| Interpretation of the Central Andean paleoclimate over the last millennia still represents a
research challenge demanding deeper studies [1,2]. Several high-resolution paleoclimate
proxies for the last 10,000 years have been developed for the northern hemisphere. However,
similar proxies are very limited for South America, particularly for high altitudes
where, for example, tree-ring chronologies are not available and instrumental records
are very limited. Consequently, our knowledge of high altitude climate changes
in arid regions of the Peruvian Andes mainly relies on ice-core and lake deposit
studies.
In our study, we used a new alternative proxy for interpretation of palaeoclimate
conditions based on a peat core taken from the Carhuasanta Valley at the foot of Nevado
Mismi in the southern Peruvian Andes (15Ë 30´S, 71Ë 43´W, 4809m a.s.l.). The stable carbon
isotope composition (δ13C) of Distichia peat reflects mainly the relative variation of the
mean air temperature during subsequent growing seasons [3], and allows reconstructions of
palaeotemperature changes. In contrast, peat organic carbon concentration (C % wt) records
mainly wetness in the valley, directly corresponding to the changes in runoff in the upper part
of the catchment.
The most prominent climate changes recorded in the peat over last 4ka occurred between
3040 and 2750 cal. yrs BP. The initial warming turned to a very rapid cooling to temperatures
at least 2Ë C lower than the mean for the Late Holocene. Initially drier conditions within this
event turned to a short wet phase after 2780 cal. yrs BP, when the temperature increased
again. This event coincides with significant changes in peat and ice core records in the
Central Andes that match the timing of the global climate event around 2.8 cal. ka BP.
Climatic conditions in the study area became relatively dry and stable after the event for
about 800 years. Highly variable temperatures and humidity prevailed during the
last 2000 years, when an extended warm and relatively humid period occurred
between 640–155 cal. yrs BP, followed by predominantly colder and drier conditions
[4].
Our study demonstrates how the δ13C value and carbon content variations in Distichia
peat can be interpreted and used for verification of other multiproxy records, particularly
these which are challenging for accurate dating.
[1] Stansell, N.D., Rodbell, D.T., Abbott, M.B., Mark, B.G., 2013. Proglacial lake
sediment records of Holocene climate change in the western Cordillera of Peru. Quat. Sci.
Rev. 10, 1–14.
[2] Engel Z., Skrzypek G., 2014. Reply to the comment by A. Sáez et al. on Climate in
the Western Cordillera of the Central Andes over the last 4300 years. Quat. Sci. Rev. (in press
10.1016/j.quascirev.2014.12.006).
[3] Skrzypek, G., Engel, Z., Chuman, T., Šefrna, L., 2011. Distichia peat - A new
stable isotope paleoclimate proxy for the Andes. Earth Planet. Sci. Lett. 307(3–4),
298–308.
[4] Engel, Z., Skrzypek, G., Chuman, T., Šefrna, L., MihaljeviÄ, M., 2014. Climate in the
Western Cordillera of the Central Andes over the last 4300 years. Quat. Sci. Rev. 99, 60–77. |