Potential effects of climate change on inundation patterns in the Amazon Basin

摘要

Floodplain forests, namely the Várzea and Igapó, cover an area ofmore than 97 000 km2. A key factor for their function and diversityis annual flooding. Increasing air temperature and higher precipitationvariability caused by climate change are expected to shift the floodingregime during this century, and thereby impact floodplain ecosystems, theirbiodiversity and riverine ecosystem services. To assess the effects ofclimate change on the flooding regime, we use the Dynamic Global Vegetationand Hydrology Model LPJmL, enhanced by a scheme that realistically simulatesmonthly flooded area. Simulation results of discharge and inundation undercontemporary conditions compare well against site-level measurements andobservations. The changes of calculated inundation duration and area underclimate change projections from 24 IPCC AR4 climate models differ regionallytowards the end of the 21st century. In all, 70% of the 24 climateprojections agree on an increase of flooded area in about one third of thebasin. Inundation duration increases dramatically by on average three monthsin western and around one month in eastern Amazonia. The time of high- andlow-water peak shifts by up to three months. Additionally, we find adecrease in the number of extremely dry years and in the probability of theoccurrence of three consecutive extremely dry years. The total number ofextremely wet years does not change drastically but the probability of threeconsecutive extremely wet years decreases by up to 30% in the east andincreases by up to 25% in the west. These changes implicate significantshifts in regional vegetation and climate, and will dramatically altercarbon and water cycles.