Extreme Temperature Diary- Friday August 5th, 2022/Main Topic: Why Most of Europe Is Becoming More Like the Sahara

The main purpose of this ongoing blog will be to track planetary extreme, or record temperatures related to climate change. Any reports I see of ETs will be listed below the main topic of the day. I’ll refer to extreme or record temperatures as ETs (not extraterrestrials).😉

Main Topic: Why Most of Europe Is Becoming More Like the Sahara

Dear Diary. Across the United States weather patterns remain changeable enough such that very hot dry seasons can revert to cooler and wetter times depending upon ENSO (El Niño and La Niña) and other worldwide factors. The jury is still out across our West, given that it is experiencing a decades long megadrought, but wet monsoon summer patterns can still bring quenching relief, as has been the case this season. This may not be the case across the bulk of Europe, however.

Our heatwaves here during 2022 pale in comparison to what has occurred in Europe the past two years. Yet another heatwave occurred across the region this week with more signs of another toasty episode in Britain:

Has the climate already changed beyond repair there? Perhaps yes given changes in the Azores high configuration.

Precipitation (left) and sea level pressure (right) during a winter with an “extremely large” Azores high. Arrows show the direction of moisture transport. Source: Cresswell-Clay et al (2022).

Here is one note I used last month noting a reinforcing feedback change:

But ultimately why has the Mediterranean turned into a tub of bathwater? Here is some good science:

For Immediate Release

Media Relations Office | media@whoi.edu | (508) 289-3340

Scientists link the changing Azores High and the drying Iberian region to anthropogenic climate change

TOPICS: CLIMATE & WEATHER / CLIMATE CHANGE

 A recent study co-led by WHOI found that the Azores High has expanded dramatically in the past century, resulting from a warming climate due to a rise in anthropogenic greenhouse gas concentrations. Researchers associated with the study collect data inside the Buraca Gloriosa cave in western Portugal, a site of the stalagmite hydroclimate proxy record. Image credit: Diana Thatcher/ © Iowa State University


July 5, 2022

Woods Hole, MA — Projected changes in wintertime precipitation make agriculture in the Iberian region some of the most vulnerable in Europe, according to a new study that links the changes to increased anthropogenic greenhouse gases.

These changes in precipitation are tied to a subtropical high-pressure system known as the Azores High that is more often significantly larger in the industrial era (since 1850 CE) than in preindustrial times, according to the paper, Twentieth Century Azores High Expansion Unprecedented in the Last 1200 Yearspublished in Nature Geoscience. The extremely large Azores Highs, which extend over the eastern subtropical North Atlantic and Europe during winter, result in anomalously dry conditions across the western Mediterranean, including the Iberian Peninsula.

Key Takeaways

  • Changes in precipitation are tied to a subtropical high-pressure system known as the Azores High that is more often significantly larger in the industrial era (since 1850 CE) than in preindustrial times, according to the paper, “Twentieth Century Azores High Expansion Unprecedented in the Last 1200 Years,” published in Nature Geoscience.
  • The Azores High “has changed dramatically in the past century” due to anthropogenic climate change and “these changes in North Atlantic climate are unprecedented within the last millennium,” according to the paper.
  • Using a set of numerical simulations known as the Last Millennium Ensemble, researchers found that extremely large Azores High areas occurred on average during 15 winters in the 20th century compared to roughly 10 winters for all other 100-year periods over the last 1200 years. In addition, researchers found that the most recent 25-year period available (1980-2005) averaged 6.5 winters with extremely large Azores High areas, while other 25 year periods since 1850 averaged 2.6  such winters. This makes it 2-3 times more likely now to experience a winter with an extremely large Azores High, compared to what it was between 1850 and 1980.
  • Observations, climate models, and proxy evidence all combine to show consistent unprecedented expansion of the Azores High.

The paper states that the “industrial-era expansion of the Azores High in a warming climate is a result of the anthropogenic increase in atmospheric greenhouse gas concentrations.”

In addition to using climate model simulations, the research also relied on observations from the stalagmite carbon isotope record of hydroclimate from Buraca Gloriosa cave, Portugal.

“Paleoclimate archives, including speleothems, have provided evidence of unique hydroclimate conditions in Iberia during the last millennium, with relatively dry conditions in the Medieval Climate Anomaly, wet conditions in the Little Ice Age, and a trend toward dry conditions since about 1850 CE. Prior to this study, we hypothesized that the hydroclimate shifts were related to changes in dynamics of the Azores High system. The modeling aspect of this study corroborates that these unique hydroclimate conditions were likely related to the size, intensity, and mean location of the Azores High system,” says Alan Wanamaker, professor in the Department of Geological and Atmospheric Sciences at Iowa State University.

“Although our previous findings using speleothems hinted at large changes in hydroclimate over the last 1000 years, the ability to diagnose the most likely causes of these shifts is exciting. Recent drying in Portugal is primarily related to greenhouse gas forcing causing an expansion of the Azores High, whereas earlier changes were largely related to the non-stationary behavior and the relative intensity of the Azores High system.”

“Our work is exciting because it uses observations, ensemble modelling, and proxy methods to characterize climate trends,” lead author Nathaniel Cresswell-Clay says. Cresswell-Clay was a guest investigator at WHOI at the time of the research; he is currently a graduate student in atmospheric sciences at the University of Washington. “We leveraged advantages of each data type to provide new insights into how the North Atlantic climate is changing.”

The study was funded by the National Science Foundation, Cornell College, the WHOI Ocean Climate Change Institute, and the James E. and Barbara V. Moltz Fellowship for Climate-Related Research.

Authors: Nathaniel Cresswell-Clay1, Caroline C. Ummenhofer1*, Diana L. Thatcher2, Alan D. Wanamaker2, Rhawn F. Denniston3, Yemane Asmerom4, and Victor J. Polyak4

Affiliations:

1Department of Physical Oceanography, Woods Hole Oceanographic Institution, Woods Hole, MA, USA

Department of Geological and Atmospheric Sciences, Iowa State University, Ames, IA, USA

Department of Geology, Cornell College, Mount Vernon, IA, USA

Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, NM, USA

*corresponding author

About Woods Hole Oceanographic Institution

The Woods Hole Oceanographic Institution (WHOI) is a private, non-profit organization on Cape Cod, Massachusetts, dedicated to marine research, engineering, and higher education. Established in 1930, its primary mission is to understand the ocean and its interaction with the Earth as a whole, and to communicate an understanding of the ocean’s role in the changing global environment. WHOI’s pioneering discoveries stem from an ideal combination of science and engineering—one that has made it one of the most trusted and technically advanced leaders in basic and applied ocean research and exploration anywhere. WHOI is known for its multidisciplinary approach, superior ship operations, and unparalleled deep-sea robotics capabilities. We play a leading role in ocean observation and operate the most extensive suite of data-gathering platforms in the world. Top scientists, engineers, and students collaborate on more than 800 concurrent projects worldwide—both above and below the waves—pushing the boundaries of knowledge and possibility. For more information, please visit www.whoi.edu

Related:

Here are some “ET’s” recorded from around the planet the last couple of days, their consequences, and some extreme temperature outlooks:

Here is more July 2022 climatology:

Here is more climate and weather news from Friday:

(As usual, this will be a fluid post in which more information gets added during the day as it crosses my radar, crediting all who have put it on-line. Items will be archived on this site for posterity. In most instances click on the pictures of each tweet to see each article. The most noteworthy items will be listed first.)

(If you like these posts and my work, please contribute via this site’s PayPal widget. Thanks in advance for any support.) 

Guy Walton “The Climate Guy”

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