Around the world, people are noticing that rainstorms and droughts are becoming more erratic. Heavy rainfall is occurring more frequently, and dry spells are lasting longer and becoming more severe. A new study provides the first systematic observational evidence that human-caused climate change is making precipitation patterns more variable around the world.
Published in the journal Science On July 26, a joint study by the Institute of Atmospheric Physics (IAP) of the Chinese Academy of Sciences, the University of the Chinese Academy of Sciences (UCAS) and the UK Met Office, entitled «Anthropogenic amplification of precipitation variability over the past century», shows a systematic increase in precipitation variability since the 1900s from global to regional scales and from daily to intra-seasonal time scales.
Precipitation variability means unevenness in time and amount. Higher variability means that precipitation is more unevenly distributed over time, resulting in wetter and drier periods. In some places, an annual amount of rain can fall in just a few days, there are long dry periods accompanied by heavy rainfall, and droughts and floods follow each other rapidly.
Climate models have predicted that variability will increase with future warming, but this study confirms that this pattern has only emerged over the past century.
The researchers found that precipitation variability has increased by more than 75% since the 1900s for the land areas studied, including Europe, Australia, and eastern North America. They found that daily precipitation variability worldwide has increased by 1.2% per decade.
«The increase in precipitation variability is mainly due to anthropogenic greenhouse gas emissions, which have led to a warmer and more humid atmosphere. This means that even if the atmospheric circulation remains the same, the additional moisture in the air leads to more intense rains and more dramatic fluctuations. These changes are also influenced by the regional atmospheric circulation on decadal time scales,» says Dr. Zhang Wenxia, lead author of the study and associate professor at IAP.
«The future we are worried about is already here. The increase in precipitation variability we’ve seen adds important evidence of larger ongoing changes, making it harder to predict and account for environmental impacts,» says Dr. Zhou Tianjun, Senior Research Fellow at IAP and UCAS Professor, and co-author of the study.
According to Dr. Wu Peili, a scientific expert at the Meteorological Bureau and co-author of the study, rapid extreme changes in climate patterns pose significant risks to the climate resilience of infrastructure, economic development, ecosystem functioning, and carbon sequestration. He insists on immediate «adaptation» measures.
Source: SciTechDaily