Benjamin J. Henley

University of Melbourne | MSD · School of Earth Sciences

Groundwater response to climate variations is often pivotal to managing groundwater sustainably. However, this relationship is rarely explicitly examined because of the complexity of surface to subsurface processes and the diverse impacts of multiple drivers, such as groundwater pumping and land use changes. In this paper, we address this challenge...

In drought-prone Australia, multi-year droughts have detrimental impacts on both the natural environment and human societies. For responsible water management, we need a thorough understanding of the full range of variability in multi-year droughts and how this might change in a warming world. But research into the long-term frequency, persistence,...

The Australian monsoon delivers seasonal rain across a vast area of the continent stretching from the far northern tropics to the semi‐arid regions. This article provides a review of advances in Australian monsoon rainfall (AUMR) research and a supporting analysis of AUMR variability, observed trends, and future projections. AUMR displays a high de...

High-resolution palaeoclimate proxies are fundamental to our understanding of the diverse climatic history of the Australian mainland, particularly given the deficiency in instrumental datasets spanning more than a century. Annually resolved, tree-ring-based proxies play a unique role in addressing limitations in our knowledge of interannual to mul...

The 2019/20 Black Summer bushfire disaster in southeast Australia was unprecedented: the extensive area of forest burnt, the radiative power of the fires, and the extraordinary number of fires that developed into extreme pyroconvective events were all unmatched in the historical record. Australia’s hottest and driest year on record, 2019, was chara...

A decades-long affair Decadal climate variability and change affects nearly every aspect of our world, including weather, agriculture, ecosystems, and the economy. Predicting its expression is thus of critical importance on multiple fronts. Power et al . review what is known about tropical Pacific decadal climate variability and change, the degree...

Given the consequences and global significance of El Niño-Southern Oscillation (ENSO) events it is essential to understand the representation of El Niño diversity in climate models for the present day and the future. In recent decades, El Niño events have occurred more frequently in the central Pacific (CP). Eastern Pacific (EP) El Niño events have...

Much of Australia has been in severe drought since at least 2017. Here we link Australian droughts to the absence of Pacific and Indian Ocean mode states that act as key drivers of drought-breaking rains. Predicting the impact of climate change on drought requires accurate modelling of these modes of variability.

There has recently been interest in understanding the differences between specific levels of global warming, especially the Paris Agreement limits of 1.5 °C and 2 °C above pre-industrial levels. However, different model experiments1–3 have been used in these analyses under varying rates of increase in global-average temperature. Here, we use climat...

Multidecadal surface temperature changes may be forced by natural as well as anthropogenic factors, or arise unforced from the climate system. Distinguishing these factors is essential for estimating sensitivity to multiple climatic forcings and the amplitude of the unforced variability. Here we present 2,000-year-long global mean temperature recon...

El Niño events of the past 400 years. Instrumental and reconstructed El Niño events. Years in italic are identified in the instrumental record (HadISST 1950-2015) and bold highlight events picked up by both reconstruction and the instrumental data. Details in Freund et al 2019 and supplement: Higher frequency of Central Pacific El Niño events in re...

El Niño events differ substantially in their spatial pattern and intensity. Canonical Eastern Pacific El Niño events have sea surface temperature anomalies that are strongest in the far eastern equatorial Pacific, whereas peak ocean warming occurs further west during Central Pacific El Niño events. The event types differ in their impacts on the loc...

The benefits of limiting global warming to the lower Paris Agreement target of 1.5 °C are substantial with respect to population exposure to heat, and should impel countries to strive towards greater emissions reductions.

Water resource system behaviour is commonly evaluated using Monte Carlo simulation of synthetic streamflow and rainfall data. Fundamental to this process is the estimation of stochastic model parameters by calibration to short observed records. The uncertainty in key hydroclimate parameters, such as the mean, variance and serial autocorrelation, fl...

Australian seasonal rainfall is strongly affected by large-scale ocean–atmosphere climate influences. In this study, we exploit the links between these precipitation influences, regional rainfall variations, and palaeoclimate proxies in the region to reconstruct Australian regional rainfall between four and eight centuries into the past. We use an...

The characteristics of El Nino–Southern Oscillation (ENSO) spectra over the Last Millennium are examined to characterise variability over past centuries. Seven published palaeo-ENSO reconstructions and Nino3.4 from six Coupled Model Intercomparison Project-Phase 5 and Paleoclimate Modelling Intercomparison Project-Phase 3 (CMIP5–PMIP3) Last Millenn...

Reproducible climate reconstructions of the Common Era (1 CE to present) are key to placing industrial-era warming into the context of natural climatic variability. Here we present a community-sourced database of temperature-sensitive proxy records from the PAGES2k initiative. The database gathers 692 records from 648 locations, including all conti...

Pacific decadal variability (PDV) plays a critical role in the climate system. Here I present a review of indices and patterns of decadal climate variability in the Pacific from observations and palaeoclimate reconstructions. I examine the spatial characteristics of Pacific sea surface temperature variability and the metrics used to track observati...

To avoid more severe impacts from climate change, there is international agreement to strive to limit warming to below 1.5 °C. However, there is a lack of literature assessing climate change at 1.5 °C and the potential benefits in terms of reduced frequency of extreme events. Here, we demonstrate that existing model simulations provide a basis for...

Global temperature is rapidly approaching the 1.5°C Paris target. In the absence of external cooling influences, such as volcanic eruptions, temperature projections are centered on a breaching of the 1.5°C target, relative to 1850–1900, before 2029. The phase of the Interdecadal Pacific Oscillation (IPO) will regulate the rate at which mean tempera...

This study presents an analysis of three palaeoclimate rainfall reconstructions from the Southern Hemisphere regions of south-eastern Australia (SEA), southern South Africa (SAF) and southern South America (SSA). We provide a first comparison of rainfall variations in these three regions over the past two centuries, with a focus on identifying sync...

Key Points • Systematic evaluation of temporal and spatial features of the IPO in CMIP5 using TPI • Decadal variance of the IPO is commonly underestimated in models relative to observations • Models that simulate the IPO spatial pattern well also tend to simulate low frequency temporal characteristics Accelerated warming and hiatus periods in...

Australian seasonal rainfall is strongly influenced by large-scale ocean-atmosphere climate influences. In this study, we exploit the links between these large-scale precipitation influences, regional rainfall variations, and palaeoclimate proxies in the region to reconstruct Australian regional rainfall between four and eight centuries into the pa...

El Niño-Southern Oscillation is the major source of interannual rainfall variability in the Australian region, with the strongest influence over eastern Australia. The strength of this regional ENSO–rainfall teleconnection varies in the observational record. Climate model simulations of the “last millennium” (850–1850 C.E.) can be used to quantify...

This study introduces the Hill model for modelling sorption kinetics and illustrates its efficacy using formal model selection procedures. Although the coefficient of determination (R 2) value can be used to ensure goodness-of-fit of a particular model to a set of data, a measure that incorporates the number of model parameters, such as the Bayesia...

A new index is developed for the Interdecadal Pacific Oscillation, termed the IPO Tripole Index (TPI). The IPO is associated with a distinct ‘tripole’ pattern of sea surface temperature anomalies (SSTA), with three large centres of action and variations on decadal timescales, evident in the second principal component (PC) of low-pass filtered globa...

Urban bulk water systems supply water with high reliability and, in the event of extreme drought, must avoid catastrophic economic and social collapse. In view of the deep uncertainty about future climate change, it is vital that robust solutions be found that secure urban bulk water systems against extreme drought. To tackle this challenge an appr...

This chapter considers the problem of finding good and robust solutions for urban bulk water systems in the presence of deep uncertainty about future climate change. It briefly describes the concept of robust multi-objective optimization and then illustrates its application in a case study. The chapter discusses the robust multi-objective optimizat...

Future climate change presents a significant challenge in the planning and management of urban water supply systems. A large number of studies have been conducted in the past decade on hydrologic impacts of climate change. These studies reveal a difficult-to-quantify uncertainty in respect to future availability of water resources. This study consi...

Key Points Climate driver informed short‐term drought risk methodology is introduced Risk evaluated in each time step conditioned on climate driver & initial storage Traditional approaches underestimate the severity and duration of drought risk

A hierarchical framework for incorporating modes of climate variability into stochastic simulations of hydrological data is developed, termed the climate-informed multi-time scale stochastic (CIMSS) framework. A case study on two catchments in eastern Australia illustrates this framework. To develop an identifiable model characterizing long-term va...

Incorporating the influence of climate change and natural variability into stochastic hydrology is a priority for water resource planners who are being challenged by changing supply and demand patterns. The influence of large scale ocean-atmosphere climate mechanisms on Australia's highly variable rainfall regimes is a valuable means for improving...

The impact of climate variability and climate change on the security of water supply has significant consequences for water resource planning. It is currently the subject of considerable uncertainty in Australia and around the world. Persistent drought across much of Australia and increasing water demand due to population growth has placed greater...

Persistent drought across much of Australia, increasing water demand due to population growth, climate variability and the drying impacts of anthropogenically-induced climate change have placed increasing stress on our water supply systems. This paper represents an alternative approach to assessing water supply system security through the use of sh...

It is well documented that large-scale climate mechanisms such as the Interdecadal Pacific Oscillation (IPO) and El Niño Southern Oscillation (ENSO) play a dominant role in the hydrological variability of Australia. The recent drought in many parts of Australia has highlighted the importance of reliably estimating drought risk. Stochastic models pl...

The impact of climate variability on water supply drought security is currently the subject of considerable uncertainty. Water resource planners feel ill-equipped to provide reliable estimates of future drought security due to the shortcomings of the current suite of stochastic models. For example, there is considerable evidence that hydrological d...