Joint probabilistic estimates of temperature and precipitation from tree ring-based reconstructions of the last millennium

Advances in statistical climatology, meteorology and oceanography · 2026-02-16

Abstract. An understanding of Earth's past climate can help put current and future changes into historical context. Widely used tree ring-based drought atlases generally target the Palmer Drought Severity Index or other metrics of soil moisture and/or drought risk. These indices reflect contemporaneous meteorological conditions, and it is possible to extract information about temperature and precipitation given the existing reconstructions. Here, we present a fully Bayesian inverse method that infers a joint posterior for monthly mean temperature and precipitation given tree ring-based PDSI reconstructions from the North American Drought Atlas. The method is skillful at reconstructing early twentieth century conditions when compared to instrumental measurements from the CRU TS dataset. Moreover, the reconstructions can capture the complex temporal and multivariate covariance structure between monthly regional temperatures and precipitation. By reconstructing regional temperature and precipitation for the last millennium, we identify the driest and wettest years and decades in each region. Our results highlight the unique nature of the 1930s Dust Bowl drought in central Kansas and the late twentieth century pluvial in the North American southwest.

Correcting the heartwood-sapwood transition in blue intensity measurements with change point detection methods

Dendrochronologia · 2025-04-14 · 1 citations

Delta blue intensity is a commonly used method to correct for the heartwood-sapwood color change in blue intensity (BI) measurements. It is based on the assumption that the heartwood-sapwood color change is similar in both earlywood and latewood. This assumption has not been supported physiologically. Furthermore, delta BI may confound the climate signals in earlywood and latewood BI as it is technically a linear combination of the other two. Here, instead of using delta BI, we used change point detection to identify the heartwood-sapwood transition, and corrected for the color change by rescaling the mean and variance of BI measurements after the transition to those immediately before. We tested three different change point detection methods and found that they agreed well with one another. Importantly, our approach preserves the climate signals in both earlywood and latewood BI data, while delta BI causes a total loss of climate signals in our test case. Therefore, we suggest that change point detection should be used instead of delta BI to account for the heartwood-sapwood color change. • Multiple methods for change point detection in blue intensity (BI) data agree well with one another. • After color change adjustment, earlywood and latewood BI capture temperature signals much better than unadjusted delta BI. • Change point detection should be used instead of delta blue intensity to correct for the heartwood-sapwood color change.

Disruption of Drought Teleconnections Between ENSO‐Influenced Regions Around 1700 CE

Geophysical Research Letters · 2025-07-11 · 3 citations

Abstract Our understanding of pre‐modern El Niño Southern Oscillation (ENSO) variability is reliant on proxy records, often distant from the center of ENSO activity in the equatorial Pacific Ocean. Here, we assess the relationship between reconstructed soil moisture in four distant ENSO‐influenced regions over the past 400 years. A major breakdown in the teleconnection of regional drought conditions in Asia, Eastern Australia, and North America is identified around 1700 CE. The statistically significant decline in inter‐series correlations ( p < 0.01) represents a previously unknown aspect of global hydroclimate dynamics. We hypothesize that the disruption was driven by ENSO weakening and/or by a large‐scale multi‐decadal reconfiguration of ocean‐atmosphere circulation. Data assimilation estimates of soil moisture from the same regions fail to produce results of the same magnitude, potentially due to an overreliance of ENSO influence on the boundaries of spatial covariance in the underlying climate models.

Land-use and climate change in the early 19th century associated with European Settlement inferred from lake sediments and tree rings, Northeast Ohio

Abstracts with programs - Geological Society of America · 2025-01-01

Varying climate signals embedded in latewood blue intensity along an elevational gradient: A multi-species case study from the Great Basin, Nevada, USA

Dendrochronologia · 2025-05-23 · 1 citations

A Common Era Tree-Ring Chronology Sensitive to Cool-Season Temperatures for the Southern Hemisphere

Tree-Ring Research · 2025-07-14

Annually resolved multi-millennial records of temperature are rare in the Southern Hemisphere (SH), and even rarer are SH records of cool-season temperature. Here we present a new tree-ring chronology extending back to 42 BCE based on Athrotaxis selaginoides from southern Tasmania. The development of this chronology was complicated by multiple tree-age cohorts and growth classes. Additionally, there was a collapse in sample depth between the mid-14th and mid-16th Centuries. Therefore, we used a multiple Regional Curve Standardization (mRCS) approach to standardization but have subsequently employed piecewise adaptive detrending (PAD). PAD utilizes the Friedman Supersmoother to remove the remaining multimillennial trend likely to be the result of changing site conditions rather than climate. The chronology is significantly associated with temperature from winter through to the end of the warm season, but its association with Austral July-October temperatures is both unusual and stable. The collapse in sample depth, and four clear cohorts of trees are most likely associated with landscape scale fire events.

Global Warming Is Likely Affecting Regional Drought Across Eurasia

AGU Advances · 2025-02-01 · 2 citations

Abstract While rising global temperatures have altered global drought risk and are projected to continue to change large‐scale hydroclimate, it has proved difficult to detect the influence of external factors on drought‐relevant variables at regional scales. In addition to the inherent difficulty in identifying signals in noisy data, detection and attribution studies generally rely on general circulation models, which may fail to accurately capture the characteristics of naturally forced and internal hydroclimate variability. Here, we use a long tree‐ring based paleoclimate record of drought to estimate pre‐industrial variability in the Palmer Drought Severity Index (PDSI), a commonly used metric of drought risk. Using a Bayesian framework, we estimate the temporal and spatial characteristics of hydroclimate variability prior to 1850. We assess whether observed twenty‐first century PDSI is compatible with this pre‐industrial variability or is better explained by a forced response that scales with the global mean temperature. Our results suggest that global warming likely contributed to dry PDSI in Eastern Europe, the Mediterranean, and Arctic Russia and to wet PDSI in Northern Europe, East‐central Asia, and Tibet.

Megadroughts in the Common Era and the Anthropocene

UNC Libraries · 2025-04-17

Reconstructed Late Summer Maximum Temperatures for the Southeastern United States From Tree‐Ring Blue Intensity

Geophysical Research Letters · 2024-06-29 · 10 citations

Abstract Over recent decades, the southeastern United States (Southeast) has become increasingly well represented by the terrestrial climate proxy record. However, while the paleo proxy records capture the region's hydroclimatic history over the last several centuries, the understanding of near surface air temperature variability is confined to the comparatively shorter observational period (1895‐present). Here, we detail the application of blue intensity (BI) methods on a network of tree‐ring collections and examine their utility for producing robust paleotemperature estimates. Results indicate that maximum latewood BI (LWBI) chronologies exhibit positive and temporally stable correlations ( r = 0.28–0.54, p < 0.01) with summer maximum temperatures. As such, we use a network of LWBI chronologies to reconstruct August‐September average maximum temperatures for the Southeast spanning the period 1760–2010 CE. Our work demonstrates the utility of applying novel dendrochronological techniques to improve the understanding of the multi‐centennial temperature history of the Southeast.

A 561-yr (1461-2022 CE) summer temperature reconstruction for Mid-Atlantic-Northeast USA shows connections to volcanic forcing and atmospheric circulation

Climatic Change · 2024-09-01 · 5 citations

Abstract Contextualizing current increases in Northern Hemisphere temperatures is precluded by the short instrumental record of the past ca. 120 years and the dearth of temperature-sensitive proxy records, particularly at lower latitudes south of <50 °N. We develop a network of 29 blue intensity chronologies derived from tree rings of Tsuga canadensis (L.) Carrière and Picea rubens Sarg. trees distributed across the Mid-Atlantic and Northeast USA (MANE)—a region underrepresented by multi-centennial temperature records. We use this network to reconstruct mean March-September air temperatures back to 1461 CE based on a model that explains 62% of the instrumental temperature variance from 1901−1976 CE. Since 1998 CE, MANE summer temperatures are consistently the warmest within the context of the past 561 years exceeding the 1951−1980 mean of +1.3 °C. Cool summers across MANE were frequently volcanically forced, with significant ( p <0.05) temperature departures associated with 80% of the largest tropical ( n =13) and extratropical ( n =15) eruptions since 1461 CE. Yet, we find that more of the identified cool events in the record were likely unforced by volcanism and either related to stochastic variability or atmospheric circulation via significant associations ( p <0.05) to regional, coastal sea-surface temperatures, 500-hpa geopotential height, and 300-hpa meridional and zonal wind vectors. Expanding the MANE network to the west and south and combining it with existing temperature-sensitive proxies across North America is an important next step toward producing a gridded temperature reconstruction field for North America.