Tree Rings
Rajesh Basnet1,2 
1Academic writer, Earth and Human | Climate Action. Sustainable lifestyle. 
2Ph.D. scholar, Guangzhou Institutes of Biomedicine and Health, UCAS, China 

Carbon dioxide levels and climatic changes are shown through tree rings. These might use them to determine how recent climatic and environmental changes have influenced tree development. Must better understand internal variability for decadal, multidecadal, and long-term adaptation to climate change, paleoclimatology is a method of extending the instrumental era of climate knowledge backward in time. The objective of the review is to check whether recent warming during the period of observational monitoring is unusual, or if rising CO2 levels in the atmosphere or other nutrient inputs cause it, and to provide data for dendroclimatology, which is the study of climate and atmospheric conditions over time using wood. Although there are outliers in specific locations, tree-ring studies from temperature-sensitive ecosystems suggest significant recent warming. It is still unclear if such an influence will occur. The evidence regarding CO2 fertilization's effect on tree rings appears lacking. The study looks at whether recent climate swings are exceptional and might be linked to human activity. It also examines whether recent enhanced radial growth is unrelated to the climate and is caused by something other than growing CO2 levels.

Keywords: Climate proxies, Climate, CO2, Paleoclimatology, Tree Rings

Table of Contents

1. Overview

Paleoclimatology solves the limits of the instrumental period by employing “proxies” and tree rings to extend climate knowledge back into the past. One of the primary wellsprings of information on the climate during several thousand years is tree rings. For decadal, multidecadal, and long-term adaptations to climate change, a better knowledge of internal variability in the climate system is needed (Evans, Tolwinski-Ward, Thompson, & Anchukaitis, 2013). One year of a tree’s life is equivalent to one bright ring plus one dark ring; this lets you know how old the tree is and what the weather was like that year. Because tree rings are sensitive to local variables like rain and temperature, they can provide information about the climate of that place in the past (Frank, Esper, Zorita, & Wilson, 2010; Fritts, 2012).

1.1. Palaeoclimatology

Paleoclimatology is the study of ancient climates before instrumental data became widely available. Tree rings, coral skeletons, and ice caps have all preserved records of the Earth’s temperature. Scientists can use environmental recorders to estimate prior circumstances. Understanding previous “climate shocks” is crucial for avoiding future rapid climate change. The yearly rings that grow in tree trunks are the most valuable proxy we have for studying recent climate change (Larsen & Barry, 2019).

1.2. Variability and change in hydroclimate

Hydroclimate variability is reflected in the bulk of available tree-ring chronologies as temperatures rise due to human-caused climate change and “hot drought” risk. The recent drought in the eastern Mediterranean is the worst in the region’s 900-year history. In the early twenty-first century, a deficit in Mongolia lasted over a decade and was one of the driest periods of the millennium (Consortium, 2017; Moshir Panahi, Kalantari, Ghajarnia, Seifollahi-Aghmiuni, & Destouni, 2020).

1.3. Tree rings as time capsules for the Earth’s former climate

Scientists study tree rings to learn more about the Earth’s climate and may use them to determine how old a tree is and the weather each year. Since tree rings are sensitive to local climatic factors such as rainfall and temperature, they can provide information about the prior environment of an area. Tree rings, for example, often grow wider in warm, rainy years and become narrower in cold, dry years. Local climatic factors such as rain and temperature affect tree rings. They provide scientists with historical data on the local climate in that location. Tree rings, for example, often grow broader in warm, rainy years and smaller in cold, dry years (Luoto & Helama, 2010; Wang et al., 2013).

1.4. Carbon dioxide, tree rings, and climate change

Several temperature-sensitive media to higher latitude tree-ring datasets from both hemispheres reveal indications of recent unusual warming in these areas. Tree rings are being studied to see if increased CO2 levels in the atmosphere help natural flora grow faster. Little is understood about whether such an impact happens on a large scale in natural vegetation, which has highly complex environmental variables (Jacoby & D’Arrigo, 1997; Montwé, Isaac-Renton, Hamann, & Spiecker, 2018; Sun et al., 2010).

1.5. Time and climatic history

The yearly rings of trees in temperate areas can be used to determine their age. You may also use them to identify the age of the wood used in the construction of structures or wooden products. Archaeologists have used ring patterns to date the construction of some of the world’s most iconic designs, including the cliff dwellings at Mesa Verde National Park. Drought and temperature have been reconstructed using tree ring data in North America and Europe during the last 2,000 years. In addition to the tree ring observations, the NCEI archives these climatic reconstructions. The derived climatic histories improve our understanding of natural climate variability and benchmark for measuring human-caused climate change (Fritts, 2012; Gea-Izquierdo, Cherubini, & Cañellas, 2011; Schweingruber, 2012). Tree growth rings in temperate regions reflect one year of growth, from October to September the following year. Students will compare tree-ring data covering about the last 100 years in five old trees using simulated core samples printed on paper (Fonti et al., 2010; Franke, Frank, Raible, Esper, & Brönnimann, 2013).

2. Methodology

This study reviews the issue of what tree rings can teach us about climate change. Books, social media, news journals, articles, and websites, including official government and non-government organization websites, were used to gather secondary data for this study. The study’s inquiry and data collection were conducted in a quantitative method. Because there are no human participants in this study and the data is obtained from publicly available sources intended for widespread use, there are no ethical considerations.

3. Results and discussion

Tree-ring data is being examined to discover if current growth fluctuations are unusual relative to the past and, if so, whether this indicates warming induced by greenhouse gases and direct CO2 fertilization (Fritts, 2012). Tree rings can tell us how old they are and what the weather has been like in each year of their life. The light-colored circles signify development in the spring and early summer, while the black rings show growth in the late summer and fall. Many issues remain unanswered, and they are unlikely to be addressed soon. 

Trees’ incremental rings may include evidence of historical earth-surface processes, making them a valuable tool for analyzing past, current, and probable future process activity. Reconstructions of previous rockfall activity based on tree rings have been limited thus far, although they have generated encouraging findings. Tree-ring-based investigations of glacier-lake outburst floods, ice avalanches, and the occurrence of volcanic lahars might be helpful. Might conduct more morphological analysis in South America, India, Africa, Northern, Eastern Europe, or Russia. Should include more thorough statistical comparisons of ring chronologies or event-response replications in research beyond basic ring counting (Stoffel & Bollschweiler, 2008, 2009).

More studies and expanded geographical and temporal coverage of tree-ring data are needed to dispel uncertainties about whether anthropogenic effects are currently happening. Understanding previous “climate shocks” is critical in this study to avoid future rapid climate change. The possibility of “hot droughts” increases as temperatures rise due to human-induced climate change (Stoffel & Bollschweiler, 2009; Ye, Jiang, Liu, Zheng, & Zhou, 2021). A study of tree rings is being done to see if greater CO2 levels in the atmosphere help natural plant development. Such controlled investigations may provide fresh insights that can aid in resolving the CO2 fertilization issue. Even though trees with a strip-bark growth form are more likely to exhibit this impact, they make up a small portion of the land biosphere.

The evidence presented here is merely a piece of the puzzle when it comes to understanding the behavior of the land biosphere. There are still a lot of unknowns, and it’s unlikely that they will resolve these difficulties very soon. Further research and enhanced regional and temporary coverage of tree-ring data are required. A tree-ring study will aid in a better understanding of the complex dynamics, causes, and triggering variables of geomorphic processes and mitigate or reduce potential difficulties.

4. Conclusion 

Over time, trees accumulate a record of climate change in their trunks, forming a “record” of our planet’s weather. More extended time series are needed to evaluate whether recent climatic shifts are unusual and might be evidence of anthropogenic change. This study describes a summer temperature reconstruction that shows proof of the recent warming of 0.5 °C to 1°C over the past century. Although there are outliers in certain places, several temperature-sensitive settings show exceptional recent warming. The evidence of a probable CO2 fertilization impact in tree rings appears to be extremely limited.

4.1. Recommendation 

The quality of the rings inside a tree can let researchers know how old a tree is and the weather conditions during each year of that tree’s life. Ancient trees can offer clues to the climate of an area long before measurements are recorded.

4.2. The past and prospects for the future

Learning about the past, as well as the present and future, requires knowledge of history. Tree-ring proxies allow us to recreate historical hydroclimate and temperature with great accuracy. They additionally give a focal point through which we may see the human imprint on today’s environment. 


CO2Carbon dioxide 
NCEI National Centers for Environmental Information


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(Last Updated on May 23, 2022 by Sadrish Dabadi)

Rajesh Basnet received his B.Pharm, Institute of Medicine, Tribhuvan University, and MSc. In Pharmacology, Shanghai Institute of Materia Medica, Shanghai (2019). He is currently a Ph.D. scholar in Biochemistry and Molecular biology, Guangzhou Institutes of Biomedicine and Health, UCAS, Guangzhou, China (2020). He was awarded a UCAS scholarship (2016) and ANSO fellowship (2020) for his study. He has published more than 15 scientific articles in national and international journals.