Climate Change Scenarios in the Pantanal

Abstract

The South America Pantanal is a large floodplain wetland in the center of the Upper Paraguay River Basin, which has a total area of around 360,000 km 2 . Large sectors of the Pantanal floodplain are submerged from 4 to 8 months each year by water depths from a few centimeters to more than 2 m. Changes in rainfall and temperature and also on land use can affect significantly the flood season with severe consequences for downstream inhabitants. However, impact of climate change on wetlands is small so far compared to the damage caused by the lack of management at the local level due to land-use change. In this chapter we assess climate and hydrology variability for the present and projections of climate change using the global climate models from the Fifth Assessment Report (AR5) from the Intergovernmental Panel on Climate Change (IPCC). Projections show that by the end of the century, temperatures can increase up to 7 C and rainfall can decrease in both summer and particularly winter. The possibility of longer dry spells and increased evaporation may affect the water balance in the region. However, uncertainties on climate projections are still high, particular for rainfall.The South America Pantanal is a large floodplain wetland in the center of the Upper Paraguay River Basin, which has a total area of around 360,000 km 2 . The Pantanal spreads for about 140,000 km 2 and is shared among Brazil (80%), Bolivia (19%), and Paraguay (1%). During the summer rainy season (November-March), the rivers overflow their banks and flood the adjacent lowlands, forming shallow lakes and innumerable swamps and marshes and leaving island-like areas of higher ground that inundates as much as 70% of the floodplain until July. Large sectors of the Pantanal floodplain are submerged from 4 to 8 months each year by water depths from a few centimeters to more than 2 m. During the drier winter season (April-September), the rivers withdraw into their banks, but the lowlands are only partially drained. The water leaves via the Paraguay River and eventually into the Paraná River, leaving behind grasslands that support grazing animals.The Pantanal functions as a large reservoir that stores water from the surrounding plateaus during the rainy season and then delivers it slowly to the lower sections of the Paraguay River, delaying for almost 6 months the maximum flows to the Paraná River, thereby minimizing downstream flooding. As a result, any significant change in the rainfall pattern is likely to have major impacts on the local ecology and socioeconomic relations. The peak flood season for the lower Paraná River basin is 2-3 months earlier than the flood season for the Upper Paraguay River. Without the Pantanal, the two flood seasons would be simultaneous, with severe consequences for downstream inhabitants. Conversely, during dry seasons, the Pantanal continuously releases water, meaning that there is more water available downstream when it is needed most.Climate change is expected to have serious impacts on the Pantanal, and a range of ins...

Avulsive Rivers in the Hydrology of the Pantanal Wetland

“…By reintroducing tree elements in the Pantanal headwater landscape, besides to recover important ecosystem services as evapotranspiration and carbon storage [40], it is likely to reduce the rate of an eventual "anthropogenic accelerated avulsions" into the plains that ultimately can reduce ecosystems' resilience and make it difficult to promote the sustainable development in the lowlands. This issue is particularly important considering the possible climate change scenarios for the region [12].…”

“…This precipitation/discharge dynamics largely relies on the "monsoon-like effect" produced by the altitudinal gradient between low-and highlands [14]. Also, the majority of the annual rainfall takes place from October to March, whereas July to September is the driest period [12]. This chapter provides insightful information interlinking climate, geology, and hydrology for better portraying and understanding the Pantanal dynamics in its particularities and as a whole system.…”

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Hidden in plain sight: How finding a lake in the Brazilian Pantanal improves understanding of wetland hydrogeomorphology

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