Tag: Hosmay Lopez

Major Heatwave Clusters (1900-2010). Image Credit NOAA.

Early Emergence of Anthropogenically Forced Heat Waves in the Western United States and Great Lakes

Climate projections for the twenty-first century suggest an increase in the occurrence of heat waves. However, the time at which externally forced signals of anthropogenic climate change (ACC) emerge against background natural variability (time of emergence (ToE)) has been challenging to quantify, which makes future heat-wave projections uncertain. In a new article published in Nature Climate Change (Lopez et al., 2018), Hosmay Lopez and his team combine observations and model simulations under present and future forcing to assess how internal variability and ACC modulate US heat waves.

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Climate Change to Drive More Extreme Heat Waves in the United States

A new analysis of heat wave patterns appearing in Nature Climate Change focuses on four regions of the United States where human-caused climate change will ultimately overtake natural variability as the main driver of heat waves. Climate change will drive more frequent and extreme summer heat waves in the Western United States by late 2020’s, the Great Lakes region by mid 2030’s, and in the northern and southern Plains by 2050’s and 2070’s, respectively.

“These are the years that climate change outweighs natural variability as the cause of heat waves in these regions,” said Hosmay Lopez, a meteorologist at NOAA’s Atlantic Oceanographic Meteorological Laboratory and the University of Miami’s Rosenstiel School Cooperative Institute for Marine and Atmospheric Studies and lead author of the study. “Without human influence, half of the extreme heat waves projected to occur in the future wouldn’t happen.”

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(left column) Seasonality of precipitation and 850mb winds for the monsoon regions as measured by the difference between June-July-August-September (JJAS) minus annual mean precipitation and winds. (middle-column) shows the composite difference of JJAS precipitation (shaded) and 850mb wind for each monsoon region with respect to weak minus strong SAMHT at lead-time 20 years after the anomalous SAMHT. Blue stipples indicates regions where precipitation differences are significant at 95% confidence level based on a non-parametric Kolmogorov-Smirnov test. (right-column) Lag-lead Spearman ranked correlation between SAMHT and NH monsoon index. The blue dashed lines depict the 95% significance level based on a non-parametric Kendall-t test. Negative lag indicates periods when SAMHT leads the NH monsoon index. Periods with significant correlation between the SAMHT and monsoon are shaded blue. Image Credit: NOAA AOML.

Meridional heat transport in the South Atlantic reveals links with global monsoons

A recent paper published in the Journal of Climate led by PHOD researchers Hosmay Lopez, Shenfu Dong, Sang-Ki Lee, and Gustavo Goni provides a physical mechanism on how low frequency variability of the South Atlantic Meridional Heat Transport (SAMHT) associated with the Atlantic Meridional Overturning Circulation ( AMOC) may influence decadal variability of atmospheric circulation and monsoons. This is the first attempt to link the South Atlantic Overturning Circulation variability to weather and climate.

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