.

Keywords: Arbovirus; Aedes spp.; Aedes aegypti; Aedes albopictus; Climate change; Global warming.

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Effects of #fossil #fuel and total #anthropogenic #emission removal on #publichealth and #climate (Proc Natl Acad Sci USA, abstract)

[Source: Proceedings of the National Academy of Sciences of the United States of America, full page: (LINK). Abstract, edited.]

Effects of fossil fuel and total anthropogenic emission removal on public health and climate

J. Lelieveld, K. Klingmüller, A. Pozzer, R. T. Burnett, A. Haines, and V. Ramanathan

PNAS published ahead of print March 25, 2019 / DOI: https://doi.org/10.1073/pnas.1819989116

Edited by Susan Solomon, Massachusetts Institute of Technology, Cambridge, MA, and approved February 27, 2019 (received for review November 27, 2018)

 

Significance

We assessed the effects of air pollution and greenhouse gases on public health, climate, and the hydrologic cycle. We combined a global atmospheric chemistry–climate model with air pollution exposure functions, based on an unmatched large number of cohort studies in many countries. We find that fossil-fuel-related emissions account for about 65% of the excess mortality rate attributable to air pollution, and 70% of the climate cooling by anthropogenic aerosols. We conclude that to save millions of lives and restore aerosol-perturbed rainfall patterns, while limiting global warming to 2 °C, a rapid phaseout of fossil-fuel-related emissions and major reductions of other anthropogenic sources are needed.

 

Abstract

Anthropogenic greenhouse gases and aerosols are associated with climate change and human health risks. We used a global model to estimate the climate and public health outcomes attributable to fossil fuel use, indicating the potential benefits of a phaseout. We show that it can avoid an excess mortality rate of 3.61 (2.96–4.21) million per year from outdoor air pollution worldwide. This could be up to 5.55 (4.52–6.52) million per year by additionally controlling nonfossil anthropogenic sources. Globally, fossil-fuel-related emissions account for about 65% of the excess mortality, and 70% of the climate cooling by anthropogenic aerosols. The chemical influence of air pollution on aeolian dust contributes to the aerosol cooling. Because aerosols affect the hydrologic cycle, removing the anthropogenic emissions in the model increases rainfall by 10–70% over densely populated regions in India and 10–30% over northern China, and by 10–40% over Central America, West Africa, and the drought-prone Sahel, thus contributing to water and food security. Since aerosols mask the anthropogenic rise in global temperature, removing fossil-fuel-generated particles liberates 0.51(±0.03) °C and all pollution particles 0.73(±0.03) °C warming, reaching around 2 °C over North America and Northeast Asia. The steep temperature increase from removing aerosols can be moderated to about 0.36(±0.06) °C globally by the simultaneous reduction of tropospheric ozone and methane. We conclude that a rapid phaseout of fossil-fuel-related emissions and major reductions of other anthropogenic sources are needed to save millions of lives, restore aerosol-perturbed rainfall patterns, and limit global warming to 2 °C.

air pollution – greenhouse gases – health impacts – climate change – hydrologic cycle

Keywords: Climate Change; Global Warming; Environmental disasters; Public Health.

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#Emerging #arboviruses of medical importance in the #Mediterranean region (J Clin Virol., abstract)

[Source: Journal of Clinical Virology, full page: (LINK). Abstract, edited.]

Journal of Clinical Virology / Available online 16 March 2019 / In Press, Accepted Manuscript

Emerging arboviruses of medical importance in the Mediterranean region

Anna Papa, Department of Microbiology, Medical School, Aristotle University of Thessaloniki, Thessaloniki, 54124, Greece

Received 12 January 2019, Revised 6 March 2019, Accepted 11 March 2019, Available online 16 March 2019. DOI: https://doi.org/10.1016/j.jcv.2019.03.007

 

Highlights

  • The epidemiology of arboviral infection in the Mediterranean region is changing.
  • 2018 was a record year for West Nile virus infections.
  • Crimean-Congo hemorrhagic fever emerged in the Western Europe.
  • Autochthonous chikungunya and dengue cases occurred in the Mediterranean countries.
  • The “One Health” initiative is required for tackling the emerging diseases.

 

Abstract

The epidemiology of viral infections transmitted by arthropods is changing due to a variety of parameters related to the virus, the host and the environment. The Mediterranean region is highly affected by changes in the intensity and extension of global-scale climate patterns, and, due to its location, provides a vulnerable environment for emergence of arboviral diseases. The main arboviruses that pose currently a public health threat in the Mediterranean region are West Nile virus and Crimean-Congo hemorrhagic fever virus and, in less extend, tick-borne encephalitis virus. Usutu virus that affects mainly birds can infect also humans, while Dengue and Chikungunya viruses showed that they are capable to cause sporadic autochthonous cases, and even outbreaks in the Mediterranean region. Sandly-transmitted viruses continue to have a public health impact, and novel ones have been identified. The presence of competent vectors (mainly mosquitoes), combined by arbovirus introduction through viremic travelers returning from endemic regions, prompt for increased surveillance to mitigate the risk for local transmission. In order to tackle efficiently and effectively the emerging arboviral diseases, an integrated “One Health initiative” is required to be maintained, involving public health, animal health and environmental authorities. Awareness of medical and veterinary staff and laboratory capacity are crucial for the early detection of pathogens, while reporting the unusual and enhance surveillance are important.

Keywords: Arbovirus – Mediterranean countries – Emerging – Humans

© 2019 Elsevier B.V. All rights reserved.

Keywords: Arbovirus; Climate Change; European Region; Chikungunya fever; Dengue fever; Zika Virus; WNV; CCHF.

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#Climate #change and climate change #velocity #analysis across #Germany (Sci Rep., abstract)

[Source: Scientific Reports, full page: (LINK). Abstract, edited.]

Article | OPEN | Published: 18 February 2019

Climate change and climate change velocity analysis across Germany

A. Kosanic, I. Kavcic, M. van Kleunen & S. Harrison

Scientific Reports, volume 9, Article number: 2196 (2019)

 

Abstract

Although there are great concerns to what extent current and future climate change impacts biodiversity across different spatial and temporal scales, we still lack a clear information on different climate change metrics across fine spatial scales. Here we present an analysis of climate change and climate change velocity at a local scale (1 × 1 km) across Germany. We focus on seasonal climate variability and velocity and investigate changes in three time periods (1901–2015, 1901–1950 and 1951–2015) using a novel statistical approach. Our results on climate variability showed the highest trends for the 1951–2015 time period. The strongest (positive/negative) and spatially the most dispersed trends were found for Summer maximum temperature and Summer minimum temperatures. For precipitation the strongest positive trends were most pronounced in the summer (1951–2015) and winter (1901–2015). Results for climate change velocity showed that almost 90% of temperature velocities were in the range of 0.5 to 3 km/year, whereas all climate velocities for precipitation were within the range of −3.5 to 4.5 km/year. The key results amplify the need for more local and regional scale studies to better understand species individualistic responses to recent climate change and allow for more accurate future projections and conservation strategies.

Keywords: Climate Change; Germany.

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#Economic #aspects of the #deployment of #fusion #energy: the valley of death and the innovation cycle (Phil Transact Roy Soc., abstract)

[Source: Philosophical Transactions of the Royal Society, full page: (LINK). Abstract, edited.]

Economic aspects of the deployment of fusion energy: the valley of death and the innovation cycle

N. J. Lopes Cardozo

Published: 04 February 2019 / DOI: https://doi.org/10.1098/rsta.2017.0444

 

Abstract

The speed at which fusion energy can be deployed is considered. Several economical factors are identified that impede this speed. Most importantly, the combination of an unprecedentedly high investment level needed for the proof of principle and the relatively long construction time of fusion plants precludes an effective innovation cycle. The valley of death is discussed, i.e. the period when a large investment is needed for the construction of early generations of fusion reactors, when there is no return yet. It is concluded that, within the mainstream scenario—a few DEMO reactors towards 2060 followed by generations of relatively large reactors—there is no realistic path to an appreciable contribution to the energy mix in the twenty-first century if economic constraints are applied. In other words, fusion will not contribute to the energy transition in the time frame of the Paris climate agreement. Within the frame of this analysis, the development of smaller, cheaper and most importantly, fast-to-build fusion plants could possibly represent an option to accelerate the introduction of fusion power. Whether this is possible is a technical question that is outside the scope of this paper, but this question is addressed in other contributions to the Royal Society workshop.

This article is part of a discussion meeting issue ‘Fusion energy using tokamaks: can development be accelerated?’.

Keywords: Fusion Energy; Renewable energy; Climate Change.

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#Global environmental #consequences of 21rst-century #icesheet #melt (Nature, abstract)

[Source: Nature, full page: (LINK). Abstract, edited.]

Global environmental consequences of twenty-first-century ice-sheet melt

Nicholas R. Golledge, Elizabeth D. Keller, Natalya Gomez, Kaitlin A. Naughten, Jorge Bernales, Luke D. Trusel & Tamsin L. Edwards

Nature, volume 566, pages65–72 (2019)

 

Abstract

Government policies currently commit us to surface warming of three to four degrees Celsius above pre-industrial levels by 2100, which will lead to enhanced ice-sheet melt. Ice-sheet discharge was not explicitly included in Coupled Model Intercomparison Project phase 5, so effects on climate from this melt are not currently captured in the simulations most commonly used to inform governmental policy. Here we show, using simulations of the Greenland and Antarctic ice sheets constrained by satellite-based measurements of recent changes in ice mass, that increasing meltwater from Greenland will lead to substantial slowing of the Atlantic overturning circulation, and that meltwater from Antarctica will trap warm water below the sea surface, creating a positive feedback that increases Antarctic ice loss. In our simulations, future ice-sheet melt enhances global temperature variability and contributes up to 25 centimetres to sea level by 2100. However, uncertainties in the way in which future changes in ice dynamics are modelled remain, underlining the need for continued observations and comprehensive multi-model assessments.

 

Data availability

CMIP5 data were downloaded from http://climexp.knmi.nl/. Antarctic bedrock topography and ice thickness data are from the BEDMAP2 compilation, available at https://secure.antarctica.ac.uk/data/bedmap2/. Greenland topography and ice thickness data are from BedMachine v3, available at https://nsidc.org/data/idbmg4. Greenland mass balance and geothermal heat flux data are available from the seaRISE website: http://websrv.cs.umt.edu/isis/index.php/Data. Information on Antarctic surface mass balance data are available at http://www.projects.science.uu.nl/iceclimate/models/antarctica.php#racmo23. Antarctic geothermal heat flux data are available at https://doi.pangaea.de/10.1594/PANGAEA.882503. Drainage basin outlines as shown in Fig. 3 are based on ICESat data96. Antarctic grounding lines and calving lines shown in Fig. 3a are from the MODIS-MOA 2009 dataset97,98. The datasets generated and analysed during this study are also available from the corresponding author on reasonable request.

 

Additional information

Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Keywords: Climate Change; Global Warming.

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