Record-breaking warming and extreme drought in the Amazon rainforest during the course of El Niño 2015–2016

The global climate during 1998 was affected by opposite extremes of the ENSO cycle, with one of the strongest Pacific warm episodes (El Niño) in the historical record continuing during January–early May and Pacific cold episode (La Niña) conditions occurring from JulyñDecember. In both periods, regional temperature, rainfall, and atmospheric circulation patterns across the Pacific Ocean and the Americas were generally consistent with those observed during past warm and cold episodes. Some of the most dramatic impacts from both episodes were observed in the Tropics, where anomalous convection was evident across the entire tropical Pacific and in most major monsoon regions of the world. Over the Americas, many of the El Niño– (La Niña–) related rainfall anomalies in the subtropical and extratropical latitudes were linked to an extension (retraction) of the jet streams and their attendant circulation features typically located over the subtropical latitudes of both the North Pacific and South Pacific. The regions most affected by excessive El Niño–related rainfall included 1) the eastern half of the tropical Pacific, including western Ecuador and northwestern Peru, which experienced significant flooding and mudslides; 2) southeastern South America, where substantial flooding was also observed; and 3) California and much of the central and southern United States during January–March, and the central United States during April–June. El Niño–related rainfall deficits during 1998 included 1) Indonesia and portions of northern Australia; 2) the Amazon Basin, in association with a substantially weaker-than-normal South American monsoon circulation; 3) Mexico, which experienced extreme drought throughout the El Niño episode; and 4) the Gulf Coast states of the United States, which experienced extreme drought during April–June 1998. The El Niño also contributed to extreme warmth across North America during January–May. The primary La Niña–related precipitation anomalies included 1) increased rainfall across Indonesia, and a nearly complete disappearance of rainfall across the east-central equatorial Pacific; 2) above-normal rains across northwestern, eastern, and northern Australia; 3) increased monsoon rains across central America and Mexico during October–December; and 4) dryness across equatorial eastern Africa. The active 1998 North Atlantic hurricane season featured 14 named storms (9 of which became hurricanes) and the strongest October hurricane (Mitch) in the historical record. In Honduras and Nicaragua extreme flooding and mudslides associated with Hurricane Mitch claimed more than 11 000 lives. During the peak of activity in August–September, the vertical wind shear across the western Atlantic, along with both the structure and location of the African easterly jet, were typical of other active seasons. Other regional aspects of the short-term climate included 1) record rainfall and massive flooding in the Yangtze River Basin of central China during June–July; 2) a drier and shorter-than-normal 1997/98 rainy season in southern Africa; 3) above-normal rains across the northern section of the African Sahel during June–September 1998; and 4) a continuation of record warmth across Canada during June–November. Global annual mean surface temperatures during 1998 for land and marine areas were 0.56°C above the 1961–90 base period means. This record warmth surpasses the previous highest anomaly of +0.43°C set in 1997. Record warmth was also observed in the global Tropics and Northern Hemisphere extratropics during the year, and is partly linked to the strong El Nino conditions during January–early May.

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ASSESSING CARBON SEQUESTRADED IN BRAZILIAN NORTHEASTERN BIOMES UNDER ENSO EVENTS

Gaia Scientia ◽

10.22478/ufpb.1981-1268.2019v13n4.46299 ◽

2019 ◽

Vol 13 (4) ◽

Author(s):

Robson de Sousa Nascimento ◽

José Ivaldo Barbosa de Brito ◽

Valéria Peixoto Borges

Keyword(s):

El Niño ◽

El Nino ◽

Southern Oscillation ◽

Net Primary Production ◽

Amazon Rainforest ◽

El Niño Southern Oscillation ◽

El Nino Southern Oscillation ◽

Tropical Atlantic ◽

Enso Events ◽

Caatinga Biome

The goal of the present study it was to know the behavior of the Net Primary Production (NPP) in years that have occurred El Niño Southern Oscillation (ENSO) and during the temperature anomalies of the surface of the Sea (SST) in the Tropical Atlantic, that is Atlantic Dipole. The results showed that the Amazon Rainforest, Atlantic Forest, and the Cerrado were not enough affected by the occurrence of El Niño Southern Oscillation and Atlantic Dipole. However, the Caatinga biome has shown to be quite sensitive to these events and patterns, especially in years of occurrence of El Niño, which contributed to a reduction in NPP; while in years of El Niña and negative dipole, the NPP achieved the highest values. The amount of rainfall in the previous year to the El Niño Southern Oscillation episodes showed influence on the amount of carbon sequestered by biomes in the year of study.

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Tree growth and stem carbon accumulation in human-modified Amazonian forests following drought and fire

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2017.0308 ◽

2018 ◽

Vol 373 (1760) ◽

pp. 20170308 ◽

Cited By ~ 10

Author(s):

Erika Berenguer ◽

Yadvinder Malhi ◽

Paulo Brando ◽

Amanda Cardoso Nunes Cordeiro ◽

Joice Ferreira ◽

...

Keyword(s):

Wood Density ◽

Tree Growth ◽

El Niño ◽

Human Disturbance ◽

Amazon Basin ◽

El Nino ◽

Carbon Accumulation ◽

Extreme Drought ◽

The Difference ◽

The Impact

Human-modified forests are an ever-increasing feature across the Amazon Basin, but little is known about how stem growth is influenced by extreme climatic events and the resulting wildfires. Here we assess for the first time the impacts of human-driven disturbance in combination with El Niño–mediated droughts and fires on tree growth and carbon accumulation. We found that after 2.5 years of continuous measurements, there was no difference in stem carbon accumulation between undisturbed and human-modified forests. Furthermore, the extreme drought caused by the El Niño did not affect carbon accumulation rates in surviving trees. In recently burned forests, trees grew significantly more than in unburned ones, regardless of their history of previous human disturbance. Wood density was the only significant factor that helped explain the difference in growth between trees in burned and unburned forests, with low wood–density trees growing significantly more in burned sites. Our results suggest stem carbon accumulation is resistant to human disturbance and one-off extreme drought events, and it is stimulated immediately after wildfires. However, these results should be seen with caution—without accounting for carbon losses, recruitment and longer-term changes in species composition, we cannot fully understand the impacts of drought and fire in the carbon balance of human-modified forests. This article is part of a discussion meeting issue ‘The impact of the 2015/2016 El Nino on the terrestrial tropical carbon cycle: patterns, mechanisms and implications’.

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Spatio-temporal patterns of thermal anomalies and drought over tropical forests driven by recent extreme climatic anomalies

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2017.0300 ◽

2018 ◽

Vol 373 (1760) ◽

pp. 20170300 ◽

Cited By ~ 6

Author(s):

Juan C. Jimenez ◽

Jonathan Barichivich ◽

Cristian Mattar ◽

Ken Takahashi ◽

Andrés Santamaría-Artigas ◽

...

Keyword(s):

Tropical Forests ◽

Spatial Patterns ◽

El Niño ◽

El Nino ◽

The Other ◽

Extreme Drought ◽

Drought Severity ◽

Tropical Regions ◽

Temperature Anomalies ◽

The Impact

The recent 2015–2016 El Niño (EN) event was considered as strong as the EN in 1997–1998. Given such magnitude, it was expected to result in extreme warming and moisture anomalies in tropical areas. Here we characterize the spatial patterns of temperature anomalies and drought over tropical forests, including tropical South America (Amazonia), Africa and Asia/Indonesia during the 2015–2016 EN event. These spatial patterns of warming and drought are compared with those observed in previous strong EN events (1982–1983 and 1997–1998) and other moderate to strong EN events (e.g. 2004–2005 and 2009–2010). The link between the spatial patterns of drought and sea surface temperature anomalies in the central and eastern Pacific is also explored. We show that indeed the EN2015–2016 led to unprecedented warming compared to the other EN events over Amazonia, Africa and Indonesia, as a consequence of the background global warming trend. Anomalous accumulated extreme drought area over Amazonia was found during EN2015–2016, but this value may be closer to extreme drought area extents in the other two EN events in 1982–1983 and 1997–1998. Over Africa, datasets disagree, and it is difficult to conclude which EN event led to the highest accumulated extreme drought area. Our results show that the highest values of accumulated drought area over Africa were obtained in 2015–2016 and 1997–1998, with a long-term drying trend not observed over the other tropical regions. Over Indonesia, all datasets suggest that EN 1982–1983 and EN 1997–1998 (or even the drought of 2005) led to a higher extreme drought area than EN2015–2016. Uncertainties in precipitation datasets hinder consistent estimates of drought severity over tropical regions, and improved reanalysis products and station records are required.This article is part of a discussion meeting issue ‘The impact of the 2015/2016 El Niño on the terrestrial tropical carbon cycle: patterns, mechanisms and implications’.

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Decadal variation of extreme drought and flood in North China revealed by documentary-based seasonal precipitation reconstruction for the past 300 years

10.5194/cp-2018-45 ◽

2018 ◽

Author(s):

Jingyun Zheng ◽

Yingzhuo Yu ◽

Xuezhen Zhang ◽

Zhixin Hao

Keyword(s):

El Niño ◽

North China ◽

El Nino ◽

Volcanic Eruptions ◽

Extreme Drought ◽

Seasonal Precipitation ◽

Extreme Floods ◽

Spatial Coverage ◽

Droughts And Floods ◽

Large Volcanic Eruptions

Abstract. Using the 17-sites seasonal precipitation reconstructions from an unique historical archive, Yu-Xue-Fen-Cun, the decadal variations of extreme droughts and floods (i.e., the event with occurrence probability of less than 10 % from 1951 to 2000) in North China were investigated, by considering both the probabilities of droughts/floods occurrence in each site and spatial coverage (i.e., percentage of sites). Then, the possible linkages of extreme droughts and floods with ENSO (i.e., El Niño and La Niña) episodes and large volcanic eruptions were discussed. The results show that there were 29 extreme droughts and 28 extreme floods in North China from 1736 to 2000. Extreme droughts occurred more frequently (2 or more events) during the 1770s–1780s, 1870s, 1900s–1920s, 1940s and 1980s–1990s, among which the most frequent (3 events) occurred in the 1900s and the 1920s. While more frequent extreme floods occurred in the 1770s, 1790s, 1820s, 1880s, 1910s and 1950s–1960s, among which the most frequent (4 events) occurred in the 1790s and 1880s. For the total of extreme droughts and floods, they are more frequent in the 1770s, 1790s, 1870s–1880s, 1900s–1920s and 1960s, and the highest frequency (5 events) occurred in the 1790s. A higher probability of the extreme drought was found when El Niño occurred in the current year or the previous year. However, no significant connections were found not only between the occurrences of extreme floods and ENSO episodes, but also between the occurrences of extreme droughts/floods and large volcanic eruptions.

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Drought Index for Peatland Wildfire Management in Central Kalimantan, Indonesia During El Niño Phenomenon

Journal of Disaster Research ◽

10.20965/jdr.2019.p0939 ◽

2019 ◽

Vol 14 (7) ◽

pp. 939-948 ◽

Cited By ~ 2

Author(s):

Novitasari Novitasari ◽

Joko Sujono ◽

Sri Harto ◽

Azwar Maas ◽

Rachmad Jayadi ◽

...

Keyword(s):

Water Table ◽

El Niño ◽

Drought Index ◽

El Nino ◽

Drainage System ◽

Extreme Drought ◽

Drought Indices ◽

Central Kalimantan ◽

Tropical Peatland ◽

The Government

Peatland wildfires, especially in tropical ecosystems, are often caused by drought, and lead to smoke and other related problems in all aspects of community life in Indonesia, especially in Central Kalimantan. Drought is worsened by the number of dry days in the dry season, known as the El Niño phenomenon, and the drainage system in a peatland. Additionally, drought decreases the water table and increases the probability of occurrence of wildfires in peatland areas. This study aims to modify the numerical formula of the drought factor (DFt) in the Keetch–Byram drought index (KBDI) based on tropical peatland wildfire conditions in Central Kalimantan during the El Niño phenomenon in 2015. Furthermore, it applies a revised peatland water table reference of 400 mm below the ground surface, based on previous research and the Government regulation on peatland ecosystem protection and management in Indonesia. These El Niño conditions caused a rain decline of approximately 35% in Block A, Ex-Mega Rice Project, Mantangai sub-District, Kapuas District, Central Kalimantan Province. The modified KBDI is compared with the Number of Fire Alerts (NFA) using NASA’s Active Fire Data in 2015. The analysis results demonstrate that the modified DFt under tropical peatland conditions leads to an increase in the drought index value, beginning on the driest days between July and November 2015. The value of the KBDI drought index increases from the high to the extreme index from September to November 2015, when as many as 61 extreme drought indices became indicators for peatland wildfire risk assessment. The extreme KBDI is directly proportional to the NFA recorded during 2015, and the highest number of fire alerts is observed for October 2015, with 1746 fire alerts within 31 days and extreme drought indices from 27 days. Hence, this modified formula is suitable for wildfire conditions on this peatland in Central Kalimantan. Overall, the modified DFt can be successfully applied to the El Niño phenomenon in 2015.

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OCO-2 Solar-Induced Chlorophyll Fluorescence Variability across Ecoregions of the Amazon Basin and the Extreme Drought Effects of El Niño (2015–2016)

Remote Sensing ◽

10.3390/rs12071202 ◽

2020 ◽

Vol 12 (7) ◽

pp. 1202 ◽

Cited By ~ 3

Author(s):

Antony Oswaldo Castro ◽

Jia Chen ◽

Christian S. Zang ◽

Ankit Shekhar ◽

Juan Carlos Jimenez ◽

...

Keyword(s):

Heat Stress ◽

Chlorophyll Fluorescence ◽

El Niño ◽

Amazon Basin ◽

Photosynthetic Activity ◽

El Nino ◽

Gross Primary Production ◽

Extreme Drought ◽

Drought Vulnerability ◽

Drought Period

Amazonian ecosystems are major biodiversity hotspots and carbon sinks that may lose species to extinction and become carbon sources due to extreme dry or warm conditions. We investigated the seasonal patterns of high-resolution solar-induced chlorophyll fluorescence (SIF) measured by the satellite Orbiting Carbon Observatory-2 (OCO-2) across the Amazonian ecoregions to assess the area´s phenology and extreme drought vulnerability. SIF is an indicator of the photosynthetic activity of chlorophyll molecules and is assumed to be directly related to gross primary production (GPP). We analyzed SIF variability in the Amazon basin during the period between September 2014 and December 2018. In particular, we focused on the SIF drought response under the extreme drought period during the strong El Niño in 2015–2016, as well as the 6-month drought peak period. During the drought´s peak months, the SIF decreased and increased with different intensities across the ecoregions of the Amazonian moist broadleaf forest (MBF) biome. Under a high temperature, a high vapor pressure deficit, and extreme drought conditions, the SIF presented differences from −31.1% to +17.6%. Such chlorophyll activity variations have been observed in plant-level measurements of active fluorescence in plants undergoing physiological responses to water or heat stress. Thus, it is plausible that the SIF variations in the ecoregions’ ecosystems occurred as a result of water and heat stress, and arguably because of drought-driven vegetation mortality and collateral effects in their species composition and community structures. The SIF responses to drought at the ecoregional scale indicate that there are different levels of resilience to drought across MBF ecosystems that the currently used climate- and biome-region scales do not capture. Finally, we identified monthly SIF values of 32 ecoregions, including non-MBF biomes, which may give the first insights into the photosynthetic activity dynamics of Amazonian ecoregions.

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ENSO effects on the transpiration of eastern Amazon trees

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2018.0085 ◽

2018 ◽

Vol 373 (1760) ◽

pp. 20180085 ◽

Cited By ~ 5

Author(s):

Mauro Brum ◽

Jose Gutiérrez López ◽

Heidi Asbjornsen ◽

Julian Licata ◽

Thomas Pypker ◽

...

Keyword(s):

Soil Moisture ◽

Water Use ◽

El Niño ◽

El Nino ◽

Southern Oscillation ◽

Critical Role ◽

Extreme Drought ◽

Flow Measurements ◽

Tree Transpiration ◽

The Impact

Tree transpiration is important in the recycling of precipitation in the Amazon and might be negatively affected by El Niño–Southern Oscillation (ENSO)–induced droughts. To investigate the relative importance of soil moisture deficits versus increasing atmospheric demand (VPD) and determine if these drivers exert different controls over tree transpiration during the wet season versus the dry season (DS), we conducted sap flow measurements in a primary lowland tropical forest in eastern Amazon during the most extreme ENSO-induced drought (2015/2016) recorded in the Amazon. We also assessed whether trees occupying different canopy strata contribute equally to the overall stand transpiration ( T stand ). Canopy trees were the primary source of T stand . However, subcanopy trees are still important as they transpired an amount similar to other biomes around the globe. Tree water use was higher during the DS, indicating that during extreme drought trees did not reduce transpiration in response to low soil moisture. Photosynthetically active radiation and VPD exerted an overriding effect on water use patterns relative to soil moisture during extreme drought, indicating that light and atmospheric constraints play a critical role in controlling ecosystem fluxes of water. Our study highlights the importance of canopy and subcanopy trees to the regional water balance and highlights the resilience to droughts that these trees show during an extreme ENSO event. This article is part of a discussion meeting issue ‘The impact of the 2015/2016 El Niño on the terrestrial tropical carbon cycle: patterns, mechanisms and implications’.

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Analysis of how the spatial and temporal patterns of fire and their bioclimatic and anthropogenic drivers vary across the Amazon rainforest in El Niño and non-El Niño years

PeerJ ◽

10.7717/peerj.12029 ◽

2021 ◽

Vol 9 ◽

pp. e12029

Author(s):

Minerva Singh ◽

Xiaoxiang Zhu

Keyword(s):

Forest Fires ◽

El Niño ◽

El Nino ◽

Canopy Cover ◽

Amazon Rainforest ◽

Strong Impact ◽

Spatial And Temporal Patterns ◽

Wet Season ◽

Fire Dynamics ◽

Mixed Effect

In the past two decades, Amazon rainforest countries (Brazil, Bolivia, Colombia, Ecuador, Guyana, Peru and Venezuela) have experienced a substantial increase in fire frequency due to the changes in the patterns of different anthropogenic and climatic drivers. This study examines how both fire dynamics and bioclimatic factors varied based on the season (wet season and dry season) El Niño years across the different countries and ecosystems within the Amazon rainforest. Data from publicly available databases on forest fires (Global Fire Atlas) and bioclimatic, topographic and anthropogenic variables were employed in the analysis. Linear mixed-effect models discovered that year type (El Niño vs. non-El Niño), seasonality (dry vs. wet), land cover and forest strata (in terms of canopy cover and intactness) and their interactions varied across the Amazonian countries (and the different ecosystems) under consideration. A machine learning model, Multivariate Adaptive Regression Spline (MARS), was utilized to determine the relative importance of climatic, topographic, forest structure and human modification variables on fire dynamics across wet and dry seasons, both in El Niño and non-El Niño years. The findings of this study make clear that declining precipitation and increased temperatures have strong impact on fire dynamics (size, duration, expansion and speed) for El Niño years. El Niño years also saw greater fire sizes and speeds as compared to non-El Niño years. Dense and relatively undisturbed forests were found to have the lowest fire activity and increased human impact on a landscape was associated with exacerbated fire dynamics, especially in the El Niño years. Additionally, the presence of grass-dominated ecosystems such as grasslands also acted as a driver of fire in both El Niño and non-El Niño years. Hence, from a conservation perspective, increased interventions during the El Niño periods should be considered.

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Severe Droughts of 1876-1878 in North China and Possible Causes

10.21203/rs.3.rs-161952/v1 ◽

2021 ◽

Author(s):

Zhixin Hao ◽

Mengxin Bai ◽

Danyang Xiong ◽

Yang Liu ◽

Jingyun Zheng

Keyword(s):

Northern Hemisphere ◽

El Niño ◽

Large Scale ◽

North China ◽

Industrial Revolution ◽

El Nino ◽

Wave Train ◽

Extreme Drought ◽

Severe Drought ◽

Price Inflation

Abstract Extreme drought of 1876–1878 occurred in most regions of Northern China after the industrial revolution which has led to a series of social impacts, including harvest failure, price inflation, and population immigration. Concurrently, most regions of Northern Hemisphere occurred extreme drought. Here, we used the reconstructed high-resolution hydroclimatic (PDSI/precipitation) datasets, investigated the seasonal-annual hydroclimatic spatial patterns and drought intensity with time evolution from 1876 to 1878 in North China. Furthermore, we selected combined Sea Surface Temperature (SST) modes with positive IOD/PDO and El Niño from the 1200-year control run simulations of HadCM3 to diagnose the causes of this severe drought. The extent and intensity of selected SST mode was similar with that in Pacific and Indian Ocean during the 1876–1878 from NOAA/ERSST dataset. The results showed that the large-scale drought of 1876–1878 was mainly driven by El Niño and positive PDO, while the effect of IOD was not significant. El Niño may trigger Circumglobal Teleconnection of Northern Hemisphere, and meridional disturbance of mid-latitude Rossby wave train changed the intensity of trough and ridge, and further blocked water vapor transportation.

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