Emerging role of wetland methane emissions in driving 21st century climate change

Wetland methane (CH4) emissions are the largest natural source in the global CH4 budget, contributing to roughly one third of total natural and anthropogenic emissions. As the second most important anthropogenic greenhouse gas in the atmosphere after CO2, CH4 is strongly associated with climate feedbacks. However, due to the paucity of data, wetland CH4 feedbacks were not fully assessed in the Intergovernmental Panel on Climate Change Fifth Assessment Report. The degree to which future expansion of wetlands and CH4 emissions will evolve and consequently drive climate feedbacks is thus a question of major concern. Here we present an ensemble estimate of wetland CH4 emissions driven by 38 general circulation models for the 21st century. We find that climate change-induced increases in boreal wetland extent and temperature-driven increases in tropical CH4 emissions will dominate anthropogenic CH4 emissions by 38 to 56% toward the end of the 21st century under the Representative Concentration Pathway (RCP2.6). Depending on scenarios, wetland CH4 feedbacks translate to an increase in additional global mean radiative forcing of 0.04 W·m−2 to 0.19 W·m−2 by the end of the 21st century. Under the “worst-case” RCP8.5 scenario, with no climate mitigation, boreal CH4 emissions are enhanced by 18.05 Tg to 41.69 Tg, due to thawing of inundated areas during the cold season (December to May) and rising temperature, while tropical CH4 emissions accelerate with a total increment of 48.36 Tg to 87.37 Tg by 2099. Our results suggest that climate mitigation policies must consider mitigation of wetland CH4 feedbacks to maintain average global warming below 2 °C.

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How Well Do We Understand and Evaluate Climate Change Feedback Processes?

Journal of Climate ◽

10.1175/jcli3819.1 ◽

2006 ◽

Vol 19 (15) ◽

pp. 3445-3482 ◽

Cited By ~ 673

Author(s):

Sandrine Bony ◽

Robert Colman ◽

Vladimir M. Kattsov ◽

Richard P. Allan ◽

Christopher S. Bretherton ◽

...

Keyword(s):

Climate Change ◽

Climate Sensitivity ◽

General Circulation ◽

External Perturbation ◽

General Circulation Models ◽

Lapse Rate ◽

Climate Feedback ◽

Climate Feedbacks ◽

Intergovernmental Panel ◽

Global Estimates

Abstract Processes in the climate system that can either amplify or dampen the climate response to an external perturbation are referred to as climate feedbacks. Climate sensitivity estimates depend critically on radiative feedbacks associated with water vapor, lapse rate, clouds, snow, and sea ice, and global estimates of these feedbacks differ among general circulation models. By reviewing recent observational, numerical, and theoretical studies, this paper shows that there has been progress since the Third Assessment Report of the Intergovernmental Panel on Climate Change in (i) the understanding of the physical mechanisms involved in these feedbacks, (ii) the interpretation of intermodel differences in global estimates of these feedbacks, and (iii) the development of methodologies of evaluation of these feedbacks (or of some components) using observations. This suggests that continuing developments in climate feedback research will progressively help make it possible to constrain the GCMs’ range of climate feedbacks and climate sensitivity through an ensemble of diagnostics based on physical understanding and observations.

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21st century ocean forcing of the Greenland Ice Sheet for modeling of sea level contribution

10.5194/tc-2019-222 ◽

2019 ◽

Cited By ~ 1

Author(s):

Donald A. Slater ◽

Denis Felikson ◽

Fiamma Straneo ◽

Heiko Goelzer ◽

Christopher M. Little ◽

...

Keyword(s):

Sea Level ◽

21St Century ◽

General Circulation ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

General Circulation Models ◽

Glacier Retreat ◽

Small Scale ◽

Intergovernmental Panel ◽

Continental Scale

Abstract. Changes in the ocean are expected to be an important determinant of the Greenland Ice Sheet's future sea level contribution. Yet representing these changes in continental-scale ice sheet models remains challenging due to the small scale of the key physics, and limitations in processing understanding. Here we present the ocean forcing strategy for Greenland Ice Sheet models taking part in the Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6), the primary community effort to provide 21st century sea level projections for the Intergovernmental Panel on Climate Change 6th Assessment Report. Beginning from global atmosphere-ocean general circulation models, we describe two complementary approaches to provide ocean boundary conditions for Greenland Ice Sheet models, termed the retreat and submarine melt implementations. The retreat implementation parameterizes glacier retreat as a function of projected submarine melting, is designed to be implementable by all ice sheet models, and results in retreat of around 1 and 15 km by 2100 in RCP2.6 and 8.5 scenarios respectively. The submarine melt implementation provides estimated submarine melting only, leaving the ice sheet model to solve for the resulting calving and glacier retreat, and suggests submarine melt rates will change little under RCP2.6 but will approximately triple by 2100 under RCP8.5. Both implementations have necessarily made use of simplifying assumptions and poorly-constrained parameterisations and as such, further research on submarine melting, calving and fjord-shelf exchange should remain a priority. Nevertheless, the presented framework will allow an ensemble of Greenland Ice Sheet models to be systematically and consistently forced by the ocean for the first time, and should therefore result in a significant improvement in projections of the Greenland ice sheet's contribution to future sea level change.

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Climate change impact on meteorological droughts in watershed scale (case study: southwestern Iran)

International Journal of Engineering & Technology ◽

10.14419/ijet.v4i1.3782 ◽

2014 ◽

Vol 4 (1) ◽

pp. 1 ◽

Cited By ~ 17

Author(s):

Alireza Nikbakht Shahbazi

Keyword(s):

Climate Change ◽

General Circulation ◽

Meteorological Data ◽

Climate Change Impacts ◽

General Circulation Models ◽

Future Climate Change ◽

Monthly Precipitation ◽

Spring Precipitation ◽

Data Simulation ◽

Intergovernmental Panel

Drought is one of the major natural disasters in the world which has a lot of social and economic impacts. There are various factors that affect climate changes; the investigation of this incident is also sensitive. Climate scenarios of future climate change studies and investigation of efficient methods for investigating these events on drought should be assumed. This study intends to investigate climate change impacts on drought in Karoon3 watershed in the future. For this purpose, the atmospheric general circulation models (GCM) data under Intergovernmental Panel on Climate Change (IPCC) scenarios should be investigated. In this study, watershed drought under climate change impacts will be simulated in future periods (2011 to 2099). In this research standard precipitation index (SPI) was calculated using mean monthly precipitation data in Karoon3 watershed. SPI was calculated in 6, 12 and 24 months periods. Statistical analysis on daily precipitation and minimum and maximum daily temperature was performed. To determine the feasibility of future periods meteorological data production of LRAS-WG5 model, calibration and verification was performed for the base year (1980-2007). Meteorological data simulation for future periods under General Circulation Models and climate change IPCC scenarios was performed and then the drought status using SPI under climate change effects analyzed. Results showed that differences between monthly maximum and minimum temperature will decrease under climate change and spring precipitation shall increase while summer and autumn rainfall shall decrease. The most increase of precipitation will take place in winter and in December. Normal and wet SPI category is more frequent in B1 and A2 emissions scenarios than A1B. Wet years increases in the study area during 2011-2030 period and the more continuous drought years gradually increases during 2046-2065 period, the more severe and frequent drought will occur during the 2080-2099 period.

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Modelling the impacts of European emission and climate change scenarios on acid-sensitive catchments in Finland

Hydrology and Earth System Sciences ◽

10.5194/hess-12-449-2008 ◽

2008 ◽

Vol 12 (2) ◽

pp. 449-463 ◽

Cited By ~ 11

Author(s):

M. Posch ◽

J. Aherne ◽

M. Forsius ◽

S. Fronzek ◽

N. Veijalainen

Keyword(s):

Climate Change ◽

Surface Water ◽

Emission Reduction ◽

General Circulation ◽

General Circulation Models ◽

Chemical Recovery ◽

Climate Change Scenarios ◽

Intergovernmental Panel ◽

Sulphur Deposition ◽

Temperature And Precipitation

Abstract. The dynamic hydro-chemical Model of Acidification of Groundwater in Catchments (MAGIC) was used to predict the response of 163 Finnish lake catchments to future acidic deposition and climatic change scenarios. Future deposition was assumed to follow current European emission reduction policies and a scenario based on maximum (technologically) feasible reductions (MFR). Future climate (temperature and precipitation) was derived from the HadAM3 and ECHAM4/OPYC3 general circulation models under two global scenarios of the Intergovernmental Panel on Climate Change (IPCC: A2 and B2). The combinations resulting in the widest range of future changes were used for simulations, i.e., the A2 scenario results from ECHAM4/OPYC3 (highest predicted change) and B2 results from HadAM3 (lowest predicted change). Future scenarios for catchment runoff were obtained from the Finnish watershed simulation and forecasting system. The potential influence of future changes in surface water organic carbon concentrations was also explored using simple empirical relationships based on temperature and sulphate deposition. Surprisingly, current emission reduction policies hardly show any future recovery; however, significant chemical recovery of soil and surface water from acidification was predicted under the MFR emission scenario. The direct influence of climate change (temperate and precipitation) on recovery was negligible, as runoff hardly changed; greater precipitation is offset by increased evapotranspiration due to higher temperatures. However, two exploratory empirical DOC models indicated that changes in sulphur deposition or temperature could have a confounding influence on the recovery of surface waters from acidification, and that the corresponding increases in DOC concentrations may offset the recovery in pH due to reductions in acidifying depositions.

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Future Changes in Precipitation and Drought Characteristics over Bangladesh Under CMIP5 Climatological Projections

Water ◽

10.3390/w11112219 ◽

2019 ◽

Vol 11 (11) ◽

pp. 2219 ◽

Cited By ~ 4

Author(s):

Kamruzzaman ◽

Jang ◽

Cho ◽

Hwang

Keyword(s):

Climate Change ◽

21St Century ◽

General Circulation ◽

General Circulation Models ◽

Northern Region ◽

Medium Term ◽

Rcp Scenarios ◽

Drought Characteristics ◽

The Future ◽

Northwestern Region

: The impacts of climate change on precipitation and drought characteristics over Bangladesh were examined by using the daily precipitation outputs from 29 bias-corrected general circulation models (GCMs) under the representative concentration pathway (RCP) 4.5 and 8.5 scenarios. A precipitation-based drought estimator, namely, the Effective Drought Index (EDI), was applied to quantify the characteristics of drought events in terms of the severity and duration. The changes in drought characteristics were assessed for the beginning (2010–2039), middle (2040–2069), and end of this century (2070–2099) relative to the 1976–2005 baseline. The GCMs were limited in regard to forecasting the occurrence of future extreme droughts. Overall, the findings showed that the annual precipitation will increase in the 21st century over Bangladesh; the increasing rate was comparatively higher under the RCP8.5 scenario. The highest increase in rainfall is expected to happen over the drought-prone northern region. The general trends of drought frequency, duration, and intensity are likely to decrease in the 21st century over Bangladesh under both RCP scenarios, except for the maximum drought intensity during the beginning of the century, which is projected to increase over the country. The extreme and medium-term drought events did not show any significant changes in the future under both scenarios except for the medium-term droughts, which decreased by 55% compared to the base period during the 2070s under RCP8.5. However, extreme drought days will likely increase in most of the cropping seasons for the different future periods under both scenarios. The spatial distribution of changes in drought characteristics indicates that the drought-vulnerable areas are expected to shift from the northwestern region to the central and the southern region in the future under both scenarios due to the effects of climate change.

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Future Changes in Precipitation and Drought Characteristics over Bangladesh under CMIP5 Climatological Projections

10.20944/preprints201909.0291.v1 ◽

2019 ◽

Author(s):

Mohammad Kamruzzaman ◽

Min-Won Jang ◽

Jaepil Cho ◽

Syewoon Hwang

Keyword(s):

Climate Change ◽

21St Century ◽

General Circulation ◽

General Circulation Models ◽

Northern Region ◽

Medium Term ◽

Rcp Scenarios ◽

Drought Characteristics ◽

The Future ◽

Northwestern Region

The impacts of climate change on precipitation and drought characteristics over Bangladesh were examined by using the daily precipitation outputs from 29 bias-corrected general circulation models (GCMs) under the representative concentration pathway (RCP) 4.5 and 8.5 scenarios. A precipitation-based drought estimator, namely, the Effective Drought Index (EDI), was applied to quantify the characteristics of drought events in terms of the severity and duration. The changes in drought characteristics were assessed for the beginning (2010–2039), middle (2040–2069), and end of this century (2070–2099) relative to the 1976–2005 baseline. The GCMs were limited in regard to forecasting the occurrence of future extreme droughts. Overall, the findings showed that the annual precipitation will increase in the 21st century over Bangladesh; the increasing rate was comparatively higher under the RCP8.5 scenario. The highest increase of rainfall is expected to happen over the drought-prone northern region. The general trends of drought frequency, duration, and intensity are likely to decrease in the 21st century over Bangladesh under both RCP scenarios, except for the maximum drought intensity during the beginning of the century, which is projected to increase over the country. The extreme and medium-term drought events did not show any significant changes in the future under both scenarios except for the medium-term droughts, which decreased by 55% compared to the base period during the 2070s under RCP8.5. However, extreme drought days will likely increase in most of the cropping seasons for the different future periods under both scenarios. The spatial distribution of changes in drought characteristics indicates that the drought-vulnerable areas are expected to shift from the northwestern region to the central and the southern region in the future under both scenarios due to the effects of climate change.

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Risk analysis of climate change on coffee nematodes and leaf miner in Brazil

Pesquisa Agropecuária Brasileira ◽

10.1590/s0100-204x2008000200005 ◽

2008 ◽

Vol 43 (2) ◽

pp. 187-194 ◽

Cited By ~ 32

Author(s):

Raquel Ghini ◽

Emília Hamada ◽

Mário José Pedro Júnior ◽

José Antonio Marengo ◽

Renata Ribeiro do Valle Gonçalves

Keyword(s):

Climate Change ◽

General Circulation ◽

Management Practices ◽

General Circulation Models ◽

Climatic Conditions ◽

Leaf Miner ◽

Intergovernmental Panel ◽

Distribution Maps ◽

Distribution Centre ◽

Disease Epidemics

The objective of this work was to assess the potential impact of climate change on the spatial distribution of coffee nematodes (races of Meloidogyne incognita) and leaf miner (Leucoptera coffeella), using a Geographic Information System. Assessment of the impacts of climate change on pest infestations and disease epidemics in crops is needed as a basis for revising management practices to minimize crop losses as climatic conditions shift. Future scenarios focused on the decades of the 2020's, 2050's, and 2080's (scenarios A2 and B2) were obtained from five General Circulation Models available on Data Distribution Centre from Intergovernmental Panel on Climate Change. Geographic distribution maps were prepared using models to predict the number of generations of the nematodes and leaf miner. Maps obtained in scenario A2 allowed prediction of an increased infestation of the nematode and of the pest, due to greater number of generations per month, than occurred under the climatological normal from 1961-1990. The number of generations also increased in the B2 scenario, but was lower than in the A2 scenario for both organisms.

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A new method for assessing the performance of general circulation models based on their ability to simulate the response to observed forcing

Journal of Climate ◽

10.1175/jcli-d-20-0510.1 ◽

2021 ◽

pp. 1-52

Author(s):

M.A. Altamirano del Carmen ◽

F. Estrada ◽

C. Gay-García

Keyword(s):

Climate Change ◽

Surface Temperature ◽

Radiative Forcing ◽

General Circulation ◽

Statistical Tests ◽

General Circulation Models ◽

Warming Trend ◽

Global Scale ◽

Adequate Representation ◽

Warming Rate

AbstractThe reliability of General Circulation Models (GCMs) is commonly associated with their ability to reproduce relevant aspects of observed climate and thus, the evaluation of GCMs performance has become a standard practice for climate change studies. As such, there is an ever-growing literature that focuses on developing and evaluating metrics to assess GCMs performance. In this paper it is shown that some commonly applied metrics provide little information for discriminating GCMs based on their performance, once uncertainty is included. A new methodology is proposed that differs from common approaches in that it focuses on evaluating GCMs ability to reproduce the observed response of surface temperature to changes in external radiative forcing (RF), while controlling for observed and simulated variability. It uses formal statistical tests to evaluate two aspects of the warming trend that are central for climate change studies: 1) if the response to RF produced by a particular GCM is compatible with observations and 2) if the magnitudes of the observed and simulated rates of warming are statistically similar. We illustrate the proposed methodology by evaluating the ability of 21 GCMs to reproduce the observed warming trend at the global scale and eight sub-continental land domains. Results show that most of the GCMs provide an adequate representation of the observed warming trend for the global scale and for domains located in the southern hemisphere. However, GCMs tend to overestimate the warming rate for domains in the northern hemisphere, particularly since the mid-1990s.

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Climate change and agricultural productivity in Brazil: future perspectives

Environment and Development Economics ◽

10.1017/s1355770x1600005x ◽

2016 ◽

Vol 21 (5) ◽

pp. 581-602 ◽

Cited By ~ 7

Author(s):

Juliano Assunção ◽

Flávia Chein

Keyword(s):

Climate Change ◽

Global Warming ◽

General Circulation ◽

Agricultural Productivity ◽

General Circulation Models ◽

Future Perspectives ◽

Intergovernmental Panel ◽

Cross Sectional ◽

The Impact ◽

Impacts Of Climate Change

AbstractThis paper evaluates the impact of climate change on agricultural productivity. Cross-sectional variation in climate among Brazilian municipalities is used to estimate an equation in which geographical attributes determine agricultural productivity. The Intergovernmental Panel on Climate Change (IPCC) predictions based on atmosphere–ocean, coupled with general circulation models (for 2030–2049), are used to simulate the impacts of climate change. Our estimates suggest that global warming under the current technological standards is expected to decrease the agricultural output per hectare in Brazil by 18 per cent, with the effects on municipalities ranging from−40 to+15 per cent.

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Uncertainties of climate and CO2 impacts on carbon stocks and biome distribution in Africa

10.5194/egusphere-egu2020-21790 ◽

2020 ◽

Author(s):

Carola Martens ◽

Thomas Hickler ◽

Claire Davis-Reddy ◽

Francois Engelbrecht ◽

Steven I. Higgins ◽

...

Keyword(s):

Climate Change ◽

General Circulation ◽

General Circulation Models ◽

Woody Encroachment ◽

Strong Increase ◽

Climate Mitigation ◽

Climate Modelling ◽

Dynamic Global Vegetation Model ◽

Mitigation And Adaptation ◽

Rcp 8.5

Climate change is expected to cause vegetation change in Africa, with profound impacts on ecosystems and biodiversity. Projections of future ecosystem states are constrained by uncertainties regarding relative impacts of climate change and CO2 fertilisation effects. Rising atmospheric CO2 drives climate change, but also directly affects plant physiological functions via carbon uptake, carbon allocation, water use efficiency, and growth. We use the adaptive Dynamic Global Vegetation Model (aDGVM) to quantify uncertainties in projected African vegetation until 2099. High-resolution climate forcing for the aDGVM, was generated by regional climate modelling. An ensemble of 24 aDGVM simulations based on six downscaled General Circulation Models (GCMs) under two Representative Concentration Pathways (RCPs 4.5 and 8.5) with plant-physiological CO2 effects enabled and disabled was implemented.Under strong climatic change with high CO2 increases (RCP 8.5), almost a third of terrestrial Africa is projected to experience biome changes with woody encroachment into grassy biomes dominating biome changes. Projections under medium-impact scenarios (RCP 4.5) still predict biome changes for around a quarter of Africa. With climate change only and elevated-CO2 effects disabled, woody encroachment is weak and reduction of forest cover in favour of savannas prevails. Change in aboveground vegetation carbon until 2099 varied from a strong increase under elevated CO2&#160;(61.5%, RCP 8.5; 33.9%, RCP 4.5) to a small increase of 5.4% (RCP 4.5) and a decrease of -13.6% (RCP 8.5) without CO2 effects.CO2 effects in combination with RCP scenarios caused the greatest uncertainty in projected ecosystem changes. Downscaled GCM projections caused weaker uncertainties in the simulations. Future biome changes due to climate and CO2 change are therefore likely in large parts of Africa. Their magnitude and location often remain uncertain. Climate mitigation and adaptation response measures that rely upon vegetation-derived ecosystem services will need to account for alternative climate futures.

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