Quick Telecast
Expect News First

Orbital-scale Asian monsoon variability and dynamics of high-CO2 world in the late Oligocene

0 94


Fig. 1. Site location map and photographs.(A) Topographic map of Asia with schematic summer monsoon, westerlies, and summer intertropical convergence zone (ITCZ) at present (11) and with the Late Oligocene proto-Paratethys Sea that was located west of the Tibetan Plateau (26). (B) Topographic map of the Lanzhou Basin and surrounding mountains with the location of the studied Duitinggou section (red solid circle). (C) Field photograph of the tilted to the west (~30°) Duitinggou section. The left-hand side (west) is younger than the right-hand side (east). Photo credit: Hong Ao, Institute of Earth Environment, Chinese Academy of Sciences. Credit: DOI: 10.1126/sciadv.abk2318

Researchers from China, the U.K., Netherlands, and Australia have revealed orbital-scale Asian monsoon variability and dynamics under conditions of high atmospheric CO2 concentrations and a warm climate during the late Oligocene.

The study was published in Science Advances on Dec. 15. It was led by Prof. Ao Hong from the Institute of Earth Environment of the Chinese Academy of Sciences.

Across the Eocene–Oligocene transition, ~34 million years ago (Ma), Earth transitioned from a warm greenhouse state with no permanent polar ice sheets to a unipolar icehouse state with continental-scale ice sheet development on Antarctica. Despite a certain amount of cooling during this transition, Earth was substantially warmer than it is today.

The Oligocene between 33.90 and 23.03 Ma represents the first epoch in the newly established unipolar icehouse world. The atmospheric CO2 concentrations at that time were between ~400 and ~800 parts per million (ppm), with an average global sea surface temperature 8 degrees Celsius higher than today and an ice-free Northern Hemisphere.

“Study of monsoon variability and dynamics in the Oligocene high-CO2 world has important implications for the rapid out-of-equilibrium, present-day monsoon responses to an anthropogenic CO2 increase,” said Prof. Ao, the principal investigator of the study. Such research also helps to improve prediction of future hydrological changes following the sustained atmospheric CO2 and temperature increases projected by the Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report.

The well-exposed fluvial-lacustrine sedimentary succession of the Lanzhou Basin on the northeastern Tibetan Plateau margin spans virtually the entire period from the Eocene to the Miocene. It provides an excellent opportunity to study the sedimentary signature of climate during past periods of persistently warmer-than-present conditions.

The researchers established 4-Myr-long summer monsoon records (magnetic susceptibility and rubidium-to-strontium ratio) continuously spanning the period from ~28.1 to ~24.1 Ma at ~4-thousand-year (kyr) resolution from a well-developed distal alluvial sedimentary sequence in the Lanzhou Basin. These records reveal orbital-scale Asian monsoon variability in the high-CO2, warm-climate world of the Late Oligocene, 20 Myr before Northern Hemisphere glaciation.

They found that Asian summer monsoon precipitation on the northeastern Tibetan Plateau margin was characterized by prominent short (~110-kyr) and long (405-kyr) eccentricity cycles between ~28.1 to ~24.1 Ma, with a weak expression of obliquity (41-kyr) and precession (19-kyr and 23-kyr) cycles.

Based on land-sea correlations and astronomical forcing theory, this orbital-scale regional monsoon precipitation variability during the late Oligocene was probably controlled by a combination of eccentricity modulation of solar insolation, a low-latitude forcing, and glacial-interglacial Antarctic ice sheet fluctuations, a high-latitude forcing.

The combined low- and high-latitude forcing drove the eccentricity-paced precipitation variability by governing regional temperatures, water vapor loading in the western Pacific and Indian Oceans, and Asian monsoon intensity and displacement.

This finding implies that the Asian monsoon may become increasingly susceptible to sustained global warming as anthropogenic emissions continue to increase.


Climate variability and dynamics across early-to-middle pliocene warm period provide clues for future climate change


More information:
Hong Ao et al, Eccentricity-paced monsoon variability on the northeastern Tibetan Plateau in the Late Oligocene high CO 2 world, Science Advances (2021). DOI: 10.1126/sciadv.abk2318

Provided by
Chinese Academy of Sciences


Citation:
Orbital-scale Asian monsoon variability and dynamics of high-CO2 world in the late Oligocene (2021, December 20)
retrieved 20 December 2021
from https://phys.org/news/2021-12-orbital-scale-asian-monsoon-variability-dynamics.html

This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.




Orbital-scale Asian monsoon variability and dynamics of high-CO2 world in the late Oligocene
Fig. 1. Site location map and photographs.(A) Topographic map of Asia with schematic summer monsoon, westerlies, and summer intertropical convergence zone (ITCZ) at present (11) and with the Late Oligocene proto-Paratethys Sea that was located west of the Tibetan Plateau (26). (B) Topographic map of the Lanzhou Basin and surrounding mountains with the location of the studied Duitinggou section (red solid circle). (C) Field photograph of the tilted to the west (~30°) Duitinggou section. The left-hand side (west) is younger than the right-hand side (east). Photo credit: Hong Ao, Institute of Earth Environment, Chinese Academy of Sciences. Credit: DOI: 10.1126/sciadv.abk2318

Researchers from China, the U.K., Netherlands, and Australia have revealed orbital-scale Asian monsoon variability and dynamics under conditions of high atmospheric CO2 concentrations and a warm climate during the late Oligocene.

The study was published in Science Advances on Dec. 15. It was led by Prof. Ao Hong from the Institute of Earth Environment of the Chinese Academy of Sciences.

Across the Eocene–Oligocene transition, ~34 million years ago (Ma), Earth transitioned from a warm greenhouse state with no permanent polar ice sheets to a unipolar icehouse state with continental-scale ice sheet development on Antarctica. Despite a certain amount of cooling during this transition, Earth was substantially warmer than it is today.

The Oligocene between 33.90 and 23.03 Ma represents the first epoch in the newly established unipolar icehouse world. The atmospheric CO2 concentrations at that time were between ~400 and ~800 parts per million (ppm), with an average global sea surface temperature 8 degrees Celsius higher than today and an ice-free Northern Hemisphere.

“Study of monsoon variability and dynamics in the Oligocene high-CO2 world has important implications for the rapid out-of-equilibrium, present-day monsoon responses to an anthropogenic CO2 increase,” said Prof. Ao, the principal investigator of the study. Such research also helps to improve prediction of future hydrological changes following the sustained atmospheric CO2 and temperature increases projected by the Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report.

The well-exposed fluvial-lacustrine sedimentary succession of the Lanzhou Basin on the northeastern Tibetan Plateau margin spans virtually the entire period from the Eocene to the Miocene. It provides an excellent opportunity to study the sedimentary signature of climate during past periods of persistently warmer-than-present conditions.

The researchers established 4-Myr-long summer monsoon records (magnetic susceptibility and rubidium-to-strontium ratio) continuously spanning the period from ~28.1 to ~24.1 Ma at ~4-thousand-year (kyr) resolution from a well-developed distal alluvial sedimentary sequence in the Lanzhou Basin. These records reveal orbital-scale Asian monsoon variability in the high-CO2, warm-climate world of the Late Oligocene, 20 Myr before Northern Hemisphere glaciation.

They found that Asian summer monsoon precipitation on the northeastern Tibetan Plateau margin was characterized by prominent short (~110-kyr) and long (405-kyr) eccentricity cycles between ~28.1 to ~24.1 Ma, with a weak expression of obliquity (41-kyr) and precession (19-kyr and 23-kyr) cycles.

Based on land-sea correlations and astronomical forcing theory, this orbital-scale regional monsoon precipitation variability during the late Oligocene was probably controlled by a combination of eccentricity modulation of solar insolation, a low-latitude forcing, and glacial-interglacial Antarctic ice sheet fluctuations, a high-latitude forcing.

The combined low- and high-latitude forcing drove the eccentricity-paced precipitation variability by governing regional temperatures, water vapor loading in the western Pacific and Indian Oceans, and Asian monsoon intensity and displacement.

This finding implies that the Asian monsoon may become increasingly susceptible to sustained global warming as anthropogenic emissions continue to increase.


Climate variability and dynamics across early-to-middle pliocene warm period provide clues for future climate change


More information:
Hong Ao et al, Eccentricity-paced monsoon variability on the northeastern Tibetan Plateau in the Late Oligocene high CO 2 world, Science Advances (2021). DOI: 10.1126/sciadv.abk2318

Provided by
Chinese Academy of Sciences


Citation:
Orbital-scale Asian monsoon variability and dynamics of high-CO2 world in the late Oligocene (2021, December 20)
retrieved 20 December 2021
from https://phys.org/news/2021-12-orbital-scale-asian-monsoon-variability-dynamics.html

This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.

FOLLOW US ON GOOGLE NEWS

Read original article here

Denial of responsibility! Quick Telecast is an automatic aggregator of the all world’s media. In each content, the hyperlink to the primary source is specified. All trademarks belong to their rightful owners, all materials to their authors. If you are the owner of the content and do not want us to publish your materials, please contact us by email – [email protected]. The content will be deleted within 24 hours.

Leave a comment
Ads Blocker Image Powered by Code Help Pro

Ads Blocker Detected!!!

We have detected that you are using extensions to block ads. Please support us by disabling these ads blocker.

buy kamagra buy kamagra online