Tamara L FletcherUniversity of Adelaide · School of Physics Chemistry and Earth Sciences
Tamara L Fletcher
PhD. BSc (Hons), Grad. Cert Arts/Communications
About
33
Publications
11,147
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371
Citations
Introduction
I am a palaeoecologist and palaeoclimatologist. My new project is on how to reconstruct palaeocloud. My previous work with PoLAR-FIT focused on the climate and palaeoenvironment of the Canadian High Arctic during the Early to mid-Pliocene Warm Period, ~4 million years ago; motivated by the puzzle of polar amplification of temperatures during past warm periods. I use biological proxies to investigate these questions.
Additional affiliations
May 2019 - present
Position
- PostDoc Position
Description
- President's International Fellowship Initiative to study palaeofire in NE Eurasia.
August 2018 - October 2018
November 2017 - present
Education
June 2009 - March 2014
March 2008 - June 2009
March 2008 - June 2009
Publications
Publications (33)
Owing to its specialised methodology, palaeoecology is often regarded as a separate field from ecology, even though it is essential for understanding long-term ecological processes that have shaped the ecosystems that ecologists study and manage. Despite advances in ecological modelling, sample dating, and proxy-based reconstructions facilitating d...
Due to a specialised methodology, palaeoecology is often regarded as a separate field from ecology even though it is essential to understand long-term ecological processes that have shaped ecosystems that ecologists study and manage. Even though advances in ecological modelling, sample dating, and proxy-based reconstructions have enabled direct com...
Wildfire has extensive and profound impacts on forest structure and function. Therefore, it is important to study the spatial and temporal patterns of forest fire regimes and their drivers in order to better understand the feedbacks between climate change, fire disturbance, and forest ecosystems. Based on the Global Fire Atlas dataset, three forest...
Reconciling palaeodata with model simulations of the Pliocene climate is essential for understanding a world with atmospheric CO2 concentration near 400 ppmv (parts per million by volume). Both models and data indicate an amplified warming of the high latitudes during the Pliocene; however, terrestrial data suggest that Pliocene northern high-latit...
Reconciling palaeodata with model simulations of the Pliocene climate is essential for understanding a world with atmospheric CO2 concentration near 400 parts per million by volume. Both models and data indicate an amplified warming of the high latitudes during the Pliocene, however terrestrial data suggests Pliocene high latitude temperatures were...
The Beaufort Formation records extraordinary details of Arctic environments and amplified temperatures at approximately modern levels of atmospheric CO2. It was deposited during the Neogene on the western side of what is now the Canadian Arctic Archipelago. Meighen Island is a key locality for studying this formation because marine sediments there...
Arctic warming is expected to accelerate northward migration of the boreal zone, altering the boreal wildfire regime, with changes in fire frequency, intensity, size, and fire season length. The closest analogue to these future high latitude climate conditions occurred during the Pliocene Epoch (2.58–5.33 Ma). Palaeoenvironmental reconstructions at...
Relative weakness in sensitivity and contribution integration, especially lack of specific indicators at spatial and temporal scales, may hinder the formation of systematic knowledge for climate change impact on vegetation activity. Considering the interannual variability and periods difference, we investigated the ecosystem sensitivity to hydrothe...
Forcings and feedbacks controlling the seasonally sea ice-free Arctic Ocean during the mid-Piacenzian Warm period (3.264–3.025 Ma, MPWP), a period when CO2 level, geography, and topography were similar to present day, remain unclear given that many complex Earth System Models with comparatively higher skills at simulating twentieth century Arctic s...
The mid-Pliocene is a valuable time interval for investigating equilibrium climate at current atmospheric CO2 concentrations because atmospheric CO2 concentrations are thought to have been comparable to the current day and yet the climate and distribution of ecosystems were quite different. One intriguing, but not fully understood, feature of the e...
Well-preserved beetle elytra from the fossil and subfossil record are used by palaeoclimatologists to estimate past temperatures. Beetle-derived estimates of temperature across the Pliocene Arctic are consistently lower than those derived from other palaeoclimate proxies. Here we test if that pattern is attributable to either the modern dataset or...
The Winton Formation is increasingly recognised as an important source of information about the Cretaceous of Australia, and, more broadly, the palaeobiogeographic history of eastern Gondwana. With more precise dating and stratigraphic controls starting to provide temporal context to the geological and palaeontological understanding of this formati...
The mid-Pliocene is a valuable time interval for understanding the mechanisms that determine equilibrium climate at current CO2 concentrations. One intriguing, but not fully understood, feature of the early to mid-Pliocene climate is the amplified arctic temperature response. Current models underestimate the degree of warming in the Pliocene Arctic...
Proxy reconstructions of the mid-Piacenzian warm period (mPWP, between 3.264 and 3.025 Ma) suggest terrestrial temperatures were much warmer in the northern high latitudes (55°–90°N, referred to as NHL) than present-day. Climate models participating in the Pliocene Model Intercomparison Project Phase 1 (PlioMIP1) tend to underestimate this warmth....
A recurring goal in ecological and paleoclimatic studies is to either forecast how ecosystems will respond to future climate or hindcast climate from past ecosystem assemblages. The Pliocene is a useful deep-time laboratory for understanding an equilibrium climate state under modern atmospheric CO2, and has been a focus for climate modelers. Accura...
This short summary presents selected results of an ongoing investigation into the feedbacks that contribute to amplified Arctic warming. The consequences of warming for Arctic biodiversity and landscape response to global warmth are currently being interpreted. Arctic North American records of largescale landscape and paleoenvironmental change duri...
Tunnels and faecal pellets likely made by oribatid mites have been found in silicified conifer wood from the Upper Cretaceous (Cenomanian–Turonian) portion of the Winton Formation, central-western Queensland, Australia. Although this is the first identified and described record of oribatid mites in the Mesozoic of Australia, other published, but un...
Although there is an emerging consensus about global climate patterns during the Cretaceous, details about the climate in Australia at this time are poorly resolved, and estimates for terrestrial climate are scarce. Using Climate Leaf Analysis Multivariate Program (CLAMP) and Bioclimatic Analysis (BA) on plant fossils from the mid- to Upper Cretace...
Psephophorus polygonus Meyer, 1847, the first fossil leatherback turtle to be named,
was described on the basis of shell ossicles from the middle Miocene (MN6–7/8?) of Slovakia. The
whereabouts of this material is uncertain but a slab on display at the Naturhistorisches Museum Wien
is considered the neotype.We rediscovered further type locality oss...
Although there is a broad knowledge of Cretaceous climate on a global scale, quantitative climate estimates for terrestrial localities are limited. One source of terrestrial palaeoproxies is foliar physiognomy. The use of foliar physiognomy to explore Cretaceous assemblages has been limited, and some of its potential sources of error have not been...
Pterosaur fossils from Australia are rare. All the specimens that have been described previously are Creta- ceous in age, with the majority deriving from the Aptian–Albian shallow marine succession within the Eromanga Basin of western Queensland. The Queensland specimens have tentatively been referred to the pterodactyloid clades Pteranodon- tidae,...
Questions
Question (1)
I have climate and vegetation data by latitude longitude. The vegetation data is a categorical variable with 20 possible options. The climate data is relative frequency of occurrence (RFO) for a dozen climate states - adding up to 100%.
What I want is a model where I can input the vegetation data classification, and it gives a most likely RFO for each climate state.
Using Random Forest models I already know that the climate data can predict the vege classification ~80% of the time, with quite a lot of 'near-misses' according to the confusion matrix, but what I need is the flip-side of this - if I input the vege data, can I get the RFO of the climate states.
I have been looking at K-means clustering, Linear Discriminant Analysis and Multiple Nominal Logistic Regression, but I am unsure if these apply to what I am trying to achieve. I also thought about producing probability densities for each climate state for each vege type, but I am not sure if there is already a method that would do that in a more functional way.
Are their existing statistical or machine learning techniques that achieve what I am trying to do?
