The art of modelling climate change in time slice integrations: The ICON-ART experience

2021 ◽  
Author(s):  
Peter Braesicke ◽  
Khompat Satitkovitchai ◽  
Marleen Braun ◽  
Roland Ruhnke
Keyword(s):  
Climate Change ◽  
Boundary Conditions ◽  
Greenhouse Gases ◽  
Ozone Hole ◽  
Time Slice ◽  
Necessary Condition ◽  
Quasi Equilibrium ◽  
Climate Change Scenarios ◽  
Near Surface ◽  
Threshold Temperatures

<p>Climate change is happening in a transient manner – with continuously increasing greenhouse gases in the atmosphere, humans have started a radiative imbalance that leads to rising near-surface temperatures. However, there are good reasons why it makes sense to look at quasi-equilibrium climate change simulations. In such simulations, we approximate climate change by “fixing” the amount of long-lived greenhouse gases and use recurring boundary conditions that are representative of a particular year - past, present or future. With such a setup any climate model should simulate a stable climate (after a spin-up phase) that reveals internal variability and does not show any trends. It is a necessary condition for the validity of the model - if no transience is provided in the boundary conditions – that the model does not drift. With such a model configuration, it is possible to estimate probability density functions, because each year of a multi-annual integration is an equally valid realisation for the meteorology of the pre-selected year.</p> <p>Using such a time-slice approach, sensitivities to well-specified individual changes can be assessed. Here, we provide a range of examples using the ICON-ART modelling system to investigate (idealised) climate change scenarios with respect to different threshold temperatures, jet variability and the climatic impact of the ozone hole. We illustrate how such integrations allow the unambiguous attribution of certain climate change effects, e.g. the change of jet stream variability under global warming or the contribution of the ozone hole to regional surface warming. However, we caution against a strict causality chain of processes in explaining the response, because given the nature of the quasi-equilibrium modelled, consistency might not always imply causality.</p>

Climate Change Scenarios and African Climate Change

2018 ◽  
Author(s):  
Kerry H. Cook
Keyword(s):  
Climate Change ◽  
Greenhouse Gases ◽  
Greenhouse Gas ◽  
Climate Model ◽  
Congo Basin ◽  
Climate Change Scenarios ◽  
Precipitation Regimes ◽  
Intense Storm ◽  
Short Rains ◽  
Projected Changes

Accurate projections of climate change under increasing atmospheric greenhouse gas levels are needed to evaluate the environmental cost of anthropogenic emissions, and to guide mitigation efforts. These projections are nowhere more important than Africa, with its high dependence on rain-fed agriculture and, in many regions, limited resources for adaptation. Climate models provide our best method for climate prediction but there are uncertainties in projections, especially on regional space scale. In Africa, limitations of observational networks add to this uncertainty since a crucial step in improving model projections is comparisons with observations. Exceeding uncertainties associated with climate model simulation are uncertainties due to projections of future emissions of CO2 and other greenhouse gases. Humanity’s choices in emissions pathways will have profound effects on climate, especially after the mid-century.The African Sahel is a transition zone characterized by strong meridional precipitation and temperature gradients. Over West Africa, the Sahel marks the northernmost extent of the West African monsoon system. The region’s climate is known to be sensitive to sea surface temperatures, both regional and global, as well as to land surface conditions. Increasing atmospheric greenhouse gases are already causing amplified warming over the Sahara Desert and, consequently, increased rainfall in parts of the Sahel. Climate model projections indicate that much of this increased rainfall will be delivered in the form of more intense storm systems.The complicated and highly regional precipitation regimes of East Africa present a challenge for climate modeling. Within roughly 5º of latitude of the equator, rainfall is delivered in two seasons—the long rains in the spring, and the short rains in the fall. Regional climate model projections suggest that the long rains will weaken under greenhouse gas forcing, and the short rains season will extend farther into the winter months. Observations indicate that the long rains are already weakening.Changes in seasonal rainfall over parts of subtropical southern Africa are observed, with repercussions and challenges for agriculture and water availability. Some elements of these observed changes are captured in model simulations of greenhouse gas-induced climate change, especially an early demise of the rainy season. The projected changes are quite regional, however, and more high-resolution study is needed. In addition, there has been very limited study of climate change in the Congo Basin and across northern Africa. Continued efforts to understand and predict climate using higher-resolution simulation must be sustained to better understand observed and projected changes in the physical processes that support African precipitation systems as well as the teleconnections that communicate remote forcings into the continent.

Synoptic-Statistical Approach to Regional Downscaling of IPCC Twenty-First-Century Climate Projections: Seasonal Rainfall over the Hawaiian Islands*

2009 ◽  
Vol 22 (16) ◽  
pp. 4261-4280 ◽  
Author(s):  
Oliver Timm ◽  
Henry F. Diaz
Keyword(s):  
Climate Change ◽  
Statistical Downscaling ◽  
Hawaiian Islands ◽  
Dry Season ◽  
First Century ◽  
Climate Projections ◽  
Climate Change Scenarios ◽  
Wet Season ◽  
Near Surface ◽  
Twenty First Century

Abstract A linear statistical downscaling technique is applied to the projection of the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) climate change scenarios onto Hawaiian rainfall for the late twenty-first century. Hawaii’s regional rainfall is largely controlled by the strength of the trade winds. During the winter months, disturbances in the westerlies can produce heavy rainfall throughout the islands. A diagnostic analysis of sea level pressure (SLP), near-surface winds, and rainfall measurements at 134 weather observing stations around the islands characterize the correlations between the circulation and rainfall during the nominal wet season (November–April) and dry season (May–October). A comparison of the base climate twentieth-century AR4 model simulations with reanalysis data for the period 1970–2000 is used to define objective selection criterion for the AR4 models. Six out of 21 available models were chosen for the statistical downscaling. These were chosen on the basis of their ability to more realistically simulate the modern large-scale circulation fields in the Hawaiian Islands region. For the AR4 A1B emission scenario, the six analyzed models show important changes in the wind fields around Hawaii by the late twenty-first century. Two models clearly indicate opposite signs in the anomalies. One model projects 20%–30% rainfall increase over the islands; the other model suggests a rainfall decrease of about 10%–20% during the wet season. It is concluded from the six-model ensemble that the most likely scenario for Hawaii is a 5%–10% reduction of the wet-season precipitation and a 5% increase during the dry season, as a result of changes in the wind field. The authors discuss the sources of uncertainties in the projected rainfall changes and consider future improvements of the statistical downscaling work and implications for dynamical downscaling methods.

scholarly journals Simulation of hydrosedimentological impacts caused by climate change in the Apucaraninha River watershed, southern Brazil

2015 ◽  
Vol 367 ◽  
pp. 366-373 ◽  
Author(s):  
I. R. Ramos Iensen ◽  
G. Bauer Schultz ◽  
I. Dos Santos
Keyword(s):  
Climate Change ◽  
Greenhouse Gases ◽  
Sediment Yield ◽  
Climate Projections ◽  
Climate Change Scenarios ◽  
Climate Scenarios ◽  
Southern Brazil ◽  
River Watershed ◽  
Daily Streamflow ◽  
Precipitation Regimes

Abstract. Climate change can cause significant modifications in hydrosedimentological processes. Climate projections indicate the occurrence of extreme events, in terms of precipitation, droughts, floods and temperature. By increasing temperatures and altering precipitation regimes, climate change is expected to affect sediment dynamics. Predictions of the effects of climate change on streamflow and sediment yield vary widely, depending on the geographical location and climate scenarios used. Mathematical modelling can be used to simulate the hydrosedimentological processes in watersheds and enable the simulation of climate change effects on sediment yield. This paper aims to simulate the impacts of climate change hydrosedimentological dynamics in the Apucaraninha River watershed (504 km²), southern Brazil, considering the climate change scenarios A2 (pessimistic about the emissions of greenhouse gases) and B2 (optimistic about the emissions of greenhouse gases), developed by the IPCC. The Soil and Water Assessment Tool (SWAT) was used to evaluate the impacts of climate projections on the sediment yield in the Apucaraninha River watershed. The model was calibrated and validated using daily streamflow and sediment data from 1987 to 2012. The model presented satisfactory fit to the observed data allowing the reproduction of the current hydrological conditions of the watershed. Based on the satisfactory results in calibration and validation, the climate scenarios A2 and B2 were inserted to simulate streamflow and sediment conditions for the period 2071–2100. The results for both scenarios indicate that simulations of both climate scenarios resulted in changes in hydrosedimentological dynamics in the Apucaraninha River watershed, mainly in terms of decrease in average sediment yield due to the reduction in precipitation amount and increase in evapotranspiration. Our results also indicate that every 1% change in precipitation has resulted in 2.8% change in soil erosion and 1.6% change in runoff under scenario A2, and 2.3% change in erosion and 1.1% in runoff under scenarios B2, thus suggesting that climate change tends to affect sediment yield more than streamflow, although seasonally both could be impacted in similar ways.

scholarly journals Climate Change from 1850 to 2005 Simulated in CESM1(WACCM)

2013 ◽  
Vol 26 (19) ◽  
pp. 7372-7391 ◽  
Author(s):  
Daniel R. Marsh ◽  
Michael J. Mills ◽  
Douglas E. Kinnison ◽  
Jean-Francois Lamarque ◽  
Natalia Calvo ◽  
...  
Keyword(s):  
Climate Change ◽  
Climate Model ◽  
Stratospheric Ozone ◽  
Lower Thermosphere ◽  
Coupled Model ◽  
Atmospheric Model ◽  
Ozone Hole ◽  
Near Surface ◽  
Global Mean Temperature ◽  
The Difference

Abstract The NCAR Community Earth System Model (CESM) now includes an atmospheric component that extends in altitude to the lower thermosphere. This atmospheric model, known as the Whole Atmosphere Community Climate Model (WACCM), includes fully interactive chemistry, allowing, for example, a self-consistent representation of the development and recovery of the stratospheric ozone hole and its effect on the troposphere. This paper focuses on analysis of an ensemble of transient simulations using CESM1(WACCM), covering the period from the preindustrial era to present day, conducted as part of phase 5 of the Coupled Model Intercomparison Project. Variability in the stratosphere, such as that associated with stratospheric sudden warmings and the development of the ozone hole, is in good agreement with observations. The signals of these phenomena propagate into the troposphere, influencing near-surface winds, precipitation rates, and the extent of sea ice. In comparison of tropospheric climate change predictions with those from a version of CESM that does not fully resolve the stratosphere, the global-mean temperature trends are indistinguishable. However, systematic differences do exist in other climate variables, particularly in the extratropics. The magnitude of the difference can be as large as the climate change response itself. This indicates that the representation of stratosphere–troposphere coupling could be a major source of uncertainty in climate change projections in CESM.

scholarly journals Deep mitigation of CO2 and non-CO2 greenhouse gases toward 1.5 °C and 2 °C futures

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yang Ou ◽  
Christopher Roney ◽  
Jameel Alsalam ◽  
Katherine Calvin ◽  
Jared Creason ◽  
...  
Keyword(s):  
Climate Change ◽  
Greenhouse Gases ◽  
Ghg Emissions ◽  
Integrated Assessment Model ◽  
Assessment Model ◽  
Mitigation Measures ◽  
Climate Change Scenarios ◽  
Ghg Mitigation ◽  
Net Zero ◽  
End Use

AbstractStabilizing climate change well below 2 °C and towards 1.5 °C requires comprehensive mitigation of all greenhouse gases (GHG), including both CO2 and non-CO2 GHG emissions. Here we incorporate the latest global non-CO2 emissions and mitigation data into a state-of-the-art integrated assessment model GCAM and examine 90 mitigation scenarios pairing different levels of CO2 and non-CO2 GHG abatement pathways. We estimate that when non-CO2 mitigation contributions are not fully implemented, the timing of net-zero CO2 must occur about two decades earlier. Conversely, comprehensive GHG abatement that fully integrates non-CO2 mitigation measures in addition to a net-zero CO2 commitment can help achieve 1.5 °C stabilization. While decarbonization-driven fuel switching mainly reduces non-CO2 emissions from fuel extraction and end use, targeted non-CO2 mitigation measures can significantly reduce fluorinated gas emissions from industrial processes and cooling sectors. Our integrated modeling provides direct insights in how system-wide all GHG mitigation can affect the timing of net-zero CO2 for 1.5 °C and 2 °C climate change scenarios.

Justification of Measures to Reduce Greenhouse Gases Emissions by Transport and Adaptation of Transport Infrastructure Facilities to Climate Change in Permafrost Zones

2019 ◽  
Vol 23 (2) ◽  
pp. 55-61
Author(s):  
Yu.V. Trofimenko ◽  
A.N. Yakubovich
Keyword(s):  
Climate Change ◽  
Greenhouse Gases ◽  
Ghg Emissions ◽  
Environmental Safety ◽  
Transport Infrastructure ◽  
Climate Change Scenarios ◽  
Effective Measure ◽  
Climate Risks ◽  
Island Species ◽  
Port Facilities

The models, methods, as well as the results of the justification of measures to reduce greenhouse gases (GHG) emissions by the transport complex for the period up to 2030 to improve its environmental safety, as well as assessing the effectiveness of measures (the use of seasonal cooling devices (SOA) – heat stabilizers) are considered transport infrastructure facilities (TIFs) of road, rail, air and water transport when implementing different climate change scenarios in the areas of permafrost. For sections of roads and railways (in the embankment), runways of airfields in the territories examined in the next 30 years, high climatic risks that require the use of heat stabilizers are not forecasted. For these objects can be applied less costly protective measures. The pile foundation of bridges and other transportation facilities can be sufficiently effectively protected by heat stabilizers from the effects of climate change. In relation to the strip and raft foundations of port facilities, other production facilities in the territories examined, the use of the SOA is a very effective measure to reduce climate risks. An increase in the expected effectiveness of measures to adapt them in the case of transition from continuous permafrost to its island and rare island species has been established for all types of TIFs. The reduced efficiency of the use of heat stabilizers in soils of low humidity, especially in sandy soils for all types of TIFs, was recorded.

scholarly journals The greenhouse gas project of ESA’s climate change initiative (GHG-CCI): overview, achievements and future plans

2015 ◽  
Vol XL-7/W3 ◽  
pp. 165-172 ◽  
Author(s):  
M. Buchwitz ◽  
M. Reuter ◽  
O. Schneising ◽  
H. Boesch ◽  
I. Aben ◽  
...  
Keyword(s):  
Climate Change ◽  
Greenhouse Gases ◽  
Near Infrared ◽  
Global Climate ◽  
Anthropogenic Sources ◽  
Change Initiative ◽  
Data Set ◽  
Near Surface ◽  
Sources And Sinks ◽  
Future Plans

The GHG-CCI project (<a href="http://www.esa-ghg-cci.org/"target="_blank">http://www.esa-ghg-cci.org/</a>) is one of several projects of the European Space Agency’s (ESA) Climate Change Initiative (CCI). The goal of the CCI is to generate and deliver data sets of various satellite-derived Essential Climate Variables (ECVs) in line with GCOS (Global Climate Observing System) requirements. The “ECV Greenhouse Gases” (ECV GHG) is the global distribution of important climate relevant gases – namely atmospheric CO2 and CH4 - with a quality sufficient to obtain information on regional CO2 and CH4 sources and sinks. The main goal of GHG-CCI is to generate long-term highly accurate and precise time series of global near-surface-sensitive satellite observations of CO2 and CH4, i.e., XCO2 and XCH4, starting with the launch of ESA’s ENVISAT satellite. These products are currently retrieved from SCIAMACHY/ENVISAT (2002-2012) and TANSO-FTS/GOSAT (2009-today) nadir mode observations in the near-infrared/shortwave-infrared spectral region. In addition, other sensors (e.g., IASI and MIPAS) and viewing modes (e.g., SCIAMACHY solar occultation) are also considered and in the future also data from other satellites. The GHG-CCI data products and related documentation are freely available via the GHG-CCI website and yearly updates are foreseen. Here we present an overview about the latest data set (Climate Research Data Package No. 2 (CRDP#2)) and summarize key findings from using satellite CO2 and CH4 retrievals to improve our understanding of the natural and anthropogenic sources and sinks of these important atmospheric greenhouse gases. We also shortly mention ongoing activities related to validation and initial user assessment of CRDP#2 and future plans.

scholarly journals Physically Plausible Methods for Projecting Changes in Great Lakes Water Levels under Climate Change Scenarios

2016 ◽  
Vol 17 (8) ◽  
pp. 2209-2223 ◽  
Author(s):  
Brent M. Lofgren ◽  
Jonathan Rouhana
Keyword(s):  
Climate Change ◽  
Great Lakes ◽  
Air Temperature ◽  
Land Surface ◽  
Statistical Significance ◽  
Climate Impact ◽  
Water Levels ◽  
Climate Change Scenarios ◽  
Conservation Of Energy ◽  
Near Surface

Abstract A method for projecting the water levels of the Laurentian Great Lakes under scenarios of human-caused climate change, used almost to the exclusion of other methods in the past, relies very heavily on the large basin runoff model (LBRM) as a component for determining the water budget for the lake system. This model uses near-surface air temperature as a primary predictor of evapotranspiration (ET); as in previous published work, it is shown here that the model’s very high sensitivity to temperature causes it to overestimate ET in a way that is greatly at variance with the fundamental principle of conservation of energy at the land surface. The traditional formulation is characterized here as being equivalent to having several suns in the virtual sky created by LBRM. More physically based methods show, relative to the traditional method, often astoundingly less potential ET and less ET, more runoff from the land and net basin supply for the lake basins, and higher lake water levels in the future. Using various methods of estimating the statistical significance, it is found that, at minimum, these discrepancies in results are significant at the 99.998% level. The lesson for the larger climate impact community is to use caution about whether an impact is forced directly by air temperature itself or is significantly forced by season or latitude independently of temperature. The results here apply only to the water levels of the Great Lakes and the hydrology of its basin and do not affect larger questions of climate change.

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