Recent climate trends

Abstract. Studies on recent climate trends from the Himalayan range are limited, and even completely absent at high elevation (> 5000 m a.s.l.). This study specifically explores the southern slopes of Mt. Everest, analyzing the time series of temperature and precipitation reconstructed from seven stations located between 2660 and 5600 m a.s.l. during 1994–2013, complemented with the data from all existing ground weather stations located on both sides of the mountain range (Koshi Basin) over the same period. Overall we find that the main and most significant increase in temperature is concentrated outside of the monsoon period. Above 5000 m a.s.l. the increasing trend in the time series of minimum temperature (+0.072 °C yr−1) is much stronger than of maximum temperature (+0.009 °C yr−1), while the mean temperature increased by +0.044 °C yr−1. Moreover, we note a substantial liquid precipitation weakening (−9.3 mm yr−1) during the monsoon season. The annual rate of decrease in precipitation at higher elevations is similar to the one at lower elevations on the southern side of the Koshi Basin, but the drier conditions of this remote environment make the fractional loss much more consistent (−47% during the monsoon period). Our results challenge the assumptions on whether temperature or precipitation is the main driver of recent glacier mass changes in the region. The main implications are the following: (1) the negative mass balances of glaciers observed in this region can be more ascribed to a decrease in accumulation (snowfall) than to an increase in surface melting; (2) the melting has only been favoured during winter and spring months and close to the glaciers terminus; (3) a decrease in the probability of snowfall (−10%) has made a significant impact only at glacier ablation zone, but the magnitude of this decrease is distinctly lower than the observed decrease in precipitation; (4) the decrease in accumulation could have caused the observed decrease in glacier flow velocity and the current stagnation of glacier termini, which in turn could have produced more melting under the debris glacier cover, leading to the formation of numerous supraglacial and proglacial lakes that have characterized the region in the last decades.

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Weak precipitation, warm winters and springs impact glaciers of south slopes of Mt. Everest (central Himalaya) in the last two decades (1994–2013)

The Cryosphere Discussions ◽

10.5194/tcd-8-5911-2014 ◽

2014 ◽

Vol 8 (6) ◽

pp. 5911-5959 ◽

Cited By ~ 5

Author(s):

F. Salerno ◽

N. Guyennon ◽

S. Thakuri ◽

G. Viviano ◽

E. Romano ◽

...

Keyword(s):

Monsoon Season ◽

High Elevation ◽

Maximum Temperature ◽

Mountain Range ◽

Central Himalaya ◽

Climate Trends ◽

Monsoon Period ◽

Mean Temperature ◽

Recent Climate ◽

Koshi Basin

Abstract. Studies on recent climate trends from the Himalayan range are limited, and even completely absent at high elevation. This contribution specifically explores the southern slopes of Mt. Everest (central Himalaya), analyzing the minimum, maximum, and mean temperature and precipitation time series reconstructed from seven stations located between 2660 and 5600m a.s.l. over the last twenty years (1994–2013). We complete this analysis with data from all the existing ground weather stations located on both sides of the mountain range (Koshi Basin) over the same period. Overall we observe that the main and more significant increase in temperature is concentrated outside of the monsoon period. At higher elevations minimum temperature (0.072 ± 0.011 °C a−1, p < 0.001) increased far more than maximum temperature (0.009 ± 0.012 °C a−1, p > 0.1), while mean temperature increased by 0.044 ± 0.008 °C a−1, p < 0.05. Moreover, we note a substantial precipitation weakening (9.3 ± 1.8mm a−1, p < 0.01 during the monsoon season). The annual rate of decrease at higher elevation is similar to the one at lower altitudes on the southern side of the Koshi Basin, but here the drier conditions of this remote environment make the fractional loss much more consistent (47% during the monsoon period). This study contributes to change the perspective on which climatic driver (temperature vs. precipitation) led mainly the glacier responses in the last twenty years. The main implications are the following: (1) the negative mass balances of glaciers observed in this region can be more ascribed to less accumulation due to weaker precipitation than to an increase of melting processes. (2) The melting processes have only been favored during winter and spring months and close to the glaciers terminus. (3) A decreasing of the probability of snowfall has significantly interested only the glaciers ablation zones (10%, p < 0.05), but the magnitude of this phenomenon is decidedly lower than the observed decrease of precipitation. (4) The lesser accumulation could be the cause behind the observed lower glacier flow velocity and the current stagnation condition of tongues, which in turn could have trigged melting processes under the debris glacier coverage, leading to the formation of numerous supraglacial and proglacial lakes that have characterized the region in the last decades. Without demonstrating the causes that could have led to the climate change pattern observed at high elevation, we conclude by listing the recent literature on hypotheses that accord with our observations.

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Assessing impact of weather variability and changing climate on oil-palm yield in major growing regions of southern Thailand

Journal of Agrometeorology ◽

10.54386/jam.v22i3.189 ◽

2021 ◽

Vol 22 (3) ◽

pp. 274-284

Author(s):

RAWEE CHIARAWIPA ◽

KANJANA THONGNA ◽

SAYAN SDOODEE

Keyword(s):

Oil Palm ◽

Precipitation Trend ◽

Climate Trends ◽

Weather Variables ◽

Temperature Trends ◽

Recent Climate ◽

Southern Thailand ◽

Dryness Index ◽

The Relationship ◽

Linear Regressions

Oil palm yield is very responsive to weather fluctuations in the growing season. The purpose of this study was to investigate the relationship between yield variation and climate trends in the major oil palm-growing regions, especially in Southern Thailand (Chumphon; CP, Ranong; RN, Krabi; KB, Trang; TR, Satun; ST, Phang-Nga; PN, SuratThani; SR and Nakhon Si Thammarat; NS) where oil palm has been grown in a large plantation. Monthly weather variables from 16 agricultural meteorological stations were analyzed by linear and non-linear regressions over 28 years in each major oil palm-producing region. To evaluate the trends of changes in weather parameters and yield, a statistical model was developed for estimating oil palm yield based on climatic trends during 1994-2017. The results showed that warming trends were observed at all major oil palm-growing regions. There were pieces of evidence of significant correlation in temperature trends which had the strongest values in KB (Tmax, R2=0.534**) and PN (Tmin, R2=0.670**). The highest trends of ET and RH were also markedly increased in SR (R2=0.618**). Whereas precipitation trend had slightly increasing changes in CP (R2=0.220**) and PN (R2=0.233**). In addition, the annual trends in the values of Heliothermal Index, Dryness Index and Cool Night Index were markedly increased in NS, RN and KB, respectively. Comparing climate variables and yield variations over 19 years, the study indicated that the relationships between observed yield and estimated yield had highly significant differences in CP (R2=0.468**), SR (R2=0.735***) and NS (R2=0.579***), but there was lower value in KB (R2=0.098*) than those of the other regions. Therefore, this study indicates that recent climate trends have had an implicit effect on oil palm yield in the major producing regions in Southern Thailand. This study could be a guideline to further planning for oil palm management.

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Recent Climate Trends in the East Asia During the Baiu Season of 1979-2003

SOLA ◽

10.2151/sola.2005-036 ◽

2005 ◽

Vol 1 ◽

pp. 137-140 ◽

Cited By ~ 10

Author(s):

Nagio Hirota ◽

Masaaki Takahashi ◽

Naoki Sato ◽

Masahide Kimoto

Keyword(s):

East Asia ◽

Climate Trends ◽

Recent Climate

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Viticulture: Climate Relationships in Greece and Impacts of Recent Climate Trends: Sensitivity to “Effective” Growing Season Definitions

Advances in Meteorology, Climatology and Atmospheric Physics - Springer Atmospheric Sciences ◽

10.1007/978-3-642-29172-2_79 ◽

2012 ◽

pp. 555-561 ◽

Cited By ~ 2

Author(s):

G. Koufos ◽

T. Mavromatis ◽

S. Koundouras ◽

N. M. Fyllas

Keyword(s):

Growing Season ◽

Climate Trends ◽

Recent Climate

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Committed retreat: controls on glacier disequilibrium in a warming climate

Journal of Glaciology ◽

10.1017/jog.2018.57 ◽

2018 ◽

Vol 64 (246) ◽

pp. 675-688 ◽

Cited By ~ 10

Author(s):

JOHN ERICH CHRISTIAN ◽

MICHELLE KOUTNIK ◽

GERARD ROE

Keyword(s):

Climate Trends ◽

Ice Dynamics ◽

Mountain Glaciers ◽

Climate Reconstructions ◽

Recent Climate ◽

Glacier Dynamics ◽

Glacier Length ◽

Future Warming ◽

Idealized Modeling ◽

Selection Of

ABSTRACTThe widespread retreat of mountain glaciers is a striking emblem of recent climate change. Yet mass-balance observations indicate that many glaciers are out of equilibrium with current climate, meaning that observed retreats do not show the full response to warming. This is a fundamental consequence of glacier dynamics: mountain glaciers typically have multidecadal response timescales, and so their response lags centennial-scale climate trends. A substantial difference between transient and equilibrium glacier length persists throughout the warming period; we refer to this length difference as ‘disequilibrium’. Forcing idealized glacier geometries with gradual warming shows that the glacier response timescale fundamentally governs the evolution of disequilibrium. Comparing a hierarchy of different glacier models suggests that accurate estimates of ice thickness and climatology, which control the timescale, are more important than higher order ice dynamics for capturing disequilibrium. Current glacier disequilibrium has previously been estimated for a selection of individual glaciers; our idealized modeling shows that sustained disequilibrium is a fundamental response of glacier dynamics, and is robust across a range of glacier geometries. This implies that many mountain glaciers are committed to additional, kilometer-scale retreats, even without further warming. Disequilibrium must also be addressed when calibrating glacier models used for climate reconstructions and projections of retreat in response to future warming.

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