Browsing by Subject "climate"

Now showing 1 - 7 of 7
  • Thumbnail Image
    Item
    Global divergent trends of algal blooms detected by satellite during 1982–2018
    (Wiley, 2022-04) Fang, Chong; Song, Kaishan; Paerl, Hans W.; Jacinthe, Pierre-Andre; Wen, Zhidan; Liu, Ge; Tao, Hui; Xu, Xiaofeng; Kutser, Tiit; Wang, Zongming; Duan, Hongtao; Shi, Kun; Shang, Yingxin; Lyu, Lili; Li, Sijia; Yang, Qian; Lyu, Dongmei; Mao, Dehua; Zhang, Baohua; Cheng, Shuai; Lyu, Yunfeng; Earth and Environmental Sciences, School of Science
    Algal blooms (ABs) in inland lakes have caused adverse ecological effects, and health impairment of animals and humans. We used archived Landsat images to examine ABs in lakes (>1 km2) around the globe over a 37-year time span (1982–2018). Out of the 176032 lakes with area >1 km2 detected globally, 863 were impacted by ABs, 708 had sufficiently long records to define a trend, and 66% exhibited increasing trends in frequency ratio (FRQR, ratio of the number of ABs events observed in a year in a given lake to the number of available Landsat images for that lake) or area ratio (AR, ratio of annual maximum area covered by ABs observed in a lake to the surface area of that lake), while 34% showed a decreasing trend. Across North America, an intensification of ABs severity was observed for FRQR (p < .01) and AR (p < .01) before 1999, followed by a decrease in ABs FRQR (p < .01) and AR (p < .05) after the 2000s. The strongest intensification of ABs was observed in Asia, followed by South America, Africa, and Europe. No clear trend was detected for the Oceania. Across climatic zones, the contributions of anthropogenic factors to ABs intensification (16.5% for fertilizer, 19.4% for gross domestic product, and 18.7% for population) were slightly stronger than climatic drivers (10.1% for temperature, 11.7% for wind speed, 16.8% for pressure, and for 11.6% for rainfall). Collectively, these divergent trends indicate that consideration of anthropogenic factors as well as climate change should be at the forefront of management policies aimed at reducing the severity and frequency of ABs in inland waters.
  • Thumbnail Image
    Item
    Grazing and ecosystem service delivery in global drylands
    (American Association for the Advancement of Science, 2022-11-24) Maestre, Fernando T.; Bagousse-Pinguet, Yoann Le; Delgado-Baquerizo, Manuel; Eldridge , David J.; Saiz, Hugo; Berdugo, Miguel; Gozalo, Beatriz; Ochoa, Victoria; Guirado, Emilio; García-Gómez, Miguel; Valencia, Enrique; Gaitán, Juan J.; Asensio, Sergio; Mendoza, Betty J.; Plaza, César; Díaz-Martínez, Paloma; Rey, Ana; Hu, Hang-Wei; He, Ji-Zheng; Wang, Jun-Tao; Lehmann, Anika; Rillig, Matthias C.; Cesarz, Simone; Esenhauer, Nico; Martínez-Valderrama, Jaime; Moreno-Jiménez, Eduardo; Sala, Osvaldo; Abedi, Mehdi; Ahmadian, Negar; Alados, Concepción L.; Aramayo, Valeria; Amghar, Fateh; Arredondo, Tulio; Ahumada, Rodrigo J.; Bahalkeh, Khadijeh; Ben Salem , Farah; Blaum, Niels; Boldgiv, Bazartseren; Bowker, Matthew A.; Bran, Donaldo; Bu, Chongfeng; Canessa, Rafaella; Castillo-Monroy, Andrea P.; Castro, Helena; Castro, Ignacio; Castro-Quezada, Patricio; Chibani, Roukaya; Conceição , Abel A.; Currier, Courtney M.; Darrouzet-Nardi, Anthony; Deák, Balázs; Donoso, David A.; Dougill, Andrew J.; Durán, Jorge; Erdenetsetseg, Batdelger; Espinosa, Carlos I.; Fajardo, Alex; Farzam, Mohammad; Ferrante, Daniela; Frank, Anke S. K.; Fraser, Lauchlan H.; Gherardi, Laureano A.; Greenville, Aaron C.; Guerra, Carlos A.; Gusmán-Montalvan, Elizabeth; Hernández-Hernández, Rosa M.; Hölzel, Norbert; Huber-Sannwald, Elisabeth; Hughes, Frederic M.; Jadán-Maza, Oswaldo; Jeltsch, Florian; Jentsch, Anke; Kaseke, Kudzai F.; Köbel, Melanie; Koopman, Jessica E.; Leder, Cintia V.; Linstädter, Anja; Le Roux, Peter C.; Li, Xinkai; Liancourt, Pierre; Liu, Jushan; Louw, Michelle A.; Maggs-Kölling, Gillian; Makhalanyane, Thulani P.; Malam Issa, Oumarou; Manzaneda, Antonio J.; Marais, Eugene; Mora, Juan P.; Moreno, Gerardo; Munson, Seth M.; Nunes, Alice; Oliva, Gabriel; Oñatibia, Gastón R.; Peter, Guadalupe; Pivari, Marco O. D.; Pueyo , Yolanda; Quiroga, R. Emiliano; Rahmanian, Soroor; Reed, Sasha C.; Rey, Pedro J.; Richard, Benoit; Rodríguez, Alexandra; Rolo, Víctor; Rubalcaba, Juan G.; Ruppert, Jan C.; Salah, Ayman; Schuchardt, Max A.; Spann, Sedona; Stavi, Ilan; Stephens, Colton R. A.; Swemmer, Anthony M.; Teixido, Alberto L.; Thomas , Andrew D.; Throop, Heather L.; Tielbörger, Katja; Travers, Samantha; Val, James; Valkó, Orsolya; Van Den Brink , Liesbeth; Ayuso, Sergio Valesco; Velbert, Frederike; Wamiti, Wanyoike; Wang, Deli; Wang, Lixin; Wardel, Glenda M.; Yahdjian, Laura; Zaady, Eli; Zhang, Yuanming; Zhou, Xiaobing; Singh, Brajesh K.; Gross, Nicolas; Earth and Environmental Sciences, School of Science
    Grazing represents the most extensive use of land worldwide. Yet its impacts on ecosystem services remain uncertain because pervasive interactions between grazing pressure, climate, soil properties, and biodiversity may occur but have never been addressed simultaneously. Using a standardized survey at 98 sites across six continents, we show that interactions between grazing pressure, climate, soil, and biodiversity are critical to explain the delivery of fundamental ecosystem services across drylands worldwide. Increasing grazing pressure reduced ecosystem service delivery in warmer and species-poor drylands, whereas positive effects of grazing were observed in colder and species-rich areas. Considering interactions between grazing and local abiotic and biotic factors is key for understanding the fate of dryland ecosystems under climate change and increasing human pressure.
  • Thumbnail Image
    Item
    Late Holocene Climate-Flood Relationships on the White River, Indiana, USA
    (2022-05) Wright, Maxwell N.; Bird, Broxton; Licht, Kathy; Gilhooly, William, III.
    The frequency and magnitude of floods in the midcontinental United States have increased in recent decades due to changing precipitation patterns as global temperatures rise. These trends pose major social and economic risks to the region, which is home to tens of millions of Americans and a global agricultural center. It is therefore critical to understand if current fluvial dynamics are within the scope of past fluvial-climate relationships, or if they represent a novel response to recent climate and land-use changes. Presented is a 1600-year-long flood frequency record for the moderately sized (~29,400 km2 watershed) White River, Indiana. Flood frequencies were determined using 14C-based sediment accumulation rates at Half Moon Pond, an oxbow lake on the lower White River’s floodplain. Comparison with regional paleoclimate data shows that White River flooding was frequent when atmospheric circulation resembled the negative mode of the Pacific-North American (PNA) teleconnection, particularly during the Medieval Climate Anomaly (950-1250 CE) and the Current Warm Period (last ~150 years). During these times, the regional climate was dominated by warm-season precipitation originating from the Gulf of Mexico. Conversely, White River flooding was less frequent during the Little Ice Age (1250-1800 CE) when cold-season precipitation from the North Pacific/Arctic dominated (+PNA-like conditions). The pre-1790 CE White River flood history was antiphased with reconstructed Ohio River flood frequencies from southern Illinois. This dynamic is consistent with discharge in small to moderate sized watersheds being sensitive to rainstorm runoff and large watersheds being sensitive to snowmelt runoff. After 1790 CE, flooding frequencies of both river systems increased to their highest levels, despite a shift to -PNA-like conditions. This change was likely due to extensive Euro-American land-clearance, which increased runoff/erosion by reducing evapotranspiration, interception, and infiltration. While the White River responded strongly to climatic conditions in the past that were similar to present conditions (-PNA-like conditions), recent land-use practices have amplified the effects of the current hydroclimate. Since a warming climate is expected to increase regional average precipitation and extreme rainfall events, and that landscape modifications have lowered surface resilience to hydroclimate events, flooding will likely become more frequent in the coming decades.
  • Thumbnail Image
    Item
    Midcontinental Native American population dynamics and late Holocene hydroclimate extremes
    (Nature, 2017) Bird, Broxton W.; Wilson, Jeremy J.; Gilhooly, William P., III; Steinman, Byron A.; Stamps, Lucas; Department of Earth Sciences, School of Science
    Climate’s influence on late Pre-Columbian (pre-1492 CE), maize-dependent Native American populations in the midcontinental United States (US) is poorly understood as regional paleoclimate records are sparse and/or provide conflicting perspectives. Here, we reconstruct regional changes in precipitation source and seasonality and local changes in warm-season duration and rainstorm events related to the Pacific North American pattern (PNA) using a 2100-year-long multi-proxy lake-sediment record from the midcontinental US. Wet midcontinental climate reflecting negative PNA-like conditions occurred during the Medieval Climate Anomaly (950–1250 CE) as Native American populations adopted intensive maize agriculture, facilitating population aggregation and the development of urban centers between 1000–1200 CE. Intensifying midcontinental socio-political instability and warfare between 1250–1350 CE corresponded with drier positive PNA-like conditions, culminating in the staggered abandonment of many major Native American river valley settlements and large urban centers between 1350–1450 CE during an especially severe warm-season drought. We hypothesize that this sustained drought interval rendered it difficult to support dense populations and large urban centers in the midcontinental US by destabilizing regional agricultural systems, thereby contributing to the host of socio-political factors that led to population reorganization and migration in the midcontinent and neighboring regions shortly before European contact.
  • Thumbnail Image
    Item
    Preface "Water, climate, and vegetation: ecohydrology in a changing world"
    (2012-12) Wang, Lixin; Liu, J.; Sun, G.; Wei, X.; Liu, S.; Dong, Q.
  • Thumbnail Image
    Item
    Shifts in stream hydrochemistry in responses to typhoon and non-typhoon precipitation
    (European Geosciences Union, 2018-04-19) Chang, Chung-Te; Huang, Jr-Chuan; Wang, Lixin; Shih, Yu-Ting; Lin, Teng-Chiu; Earth Sciences, School of Science
    Climate change is projected to increase the intensity and frequency of extreme climatic events such as tropical cyclones. However, few studies have examined the responses of hydrochemical processes to climate extremes. To fill this knowledge gap, we compared the relationship between stream discharge and ion input–output budget during typhoon and non-typhoon periods in four subtropical mountain watersheds with different levels of agricultural land cover in northern Taiwan. The results indicated that the high predictability of ion input–output budgets using stream discharge during the non-typhoon period largely disappeared during the typhoon periods. For ions such as Na+, NH+4, and PO3−4, the typhoon period and non-typhoon period exhibited opposite discharge–budget relationships. In other cases, the discharge–budget relationship was driven by the typhoon period, which consisted of only 7 % of the total time period. The striking differences in the discharge–ion budget relationship between the two periods likely resulted from differences in the relative contributions of surface runoff, subsurface runoff and groundwater, which had different chemical compositions, to stream discharge between the two periods. Watersheds with a 17–22 % tea plantation cover showed large increases in NO−3 export with increases in stream discharge. In contrast, watersheds with 93–99 % forest cover showed very mild or no increases in NO−3 export with increases in discharge and very low levels of NO−3 export even during typhoon storms. The results suggest that even mild disruption of the natural vegetation could largely alter hydrochemical processes. Our study clearly illustrates significant shifts in hydrochemical responses between regular and typhoon precipitation. We propose that hydrological models should separate hydrochemical processes into regular and extreme conditions to better capture the whole spectrum of hydrochemical responses to a variety of climate conditions.
  • Thumbnail Image
    Item
    Spatiotemporal Variations in Heat-Related Health Risk in Three Midwestern U.S. Cities Between 1990 and 2010
    (Taylor & Francis Group in Geocarto International, 2013-04-15) Johnson, Daniel P.; Webber, Jeremy; Urs Beerval Ravichandra, Kavya; Lulla, Vijay; Stanforth, Austin
    Mortality from extreme heat is a leading cause of weather-related fatality, which is expected to increase in frequency with future climate scenarios. This study examines the spatiotemporal variations in heat-related health risk in three Midwestern cities in the United States between the years 1990 to 2010; cities include Chicago, Illinois, Indianapolis, IN, and Dayton, OH. In order to examine these variations we utilize the recently developed Extreme Heat Vulnerability Index (EHVI) that uses a principal components solution to vulnerability. The EHVI incorporates data from the U.S. Decadal Census and remotely sensed variables to determine heat-related vulnerability at an intra-urban level (census block group). The results demonstrate significant spatiotemporal variations in heat-health risk within the cities involved.