Michael-Shawn Fletcher

University of Melbourne | MSD · School of Geography Earth and Atmospheric Sciences

We set out to test the ability to detect vegetation change from organic soil nutrient (carbon and nitrogen) composition in the fire-determined forest/non-forest mosaic of western Tasmania, Australia. We find no relationship between organic soil nitrogen and carbon content, despite widely varying local vegetation and fire regimes. Pollen evidence su...

Recognition of the effects of inter-annual climate change on earth systems has led to a greater understanding of the various forces that influence natural systems. The El Niño-Southern Oscillation (ENSO) is, arguably, the most well-known and widely researched inter-annual climate mode. The effects of ENSO on natural systems include changes in fire-...

The prevailing view in the palaeoclimate literature of the last 20 years is that the Southern Westerly Winds (SWW) were intensified over southern Australia and Tasmania during the warmer-than-present early Holocene (11-8 ka). At similar latitudes on the opposite side of the southern mid-latitudes, palaeoclimate studies have suggested a poleward shi...

Wildfires in forests globally have become more frequent and intense because of changes in climate and human management. Shrub layer fuels allow fire to spread vertically to forest canopy, creating high-intensity fires. Our research provides a deep-time perspective on shrub fuel loads in fire-prone southeastern Australia. Comparing 2833 records for...

This is a reply to the comments of Penna [1] and Feller [2] on our paper “The Curse of Conservation: empirical evidence demonstrating that changes in land-use legislation drove catastrophic bushfires in Southeast Australia” [3]. Penna [1] and Feller [2] present a series of critiques of our data and narrative that we summarise under two central them...

It has been argued that we have now entered the Anthropocene, a proposed epoch in which humans are having a dominant impact on the Earth system. While some geologists have sought to formalize the Anthropocene as beginning in the mid-twentieth century, its social, geophysical, and environmental roots undoubtedly lie deeper in the past. In this revie...

It has been argued that we have now entered the Anthropocene, a proposed epoch in which humans are having a dominant impact on the Earth system. While some geologists have sought to formalize the Anthropocene as beginning in the mid-twentieth century, its social, geophysical, and environmental roots undoubtedly lie deeper in the past. In this revie...

Here, we explore the profound impact of the Tasmanian Aboriginal (Palawa) people on Tasmanian landscapes by examining a 22,000-year record of landscape change from Lake Selina in western Tasmania, Australia. We analysed a sediment core for palaeoecological proxies, namely, pollen (vegetation), charcoal (fire), and geochemical data (landscape weathe...

Humans undertake land management and care of landscapes to maintain safe, healthy, productive and predictable environments. Often, this is achieved through creating spatial and temporal heterogeneity in a way that leverages the natural world; both amplifying natural trends and, in some cases, driving shifts counter to natural processes. However, a...

This Element addresses a burning question – how can archaeologists best identify and interpret cultural burning, the controlled use of fire by people to shape and curate their physical and social landscapes? This Element describes what cultural burning is and presents current methods by which it can be identified in historical and archaeological re...

Fire is an integral part of the Earth System and humans have skillfully used fire for millennia. Yet human activities are scaling up and reinforcing each other in ways that are reshaping fire patterns across the planet. We review these changes using the concept of the fire regime, which describes the timing, location, and type of fires. We then exp...

A thorough understanding of controls over terrestrial sedimentary organic carbon characteristics in both the present and the past is pivotal to better understand atmospheric CO2 pathways into depositional sinks such as peats, swamps, and lakes. We explored the relationship between wetland sediment organic matter storage, climate (precipitation, tem...

Protecting “wilderness” and removing human involvement in “nature” was a core pillar of the modern conservation movement through the 20th century. Conservation approaches and legislation informed by this narrative fail to recognise that Aboriginal people have long valued, used, and shaped most landscapes on Earth. Aboriginal people curated open and...

What do you need to know to prosper as a people for at least 65,000 years? The First Knowledges series provides a deeper understanding of the expertise and ingenuity of Indigenous Australians. Plants are the foundation of life on Earth. Aboriginal and Torres Strait Islander peoples have always known this to be true. For millennia, reciprocal rela...

Background ‘Megafire’ is an emerging concept commonly used to describe fires that are extreme in terms of size, behaviour, and/or impacts, but the term’s meaning remains ambiguous. Approach We sought to resolve ambiguity surrounding the meaning of ‘megafire’ by conducting a structured review of the use and definition of the term in several languag...

This Data in Brief paper comprises dataset obtained for sediment cores collected from Lake Selina, located in the West Coast Range of Tasmania, Australia. Datasets include radiocarbon and optically stimulated luminescence age estimates, elemental composition, beryllium isotopes, magnetic properties and the paleomagnetic record measured on the cores...

Recent catastrophic fires in Australia and North America have raised broad‐scale questions about how the cessation of Indigenous burning practices has impacted fuel accumulation and structure. For sustainable coexistence with fire, a better understanding of the ancient nexus between humans and flammable landscapes is needed. We used novel palaeoeco...

Nature as a climate solution: Country, culture and nature-based solutions for mitigating climate change

Inter-hemispheric asynchrony of climate change through the last deglaciation has been theoretically linked to latitudinal shifts in the southern westerlies via their influence over CO2 out-gassing from the Southern Ocean. Proxy-based reconstructions disagree on the behaviour of the westerlies through this interval. The last deglaciation was interru...

The environmental crises currently gripping the Earth have been codified in a new proposed geological epoch: the Anthropocene. This epoch, according to the Anthropocene Working Group, began in the mid-20th century and reflects the “great acceleration” that began with industrialization in Europe [J. Zalasiewicz et al., Anthropocene 19, 55–60 (2017)]...

The Indo-Australian Summer Monsoon (IASM) is the dominant climate feature of northern Australia, affecting rainfall/runoff patterns over a large portion of the continent and exerting a major control on the ecosystems of the Australia's Top End, including the viability of wetland ecosystems and the structure of the woody savanna, which characterises...

The catastrophic 2019/2020 Black Summer bushfires were the worst fire season in the recorded history of Southeast Australia. These bushfires were one of several recent global conflagrations across landscapes that are homelands of Indigenous peoples, homelands that were invaded and colonised by European nations over recent centuries. The subsequent...

We aim to understand how did cool temperate rainforest respond to changes in climate and fire activity over the past 18 kcal yrs, interrogating the role that flammable plant species (such as Eucalyptus) have in the long-term dynamics of rainforest vegetation. We used high-resolution pollen and charcoal analysis, radiometric dating (lead and carbon)...

Lake sediment archives covering several glacial cycles are scarce in the Southern Hemisphere and they are challenging to date. Here we present the chronostratigraphy of the oldest continuous lake sediment archive in Tasmania, Australia; a 5.5 m and 270 ka (Marine Isotope Stage 8) sediment core from Lake Selina. We employ radiometric dating (radioca...

An important coupled ocean-atmospheric system in the mid-and high latitudes involves the Southern Westerly Winds (SWW) and the Southern Ocean (SO), which controls climate in the southernmost third of the world, deep water formation, and ventilation of CO 2 from the deep ocean. Most studies have examined its role as a driver of atmospheric CO 2 conc...

Mining has been a major contributor to economic development in Australia since British arrival in the late 1700s, with little to no thought regarding the long-term environmental consequences. This study assesses the metal pollution legacy caused by different smelting methods and mining activities during the British colonialism in western Tasmania....

Waterways in the Southern Hemisphere, including on the Australian continent, are facing increasing levels of mercury contamination due to industrialization, agricultural intensification, energy production, urbanization, and mining. Mercury contamination undermines the use of waterways as a source of potable water and also has a deleterious effect o...

Aim: To assess the relative roles of long-term climatic change, fire, and volcanic disturbance on the dynamics of Araucaria-Nothofagus forests of south-central Chile. Location: Lago Cilantro is in south-central Chile (38°51'36.72S, 71°17'14.52 W, 1400 masl), proximal to several active volcanos within the Southern Volcanic Zone of the Andes Mountai...

Context: Forest systems are dynamic and can alternate between alternative stable states in response to climate, disturbance and internal abiotic and biotic conditions. Switching between states depends on the crossing of critical thresholds and the establishment of feedbacks that drive (and maintain) changes in ecosystem functioning. The nature of t...

Indigenous people play an integral role in shaping natural environments, and the disruption to Indigenous land management practices has profound effects on the biosphere. Here, we use pollen, charcoal and dendrochronological analyses to demonstrate that the Australian landscape at the time of British invasion in the 18th century was a heavily const...

The impacts of fire and climate on freshwater ecosystems are not well understood, masking the potential impacts of anthropogenic climate change on these systems. A 9200 year Holocene record of sedimentary Carbon/Nitrogen, x-ray fluorescence, charcoal, pollen, and diatoms preserved within a freshwater lake in Tasmania was used to understand the infl...

Continuous continental records are critical to understanding how terrestrial environments responded to the large-scale shifts between glacial and interglacial climate states, providing valuable insights into the interactions between the atmosphere, oceans, cryosphere and biosphere, and the long-term context from which to interpret current and futur...

The current southward shift in the southern westerlies that is stripping southern Australia of rainfall is unprecedented over the past 12 kyrs years at least, and is due to the effects of both the anthropogenic hole in the ozone layer and greenhouse gas-driven global warming. Predictions of future climate suggest the Earth is moving in to a “super-...

Mining has caused extensive damage to aquatic systems worldwide with acidification, heavy metal pollution, increased sediment loading and Ca decline of freshwaters. While some aquatic ecosystems are thought to be recovering from past mining, a long-term context is needed to determine if pre-impact conditions have been restored. Here we explore the...

A multi-proxy palaeoenvironmental record from a lake (36° 5'37.33"S; 150° 7'26.02"E) on the east coast of Australia provides a record of coastal development and vegetation succession over the last 3,800 cal. yr BP. Lead-210 and 14C dating built a robust age-depth chronology for the 61cm long core. Pollen, charcoal and x-ray fluorescence analysis pr...

Tasmania's montane temperate rainforests contain some of Australia's most ancient and endemic flora. Recent landscape‐scale fires have impacted a significant portion of these rainforest ecosystems. The complex and rugged topography of Tasmania results in a highly variable influence of fire across the landscape, rendering predictions of ecosystem re...

A 70 m long continental sediment record was recovered at Darwin Crater in western Tasmania, Australia. The sediment succession includes a pre-lake silty sand deposit overlain by lacustrine silts that have accumulated in the ∼816 ka meteorite impact crater. A total of 160 m of overlapping sediment cores were drilled from three closely spaced holes....

Climate change is affecting the distribution of species and the functioning of ecosystems. For species that are slow growing and poorly dispersed, climate change can force a lag between the distributions of species and the geographic distributions of their climatic envelopes, exposing species to the risk of extinction. Climate also governs the resi...

A 70m long continental sediment record was recovered at Darwin Crater in western Tasmania, Australia. The sediment succession includes a pre-lake silty sand deposit overlain by lacustrine silts that have accumulated in the � 816 ka meteorite impact crater. A total of 160m of overlapping sediment cores were drilled from three closely spaced holes. H...

This study investigated metal contamination from historical mining in lakes in the Tasmanian Wilderness World Heritage Area (TWWHA) and surrounding region. The largest increase in sedimentation and metal contamination occurred ca. 1930 when open-cut mining commenced and new mining technology was introduced into the region. The geochemical signal of...

In the version of this Perspective originally published, affiliations 1 and 4 ware incorrect, and should have read: “¹Antarctic Climate & Ecosystems CRC, University of Tasmania, Hobart, Tasmania, Australia” and “⁴Centre for Water, Climate and Land (CWCL), University of Newcastle, Callaghan, NSW, Australia”. These have been corrected in the online v...

Poster presentation for the British Ecological Society Palaeoecology SIG launch meeting

The interaction of gradual climate trends and extreme weather events since the turn of the century has triggered complex and, in some cases, catastrophic ecological responses around the world. We illustrate this using Australian examples within a press-pulse framework. Despite the Australian biota being adapted to high natural climate variability,...

Recent changes in trend and variability of the main Southern Hemisphere climate modes are driven by a variety of factors, including increasing atmospheric greenhouse gases, changes in tropical sea surface temperature, and stratospheric ozone depletion and recovery. One of the most important implications for climatic change is its effect via climate...

The Cenozoic spore-pollen zonation scheme of southeastern Australia is used to constrain the ages of marine and terrestrial strata throughout Australasia. New palynological, strontium isotope and foraminiferal data from the Torquay and Gippsland basins in southeastern Australia are here used to revise and chronologically calibrate the Oligocene and...

Environmental changes such as climate, land-use, and fire activity affect terrestrial and aquatic ecosystems at multiple scales of space and time. Due to the nature of the interactions between terrestrial and aquatic dynamics, an integrated study using multiple proxies is critical for a better understanding of climate- and fire- driven impacts on e...

Critical transitions in ecosystem states are often sudden and unpredictable. Consequently, there is a concerted effort to identify measurable early warning signals (EWS) for these important events. Aquatic ecosystems provide an opportunity to observe critical transitions due to their high sensitivity and rapid response times. Using palaeoecological...

Millennial-scale latitudinal shifts in the SWW drive changes in Southern Ocean upwelling, leading to changes in atmospheric carbon dioxide levels thereby affecting the global climate and carbon cycle. Our aim here is to understand whether century-scale shifts in the SWW also drive changes in atmospheric CO2 content. We report new multi-proxy lake s...

This study uses the “simplified patterns of temperature and effective precipitation” approach from the Australian component of the international palaeoclimate synthesis effort (INTegration of Ice core, MArine and TErrestrial records – OZ-INTIMATE) to compare atmosphere–ocean general circulation model (AOGCM) simulations and proxy reconstructions. T...

Aim- To assess whether climate directly influences aquatic ecosystem dynamics in the temperate landscape of Tasmania or whether the effects of long-term climatic change are mediated through the terrestrial environment (indirect climate influence). Location- Paddy’s Lake is located at 1065 m asl in temperate north-west Tasmania, a continental island...

Conceptual models predict a tight coupling between the Intertropical Convergence Zone (ITCZ) and the Southern Westerly Winds (SWW) in response to glacial-interglacial transitions, yet little is known about this relationship under Holocene boundary conditions. Here we present a synthesis of Holocene pollen and charcoal data from the southwest Pacifi...

Aim: To test competing hypotheses about the timing and extent of Holocene landscape opening using pollen-based quantitative land-cover estimates. Location: Dove Lake, Tasmanian Wilderness World Heritage Area, Australia. Methods: Fossil pollen data were incorporated into pollen dispersal models and corrected for differences in pollen productivity...

Tasmania’s dry, inland east is ideally positioned to inform models of late Quaternary environmental change in southern Australasia. Despite this, it remains poorly represented in the palaeoecological record. Here, we seek to address this with a >13,000-year vegetation and fire history from Stoney Lagoon, a site at the eastern margin of Tasmania’s i...

Paleoclimate proxy reconstruction initiatives, such as the Australian component of the international paleoclimate synthesis effort: INTegration of Ice core, MArine and Terrestrial records (OZ-INTIMATE), are important as they provide evidence of past climatic conditions that are necessary to evaluate global General Circulation Models (GCMs). One of...

The Winds of Change: understanding millennial-scale variability of the Southern Westerly Winds The behaviour of the Southern Westerly Winds (SWW) in the Australian sector during the Last Glacial Cycle has been the source of continuing and unresolved debate for decades. We have recently developed a high resolution multi-proxy analysis from Lake Seli...

Bushfires are one of the most frequent natural hazards experienced in Australia.Fires play an important role in shaping the landscape and its ecological dynamics, but may also have devastating effects that cause human injuries and fatalities, as well as broad-scale environmental damage. While there has been considerable effort to quantify changes i...

El Niño Southern Oscillation (ENSO) is the main mode controlling the variability in the ocean-atmosphere system in the South Pacific. While the ENSO influence on rainfall regimes in the South Pacific is well documented, its role in driving spatiotemporal trends in fire activity in this region has not been rigorously investigated. This is particular...

- The Southern Annular Mode (SAM) is the dominant control over Southern Hemisphere climates >40°S via modulation of the latitudinal position of the Southern Westerly Winds (SWW). - The SWW modulate global atmospheric CO2 content via wind-driven overturning of the Southern Ocean. - The longest reconstruction of SAM spans the last 1000 years. - A s...

Southern Annular Mode (SAM) is the primary mode of atmospheric variability in the Southern Hemisphere. While it is well established that the current anthropogenic-driven trend in SAM is responsible for decreased rainfall in southern Australia, its role in driving fire regimes in this region has not been explored. We examined the connection between...

Here, we use a synthesis of 14 new palaeofire records across the island of Tasmania, Australia (41-44S), to identify an island-wide ‘megafire’ that occurred at 3000 +/-500 years before present (yr BP). This palaeofire period occurs during a phase of amplified activity of the warm phase (El Niño) of the El Niño-Southern Oscillation (ENSO). We analys...

The El Nino-Southern Oscillation (ENSO) exerts an important influence over rainfall patterns and fire regimes in Australia. Recent evidence reveals that Tasmanian vegetation, in particular, is highly sensitive to fires that result from the fluctuations in the ENSO climate system. What is less certain is how the impact of ENSO-driven climate and fir...

We test the validity of applying the alternative stable state paradigm to account for the landscape-scale forest/non-forest mosaic that prevails in temperate Tasmania, Australia. This test is based on fine scale pollen, spore and charcoal analyses of sediments located within a small patch of non-forest vegetation surrounded by temperate forest. Fol...