Takuro Kobashi

Prof. Takuro Kobashi

orcid

Research Focus & Metrics

Academic Career Length

26Years (2001-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

View All Publications
1 May 2007 in Quaternary Science Reviews
Verified
Journal Article
Closed access
TKTakuro Kobashi
Takuro Kobashi
JSJeffrey P. Severinghaus
Jeffrey P. Severinghaus
EBEdward J. Brook
Edward J. Brook
JBJean-Marc Barnola
Jean-Marc Barnola
AGAlexi M. Grachev
Alexi M. Grachev

3 May 2017 in Scientific Reports
Verified
Journal Article
Open access
PDF file
TKTakuro Kobashi
Takuro Kobashi
LMLaurie Menviel
Laurie Menviel
AJAurich Jeltsch-Thömmes
Aurich Jeltsch-Thömmes
BVBo M. Vinther
Bo M. Vinther
JBJason Box
Jason Box
AOAtsumu Ohmura
Atsumu Ohmura
Solar variability has been hypothesized to be a major driver of North Atlantic millennial-scale climate variations through the Holocene along with orbitally induced insolation change. However, another important climate driver, volcanic forcing has generally been underestimated prior to the past 2,500 years partly owing to the lack of proper proxy temperature records. Here, we reconstruct seasonally unbiased and physically constrained Greenland Summit temperatures over the Holocene using argon and nitrogen isotopes within trapped air in a Greenland ice core (GISP2). We show that a series of volcanic eruptions through the Holocene played an important role in driving centennial to millennial-scale temperature changes in Greenland. The reconstructed Greenland temperature exhibits significant millennial correlations with K+ and Na+ ions in the GISP2 ice core (proxies for atmospheric circulation patterns), and δ18O of Oman and Chinese Dongge cave stalagmites (proxies for monsoon activity), indicating that the reconstructed temperature contains hemispheric signals. Climate model simulations forced with the volcanic forcing further suggest that a series of large volcanic eruptions induced hemispheric-wide centennial to millennial-scale variability through ocean/sea-ice feedbacks. Therefore, we conclude that volcanic activity played a critical role in driving centennial to millennial-scale Holocene temperature variability in Greenland and likely beyond.

10 November 2011 in Geophysical Research Letters
Verified
Journal Article
Open access
PDF file
TKTakuro Kobashi
Takuro Kobashi
KKKenji Kawamura
Kenji Kawamura
JSJeffrey P. Severinghaus
Jeffrey P. Severinghaus
JBJean-Marc Barnola
Jean-Marc Barnola
TNToshiyuki Nakaegawa
Toshiyuki Nakaegawa
JBJason Box
Jason Box
[1] Greenland recently incurred record high temperatures and ice loss by melting, adding to concerns that anthropogenic warming is impacting the Greenland ice sheet and in turn accelerating global sea‐level rise. Yet, it remains imprecisely known for Greenland how much warming is caused by increasing atmospheric greenhouse gases versus natural variability. To address this need, we reconstruct Greenland surface snow temperature variability over the past 4000 years at the GISP2 site (near the Summit of the Greenland ice sheet; hereafter referred to as Greenland temperature) with a new method that utilises argon and nitrogen isotopic ratios from occluded air bubbles. The estimated average Greenland snow temperature over the past 4000 years was −30.7°C with a standard deviation of 1.0°C and exhibited a long‐term decrease of roughly 1.5°C, which is consistent with earlier studies. The current decadal average surface temperature (2001–2010) at the GISP2 site is −29.9°C. The record indicates that warmer temperatures were the norm in the earlier part of the past 4000 years, including century‐long intervals nearly 1°C warmer than the present decade (2001–2010). Therefore, we conclude that the current decadal mean temperature in Greenland has not exceeded the envelope of natural variability over the past 4000 years, a period that seems to include part of the Holocene Thermal Maximum. Notwithstanding this conclusion, climate models project that if anthropogenic greenhouse gas emissions continue, the Greenland temperature would exceed the natural variability of the past 4000 years sometime before the year 2100.

1 October 2020 in Applied Energy
Verified
Journal Article
Closed access
TKTakuro Kobashi
Takuro Kobashi
TYTakahiro Yoshida
Takahiro Yoshida
YYYoshiki Yamagata
Yoshiki Yamagata
KNKatsuhiko Naito
Katsuhiko Naito
SPStefan Pfenninger
Stefan Pfenninger
KHKeishiro Hara
Keishiro Hara

3 October 2009 in Climatic Change
Verified
Journal Article
Open access
PDF file
TKTakuro Kobashi
Takuro Kobashi
JSJeffrey P. Severinghaus
Jeffrey P. Severinghaus
JBJean-Marc Barnola
Jean-Marc Barnola
KKKenji Kawamura
Kenji Kawamura
TCTara Carter
Tara Carter
TNTosiyuki Nakaegawa
Tosiyuki Nakaegawa
Future Greenland temperature evolution will affect melting of the ice sheet and associated global sea-level change. Therefore, understanding Greenland temperature variability and its relation to global trends is critical. Here, we reconstruct the last 1,000 years of central Greenland surface temperature from isotopes of N2 and Ar in air bubbles in an ice core. This technique provides constraints on decadal to centennial temperature fluctuations. We found that northern hemisphere temperature and Greenland temperature changed synchronously at periods of ~20 years and 40–100 years. This quasi-periodic multi-decadal temperature fluctuation persisted throughout the last millennium, and is likely to continue into the future.

1 April 2008 in Earth and Planetary Science Letters
Verified
Journal Article
Closed access
TKTakuro Kobashi
Takuro Kobashi
JSJeffrey P. Severinghaus
Jeffrey P. Severinghaus
JBJean-Marc Barnola
Jean-Marc Barnola