Uncertainty and the changing hydroclimatology of the Amazon

Moore, Nathan; Arima, Eugênio; Walker, Robert; Silva, Renato Ramos da

doi:10.1029/2007gl030157

Cited by 31 publications

(30 citation statements)

References 26 publications

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“…4D) that is larger than the increase in the Temperate case and comparable to the Boreal case. This decrease is also consistent with several Amazon deforestation studies (17,35,36) that showed reduced annual mean rainfall. We conclude from Fig.…”

Section: Significancesupporting

confidence: 76%

Effects of large-scale deforestation on precipitation in the monsoon regions: Remote versus local effects

Devaraju

Bala

Modak

2015

Proc. Natl. Acad. Sci. U.S.A.

157

136

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In this paper, using idealized climate model simulations, we investigate the biogeophysical effects of large-scale deforestation on monsoon regions. We find that the remote forcing from largescale deforestation in the northern middle and high latitudes shifts the Intertropical Convergence Zone southward. This results in a significant decrease in precipitation in the Northern Hemisphere monsoon regions (East Asia, North America, North Africa, and South Asia) and moderate precipitation increases in the Southern Hemisphere monsoon regions (South Africa, South America, and Australia). The magnitude of the monsoonal precipitation changes depends on the location of deforestation, with remote effects showing a larger influence than local effects. The South Asian Monsoon region is affected the most, with 18% decline in precipitation over India. Our results indicate that any comprehensive assessment of afforestation/ reforestation as climate change mitigation strategies should carefully evaluate the remote effects on monsoonal precipitation alongside the large local impacts on temperatures.deforestation | biogeophysical effects | Hadley Cell movement | ITCZ shift | monsoon regions H istorical land cover change has been one of the major drivers of climate change. By the 1750s, ∼6-7% of the global land surface area had been deforested for agriculture. Today, croplands and pasture lands make up approximately one third of the global land surface (1-4). In terms of area, croplands and pasture lands increased globally from 620 million ha in 1700 to 4,960 million ha by 2000 (1). This large-scale conversion of forests to croplands or grasslands can impact climate through biogeochemical (changes in atmospheric composition) and biogeophysical (changes in physical land surface characteristics such as albedo, evapotranspiration, and roughness length) processes.The impacts of past, present, and future biogeochemical and biogeophysical effects from land use change have been investigated by numerous studies (5-10). These studies find that the biogeochemical process primarily causes global effects while biogeophysical processes cause strong local effects. The combined biogeochemical and biogeophysical effects from land cover change in the Holocene before 1850 were modeled as a global mean warming of 0.73 K (9).During the historical period (1750 to present day), deforestationassociated CO 2 emissions have contributed ∼180 ± 80 PgC to the cumulative anthropogenic CO 2 emissions (11) and a warming of ∼0.16-0.30 K (biogeochemical effect) to anthropogenic climate change (5, 6). This warming is probably partly offset by the biogeophysical effect of albedo increase, which may have caused a global mean cooling by ∼0.03-0.27 K (5, 7, 8). However, other major biogeophysical processes, such as reduction in evapotranspiration and roughness length due to deforestation, could result in warming (12).Several studies have investigated the link between land cover change and local climate change (13-16). For example, deforestation (16) in the tropics (18....

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Section: Significancesupporting

confidence: 76%

Effects of large-scale deforestation on precipitation in the monsoon regions: Remote versus local effects

Devaraju

Bala

Modak

2015

Proc. Natl. Acad. Sci. U.S.A.

157

136

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“…Recent studies have investigated the hydrological cycle at the ARB, confirming the occurrence of several extreme hydrological events like droughts, floods, and a marked terrestrial water storage variability during the last years [1][2][3][4][5]. Future scenarios of a complete deforestation in the region point to a restrained water cycle [6,7]. Moore et al [6] suggest that total deforestation of the Amazon would result in a 10-20% decrease in annual rainfall across the entire Amazon basin.…”

Section: Introductionmentioning

confidence: 99%

“…Future scenarios of a complete deforestation in the region point to a restrained water cycle [6,7]. Moore et al [6] suggest that total deforestation of the Amazon would result in a 10-20% decrease in annual rainfall across the entire Amazon basin. The acceleration of human-driven climate change poses serious questions and challenges for conservation strategies at the ARB [8].…”

Section: Introductionmentioning

confidence: 99%

<strong>Drought and </strong><strong>wet episodes in Amazonia: the role of atmospheric moisture transport</strong>

Sorí

Marengo

Nieto

et al. 2017

Proceedings of First International Electronic Conference on the Hydrological Cycle

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Abstract:The Amazon River basin (ARB) in South America contains the largest rainforest and biodiversity in the world, and plays an important role in the regional and global hydrological cycle. It consists of several sub-basins as the Negro River basin (NRB) in the north and the Madeira River basin (MRB) to the south, both considered of utmost importance in the Amazonia for the Amazon River. The precipitation annual cycle in both basins experiences an opposite annual cycle. Here we utilized the Standardized Precipitation Index (SPEI) to identify drought and wet conditions in the NRB and MRB along the period 1980-2016. Besides, the Lagrangian dispersion model FLEXPART v9.0 was used to track backward in time the air masses residing over the basins and to calculate along the trajectories the budget of (E -P). This permitted to identify those regions from where air masses gain humidity (E -P > 0) before arriving at the basins, what we consider as moisture sources. FLEXPART has been successfully utilized for the same goal in several studies. This study examines the variability of moisture uptake by the basins from these sources during drought and wet episodes in the basins. We consider this a new approach to be a useful method for understanding the causes and variability of drought and wet events in other regions worldwide.

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“…Moore et al 2007; Ramos da Silva et al 2008;Walker et al 2009). Their higher resolution presents several advantages.…”

Section: Introductionmentioning

confidence: 99%

Influence of Amazonian deforestation on the future evolution of regional surface fluxes, circulation, surface temperature and precipitation

et al. 2014

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The extent of the Amazon rainforest is projected to drastically decrease in future decades because of land-use changes. Previous climate modelling studies have found that the biogeophysical effects of future Amazonian deforestation will likely increase surface temperatures and reduce precipitation locally. However, the magnitude of these changes and the potential existence of tipping points in the underlying relationships is still highly uncertain. Using a regional climate model at a resolution of about 50 km over the South American continent, we perform four ERAinterim-driven simulations with prescribed land cover maps corresponding to present-day vegetation, two deforestation scenarios for the twenty-first century, and a totally-deforested Amazon case. In response to projected land cover changes for 2100, we find an annual mean surface temperature increase of 0:5 C over the Amazonian region and an annual mean decrease in rainfall of 0.17 mm/day compared to present-day conditions. These estimates reach 0:8 C and 0.22 mm/day in the total-deforestation case. We also compare our results to those from 28 previous (regional and global) climate modelling experiments. We show that the historical development of climate models did not modify the median estimate of the Amazonian climate sensitivity to deforestation, but led to a reduction of its uncertainty. Our results suggest that the biogeophysical effects of deforestation alone are unlikely to lead to a tipping point in the evolution of the regional climate under present-day climate conditions. However, the conducted synthesis of the literature reveals that this behaviour may be model-dependent, and the greenhouse gas-induced climate forcing and biogeochemical feedbacks should also be taken into account to fully assess the future climate of this region.

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Uncertainty and the changing hydroclimatology of the Amazon

Cited by 31 publications

References 26 publications

Effects of large-scale deforestation on precipitation in the monsoon regions: Remote versus local effects

Effects of large-scale deforestation on precipitation in the monsoon regions: Remote versus local effects

<strong>Drought and </strong><strong>wet episodes in Amazonia: the role of atmospheric moisture transport</strong>

Influence of Amazonian deforestation on the future evolution of regional surface fluxes, circulation, surface temperature and precipitation

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