Past Life and Climates

Period: first semester

Course unit contents:

1st Module: Past life

One of the basic tenets of geology is that the present is the key to the past. In recent years, however and especially considering the increasingly
important role played by humans in changing our Planet, scientists are turning that basic tenet around to the past is the key to the future. In this
perspective the reconstruction of past environments grounded on a proxy-based approach is one of the hot topics in the geosciences.
Proxies are physical, chemical and biological materials preserved within the geologic record that can be analyzed and correlated with climatic or
environmental conditions. Proxy-based reconstructions span all timescales, from year-to-year variations to those that occurred over millions of years and provide a tool in order better understand how climate and environments has varied trough time both before and after human-related alteration of the Earth.
In this context this course will be focused on:
1) Main geological archives (sediments, corals, trees, ice cores, speleothems, instrumental datasets). Completeness, Resolution and time frame.

2) Overview of main proxies in terms of their rationale, calibration (direct, indirect) and possible applications with the final aims to reconstruct past
environments and climates.
Proxies that will be presented in this course are subdivided in:
• Physical proxies
Sediment Composition. Types of minerals and fossils that are preserved in the geological archives and can inform about salinity, temperature, ice
cover, oxygen levels, nutrient levels, ect
• Biological proxies
Biological proxies that include remains of living organisms (terrestrial and marine) the distribution of which is controlled by temperature, moisture
availability, and other environmental factors.
Examples of biological proxies that will be treated during the course are:
- Terrestrial Biological Proxies: pollen and spores; plant macrofossils;
- Aquatic Biotic Proxies: foraminifers; calcareous nannofossils,
ostracodes, biogenic silica (diatoms, radiolarians and silicoflagellates),
corals, dinoflagellates cysts, mollusks;
• Chemical Proxies: composition of shells of aquatic organisms; biomarkers, elemental analysis

3) Applications of the basic information acquired in the first part of the course by means of a discussion of a case study that will change every
year and would serve to emphasize the potential of the fossil record in reconstructing environments in the geological past (e.g., modern
analogues) as well as interpreting changes observed in perturbated present day environments.

2nd Module: Past Climates

Compelling evidence indicates that, since the early days of its Byr-long history, our planet had to cope unceasingly with changes in regional and global climates, which occurred on different time scales and amplitudes. However, predictive models proved to fall short when attempting precise forecasts of future climate trends, since the Earth climate system is complex, manifold and hardly predictable in its behavior. Crucial insights are provided by investigating the climate history in the Geologic past, which holds the key for understanding the future of our planet.

The Course will be organized as follows:
1 - Introduction to the Climate System (2.5 CFU).
Climate: definitions and calculation of the Earth radiative balance. Elements of descriptive and dynamic Oceanography. The astronomical theory of climate. Stable oxygen isotopes for paleoclimate reconstructions.
2 - Past climates of the Earth (3 CFU)
The great Proterozoic and Paleozoic glaciations. Mesozoic:
from the Early Triassic wastelands to the Cretaceous Thermal Maximum. Paleogene: the beginning of the Southern Hemisphere Glaciation. The Neogene and the Northern Hemisphere Glaciation.
The Pleistocene: evolution of climate cycles and orbitally-paced glacial dynamics. High-frequency climate variability: the Holocene. Climate cycles at the centennial and decadal scales. Open discussion (class lab).

Planned learning activities and teaching methods: 

1st Module: Past Life
Frontal lectures (5 CFU)
Class laboratories (1 CFU)

Lectures with the support of on-screen presentations. Lab classes (group work) for discussing a case study (different every year) + Lab classes to
give an overview of the main fossil groups (1st Module). A one-day field trip to outcrops where rocks with paleoclimatic significance are exposed

(2nd Module): Past Climates
Frontal lectures (5.5 CFU = 44 hours)
Field and class laboratories (0.5 CFU = 5 field + 3 lab hours) one-day field trip to outcrops where rocks with paleoclimatic significance are exposed, and in-class discussions on hot paleoclimate and climate topics.