Simultaneous Regional Detection of Land-Use Changes and Elevated GHG Levels: The Case of Spring Precipitation in Tropical South America
Simultaneous Regional Detection of Land-Use Changes and Elevated GHG Levels: The Case of Spring Precipitation in Tropical South America
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DOI：
10.1029/2018gl078041
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发表时间：
2018-06-28
影响因子：
5.2
通讯作者：
Detzer, Judah
中科院分区：
文献类型：
--
作者：
Barkhordarian, Armineh;von Storch, Hans;Detzer, Judah
南美洲热带地区旱季降水量的减少对该地区的生态系统健康产生了很大影响。这里的结果表明，在过去的几十年中，旱季降水的负趋势的幅度超过了估计的趋势范围，由于工业化前的气候和850-1850千年期间定义的气候系统的自然变异。观察到的干燥与蒸汽压不足的增加有关。单变量检测分析表明，温室气体（GHG）强迫有一个系统的影响，在负30年的降水趋势结束于1998年及以后的双变量归因分析表明，强迫升高的温室气体水平和土地利用变化是由于在1983-2012年在亚马逊河流域南部和巴西中部观测到的干旱的主要原因。我们进一步表明，GS信号（温室气体和硫酸盐气溶胶）的影响，根据RCP4.5的情况下已经有一个可检测的影响，在所观察到的干燥。因此，我们认为，最近观察到的干燥的旱季是一个特征，将继续和加强在人类活动的气候变化过程中展开。这种变化可能会对该地区的社会和生态系统产生深远的影响。简明扼要本研究使用统计技术将最近观察到的南美洲热带干旱季节归因于人为和自然发生的气候变化的外部驱动因素。旱季降水量的减少对该地区的生态系统健康有很大影响。因此，将观测到的干旱季节的强迫因素归因于气候变化的外部驱动因素，对社会具有重大的实际意义。结果表明，所观察到的干燥是远远超出了由于气候系统的自然变率的趋势范围，并发现系统和外部强迫。温室气体水平升高和土地利用变化（主要是森林砍伐）造成的强迫是亚马逊河流域南部和巴西中部观测到的干旱的主要原因。我们进一步证明，最近观察到的干燥的旱季是一个功能，将继续和加强在人类活动的气候变化过程中。这种评估对于适应规划和减缓战略至关重要。
A decline in dry season precipitation over tropical South America has a large impact on ecosystem health of the region. Results here indicate that the magnitude of negative trends in dry season precipitation in the past decades exceeds the estimated range of trends due to natural variability of the climate system defined in both the preindustrial climate and during the 850-1850 millennium. The observed drying is associated with an increase in vapor pressure deficit. The univariate detection analysis shows that greenhouse gas (GHG) forcing has a systematic influence in negative 30-year trends of precipitation ending in 1998 and later on. The bivariate attribution analysis demonstrates that forcing by elevated GHG levels and land-use change are attributed as key causes for the observed drying during 1983-2012 over the southern Amazonia and central Brazil. We further show that the effect of GS signal (GHG and sulfate aerosols) based on RCP4.5 scenario already has a detectable influence in the observed drying. Thus, we suggest that the recently observed drier dry season is a feature which will continue and intensify in the course of unfolding anthropogenic climate change. Such change could have profound societal and ecosystem impacts over the region.Plain Language Summary This study uses statistical techniques to attribute the recently observed drier dry season over tropical South America to external drivers of climate change, both human-induced and naturally occurring. A decline in dry season precipitation has a large impact on ecosystem health of the region. Thus, attributing the forced components of the observed drier dry season to external drivers of climate change is of great practical importance to societies. Results indicate that the observed drying is well beyond the range of trends due to natural variability of the climate system and is found to be systematically and externally forced. The forcing by elevated greenhouse gas levels and land-use change (mainly deforestation) are attributed as key causes for the observed drying over the southern Amazonia and central Brazil. We further demonstrate that the recently observed drier dry season is a feature which will continue and intensify in the course of unfolding anthropogenic climate change. Such an assessment is critical for adaptation planning and mitigation strategies.