Seven hundred years of human-driven and climate-influenced fire activity in a British Columbia coastal temperate rainforest

While wildland fire is globally most common at the savannah-grassland ecotone, there is little evidence of fire in coastal temperate rainforests. We reconstructed fire activity with a ca 700-year fire history derived from fire scars and stand establishment from 30 sites in a very wet (up to 4000 mm annual precipitation) temperate rainforest in coastal British Columbia, Canada. Drought and warmer temperatures in the year prior were positively associated with fire events though there was little coherence of climate indices on the years of fires. At the decadal scale, fires were more likely to occur after positive El Niño-Southern Oscillation and Pacific Decadal Oscillation phases and exhibited 30-year periods of synchrony with the negative phase of the Arctic Oscillation. Fire frequency was significantly inversely correlated with the distance from former Indigenous habitation sites and fires ceased following cultural disorganization caused by disease and other European impacts in the late nineteenth century. Indigenous people were likely to have been the primary ignition source in this and many coastal temperate rainforest settings. These data are directly relevant to contemporary forest management and discredit the myth of coastal temperate rainforests as pristine landscapes.

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Variability of Arctic Sea Ice Based on Quantile Regression and the Teleconnection with Large-Scale Climate Patterns

Journal of Climate ◽

10.1175/jcli-d-19-0375.1 ◽

2020 ◽

Vol 33 (10) ◽

pp. 4009-4025

Author(s):

Shuyu Zhang ◽

Thian Yew Gan ◽

Andrew B. G. Bush

Keyword(s):

Sea Ice ◽

Quantile Regression ◽

Large Scale ◽

Southern Oscillation ◽

Arctic Sea Ice ◽

The Arctic ◽

Climate Indices ◽

The Pacific ◽

Arctic Sea ◽

Climate Patterns

AbstractUnder global warming, Arctic sea ice has declined significantly in recent decades, with years of extremely low sea ice occurring more frequently. Recent studies suggest that teleconnections with large-scale climate patterns could induce the observed extreme sea ice loss. In this study, a probabilistic analysis of Arctic sea ice was conducted using quantile regression analysis with covariates, including time and climate indices. From temporal trends at quantile levels from 0.01 to 0.99, Arctic sea ice shows statistically significant decreases over all quantile levels, although of different magnitudes at different quantiles. At the representative extreme quantile levels of the 5th and 95th percentiles, the Arctic Oscillation (AO), the North Atlantic Oscillation (NAO), and the Pacific–North American pattern (PNA) have more significant influence on Arctic sea ice than El Niño–Southern Oscillation (ENSO), the Pacific decadal oscillation (PDO), and the Atlantic multidecadal oscillation (AMO). Positive AO as well as positive NAO contribute to low winter sea ice, and a positive PNA contributes to low summer Arctic sea ice. If, in addition to these conditions, there is concurrently positive AMO and PDO, the sea ice decrease is amplified. Teleconnections between Arctic sea ice and the climate patterns were demonstrated through a composite analysis of the climate variables. The anomalously strong anticyclonic circulation during the years of positive AO, NAO, and PNA promotes more sea ice export through Fram Strait, resulting in excessive sea ice loss. The probabilistic analyses of the teleconnections between the Arctic sea ice and climate patterns confirm the crucial role that the climate patterns and their combinations play in overall sea ice reduction, but particularly for the low and high quantiles of sea ice concentration.

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Effect of Autocorrelation On Temporal Trends In Air-Temperature In A Northern Algeria And Links With Teleconnections Patterns

10.21203/rs.3.rs-491178/v1 ◽

2021 ◽

Author(s):

Sabrina Taïbi ◽

Ayoub Zeroual ◽

Mohamed Meddi

Keyword(s):

Southern Oscillation ◽

Statistical Tests ◽

Temporal Trends ◽

Step Change ◽

The Arctic ◽

Climate Indices ◽

East Atlantic ◽

Entire Study ◽

The North ◽

Mediterranean Oscillation

Abstract This study investigates the effect of autocorrelation on temporal trends and step change on monthly, seasonal and annual temperatures of six meteorological stations of the North of Algeria from 1950 to 2016. Afterwards, links between the general atmospheric circulation, via six climate indices, and temperature are examined. Trends of temperature are analysed using six different versions of the Mann Kendall approach while the step change of the time series is computed using the original Pettitt test and the modified-Pettitt. Statistical tests have shown an increase in annual temperatures from 0.8 to 0.9°C since the 1980’s on the coastal regions and 90’s on the highlands. This warming most often exceeds 1°C on a seasonal scale, particularly in summer, while no significant trend is observed in winter. On a monthly scale, the increase in temperatures is marked between April and October. The analysis of relationships between six climate indices and average temperatures has shown that inter-annual temperature variability is most often associated with the East Atlantic oscillation for the entire study area. Winter temperatures are influenced by the Mediterranean oscillation as well as the North Atlantic oscillation. The East Atlantic oscillation is the dominant mode of circulation in spring and summer, while in autumn temperatures are strongly linked to West Mediterranean Oscillation. However, no significant correlations have been observed between temperatures and the Arctic Oscillation and El Nino southern oscillation.

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Spatiotemporal Variations of Drought and Their Teleconnections with Large-Scale Climate Indices over the Poyang Lake Basin, China

Sustainability ◽

10.3390/su12093526 ◽

2020 ◽

Vol 12 (9) ◽

pp. 3526 ◽

Cited By ~ 2

Author(s):

Weilin Liu ◽

Shengnan Zhu ◽

Yipeng Huang ◽

Yifan Wan ◽

Bin Wu ◽

...

Keyword(s):

Water Resource Management ◽

Large Scale ◽

Poyang Lake ◽

Southern Oscillation ◽

Trend Test ◽

Climate Indices ◽

Lake Basin ◽

Spatiotemporal Variations ◽

Poyang Lake Basin ◽

Decadal Scale

The intensity and frequency of droughts in Poyang Lake Basin have been increasing due to global warming. To properly manage water resources and mitigate drought disasters, it is important to understand the long-term characteristics of drought and its possible link with large-scale climate indices. Based on the monthly meteorological data of 41 meteorological stations in Poyang Lake Basin from 1958 to 2017, the spatiotemporal variations of drought were investigated using the standardized precipitation evapotranspiration index (SPEI). Ensemble empirical mode decomposition (EEMD) methods and the modified Mann–Kendall (MMK) trend test were used to explore the spatiotemporal characteristics and trends of drought. Furthermore, to reveal possible links between drought variations and large-scale climate indices in Poyang Lake Basin, the relationships between SPEI and large-scale climate indices, such as North Atlantic Oscillation (NAO), El Niño–Southern Oscillation (ENSO), Arctic Oscillation (AO), Indian Ocean Dipole (IOD) and Pacific Decadal Oscillation (PDO) were examined using cross-wavelet transform. The results showed that the SPEI in Poyang Lake Basin exhibited relatively stable quasi-periodic oscillation, with approximate quasi-3-year and quasi-6-year periods at the inter-annual scale and quasi-15-year and quasi-30-year periods at the inter-decadal scale from 1958 to 2017. Moreover, the Poyang Lake Basin experienced an insignificantly wetter trend as a whole at the annual and seasonal scales during the period of 1958–2017, except for spring, which had a drought trend. The special characteristics of the trend variations were markedly different in the basin. The areas in which drought was most likely to occur were mainly located in the Poyang Lake region, northwest and south of the basin, respectively. Furthermore, relationships between the drought and six climate indices showed that the drought exhibited a significant temporal correlation with five climate indices at restricted intervals, except for IOD. The dominant influences of the large-scale climate indices on the drought evolutions shifted in the Poyang Lake Basin during 1958–2017, from the NAO, Niño 3.4, and the Southern Oscillation Index (SOI) before the late 1960s and early 1970s, to the AO and PDO during the 1980s, then to the NAO, AO and SOI after the early 2000s. The NAO, AO and SOI exerted a significant influence on the drought events in the basin. The results of this study will benefit regional water resource management, agriculture production, and ecosystem protection in the Poyang Lake Basin.

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Climate Change on the Northern Tibetan Plateau during 1957–2009: Spatial Patterns and Possible Mechanisms

Journal of Climate ◽

10.1175/jcli-d-11-00738.1 ◽

2013 ◽

Vol 26 (1) ◽

pp. 85-109 ◽

Cited By ~ 63

Author(s):

Lan Cuo ◽

Yongxin Zhang ◽

Qingchun Wang ◽

Leilei Zhang ◽

Bingrong Zhou ◽

...

Keyword(s):

Wind Speed ◽

Tibetan Plateau ◽

Large Scale ◽

Southern Oscillation ◽

Warm Season ◽

The Arctic ◽

Climate Indices ◽

High Mountain ◽

Gridded Data ◽

Northern Tibetan Plateau

Abstract Gridded daily precipitation, temperature minima and maxima, and wind speed are generated for the northern Tibetan Plateau (NTP) for 1957–2009 using observations from 81 surface stations. Evaluation reveals reasonable quality and suitability of the gridded data for climate and hydrology analysis. The Mann–Kendall trends of various climate elements of the gridded data show that NTP has in general experienced annually increasing temperature and decreasing wind speed but spatially varied precipitation changes. The northwest (northeast) NTP became dryer (wetter), while there were insignificant changes in precipitation in the south. Snowfall has decreased along high mountain ranges during the wet and warm season. Averaged over the entire NTP, snowfall, temperature minima and maxima, and wind speed experienced statistically significant linear trends at rates of −0.52 mm yr−1 (water equivalent), +0.04°C yr−1, +0.03°C yr−1, and −0.01 m s−1 yr−1, respectively. Correlation between precipitation/wind speed and climate indices characterizing large-scale weather systems for four subregions in NTP reveals that changes in precipitation and wind speed in winter can be attributed to changes in the North Atlantic Oscillation (NAO), the Arctic Oscillation (AO), the East Asian westerly jet (WJ), and the El Niño–Southern Oscillation (ENSO) (wind speed only). In summer, the changes in precipitation and wind are only weakly related to these indices. It is speculated that in addition to the NAO, AO, ENSO, WJ, and the East and South Asian summer monsoons, local weather systems also play important roles.

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Wildfire activity in rainforests in western Patagonia linked to the Southern Annular Mode

International Journal of Wildland Fire ◽

10.1071/wf10121 ◽

2012 ◽

Vol 21 (2) ◽

pp. 114 ◽

Cited By ~ 32

Author(s):

Andrés Holz ◽

Thomas T. Veblen

Keyword(s):

Fire History ◽

Southern Oscillation ◽

Climatic Variability ◽

Regional Climate ◽

Southern Annular Mode ◽

Strong Increase ◽

Annular Mode ◽

Decadal Scale ◽

In Fire

Increased wildfire activity in relation to future climate warming is likely for temperate rainforest biomes where fire depends on anomalously dry fuel conditions. Tree-ring fire history records were developed from fires scars in western Patagonia, and synchrony in fire activity was examined to determine the role of regional climate variability in promoting fires. Interannual variability in the multicentury fire history records was related to El Niño–Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO) and the Southern Annular Mode (SAM). Interannual fire synchrony and decadal-scale trends in wildfires document a strong influence of broad-scale climatic variability on wildfires in western Patagonia. SAM is above average during years of regional drought that coincide with widespread fires. Analyses of contingent interactions of ENSO, PDO and SAM revealed that fire frequencies were greater than expected only when SAM was in its positive phase, regardless of the phase of ENSO and PDO. The fire-enhancing influence of SAM was greatest when PDO was also positive, which indicates Pacific-wide warmer conditions. There is a strong increase in wildfire activity coincident with warming and drying trends during the 20th century and with variability in SAM, which is predicted to continue to be in this fire-conducive phase for the 21st century.

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First Passage Time Analysis on Climate Indices

Journal of Atmospheric and Oceanic Technology ◽

10.1175/2007jtecha991.1 ◽

2008 ◽

Vol 25 (2) ◽

pp. 258-270 ◽

Cited By ~ 1

Author(s):

Peter C. Chu

Keyword(s):

Southern Oscillation ◽

Past History ◽

First Passage Time ◽

Passage Time ◽

The Arctic ◽

Climate Indices ◽

First Passage ◽

Teleconnection Patterns ◽

The Arctic Oscillation ◽

Basic Features

Abstract Climate variability is simply represented by teleconnection patterns such as the Arctic Oscillation (AO), Antarctic Oscillation (AAO), North Atlantic Oscillation (NAO), Pacific–North American pattern (PNA), and Southern Oscillation (SO) with associated indices. Two approaches can be used to predict the indices: forward and backward methods. The forward method is commonly used to predict the index fluctuation ρ at time t with a given temporal increment τ. Using this method, it was found that the index (such as for NAO) has the Brownian fluctuations. On the basis of the first passage time (FPT) concept, the backward method is introduced in this study to predict the typical time span (τ) needed to generate a fluctuation in the index of a given increment ρ. After the five monthly indices (AO, AAO, NAO, PNA, and SO) run through the past history, the FPT density functions are obtained. FPT presents a new way to detect the temporal variability of the climate indices. The basic features for the index prediction are also discussed.

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Fire history in western Patagonia from paired tree-ring fire-scar and charcoal records

Climate of the Past ◽

10.5194/cp-8-451-2012 ◽

2012 ◽

Vol 8 (2) ◽

pp. 451-466 ◽

Cited By ~ 19

Author(s):

A. Holz ◽

S. Haberle ◽

T. T. Veblen ◽

R. De Pol-Holz ◽

J. Southon

Keyword(s):

South America ◽

Tree Ring ◽

Large Scale ◽

Fire History ◽

Southern Oscillation ◽

Climatic Variability ◽

Regional Climate ◽

Southern South America ◽

Fire Scar ◽

Fire Activity

Abstract. Fire history reconstructions are typically based on tree ages and tree-ring fire scars or on charcoal in sedimentary records from lakes or bogs, but rarely on both. In this study of fire history in western Patagonia (47–48° S) in southern South America (SSA) we compared three sedimentary charcoal records collected in bogs with tree-ring fire-scar data collected at 13 nearby sample sites. We examined the temporal and spatial correspondence between the two fire proxies and also compared them to published charcoal records from distant sites in SSA, and with published proxy reconstructions of regional climate variability and large-scale climate modes. Two of our three charcoal records record fire activity for the last 4 ka yr and one for the last 11 ka yr. For the last ca. 400 yr, charcoal accumulation peaks tend to coincide with high fire activity in the tree-ring fire scar records, but the charcoal records failed to detect some of the fire activity recorded by tree rings. Potentially, this discrepancy reflects low-severity fires that burn in herbaceous and other fine fuels without depositing charcoal in the sedimentary record. Periods of high fire activity tended to be synchronous across sample areas, across proxy types, and with proxy records of regional climatic variability as well as major climate drivers. Fire activity throughout the Holocene in western Patagonia has responded to regional climate variation affecting a broad region of southern South America that is teleconnected to both tropical- and high-latitude climate drivers-El Niño-Southern Oscillation and the Southern Annular Mode. An early Holocene peak in fire activity pre-dates any known human presence in our study area, and consequently implicates lightning as the ignition source. In contrast, the increased fire activity during the 20th century, which was concomitantly recorded by charcoal from all the sampled bogs and at all fire-scar sample sites, is attributed to human-set fires and is outside the range of variability characteristic of these ecosystems over many centuries and probably millennia.

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Fire history in western Patagonia from paired tree-ring fire-scar and charcoal records

Climate of the Past Discussions ◽

10.5194/cpd-7-3203-2011 ◽

2011 ◽

Vol 7 (5) ◽

pp. 3203-3238 ◽

Cited By ~ 4

Author(s):

A. Holz ◽

S. Haberle ◽

T. T. Veblen ◽

R. De Pol-Holz ◽

J. Southon

Keyword(s):

South America ◽

Tree Ring ◽

Large Scale ◽

Fire History ◽

Southern Oscillation ◽

Climatic Variability ◽

Regional Climate ◽

Southern South America ◽

Fire Scar ◽

Fire Activity

Abstract. Fire history reconstructions are typically based on tree ages and tree-ring fire scars or on charcoal in sedimentary records from lakes or bogs, but rarely on both. In this study of fire history in western Patagonia (47–48° S) in southern South America (SSA) we compared three sedimentary charcoal records collected in bogs with tree-ring fire-scar data collected at 13 nearby sample sites. We examined the temporal and spatial correspondence between the two fire proxies and also compared them to published charcoal records from distant sites in SSA, and with published proxy reconstructions of regional climate variability and large-scale climate modes. Two of our three charcoal records show fire activity for the last 4ka yrs and one for the last 11 ka yr. For the last ca. 400 yr, charcoal accumulation peaks tend to coincide with high fire activity in the tree-ring fire scar records, but the charcoal records failed to detect some of the fire activity recorded by tree rings. Potentially, this discrepancy reflects low-severity fires that burn in herbaceous and other fine fuels without depositing charcoal in the sedimentary record. Periods of high fire activity tended to be synchronous across sample areas, across proxy types, and with proxy records of regional climatic variability as well as major climate drivers. Fire activity throughout the Holocene in western Patagonia has responded to regional climate variation affecting a broad region of southern South America that is teleconnected to both tropical- and high-latitude climate drivers – El Nino-Southern Oscillation and the Southern Annular Mode. An early Holocene peak in fire activity pre-dates any known human presence in our study area, and consequently implicates lightning as the ignition source. In contrast, the increased fire activity during the 20th century, which was concomitantly recorded by charcoal from all the sampled bogs and at all fire-scar sample sites, is attributed to human-set fires and is outside the range of variability characteristic of these ecosystems over many centuries and probably millennia.

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Streamflow Variability in Colombian Pacific Basins and Their Teleconnections with Climate Indices

Water ◽

10.3390/w12020526 ◽

2020 ◽

Vol 12 (2) ◽

pp. 526 ◽

Cited By ~ 3

Author(s):

Teresita Canchala ◽

Wilmar Loaiza Cerón ◽

Félix Francés ◽

Yesid Carvajal-Escobar ◽

Rita Andreoli ◽

...

Keyword(s):

River Basin ◽

El Niño ◽

El Nino ◽

Southern Oscillation ◽

Wavelet Coherence ◽

Climate Indices ◽

Decadal Scale ◽

Streamflow Variability ◽

Wavelet Coherence Analysis ◽

Colombian Pacific

Oceanic-atmospheric phenomena of different time scales concurrently might affect the streamflow in several basins around the world. The Atrato River Basin (ARB) and Patía River Basin (PRB) of the Colombian Pacific region are examples of such basins. Nevertheless, the relations between the streamflows in the ARB and PRB and the oceanic-atmospheric factors have not been examined considering different temporal scales. Hence, this article studies the relations of the climate indices and the variability of the streamflows in the ARB and PRB at interannual and decadal timescales. To this, the streamflow variability modes were obtained from the principal component analysis (PCA); furthermore, their linear dependence with indices of the El Niño/Southern Oscillation (ENSO), precipitation (PRP), the Choco low-level jet (CJ), and other indices were quantified through (a) Pearson and Kendall’s tau correlations, and (b) wavelet transform. The PCA presented a single significant mode for each basin, with an explained variance of around 80%. The correlation analyses between the PC1s of the ARB and PRB, and the climate indices showed significant positive (negative) high correlations with PRP, CJ, and Southern Oscillation Index (SOI) (ENSO indices). The wavelet coherence analysis showed significant coherencies between ENSO and ARB: at interannual (2–7 years) and decadal scale (8–14), preferably with the sea surface temperature (SST) in the east and west Tropical Pacific Ocean (TPO). For PRB with the SST in the central and western regions of the TPO in the interannual (4–8 years) and decadal (8–14 years) scales, the decreases (increases) in streamflow precede the El Niño (La Niña) events. These results indicate multiscale relations between the basins’ streamflow and climate phenomena not documented in previous works, relevant to forecast the extreme flow events in the Colombian Pacific rivers and for planning and implementing strategies for the sustainable use of water resources in the basins studied.

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Late Holocene fire history documented at Lake Khamra, SW Yakutia (Eastern Siberia)

10.5194/egusphere-egu2020-1018 ◽

2020 ◽

Author(s):

Ramesh Glückler ◽

Ulrike Herzschuh ◽

Luidmila Pestryakova ◽

Stefan Kruse ◽

Stuart Vyse ◽

...

Keyword(s):

Boreal Forest ◽

Boreal Forests ◽

Late Holocene ◽

Fire History ◽

The Arctic ◽

Permafrost Degradation ◽

Reconstructed Temperature ◽

Fire Activity ◽

Microscopic Charcoal ◽

Macroscopic Charcoal

<p>Recent large-scale fire events in Siberia have drawn increased attention to boreal forest fire history. Boreal forests contain about 25% of all global biomass and act as an enormous carbon storage. Fire events are important ecological disturbances connected to the overarching environmental changes that face the Arctic and Subarctic, like vegetation dynamics, permafrost degradation, changes in soil nutrient cycling and global warming, and act as the dominant driver behind boreal forest&#8217;s landscape carbon balance. By looking into past fire regimes we can learn about fire frequency and potential linkages to other environmental factors, e.g. fuel types, reconstructed temperature/humidity or geomorphologic landscape dynamics. Unfortunately, fire history data is still very sparse in large parts of Siberia, a region strongly influenced by climate change. The Global Charcoal Database (www.paleofire.org) lists only a handful of continuous charcoal records for all of Siberia, with only three of those featuring published data from macroscopic charcoal as opposed to microscopic charcoal from pollen slides.</p><p>We aim to reconstruct the late Holocene fire history using lacustrine sediments of Lake Khamra (SW Yakutia at N 59.99&#176;, E 112.98&#176;). It covers an area of c. 4.6 km&#178; with about 22 m maximum water depth, located within the zone of transition from summer-green and larch-dominated to evergreen boreal forest. We present the first continuous, high-resolution (c. 10 years/sample) macroscopic charcoal record (> 150 &#956;m) including information on particle size and morphology for the past c. 2200 years. We compare this to complementary information from microscopic charcoal in pollen slides, a pollen and non-pollen palynomorph record as well as &#956;XRF data. This multi-proxy approach adds valuable data about fire activity in the region and allows a comparison of different prevalent fire reconstruction methods. As the first record of its kind from Siberia, it provides a long-term context for current fire activity in central Siberian boreal forests and enables a better understanding of the environmental interactions occurring in the changing subarctic landscape.</p>

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