scholarly journals The origin of the European "Medieval Warm Period"

2006 ◽  
Vol 2 (2) ◽  
pp. 99-113 ◽  
Author(s):  
H. Goosse ◽  
O. Arzel ◽  
J. Luterbacher ◽  
M. E. Mann ◽  
H. Renssen ◽  
...  
Keyword(s):  
Land Use ◽  
20Th Century ◽  
Climate Model ◽  
Land Use Changes ◽  
Medieval Warm Period ◽  
Forced Response ◽  
Warm Period ◽  
Ice Age ◽  
Climate History ◽  
Proxy Records

Abstract. Proxy records and results of a three dimensional climate model show that European summer temperatures roughly a millennium ago were comparable to those of the last 25 years of the 20th century, supporting the existence of a summer "Medieval Warm Period" in Europe. Those two relatively mild periods were separated by a rather cold era, often referred to as the "Little Ice Age". Our modelling results suggest that the warm summer conditions during the early second millennium compared to the climate background state of the 13th–18th century are due to a large extent to the long term cooling induced by changes in land-use in Europe. During the last 200 years, the effect of increasing greenhouse gas concentrations, which was partly levelled off by that of sulphate aerosols, has dominated the climate history over Europe in summer. This induces a clear warming during the last 200 years, allowing summer temperature during the last 25 years to reach back the values simulated for the early second millennium. Volcanic and solar forcing plays a weaker role in this comparison between the last 25 years of the 20th century and the early second millennium. Our hypothesis appears consistent with proxy records but modelling results have to be weighted against the existing uncertainties in the external forcing factors, in particular related to land-use changes, and against the uncertainty of the regional climate sensitivity. Evidence for winter is more equivocal than for summer. The forced response in the model displays a clear temperature maximum at the end of the 20th century. However, the uncertainties are too large to state that this period is the warmest of the past millennium in Europe during winter.

scholarly journals The origin of the European "Medieval Warm Period"

2006 ◽  
Vol 2 (3) ◽  
pp. 285-314 ◽  
Author(s):  
H. Goosse ◽  
O. Arzel ◽  
J. Luterbacher ◽  
M. E. Mann ◽  
H. Renssen ◽  
...  
Keyword(s):  
20Th Century ◽  
Climate Model ◽  
Three Dimensional ◽  
Medieval Warm Period ◽  
Forced Response ◽  
Warm Period ◽  
Temperature History ◽  
Late 20Th Century ◽  
Proxy Records ◽  
Sulphate Aerosols

Abstract. Using a combination of proxy records and results of a three dimensional climate model, we show that European summer temperatures roughly a millennium ago were comparable to those of the late 20th century. Those two relatively mild periods are separated by a rather cold era, supporting the existence of a summer ``Medieval Warm Period" in Europe. The long-term temperature history appears to result from the superposition of various anthropogenic forcings, the summer cooling associated with changes in land-use over the last 1000 years having the same magnitude as the net warming due to the combined increase in greenhouse gas concentration and in sulphate aerosols during the last 200 years. Volcanic and solar forcing plays a weaker role in this comparison between the late 20th century and the early second millennium. Evidence for winter is more equivocal. The forced response in the model displays a clear temperature maximum at the end of the 20th century but the uncertainties are too large to state that this period is the warmest of the past millennium in Europe in winter.

scholarly journals A comparison of the Medieval Warm Period, Little Ice Age and 20th century warming simulated by the FGOALS climate system model

2011 ◽  
Vol 56 (28-29) ◽  
pp. 3028-3041 ◽  
Author(s):  
TianJun Zhou ◽  
Bo Li ◽  
WenMin Man ◽  
LiXia Zhang ◽  
Jie Zhang
Keyword(s):  
20Th Century ◽  
Little Ice Age ◽  
Medieval Warm Period ◽  
Warm Period ◽  
Climate System ◽  
Ice Age ◽  
System Model ◽  
Climate System Model

scholarly journals Centennial Variations of the Global Monsoon Precipitation in the Last Millennium: Results from ECHO-G Model

2009 ◽  
Vol 22 (9) ◽  
pp. 2356-2371 ◽  
Author(s):  
Jian Liu ◽  
Bin Wang ◽  
Qinghua Ding ◽  
Xueyuan Kuang ◽  
Willie Soon ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Carbon Dioxide Concentration ◽  
Medieval Warm Period ◽  
Forced Response ◽  
Warm Period ◽  
Ice Age ◽  
Last Millennium ◽  
Solar Forcing ◽  
Global Monsoon ◽  
Northern And Southern Hemispheres

Abstract The authors investigate how the global monsoon (GM) precipitation responds to the external and anthropogenic forcing in the last millennium by analyzing a pair of control and forced millennium simulations with the ECHAM and the global Hamburg Ocean Primitive Equation (ECHO-G) coupled ocean–atmosphere model. The forced run, which includes the solar, volcanic, and greenhouse gas forcing, captures the major modes of precipitation climatology comparably well when contrasted with those captured by the NCEP reanalysis. The strength of the modeled GM precipitation in the forced run exhibits a significant quasi-bicentennial oscillation. Over the past 1000 yr, the simulated GM precipitation was weak during the Little Ice Age (1450–1850) with the three weakest periods occurring around 1460, 1685, and 1800, which fell in, respectively, the Spörer Minimum, Maunder Minimum, and Dalton Minimum periods of solar activity. Conversely, strong GM was simulated during the model Medieval Warm Period (ca. 1030–1240). Before the industrial period, the natural variations in the total amount of effective solar radiative forcing reinforce the thermal contrasts both between the ocean and continent and between the Northern and Southern Hemispheres resulting in the millennium-scale variation and the quasi-bicentennial oscillation in the GM index. The prominent upward trend in the GM precipitation occurring in the last century and the notable strengthening of the global monsoon in the last 30 yr (1961–90) appear unprecedented and are due possibly in part to the increase of atmospheric carbon dioxide concentration, though the authors’ simulations of the effects from recent warming may be overestimated without considering the negative feedbacks from aerosols. The simulated change of GM in the last 30 yr has a spatial pattern that differs from that during the Medieval Warm Period, suggesting that global warming that arises from the increases of greenhouse gases and the input solar forcing may have different effects on the characteristics of GM precipitation. It is further noted that GM strength has good relational coherence with the temperature difference between the Northern and Southern Hemispheres, and that on centennial time scales the GM strength responds more directly to the effective solar forcing than the concurrent forced response in global-mean surface temperature.

scholarly journals Medieval Warm Period, Little Ice Age and 20th century temperature variability from Chesapeake Bay

2003 ◽  
Vol 36 (1-2) ◽  
pp. 17-29 ◽  
Author(s):  
T.M Cronin ◽  
G.S Dwyer ◽  
T Kamiya ◽  
S Schwede ◽  
D.A Willard
Keyword(s):  
Chesapeake Bay ◽  
20Th Century ◽  
Little Ice Age ◽  
Medieval Warm Period ◽  
Temperature Variability ◽  
Warm Period ◽  
Ice Age

scholarly journals Climate Variability in Central Europe during the Last 2500 Years Reconstructed from Four High-Resolution Multi-Proxy Speleothem Records

Geosciences ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 166
Author(s):  
Sarah Waltgenbach ◽  
Dana F. C. Riechelmann ◽  
Christoph Spötl ◽  
Klaus P. Jochum ◽  
Jens Fohlmeister ◽  
...  
Keyword(s):  
Trace Elements ◽  
High Resolution ◽  
Climate Variability ◽  
Little Ice Age ◽  
Medieval Warm Period ◽  
Warm Period ◽  
Ice Age ◽  
Cold Period ◽  
Cave System ◽  
Dark Ages

The Late Holocene was characterized by several centennial-scale climate oscillations including the Roman Warm Period, the Dark Ages Cold Period, the Medieval Warm Period and the Little Ice Age. The detection and investigation of such climate anomalies requires paleoclimate archives with an accurate chronology as well as a high temporal resolution. Here, we present 230Th/U-dated high-resolution multi-proxy records (δ13C, δ18O and trace elements) for the last 2500 years of four speleothems from Bunker Cave and the Herbstlabyrinth cave system in Germany. The multi-proxy data of all four speleothems show evidence of two warm and two cold phases during the last 2500 years, which coincide with the Roman Warm Period and the Medieval Warm Period, as well as the Dark Ages Cold Period and the Little Ice Age, respectively. During these four cold and warm periods, the δ18O and δ13C records of all four speleothems and the Mg concentration of the speleothems Bu4 (Bunker Cave) and TV1 (Herbstlabyrinth cave system) show common features and are thus interpreted to be related to past climate variability. Comparison with other paleoclimate records suggests a strong influence of the North Atlantic Oscillation at the two caves sites, which is reflected by warm and humid conditions during the Roman Warm Period and the Medieval Warm Period, and cold and dry climate during the Dark Ages Cold period and the Little Ice Age. The Mg records of speleothems Bu1 (Bunker Cave) and NG01 (Herbstlabyrinth) as well as the inconsistent patterns of Sr, Ba and P suggests that the processes controlling the abundance of these trace elements are dominated by site-specific effects rather than being related to supra-regional climate variability.

scholarly journals Strong increases in flood frequency and discharge of the River Meuse over the late Holocene: impacts of long-term anthropogenic land use change and climate variability

2008 ◽  
Vol 12 (1) ◽  
pp. 159-175 ◽  
Author(s):  
P. J. Ward ◽  
H. Renssen ◽  
J. C. J. H. Aerts ◽  
R. T. van Balen ◽  
J. Vandenberghe
Keyword(s):  
Land Use ◽  
Land Use Change ◽  
Climate Model ◽  
Land Use Changes ◽  
Winter Precipitation ◽  
Flood Frequency ◽  
High Flow ◽  
Recurrence Time ◽  
Strong Increase ◽  
Historical Sources

Abstract. In recent years the frequency of high-flow events on the Meuse (northwest Europe) has been relatively great, and flooding has become a major research theme. To date, research has focused on observed discharge records of the last century and simulations of the coming century. However, it is difficult to delineate changes caused by human activities (land use change and greenhouse gas emissions) and natural fluctuations on these timescales. To address this problem we coupled a climate model (ECBilt-CLIO-VECODE) and a hydrological model (STREAM) to simulate daily Meuse discharge in two time-slices: 4000–3000 BP (natural situation), and 1000–2000 AD (includes anthropogenic influence). For 4000–3000 BP the basin is assumed to be almost fully forested; for 1000–2000 AD we reconstructed land use based on historical sources. For 1000–2000 AD the simulated mean annual discharge (260.9 m3 s−1) is significantly higher than for 4000–3000 BP (244.8 m3 s−1), and the frequency of large high-flow events (discharge >3000 m3 s−1) is higher (recurrence time decreases from 77 to 65 years). On a millennial timescale almost all of this increase can be ascribed to land use changes (especially deforestation); the effects of climatic change are insignificant. For the 20th Century, the simulated mean discharge (270.0 m3 s−1) is higher than in any other century studied, and is ca. 2.5% higher than in the 19th Century (despite an increase in evapotranspiration). Furthermore, the recurrence time of large high-flow events is almost twice as short as under natural conditions (recurrence time decreases from 77 to 40 years). On this timescale climate change (strong increase in annual and winter precipitation) overwhelmed land use change as the dominant forcing mechanism.

scholarly journals Understanding drivers of glacier-length variability over the last millennium

2021 ◽  
Vol 15 (3) ◽  
pp. 1645-1662
Author(s):  
Alan Huston ◽  
Nicholas Siler ◽  
Gerard H. Roe ◽  
Erin Pettit ◽  
Nathan J. Steiger
Keyword(s):  
Climate Variability ◽  
Climate Model ◽  
Volcanic Eruptions ◽  
Internal Variability ◽  
Forced Response ◽  
Last Millennium ◽  
External Forcing ◽  
Climate History ◽  
Temperature And Precipitation ◽  
Glacier Length

Abstract. Changes in glacier length reflect the integrated response to local fluctuations in temperature and precipitation resulting from both external forcing (e.g., volcanic eruptions or anthropogenic CO2) and internal climate variability. In order to interpret the climate history reflected in the glacier moraine record, the influence of both sources of climate variability must therefore be considered. Here we study the last millennium of glacier-length variability across the globe using a simple dynamic glacier model, which we force with temperature and precipitation time series from a 13-member ensemble of simulations from a global climate model. The ensemble allows us to quantify the contributions to glacier-length variability from external forcing (given by the ensemble mean) and internal variability (given by the ensemble spread). Within this framework, we find that internal variability is the predominant source of length fluctuations for glaciers with a shorter response time (less than a few decades). However, for glaciers with longer response timescales (more than a few decades) external forcing has a greater influence than internal variability. We further find that external forcing also dominates when the response of glaciers from widely separated regions is averaged. Single-forcing simulations indicate that, for this climate model, most of the forced response over the last millennium, pre-anthropogenic warming, has been driven by global-scale temperature change associated with volcanic aerosols.

Sign in / Sign up

Export Citation Format

Share Document