Extra-tropical Northern Hemisphere land temperature variability over the past 1000 years

2004 ◽  
Vol 23 (20-22) ◽  
pp. 2063-2074 ◽  
Author(s):  
Edward R. Cook ◽  
Jan Esper ◽  
Rosanne D. D’Arrigo
Keyword(s):  
Northern Hemisphere ◽  
Temperature Variability ◽  
The Past ◽  
Past 1000 Years

scholarly journals Northern Hemisphere atmospheric pattern enhancing Eastern Mediterranean Transient-type events during the past 1000 years 

2021 ◽  
Author(s):  
Aleix Cortina-Guerra ◽  
Juan José Gomez-Navarro ◽  
Belen Martrat ◽  
Juan Pedro Montávez ◽  
Alessandro Incarbona ◽  
...  
Keyword(s):  
Northern Hemisphere ◽  
Climate Model ◽  
Eastern Mediterranean ◽  
Aegean Sea ◽  
Sea Surface ◽  
The West ◽  
The Past ◽  
Main Driver ◽  
Climate Model Simulations ◽  
Past 1000 Years

Abstract. High resolution climate model simulations for the last millennium were used to elucidate the main winter Northern Hemisphere atmospheric pattern during enhanced Eastern Mediterranean Transient (EMT-type) events, a situation in which an additional overturning cell is detected in the Mediterranean at the Aegean Sea. The differential upward heat flux between the Aegean Basin and the Gulf of Lions was taken as a proxy of EMT-type events and correlated with winter mean geopotential height at 500 mb in the Northern Hemisphere (200 N-900 N and 1000 W-800 E). Correlations revealed a pattern similar to the Eastern Atlantic/Western Russian (EA/WR) mode as the main driver of EMT-type events, with the past 1000 yr of EA/WR-like mode simulations being enhanced during insolation minima. Our model results are consistent with alkenone Sea Surface Temperature (SST) reconstructions that documented an increase in the west-east basin gradients during EMT-type events.

Environmental information in the isotopic record in trees

1990 ◽  
Vol 330 (1615) ◽  
pp. 427-439 ◽  
Keyword(s):  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Environmental Information ◽  
Anthropogenic Effect ◽  
Geographic Locations ◽  
The Past ◽  
Past 1000 Years

Twenty-three trees from widely different geographic locations and different environments were analysed for the 8D and 8 13 C records. The 8D values suggested that the temperature of the Earth’s surface rose over the past 100 years and probably for the past 1000 years. The rate of warming appears to be latitude dependent, greatest in the cooler areas. The 8 13 C record, obtained for seven of the 23 trees, contain the 8 13 C decrease due to the anthropogenic effect, the addition of CO 2 from coal and petroleum burning. This effect appears to be twice as high in the Northern Hemisphere as in the Southern Hemisphere.

scholarly journals Northern Hemisphere atmospheric pattern enhancing Eastern Mediterranean Transient-type events during the past 1000 years

2021 ◽  
Vol 17 (4) ◽  
pp. 1523-1532
Author(s):  
Aleix Cortina-Guerra ◽  
Juan José Gomez-Navarro ◽  
Belen Martrat ◽  
Juan Pedro Montávez ◽  
Alessandro Incarbona ◽  
...  
Keyword(s):  
Northern Hemisphere ◽  
Climate Model ◽  
Eastern Mediterranean ◽  
Aegean Sea ◽  
East Atlantic ◽  
The Past ◽  
Gulf Of Lion ◽  
Main Driver ◽  
Climate Model Simulations ◽  
Past 1000 Years

Abstract. High-resolution climate model simulations for the last millennium were used to elucidate the main winter Northern Hemisphere atmospheric pattern during enhanced Eastern Mediterranean Transient (EMT-type) events, a situation in which an additional overturning cell is detected in the Mediterranean at the Aegean Sea. The differential upward heat flux between the Aegean Basin and the Gulf of Lion was taken as a proxy of EMT-type events and correlated with winter mean geopotential height at 500 mbar in the Northern Hemisphere (20–90∘ N and 100∘ W–80∘ E). Correlations revealed a pattern similar to the East Atlantic/Western Russian (EA/WR) mode as the main driver of EMT-type events, with the past 1000 years of EA/WR-like mode simulations being enhanced during insolation minima. Our model results are consistent with alkenone sea surface temperature (SST) reconstructions that documented an increase in the west–east basin gradients during EMT-type events.

scholarly journals Distribution and Attribution of Terrestrial Snow Cover Phenology Changes over the Northern Hemisphere during 2001–2020

2021 ◽  
Vol 13 (9) ◽  
pp. 1843
Author(s):  
Xiaona Chen ◽  
Yaping Yang ◽  
Yingzhao Ma ◽  
Huan Li
Keyword(s):  
Snow Cover ◽  
Northern Hemisphere ◽  
Onset Date ◽  
Driving Factor ◽  
Climate Variables ◽  
Significance Level ◽  
The Past ◽  
Attribution Analysis ◽  
Altitudinal Distributions ◽  
Melting Season

Snow cover phenology has exhibited dramatic changes in the past decades. However, the distribution and attribution of the hemispheric scale snow cover phenology anomalies remain unclear. Using satellite-retrieved snow cover products, ground observations, and reanalysis climate variables, this study explored the distribution and attribution of snow onset date, snow end date, and snow duration days over the Northern Hemisphere from 2001 to 2020. The latitudinal and altitudinal distributions of the 20-year averaged snow onset date, snow end date, and snow duration days are well represented by satellite-retrieved snow cover phenology matrixes. The validation results by using 850 ground snow stations demonstrated that satellite-retrieved snow cover phenology matrixes capture the spatial variability of the snow onset date, snow end date, and snow duration days at the 95% significance level during the overlapping period of 2001–2017. Moreover, a delayed snow onset date and an earlier snow end date (1.12 days decade−1, p < 0.05) are detected over the Northern Hemisphere during 2001–2020 based on the satellite-retrieved snow cover phenology matrixes. In addition, the attribution analysis indicated that snow end date dominates snow cover phenology changes and that an increased melting season temperature is the key driving factor of snow end date anomalies over the NH during 2001–2020. These results are helpful in understanding recent snow cover change and can contribute to climate projection studies.

Northern Hemisphere Controls on Tropical Southeast African Climate During the Past 60,000 Years

Science ◽  
2008 ◽  
Vol 322 (5899) ◽  
pp. 252-255 ◽  
Author(s):  
J. E. Tierney ◽  
J. M. Russell ◽  
Y. Huang ◽  
J. S. S. Damste ◽  
E. C. Hopmans ◽  
...  
Keyword(s):  
Northern Hemisphere ◽  
The Past ◽  
African Climate

scholarly journals Effect of climate and CO2changes on the greening of the Northern Hemisphere over the past two decades

2006 ◽  
Vol 33 (23) ◽  
Author(s):  
Shilong Piao ◽  
Pierre Friedlingstein ◽  
Philippe Ciais ◽  
Liming Zhou ◽  
Anping Chen
Keyword(s):  
Northern Hemisphere ◽  
The Past

scholarly journals Fast Warming Has Accelerated Snow Cover Loss during Spring and Summer across the Northern Hemisphere over the Past 52 Years (1967–2018)

Atmosphere ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 728
Author(s):  
Xuejiao Wu ◽  
Yongping Shen ◽  
Wei Zhang ◽  
Yinping Long
Keyword(s):  
Snow Cover ◽  
Northern Hemisphere ◽  
Spatial Scales ◽  
Summer Precipitation ◽  
Temperature Changes ◽  
The Past ◽  
Four Seasons ◽  
Snow Cover Extent ◽  
Summer Temperatures ◽  
Substantial Decline

With snow cover changing worldwide in several worrisome ways, it is imperative to determine both the variability in snow cover in greater detail and its relationship with ongoing climate change. Here, we used the satellite-based snow cover extent (SCE) dataset of National Oceanic and Atmospheric Administration (NOAA) to detect SCE variability and its linkages to climate over the 1967–2018 periods across the Northern Hemisphere (NH). Interannually, the time series of SCE across the NH reveal a substantial decline in both spring and summer (−0.54 and −0.71 million km2/decade, respectively), and this decreasing trend corresponded with rising spring and summer temperatures over high-latitude NH regions. Among the four seasons, the temperature rise over the NH was the highest in winter (0.39 °C/decade, p < 0.01). More precipitation in winter was closely related to an increase of winter SCE in mid-latitude areas of NH. Summer precipitation over the NH increased at a significant rate (1.1 mm/decade, p < 0.01), which likely contribute to the accelerated reduction of summer’s SCE across the NH. However, seasonal sensitivity of SCE to temperature changes differed between the Eurasian and North American continents. Thus, this study provides a better understanding of seasonal SCE variability and climatic changes that occurred at regional and hemispheric spatial scales in the past 52 years.

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