skip to main content


Title: Climate and the Global Famine of 1876–78
From 1875 to 1878, concurrent multiyear droughts in Asia, Brazil, and Africa, referred to as the Great Drought, caused widespread crop failures, catalyzing the so-called Global Famine, which had fatalities exceeding 50 million people and long-lasting societal consequences. Observations, paleoclimate reconstructions, and climatemodel simulations are used 1) to demonstrate the severity and characterize the evolution of drought across different regions, and 2) to investigate the underlying mechanisms driving its multiyear persistence. Severe or record-setting droughts occurred on continents in both hemispheres and in multiple seasons, with the ‘‘Monsoon Asia’’ region being the hardest hit, experiencing the single most intense and the second most expansive drought in the last 800 years. The extreme severity, duration, and extent of this global event is associated with an extraordinary combination of preceding cool tropical Pacific conditions (1870–76), a record-breaking El Niño (1877–78), a record strong Indian Ocean dipole (1877), and record warm North Atlantic Ocean (1878) conditions. Composites of historical analogs and two sets of ensemble simulations—one forced with global sea surface temperatures (SSTs) and another forced with tropical Pacific SSTs—were used to distinguish the role of the extreme conditions in different ocean basins. While the drought in most regions was largely driven by the tropical Pacific SST conditions, an extreme positive phase of the Indian Ocean dipole and warm NorthAtlantic SSTs, both likely aided by the strong El Niño in 1877–78, intensified and prolonged droughts in Australia and Brazil, respectively, and extended the impact to northern and southeastern Africa. Climatic conditions that caused the Great Drought and Global Famine arose from natural variability, and their recurrence, with hydrological impacts intensified by global warming, could again potentially undermine global food security.  more » « less
Award ID(s):
1243204
NSF-PAR ID:
10089000
Author(s) / Creator(s):
Date Published:
Journal Name:
Journal of climate
Volume:
31
ISSN:
1520-0442
Page Range / eLocation ID:
9445
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. The so-called “4.2 ka event” is a dramatic climate oscillation that impacted many areas of the mid-to-low latitudes spanning roughly 4.2-3.9 ka (ka = thousands of years ago). Records of this event have been identified on every continent except Antarctica, with clear evidence of precipitation being affected on a large scale. Subtropical and tropical regions of Africa and Asia experienced drought, while mid-latitude areas of Africa and Europe saw anomalously wet conditions. The 4.2 ka event is argued to have had a substantial cultural impact, including the collapse of numerous dynasties and cultures such as in the Indus valley and south-central China, as well as parts of Mesopotamia, northeastern Africa, and across parts of southeast Asia. However, despite its wide geographic extent and societal importance, a great deal remains unknown about the 4.2 ka event, its global effects, and its origins. The apparent lack of a climate anomaly in the polar regions at 4.2 ka suggests it may have originated in the tropics, possibly through the El Niño-Southern Oscillation (ENSO). I analyzed a stalagmite (SB-18) from Siddha Cave, located in the Pokhara Valley of central Nepal (28.0N, 84.0E elev.~600 meters), a region that receives 80% of its annual 1500 mm of rainfall from the Indian Summer Monsoon (ISM). In contrast to many tropical stalagmite records, which use oxygen isotopes to track past monsoon rainfall, I focused on carbon isotopes because at Siddha Cave, oxygen isotopes in rainfall do not have a strong correlation to rainfall amount (the so-called “amount effect”). Carbon isotopes respond to hydroclimate variability through prior aragonite precipitation (PAP), which reflects out-gassing of carbon dioxide and precipitation of aragonite in voids in the bedrock above the cave. This process preferentially removes 12C from the infiltrating water that subsequently migrates downward into the cave. During periods with less rainfall, open spaces in the bedrock are more likely to be dewatered, thereby allowing for more prior aragonite precipitation. In order to ensure that carbon isotopes accurately capture ISM rainfall variability, I also examined uranium abundances in the same stalagmite. Changes in the concentration of uranium are also driven by PAP: uranium is incorporated into aragonite preferentially over dripwater and thus PAP reduces the amount of uranium in dripwater, thereby decreasing uranium in the underlying stalagmite. Carbon isotopes and U abundances in SB-18 suggest that central Nepal experienced anomalously high rainfall during the 4.2 ka event, in contrast with the majority of lower latitude sites around the globe, including a cave record from northeastern India, that record a reduction in rainfall at this time. This rainfall dipole provides an important climatic fingerprint that allows us to investigate the origins of the 4.2 ka event through analysis of modern climate data, including rainfall anomalies associated with ENSO. 
    more » « less
  2. null (Ed.)
    Abstract Droughts that span the states of Washington, Oregon, and California are rare but devastating due to their large spatial coverage and potential loss of redundancies in water, agricultural, and fire-fighting resources. Such pan-coastal droughts [which we define using boreal summer volumetric soil moisture along the U.S. Pacific coast (32°–50°N, 115°–127°W)] require a more precise understanding of the roles played by the Pacific Ocean and internal atmospheric variability. We employ 16-member ensembles of the Community Atmosphere Model version 5 and Community Climate Model version 3 forced with observed sea surface temperatures (SSTs) from 1856 to 2012 to separate and quantify the influences of the tropical Pacific and internal atmospheric variability on pan-coastal droughts; all other boundary conditions are kept at climatological levels to explicitly isolate for the impacts of SST changes. Internal atmospheric variability is the dominant driver of pan-coastal droughts, accounting for 84% of their severity, and can reliably generate pan-coastal droughts even when ocean conditions do not favor drought. Cold phases of the Pacific Ocean play a secondary role and contribute, on average, only 16% to pan-coastal drought severity. Spatiotemporal analyses of precipitation and soil moisture along the U.S. Pacific coast corroborate these findings and identify an antiphased wet–dry dipole pattern induced by the Pacific to play a more secondary role. Our model framework expands on previous observational analyses that point to the spatially uniform forcing of internal atmospheric variability as the more dominant mode of hydroclimate variability along the U.S. Pacific coast. The secondary nature of oceanic forcing suggests limited predictability of pan-continental droughts. 
    more » « less
  3. null (Ed.)
    Abstract Substantial research on the teleconnections between rainfall and sea-surface temperatures (SSTs) has been conducted across equatorial Africa as a whole, but currently no focused examination exists for western Uganda, a rainfall transition zone between eastern equatorial Africa (EEA) and central equatorial Africa (CEA). This study examines correlations between satellite-based rainfall totals in western Uganda and SSTs – and associated indices – across the tropics over 1983-2019. It is found that rainfall throughout western Uganda is teleconnected to SSTs in all tropical oceans, but much more strongly to SSTs in the Indian and Pacific Oceans than the Atlantic Ocean. Increased Indian Ocean SSTs during boreal winter, spring, and autumn and a pattern similar to a positive Indian Ocean Dipole during boreal summer are associated with increased rainfall in western Uganda. The most spatially complex teleconnections in western Uganda occur during September-December, with northwestern Uganda being similar to EEA during this period and southwestern Uganda being similar to CEA. During boreal autumn and winter, northwestern Uganda has increased rainfall associated with SST patterns resembling a positive Indian Ocean Dipole or El Niño. Southwestern Uganda does not have those teleconnections; in fact, increased rainfall there tends to be more associated with La Niña-like SST patterns. Tropical Atlantic Ocean SSTs also appear to influence rainfall in southwestern Uganda in boreal winter as well as in boreal summer. Overall, western Uganda is a heterogeneous region with respect to rainfall-SST teleconnections; therefore, southwestern Uganda and northwestern Uganda require separate analyses and forecasts, especially during boreal autumn and winter. 
    more » « less
  4. null (Ed.)
    Heavy monsoon rainfall ravaged a large swath of East Asia in summer 2020. Severe flooding of the Yangtze River displaced millions of residents in the midst of a historic public health crisis. This extreme rainy season was not anticipated from El Niño conditions. Using observations and model experiments, we show that the record strong Indian Ocean Dipole event in 2019 is an important contributor to the extreme Yangtze flooding of 2020. This Indian Ocean mode and a weak El Niño in the Pacific excite downwelling oceanic Rossby waves that propagate slowly westward south of the equator. At a mooring in the Southwest Indian Ocean, the thermocline deepens by a record 70 m in late 2019. The deepened thermocline helps sustain the Indian Ocean warming through the 2020 summer. The Indian Ocean warming forces an anomalous anticyclone in the lower troposphere over the Indo-Northwest Pacific region and intensifies the upper-level westerly jet over East Asia, leading to heavy summer rainfall in the Yangtze Basin. These coupled ocean-atmosphere processes beyond the equatorial Pacific provide predictability. Indeed, dynamic models initialized with observed ocean state predicted the heavy summer rainfall in the Yangtze Basin as early as April 2020. 
    more » « less
  5. Abstract

    The contributions of oceanic and atmospheric variability to spatially widespread summer droughts in the contiguous United States (hereafter, pan‐CONUS droughts) are investigated using 16‐member ensembles of the Community Climate Model version 3 (CCM3) forced with observed sea surface temperatures (SSTs) from 1856–2012. The employed SST forcing fields are either (i) global or restricted to the (ii) tropical Pacific or (iii) tropical Atlantic to isolate the impacts of these two ocean regions on pan‐CONUS droughts. Model results show that SST forcing of pan‐CONUS droughts originates almost entirely from the tropical Pacific because of atmospheric highs from the northern Pacific to eastern North America established by La Niña conditions, with little contribution from the tropical Atlantic. Notably, in all three model configurations, internal atmospheric variability influences pan‐CONUS drought occurrence by as much or more than the ocean forcing and can alone cause pan‐CONUS droughts by establishing a dominant high centered over the U.S. montane west. Similar results are found for the Community Atmosphere Model version 5 (CAM5). Model results are compared to the observational record, which supports model‐inferred contributions to pan‐CONUS droughts from La Niñas and internal atmospheric variability. While there may be an additional association with warm Atlantic SSTs in the observational record, this association is ambiguous due to the limited number of observed pan‐CONUS droughts. The ambiguity thus opens the possibility that the observational results are limited by sampling over the twentieth century and not at odds with the suggested dominance of Pacific Ocean forcing in the model ensembles.

     
    more » « less