The Arctic cryosphere in the Mid-Pliocene and the future

2008 ◽  
Vol 367 (1886) ◽  
pp. 49-67 ◽  
Author(s):  
Daniel J Lunt ◽  
Alan M Haywood ◽  
Gavin L Foster ◽  
Emma J Stone
Keyword(s):  
Climate Change ◽  
General Circulation ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Circulation Model ◽  
Future Climate ◽  
Arctic Climate ◽  
The Arctic ◽  
Future Climate Change ◽  
The Future

The Mid-Pliocene ( ca 3 Myr ago) was a relatively warm period, with increased atmospheric CO 2 relative to pre-industrial. It has therefore been highlighted as a possible palaeo-analogue for the future. However, changed vegetation patterns, orography and smaller ice sheets also influenced the Mid-Pliocene climate. Here, using a general circulation model and ice-sheet model, we determine the relative contribution of vegetation and soils, orography and ice, and CO 2 to the Mid-Pliocene Arctic climate and cryosphere. Compared with pre-industrial, we find that increased Mid-Pliocene CO 2 contributes 35 per cent, lower orography and ice-sheet feedbacks contribute 42 per cent, and vegetation changes contribute 23 per cent of Arctic temperature change. The simulated Mid-Pliocene Greenland ice sheet is substantially smaller than that of modern, mostly due to the higher CO 2 . However, our simulations of future climate change indicate that the same increase in CO 2 is not sufficient to melt the modern ice sheet substantially. We conclude that, although the Mid-Pliocene resembles the future in some respects, care must be taken when interpreting it as an exact analogue due to vegetation and ice-sheet feedbacks. These act to intensify Mid-Pliocene Arctic climate change, and act on a longer time scale than the century scale usually addressed in future climate prediction.

Evaluation of climate change impacts and adaptation strategies for maize cultivation in the Himalayan foothills of India

2015 ◽  
Vol 6 (3) ◽  
pp. 596-614 ◽  
Author(s):  
Proloy Deb ◽  
Anthony S. Kiem ◽  
Mukand S. Babel ◽  
Sang Thi Chu ◽  
Biplab Chakma
Keyword(s):  
Climate Change ◽  
General Circulation ◽  
Circulation Model ◽  
Maize Yield ◽  
Future Climate ◽  
Future Climate Change ◽  
Daily Maximum ◽  
Study Region ◽  
Supplementary Irrigation ◽  
The Future

This study evaluates the impacts of climate change on rainfed maize (Zea mays) yield and evaluates different agro-adaptation measures to counteract its negative impacts at Sikkim, a Himalayan state of India. Future climate scenarios for the 10 years centered on 2025, 2055 and 2085 were obtained by downscaling the outputs of the HadCM3 General Circulation Model (GCM) under for A2 and B2 emission scenarios. HadCM3 was chosen after assessing the performance analysis of six GCMs for the study region. The daily maximum and minimum temperatures are projected to rise in the future and precipitation is projected to decrease (by 1.7 to 22.6% relative to the 1991–2000 baseline) depending on the time period and scenarios considered. The crop simulation model CERES-Maize was then used to simulate maize yield under future climate change for the future time windows. Simulation results show that climate change could reduce maize productivity by 10.7–18.2%, compared to baseline yield, under A2 and 6.4–12.4% under B2 scenarios. However, the results also indicate that the projected decline in maize yield could be offset by early planting of seeds, lowering the farm yard manure application rate, introducing supplementary irrigation and shifting to heat tolerant varieties of maize.

Early Holocene ocean conditions off the Zachariæ Isstrøm, Northeast Greenland

2021 ◽  
Author(s):  
Joanna Davies ◽  
Anders Møller Mathiasen ◽  
Kristiane Kristensen ◽  
Christof Pearce ◽  
Marit-Solveig Seidenkrantz
Keyword(s):  
Climate Change ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Atlantic Water ◽  
The Arctic ◽  
Future Climate Change ◽  
Polar Regions ◽  
Ice Shelf ◽  
Outlet Glacier ◽  
The Impact

<p>The polar regions exhibit some of the most visible signs of climate change globally; annual mass loss from the Greenland Ice Sheet (GrIS) has quadrupled in recent decades, from 51 ± 65 Gt yr<sup>−1</sup> (1992-2001) to 211 ± 37 Gt yr<sup>−1</sup> (2002-2011). This can partly be attributed to the widespread retreat and speed-up of marine-terminating glaciers. The Zachariae Isstrøm (ZI) is an outlet glacier of the Northeast Greenland Ice Steam (NEGIS), one of the largest ice streams of the GrIS (700km), draining approximately 12% of the ice sheet interior. Observations show that the ZI began accelerating in 2000, resulting in the collapse of the floating ice shelf between 2002 and 2003. By 2014, the ice shelf extended over an area of 52km<sup>2</sup>, a 95% decrease in area since 2002, where it extended over 1040km<sup>2</sup>. Paleo-reconstructions provide an opportunity to extend observational records in order to understand the oceanic and climatic processes governing the position of the grounding zone of marine terminating glaciers and the extent of floating ice shelves. Such datasets are thus necessary if we are to constrain the impact of future climate change projections on the Arctic cryosphere.</p><p>A multi-proxy approach, involving grain size, geochemical, foraminiferal and sedimentary analysis was applied to marine sediment core DA17-NG-ST8-92G, collected offshore of the ZI, on  the Northeast Greenland Shelf. The aim was to reconstruct changes in the extent of the ZI and the palaeoceanographic conditions throughout the Early to Mid Holocene (c.a. 12,500-5,000 cal. yrs. BP). Evidence from the analysis of these datasets indicates that whilst there has been no grounded ice at the site over the last 12,500 years, the ice shelf of the ZI extended as a floating ice shelf over the site between 12,500 and 9,200 cal. yrs. BP, with the grounding line further inland from our study site. This was followed by a retreat in the ice shelf extent during the Holocene Thermal Maximum; this was likely to have been governed, in part, by basal melting driven by Atlantic Water (AW) recirculated from Svalbard or from the Arctic Ocean. Evidence from benthic foraminifera suggest that there was a shift from the dominance of AW to Polar Water at around 7,500 cal. yrs. BP, although the ice shelf did not expand again despite of this cooling of subsurface waters.</p>

scholarly journals Large and irreversible future decline of the Greenland ice-sheet

2020 ◽  
Author(s):  
Jonathan M. Gregory ◽  
Steven E. George ◽  
Robin S. Smith
Keyword(s):  
Climate Change ◽  
Steady State ◽  
Sea Level ◽  
General Circulation ◽  
Initial Perturbation ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Circulation Model ◽  
Intergovernmental Panel ◽  
Recent Climate

Abstract. We have studied the evolution of the Greenland ice-sheet under a range of constant climates typical of those projected for the end of the present century, using a dynamical ice-sheet model (Glimmer) coupled to an atmospheric general circulation model (FAMOUS-ice AGCM). The ice-sheet surface mass balance (SMB) is simulated by the AGCM, including its dependence on altitude within AGCM gridboxes. Over millennia under a warmer climate, the ice-sheet reaches a new steady state, whose mass is correlated with the initial perturbation in SMB, and hence with the magnitude of global climate change imposed. For the largest global warming considered (about +5 K), the contribution to global-mean sea-level rise (GMSLR) is initially 2.7 mm yr−1, and the ice-sheet is eventually practically eliminated (giving over 7 m of GMSLR). For all RCP8.5 climates, final GMSLR exceeds 4 m. If recent climate were maintained, GMSLR would reach 1.5–2.5 m. Contrary to expectation from earlier work, we find no evidence for a threshold warming that divides scenarios in which the ice-sheet suffers little reduction from those which it is mostly lost. This is because the dominant effect is reduction of area, not reduction of surface altitude, and the geographical variation of SMB must be taken into account. The final steady state is achieved by withdrawal from the coast in some places, and a tendency for increasing SMB due to enhancement of cloudiness and snowfall over the remaining ice-sheet, through the effects of topographic change on atmospheric circulation. If late twentieth-century climate is restored, the ice-sheet will not regrow to its present extent, owing to such effects, once its mass has fallen below a threshold of about 4 m of sea-level equivalent. In that case, about 2 m of GMSLR would become irreversible. In order to avoid this outcome, anthropogenic climate change must be reversed before the ice-sheet has declined to the threshold mass, which would be reached in about 600 years at the highest rate of mass-loss within the likely range of the Fifth Assessment Report of the Intergovernmental Panel on Climate Change.

scholarly journals The relevance of mid-Holocene Arctic warming to the future

2018 ◽  
Author(s):  
Masakazu Yoshimori ◽  
Marina Suzuki
Keyword(s):  
Climate Change ◽  
General Circulation ◽  
General Circulation Models ◽  
Heat Fluxes ◽  
Arctic Climate ◽  
The Arctic ◽  
Future Projections ◽  
Arctic Warming ◽  
The Future ◽  
Arctic Climate Change

Abstract. There remain substantial uncertainties in future projections of Arctic climate change. Schmidt et al. (2014) demonstrated the potential to constrain these uncertainties using a combination of paleoclimate simulations and proxy data. They found a weak correlation between sea ice changes in the mid-Holocene (MH) and in future projections, relative to the modern period. Such an “emergent constraint” provides a powerful tool to directly reduce the range of uncertainty, provided that the necessary paleoenvironmental information is available. In the current study, we examine the relevance of Arctic warming in the past to the future through process understanding, rather than seeking a statistical relation. We conducted a surface energy balance analysis on 10 atmosphere and ocean general circulation models under the MH and future RCP4.5-scenario forcing. We found that many of the dominant processes that amplify Arctic warming from late autumn to winter are common between the two periods, despite the difference in the source of the forcing (insolation vs. greenhouse gases). We also quantified the contribution of individual processes to the inter-model variance in the surface temperature changes. The controlling term varies with the season, but the results suggest that the models’ representations of the surface albedo feedback, cloud greenhouse effect, turbulent surface heat fluxes, and indirect atmospheric stratification are important contributors. Based on the results for the Arctic warming mechanism obtained from this study, we conclude that proxy records of Arctic warming during the MH contain useful information that is relevant for understanding future Arctic climate change.

scholarly journals The response of the Greenland ice sheet to climate changes in the 21st century by interactive coupling of an AOGCM with a thermomechanical ice-sheet model

2002 ◽  
Vol 35 ◽  
pp. 409-415 ◽  
Author(s):  
Philippe Huybrechts ◽  
Ives Janssens ◽  
Chantal Poncin ◽  
Thierry Fichefet
Keyword(s):  
Climate Change ◽  
Sea Ice ◽  
Sea Level Rise ◽  
Sea Level ◽  
Fresh Water ◽  
General Circulation Model ◽  
General Circulation ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Circulation Model

AbstractWe present results from a greenhouse warming experiment obtained from an atmosphere–ocean–sea-ice general circulation model that is interactively coupled with a three-dimensional model of the Greenland ice sheet. the experiment covers the period 1970–2099 and is driven by the mid-range Intergovernmental Panel on Climate Change SRESB2 scenario. the Greenland model is a thermomechanical high-resolution (20 km) model coupled with a viscoelastic bedrock model. the melt-and-runoff model is based on the positive degree-day method and includes meltwater retention in the snowpack and the formation of superimposed ice. the atmospheric–oceanic general circulation model (AOGCM) is a coarse-resolution model without flux correction based on the Laboratoire de Météorologie Dynamique (Paris) LMD 5.3 atmospheric model coupled with a primitive-equation, free-surface oceanic component incorporating sea ice (coupled large-scale ice–ocean (CLIO)). By 2100, average Greenland annual temperature is found to rise by about 4.5˚C and mean precipitation by about 35%. the total fresh-water flux approximately doubles over this period due to increased runoff from the ice sheet and the ice-free land, but the calving rate is found to decrease by 25%. the ice sheet shrinks equivalent to 4 cm of sea-level rise. the contribution from the background evolution is not more than 5% of the total predicted sea-level rise. We did not find significant changes in the patterns of climate change over the North Atlantic region compared with a climate-change run without Greenland fresh-water feedback.

scholarly journals Investigating the sensitivity of numerical model simulations of the modern state of the Greenland ice-sheet and its future response to climate change

2010 ◽  
Vol 4 (3) ◽  
pp. 397-417 ◽  
Author(s):  
E. J. Stone ◽  
D. J. Lunt ◽  
I. C. Rutt ◽  
E. Hanna
Keyword(s):  
Boundary Conditions ◽  
General Circulation ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Circulation Model ◽  
Future Climate ◽  
Ice Thickness ◽  
Climate Scenarios ◽  
Ice Volume ◽  
Ice Surface

Abstract. Ice thickness and bedrock topography are essential boundary conditions for numerical modelling of the evolution of the Greenland ice-sheet (GrIS). The datasets currently in use by the majority of GrIS modelling studies are over two decades old and based on data collected from the 1970s and 80s. We use a newer, high-resolution Digital Elevation Model of the GrIS and new temperature and precipitation forcings to drive the Glimmer ice-sheet model offline under steady state, present day climatic conditions. Comparisons are made of ice-sheet geometry between these new datasets and older ones used in the EISMINT-3 exercise. We find that changing to the newer bedrock and ice thickness makes the greatest difference to Greenland ice volume and ice surface extent. When all boundary conditions and forcings are simultaneously changed to the newer datasets the ice-sheet is 33% larger in volume compared with observation and 17% larger than that modelled by EISMINT-3. We performed a tuning exercise to improve the modelled present day ice-sheet. Several solutions were chosen in order to represent improvement in different aspects of the GrIS geometry: ice thickness, ice volume and ice surface extent. We applied these new parameter sets for Glimmer to several future climate scenarios where atmospheric CO2 concentration was elevated to 400, 560 and 1120 ppmv (compared with 280 ppmv in the control) using a fully coupled General Circulation Model. Collapse of the ice-sheet was found to occur between 400 and 560 ppmv, a threshold substantially lower than previously modelled using the standard EISMINT-3 setup. This work highlights the need to assess carefully boundary conditions and forcings required by ice-sheet models, particularly in terms of the abstractions required for large-scale ice-sheet models, and the implications that these can have on predictions of ice-sheet geometry under past and future climate scenarios.

QUANTITATIVE ESTIMATION OF THE IMPACT OF CLIMATE CHANGE ON CROP EVAPOTRANSPIRATION AND YIELD IN THE CENTRAL REGION OF INDIA

2021 ◽  
pp. 83-89
Author(s):  
A. BALVANSHI ◽  
◽  
H. L. TIWARI ◽  
Keyword(s):  
Climate Change ◽  
General Circulation ◽  
Quantitative Estimation ◽  
Circulation Model ◽  
Future Climate Change ◽  
Crop Evapotranspiration ◽  
Yield Data ◽  
Aquacrop Model ◽  
The Future ◽  
The Impact

The present work focuses on estimation of future evapotranspiration of paddy, maize, soybean and assessment of yields of these crops under RCP scenarios 2.6, 4.5, and 8.5 for years 1997-2099 using FAO Cropwat and AquaCrop yield simulating models for the Sehore district, in central state of India. Statistically downscaled General Circulation Model CanESM2 data were used as input to Cropwat and AquaCrop tools for generation of future crop evapotranspiration and crop yield data. The AquaCrop yield model was first checked for its suitability and accuracy in prediction of yield for years 1997-2010. The future scenario RCP 8.5 shows the highest reduction in the yield of paddy (-8.5%), maize (-4.52%), and soybean (-3.93%) during the future period. It was concluded that the FAO AquaCrop model can be applied to many other crops as well as in the other regions to formulate proper cropping strategies that will help to decrease the risks due to future climate change.

Recent climate variability and future climate change scenarios for

1998 ◽  
Vol 22 (3) ◽  
pp. 350-374 ◽  
Author(s):  
Great Britain ◽  
D. Conway
Keyword(s):  
Climate Change ◽  
Great Britain ◽  
General Circulation ◽  
Circulation Model ◽  
Future Climate ◽  
Future Climate Change ◽  
Climate Change Scenarios ◽  
Temperature And Precipitation ◽  
Sulphate Aerosols ◽  
Recent Climate

This article reviews recent climatically extreme periods in Great Britain and presents results from the latest general circulation model (GCM) experiments showing the possible spatial patterns and magnitude of future climate change for this region. During the last decade the British Isles has seen record-breaking periods of above-average temperatures, alongside periods with above and below-average precipitation, combined with an increase in winter precipitation and a decrease in summer precipitation. The impacts of these anomalies, coupled with the possibility that future climate change may increase their frequency and/or severity, have prompted the UK Department of the Environment, Transport and Regions and other organizations involved in environmental management, such as the Environment Agency, to commission a number of studies into their impacts. These have highlighted wide-ranging impacts on the natural environment of Great Britain and on human ativities to the extent of affecting the national economy. The use of GCMs for the development of future climate change scenarios is reviewed. Results from recent ensemble GCM experiments with and without the effects of sulphate aerosols are presented. These show broadly similar changes in temperature and precipitation to previous climate change scenarios prepared for Great Britain. In summary, the scenarios suggest the following: a warming of about 3 8C (3.5 8C) over the region by 2100 with (without) the effects of sulphate aerosols; slight increases in annual precipitation over northern England and Scotland, more pronounced increases over the whole of the region in winter; and slight decreases in precipitation over Wales and central England in summer. These changes are synchronous with decreases in the number of wet-days and increases in the intensity of precipitation on wet-days. The high level of uncertainty associated with regional scenarios of temperature and precipitation is discussed and emphasized

scholarly journals Changes in Future Drought with HadGEM2-AO Projections

Water ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 312 ◽  
Author(s):  
Minsung Kwon ◽  
Jang Hyun Sung
Keyword(s):  
Climate Change ◽  
General Circulation ◽  
Standardized Precipitation Index ◽  
Circulation Model ◽  
Meteorological Drought ◽  
Future Climate ◽  
Future Climate Change ◽  
Exceedance Probability ◽  
Climate Change Scenarios ◽  
Baseline Climate

The standardized precipitation index (SPI)—a meteorological drought index—uses various reference precipitation periods. Generally, drought projections using future climate change scenarios compare reference SPIs between baseline and future climates. Here, future drought was projected based on reference precipitation under the baseline climate to quantitatively compare changes in the frequency and severity of future drought. High-resolution climate change scenarios were produced using HadGEM2-AO General Circulation Model (GCM) scenarios for Korean weather stations. Baseline and future 3-month cumulative precipitation data were fitted to gamma distribution; results showed that precipitation of future climate is more than the precipitation of the baseline climate. When future precipitation was set as that of the baseline climate instead of the future climate, results indicated that drought intensity and frequency will decrease because the non-exceedance probability for the same precipitation is larger in the baseline climate than in future climate. However, due to increases in regional precipitation variability over time, some regions with opposite trends were also identified. Therefore, it is necessary to understand baseline and future climates in a region to better design resilience strategies and mechanisms that can help cope with future drought.

scholarly journals Large and irreversible future decline of the Greenland ice sheet

2020 ◽  
Vol 14 (12) ◽  
pp. 4299-4322
Author(s):  
Jonathan M. Gregory ◽  
Steven E. George ◽  
Robin S. Smith
Keyword(s):  
Climate Change ◽  
Global Warming ◽  
Steady State ◽  
Sea Level ◽  
General Circulation ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Circulation Model ◽  
Intergovernmental Panel ◽  
Late 20Th Century

Abstract. We have studied the evolution of the Greenland ice sheet under a range of constant climates typical of those projected for the end of the present century using a dynamical ice sheet model (Glimmer) coupled to an atmosphere general circulation model (FAMOUS–ice AGCM). The ice sheet surface mass balance (SMB) is simulated within the AGCM by a multilayer snow scheme from snowfall and surface energy fluxes, including refreezing and dependence on altitude within AGCM grid boxes. Over millennia under any warmer climate, the ice sheet reaches a new steady state, whose mass is correlated with the magnitude of global climate change imposed. If a climate that gives the recently observed SMB were maintained, global-mean sea level rise (GMSLR) would reach 0.5–2.5 m. For any global warming exceeding 3 K, the contribution to GMSLR exceeds 5 m. For the largest global warming considered (about +5 K), the rate of GMSLR is initially 2.7 mm yr−1, and eventually only a small ice cap endures, resulting in over 7 m of GMSLR. Our analysis gives a qualitatively different impression from previous work in that we do not find a sharp threshold warming that divides scenarios in which the ice sheet suffers little reduction from those in which it is mostly lost. The final steady state is achieved by withdrawal from the coast in some places and a tendency for increasing SMB due to enhancement of cloudiness and snowfall over the remaining ice sheet by the effects of topographic change on atmospheric circulation, outweighing the tendency for decreasing SMB from the reduction in surface altitude. If late 20th-century climate is restored after the ice sheet mass has fallen below a threshold of about 4 m of sea level equivalent, it will not regrow to its present extent because the snowfall in the northern part of the island is reduced once the ice sheet retreats from there. In that case, about 2 m of GMSLR would become irreversible. In order to avoid this outcome, anthropogenic climate change must be reversed before the ice sheet has declined to the threshold mass, which would be reached in about 600 years at the highest rate of mass loss within the likely range of the Fifth Assessment Report of the Intergovernmental Panel on Climate Change.

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