Climate Changes in the Mediterranean
During the Development of
Northern Hemispheric Glaciation
Gideon Ng
Primary Advisor: Timothy Herbert
Readers: Steven Hamburg
Stephen Porder
Outside Advisor: Laura Cleaveland
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Insights on Mediterranean Climate Changes During Glaciation, Papers of Asian literature
The relationship between greenhouse gas emissions and climate fluctuations during the development of northern hemispheric glaciation, using data from the vostok ice core and benthic oxygen isotope records. It also discusses the impact of these climate changes on mediterranean vegetation and biome distribution, as well as the evolution of arid- and grassland-adapted species. The document also introduces the alkenone paleotemperature method and its application to mediterranean sea sediments.
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Climate Changes in the Mediterranean
During the Development ofNorthern Hemispheric Glaciation
Gideon NgPrimary Advisor:
Timothy Herbert
Readers:
Steven HamburgStephen Porder
Outside Advisor:
Laura Cleaveland
•Greenhouse gas andclimate fluctuations in thegeological past offerinsight into modernclimate change•Glaciation andatmospheric CO
are 2 closely linked•Due to anthropogenicclimate change, modern[CO]^2 atm^
is ~380 ppm and climbing, far beyond the[CO]^ range of the most^2 atm^ recent (late Pleistocene)glacial cycles of ~180-280ppm
Record of [CO
], deuterium isotopes, and ice sheet 2 atm^ growth of the past 450 kyr from the Vostok ice core inAntarctica.
Source: Sigman et al 2000.
Pollen records displaying climate control on Mediterranean vegetationalecology. Left: succession of vegetation species during a glacial cycle.Right: temperate tree pollen percentage (middle) compared to
(^18) δO
(bottom) and high-latitude solar insolation (top).
Source: Tzedakis 2007.
QuickTime™ and aTIFF (Uncompressed) decompressoare needed to see this picture.
QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.
Modern biome distribution of North Africa. Source: deMenocal 2004. Percentage of grassland-adapted taxa (left)and arid-adapted species in mammalianfossil record in Ethiopia.
Source: Bobe 2002.
•The distribution of biomes isgoverned by climatic variations inprecipitation and temperaturepatterns•Cold North Atlantic SST’s duringglaciations cause cooler and drierconditions in North Africa•Intensification of NorthernHemispheric Glaciation causedexpansions of deserts andgrasslands, contractions ofwoodlands• Habitat selection hypothesis
climate-forced shifts in habitatdistributions led to the evolution ofarid-, grassland-adapted speciesand extinction of humid,-woodland- adapted species
Evolutionary history of hominids, and East African soilcarbonate carbon isotopes reflecting the relative abundanceof woodland versus grassland.
Source: deMenocal 2004.
Alkenone Paleotemperature MethodThe haptophyte algae
Emiliana huxleyi. Correlation between Uk37 indexand sea-surface temperature.Source: Herbert 2003.
- Emiliana huxleyi The 37:3 and 37:2 alkenoneunsaturation forms in a gaschromatogram.
and other haptophyte algae produce alkenones in variousunsaturation forms, depending on growthtemperature^37 •The U^ k
index is calculated using the ratio of tri-unsaturated (37:3) to di-unsaturated (37:2) alkenones and usedto estimated sea-surface temperature
The SST (top) and C
-total (bottom) records from Vrica (red) (Cleaveland 37
2009), San Nicola (purple), Punta Piccola Monte Narbonne section (darkblue), and Punta Piccola Trubi section (light blue).
•Two distinct transitions: ~2.5 Mya and ~1.8 Mya•Increases in the amplitude of SST cycles•The ~1.8 Mya transition (Plio-Pleistocene boundary) not observed in otherpaleoclimate records
Spectral analysis of the Mediterranean SST record •Precession’s 23 kyr periodicity most consistent before ~2.5 Mya –suggesting dominance of local solar insolation•Obliquity’s 41 kyr band strengthens after ~2.5 Mya and develops into thestrongest spectral power of the dataset at ~1.8 Mya•Obliquity has little direct influence on solar insolation on Mediterranean’sO^35 N latitude, but controls high-latitude glaciation
QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.