Modeling extreme Black Sea and Caspian Sea levels of the past 21,000 years with general circulation models

The advent of climate science can be defined as the historical emergence of a research program to study climate according to a modern definition of climate. Climate in this sense: (1) refers not simply to the average state of the atmosphere but also to its variability; (2) is multiscalar, concerned with phenomena ranging from the very small and fast to the very large and slow; and (3) is understood to be influenced by the oceans, lithosphere, cryosphere, and biosphere. Most accounts of the history of climate science to date have focused on the development of computerized general circulation models since World War Two. However, following this definition, the advent of climate science occurred well before the computer age. This entry therefore seeks to dispel the image of climate science as a recent invention and as the preserve of an exclusive, North American elite. The historical roots of today’s knowledge of climate change stretch surprisingly far back into the past and clear across the world, though the geographic focus here is on Europe and North America. The modern science of climate emerged out of interactions between learned and vernacular knowledge traditions, and has simultaneously appropriated and undermined traditional and indigenous forms of climate knowledge. Important precedents emerged in the 17th and 18th centuries, and it was in the late 19th century that a modern science of climate coalesced into a coordinated research program in part through the unification of divergent knowledge traditions around standardized techniques of measurement and analysis.

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Spatiotemporal Trends and Attribution of Drought across China from 1901–2100

Sustainability ◽

10.3390/su12020477 ◽

2020 ◽

Vol 12 (2) ◽

pp. 477

Author(s):

Yongxia Ding ◽

Shouzhang Peng

Keyword(s):

Adverse Effects ◽

General Circulation ◽

Potential Evapotranspiration ◽

Northern China ◽

General Circulation Models ◽

Research Unit ◽

Mitigation Strategies ◽

Climatic Research Unit ◽

The Past ◽

Spatiotemporal Trends

Investigating long-term drought trends is of great importance in coping with the adverse effects of global warming. However, little attention has been focused on studying the detailed spatial variability and attribution of drought variation in China. In this study, we first generated a 1 km resolution monthly climate dataset for the period 1901–2100 across China using the delta spatial downscaling method to assess the variability of the Standardized Precipitation Evaporation Index (SPEI). We then developed a simple approach to quantifying the contributions of water supply (precipitation) and demand (potential evapotranspiration, PET) on SPEI variability, according to the meaning of the differentiating SPEI equation. The results indicated that the delta framework could accurately downscale and correct low-spatial-resolution monthly temperatures and precipitation from the Climatic Research Unit and general circulation models (GCMs). Of the 27 GCMs analyzed, the BNU-ESM, CESM1-CAM5, and GFDL-ESM2M were found to be the most accurate in modeling future temperatures and precipitation. We also found that, compared with the past (1901–2017), the climate in the future (2018–2100) will tend toward significant droughts, although both periods showed a high spatial heterogeneity across China. Moreover, the proportion of areas with significantly decreasing SPEI trends was far greater than the proportion of those with increasing trends in most cases, especially for northwestern and northern China. Finally, the proposed approach to quantifying precipitation and PET contributions performed well according to logical evaluations. The percentage contributions of precipitation and PET on SPEI variability varied with study periods, representative concentration pathway scenarios, trend directions, and geographic spaces. In the past, PET contributions for significant downward trends and precipitation contributions for significantly upward trends accounted for 95% and 72%, while their future contributions were 57 ± 22%–149 ± 20% and 95 ± 27%–190 ± 58%, respectively. Overall, our results provide detailed insights for planning flexible adaptation and mitigation strategies to cope with the adverse effects of climate drought across China.

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Possible pathways to a Dansgaard-Oeschger (DO) PMIP protocol

10.5194/egusphere-egu21-8730 ◽

2021 ◽

Author(s):

Irene Malmierca-Vallet ◽

Louise C. Sime ◽

Paul J. Valdes

Keyword(s):

General Circulation ◽

Climate Changes ◽

General Circulation Models ◽

Ice Age ◽

Climate Change Projections ◽

The Past ◽

External Perturbations ◽

Mis 3 ◽

Last Ice Age ◽

Earth System Models

The DO events of the last ice age represent one of the best studied abrupt climate transitions, yet we still lack a comprehensive explanation for them. There is uncertainty whether current IPCC-relevant models can effectively represent the processes that cause DO events. Current Earth system models (ESMs) seem overly stable against external perturbations and incapable of reproducing most abrupt climate changes of the past (Valdes, 2011). If this holds true, this could noticeably influence their capability to predict future abrupt transitions, with significant consequences for the delivery of precise climate change projections. &#160;In this task, the objectives of this study are (1) to cross compare existing simulations that show spontaneous DO-type oscillations using a common set of diagnostics so we can compare the mechanisms and the characteristics of the oscillations, and (2) to formulate possible pathways to a DO PMIP protocol that could help investigate cold-period instabilities through a range of insolation-, freshwater-, GHG-, and NH ice sheet-related forcings, as well as evaluating the possibility of spontaneous internal oscillations.Although most abrupt DO events happened during MIS3, only few studies investigate DO events in coupled general circulation models under MIS 3 conditions (e.g., Kawamura et al., 2017; Zhang and Prange, 2020). Here, we thus propose that the MIS3 period could be the focus of such a DO-event modelling protocol. More specific sensitivity experiments performed under MIS 3 boundary conditions are needed in order to (1) better understand the mechanisms behind millennial-scale climate variability, (2) explore AMOC variability under intermediate glacial conditions, and (3) help answer the question: &#8220;are models too stable?&#8221;.

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A climate model intercomparison for the Antarctic region: present and past

Climate of the Past ◽

10.5194/cp-8-803-2012 ◽

2012 ◽

Vol 8 (2) ◽

pp. 803-814 ◽

Cited By ~ 7

Author(s):

M. N. A. Maris ◽

B. de Boer ◽

J. Oerlemans

Keyword(s):

General Circulation ◽

Climate Model ◽

Reference Data ◽

Regional Climate ◽

Ice Core ◽

Ice Sheet ◽

General Circulation Models ◽

Antarctic Region ◽

The Past ◽

The Antarctic

Abstract. Eighteen General Circulation Models (GCMs) are compared to reference data for the present, the Mid-Holocene (MH) and the Last Glacial Maximum (LGM) for the Antarctic region. The climatology produced by a regional climate model is taken as a reference climate for the present. GCM results for the past are compared to ice-core data. The goal of this study is to find the best GCM that can be used to drive an ice sheet model that simulates the evolution of the Antarctic Ice Sheet. Because temperature and precipitation are the most important climate variables when modelling the evolution of an ice sheet, these two variables are considered in this paper. This is done by ranking the models according to how well their output corresponds with the references. In general, present-day temperature is simulated well, but precipitation is overestimated compared to the reference data. Another finding is that model biases play an important role in simulating the past, as they are often larger than the change in temperature or precipitation between the past and the present. Considering the results for the present-day as well as for the MH and the LGM, the best performing models are HadCM3 and MIROC 3.2.2.

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Influence of Tropical Tropopause Layer Cooling on Atlantic Hurricane Activity

Journal of Climate ◽

10.1175/jcli-d-12-00242.1 ◽

2013 ◽

Vol 26 (7) ◽

pp. 2288-2301 ◽

Cited By ~ 95

Author(s):

Kerry Emanuel ◽

Susan Solomon ◽

Doris Folini ◽

Sean Davis ◽

Chiara Cagnazzo

Keyword(s):

Tropical Cyclone ◽

General Circulation ◽

General Circulation Models ◽

Tropical Cyclone Activity ◽

Sea Surface ◽

Cyclone Activity ◽

Tropical Tropopause Layer ◽

The Past ◽

Tropical Tropopause ◽

Atlantic Tropical Cyclone

Abstract Virtually all metrics of Atlantic tropical cyclone activity show substantial increases over the past two decades. It is argued here that cooling near the tropical tropopause and the associated decrease in tropical cyclone outflow temperature contributed to the observed increase in tropical cyclone potential intensity over this period. Quantitative uncertainties in the magnitude of the cooling are important, but a broad range of observations supports some cooling. Downscalings of the output of atmospheric general circulation models (AGCMs) that are driven by observed sea surface temperatures and sea ice cover produce little if any increase in Atlantic tropical cyclone metrics over the past two decades, even though observed variability before roughly 1970 is well simulated by some of the models. Part of this shortcoming is traced to the failure of the AGCMs examined to reproduce the observed cooling of the lower stratosphere and tropical tropopause layer (TTL) over the past few decades. The authors caution against using sea surface temperature or proxies based on it to make projections of tropical cyclone activity as there can be significant contributions from other variables such as the outflow temperature. The proposed mechanisms of TTL cooling (e.g., ozone depletion and stratospheric circulation changes) are reviewed, and the need for improved representations of these processes in global models in order to improve projections of future tropical cyclone activity is emphasized.

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Present and future trends in winds and SST off central East Africa

Western Indian Ocean Journal of Marine Science ◽

10.4314/wiojms.si2020.1.6 ◽

2021 ◽

pp. 63-70

Author(s):

Marisol García-Reyes ◽

Shigalla B. Mahongo

Keyword(s):

East Africa ◽

General Circulation ◽

General Circulation Models ◽

Coastal Current ◽

Future Trends ◽

East African ◽

Related Services ◽

Water Column Stability ◽

The Past ◽

Regional Dynamics

The coast of central East Africa (CEA) is a dynamic region in terms of climate, in which fisheries and marine-related services impact a large portion of the population. The main driver of regional dynamics is the seasonal alternation of the Northeast (NE) and Southeast (SE) monsoons. Winds associated with these monsoons modulate the prevalent, remotely-forced East African Coastal Current (EACC). Here, present and future trends in winds and sea surface temperature (SST) of the CEA and adjacent regions are investigated using reanalysis and reconstructed data, and an ensemble of General Circulation Models. It was found that the winds and SST show unidirectional trends, with magnitude and spatial differences between the NE and SE monsoons. Winds show weakening trends during the NE monsoon, in the past and future, of the Somali region; with no significant trends during the SE monsoon. SST shows increasing trends in the entire region in the past and future, with stronger warming during the NE monsoon off Somalia; SST trends are smaller in the CEA. These trends could impact the CEA through increased water-column stability and decreased upwelling due to shifting of the EACC separation from the continent. However, given the coarse resolution of data analyzed, regional modeling is still necessary to understand the impacts on local dynamics and productivity in the CEA.

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Past Evaluation and Future Projection of Sea Level Rise Related to Climate Change Around Japan

Journal of Disaster Research ◽

10.20965/jdr.2008.p0119 ◽

2008 ◽

Vol 3 (2) ◽

pp. 119-130 ◽

Cited By ~ 1

Author(s):

Sin-Iti Iwasaki ◽

◽

Wataru Sasaki ◽

Tomonori Matsuura

Keyword(s):

Climate Change ◽

Linear Regression ◽

Regression Model ◽

Sea Level ◽

Linear Regression Model ◽

General Circulation ◽

General Circulation Models ◽

Sea Levels ◽

Level Data ◽

Western Japan

Using new sea level data on 71 points on Japan’s coast during 1966-2003 in which crustal movement is eliminated from tide records, we evaluate long-term oceanic-origin sea levels and project sea level rises (SLR). We classify Japan’s coast into seven regions of about 100 km^2 by applying cluster analysis to the sea level data. For western Japan, we propose a linear regression model enabling us to predict sea levels based on sea surface temperature (SST). SLR are projected for the 21stcentury using our linear regression model to SSTs of 10 coupled general circulation models (CGCMs), based on the SRES A1B scenario of the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report. The mean SLR in western Japan in the 21stcentury is 12 cm, almost the same as the SLR around Japan’s coast predicted dynamically by CGCMs. We found that the SLR predicted by our linear regression model is high in the western Japan, particularly at about 17 cm/century in western Kyushu.

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Comparison of isotopic signatures in speleothem records and model simulations for the past millennium

10.5194/egusphere-egu2020-8982 ◽

2020 ◽

Author(s):

Janica Buehler ◽

Moritz Kirschner ◽

Carla Roesch ◽

Max D. Holloway ◽

Louise Sime ◽

...

Keyword(s):

Climate Variability ◽

Time Scales ◽

General Circulation ◽

General Circulation Models ◽

Global Changes ◽

Climate Change Scenarios ◽

The Past ◽

Proxy Records ◽

Parameter Constraints ◽

Past Millennium

Global changes in climate, especially in mean temperature, receive increasing public as well as scientific attention under the current warming trend. However, the probability of extreme events and their societal impact is also governed by changes in climate variability. Improving the understanding of changes in both and their relationship is crucial for projecting reliable climate change scenarios. Model-data comparisons between general circulation models and speleothem paleoclimate archives, with &#948;18O as a temperature and precipitation proxy, have been suggested to test and validate the capability of different climate models.Speleothems are precisely date-able and provide well preserved (semi-)continuous climate signals in the lower and mid-latitudes, providing a suitable archive to assess a model&#8217;s capability to simulate climate variability on time scales longer than those observable. However, the &#948;18O measured in speleothem calcite does not directly represent temperature or precipitation but results from multivariate, non-linear processes on top of the dominant meteoric controls on &#948;18O in precipitation.Here, we evaluate correlations and networks between different records and power spectral densities across a speleothem database for the past millennium (850-2000CE), testing for representativity of individual records for the time period. Similarity measures are applied to proxy records and to the local climate variables obtained from three isotope-enabled HadCM3 simulations to evaluate simulation biases across different parameters and to distinguish main climate drivers for individual records or regions. The proxy records show strong damping of variability on shorter time scales compared to simulations down-sampled to record-resolution, acting like simple filter processes with realistic time scales for karst transit times.Based on the evidence from proxies and models for the past 1000 years, we test for realistic parameter constraints and sufficient complexity of a speleothem proxy system model to represent low-latitude changes in climate variability on interannual to centennial timescales.

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Constructing Records of Storminess

Oxford Research Encyclopedia of Climate Science ◽

10.1093/acrefore/9780190228620.013.5 ◽

2018 ◽

Author(s):

Frauke Feser

Keyword(s):

General Circulation ◽

Climate Models ◽

Climate Model ◽

Measurement Data ◽

General Circulation Models ◽

Extreme Weather Events ◽

Storm Events ◽

Model Data ◽

Storm Activity ◽

The Past

Storms are characterized by high wind speeds; often large precipitation amounts in the form of rain, freezing rain, or snow; and thunder and lightning (for thunderstorms). Many different types exist, ranging from tropical cyclones and large storms of the midlatitudes to small polar lows, Medicanes, thunderstorms, or tornadoes. They can lead to extreme weather events like storm surges, flooding, high snow quantities, or bush fires. Storms often pose a threat to human lives and property, agriculture, forestry, wildlife, ships, and offshore and onshore industries. Thus, it is vital to gain knowledge about changes in storm frequency and intensity. Future storm predictions are important, and they depend to a great extent on the evaluation of changes in wind statistics of the past. To obtain reliable statistics, long and homogeneous time series over at least some decades are needed. However, wind measurements are frequently influenced by changes in the synoptic station, its location or surroundings, instruments, and measurement practices. These factors deteriorate the homogeneity of wind records. Storm indexes derived from measurements of sea-level pressure are less prone to such changes, as pressure does not show very much spatial variability as wind speed does. Long-term historical pressure measurements exist that enable us to deduce changes in storminess for more than the last 140 years. But storm records are not just compiled from measurement data; they also may be inferred from climate model data. The first numerical weather forecasts were performed in the 1950s. These served as a basis for the development of atmospheric circulation models, which were the first generation of climate models or general-circulation models. Soon afterward, model data was analyzed for storm events and cyclone-tracking algorithms were programmed. Climate models nowadays have reached high resolution and reliability and can be run not just for the past, but also for future emission scenarios which return possible future storm activity.

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Precession modulation of the South Pacific westerly wind belt over the past million years

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1905847116 ◽

2019 ◽

Vol 116 (47) ◽

pp. 23455-23460 ◽

Cited By ~ 2

Author(s):

Frank Lamy ◽

John C. H. Chiang ◽

Gema Martínez-Méndez ◽

Mieke Thierens ◽

Helge W. Arz ◽

...

Keyword(s):

General Circulation ◽

Mixed Layer Depth ◽

Atacama Desert ◽

South Pacific ◽

General Circulation Models ◽

Water Vapor Transport ◽

Intermediate Water ◽

Westerly Wind ◽

The South ◽

The Past

The southern westerly wind belt (SWW) interacts with the Antarctic Circumpolar Current and strongly impacts the Southern Ocean carbon budget, and Antarctic ice-sheet dynamics across glacial–interglacial cycles. We investigated precipitation-driven sediment input changes to the Southeast Pacific off the southern margin of the Atacama Desert over the past one million years, revealing strong precession (19/23-ka) cycles. Our simulations with 2 ocean–atmosphere general circulation models suggest that observed cyclic rainfall changes are linked to meridional shifts in water vapor transport from the tropical Pacific toward the southern Atacama Desert. These changes reflect a precessional modulation of the split in the austral winter South Pacific jet stream. For precession maxima, we infer significantly enhanced rainfall in the southern Atacama Desert due to a stronger South Pacific split jet with enhanced subtropical/subpolar jets, and a weaker midlatitude jet. Conversely, we derive dry conditions in northern Chile related to reduced subtropical/subpolar jets and an enhanced midlatitude jet for precession minima. The presence of precessional cycles in the Pacific SWW, and lack thereof in other basins, indicate that orbital-scale changes of the SWW were not zonally homogeneous across the Southern Hemisphere, in contrast to the hemispherewide shifts of the SWW suggested for glacial terminations. The strengthening of the jet is unique to the South Pacific realm and might have affected winter-controlled changes in the mixed layer depth, the formation of intermediate water, and the buildup of sea-ice around Antarctica, with implications for the global overturning circulation and the oceanic storage of atmospheric CO2.

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