Scientists Reconstruct Subarctic Climate Using Tree Ring Data, Highlighting Urgency of Climate Change
Researchers from Siberian Federal University (SibFU) have collaborated with an international scientific group to study the changes in stable isotopes of oxygen, carbon, and hydrogen in the annual rings of coniferous trees in Subarctic regions. The study, published in the Science of The Total Environment journal, demonstrates how tree ring data can provide insights into past climate patterns and even simulate future climate scenarios.
Boreal forests, which span a vast area from 50° to 70° north, are particularly susceptible to climate change. Large portions of these forests in northern Canada and northeastern Siberia are overlapped by permafrost, which releases additional carbon into the atmosphere as it thaws due to rising air temperatures. The melting permafrost and the uneven subsidence of rocks and soil in these areas make boreal forests highly vulnerable to climate warming.
Previous research has shown that boreal forest trees are highly sensitive to climate change, with the ability to register signals of summer air temperature. However, scientists have observed a decrease in the sensitivity of tree growth to summer air temperature in certain regions of the American and Canadian subarctic since the 1990s. This decline in sensitivity could be attributed to factors such as dry conditions, reduced precipitation, and increased air temperatures.
Dr. Olga Churakova, a leading researcher at the Ecosystem Biogeochemistry Laboratory, SibFU, explained that changes in spring-summer air temperature have a significant impact on tree growth in regions with a continental climate. These changes leave traces in the stable isotopes of carbon, oxygen, and hydrogen found in tree rings. By analyzing these isotopes along with climate data, it becomes possible to reconstruct the climate of centuries or even millennia ago.
The combination of these three stable isotopes in tree ring studies offers a comprehensive understanding of climate variability in the boreal forest zone. This data can then be used to improve temperature and ecohydrological simulations, leading to more accurate models and forecasts of future climate change.
The research conducted by SibFU scientists focused on subarctic regions in Siberia and Canada, where comprehensive data on all three stable isotopes were obtained. These isotopes are crucial for modeling sunshine duration, relative humidity, and winter-spring temperatures, which can be extracted from tree growth rings.
To enhance the reliability of climate forecasts, it is essential to delve into the study of past climate changes comprehensively. This requires examining changes in air temperature and considering hydroecological characteristics, including the impacts of permafrost in the subarctic region of Eurasia.
The scientists emphasized that the melting of permafrost and the formation of thermokarst lakes can lead to a decline in tree health and damage to infrastructure. Additionally, the isotopic ratio of stable oxygen isotopes found in tree rings can reveal how trees utilize meltwater during warm periods of growth.
The ongoing task for the scientific team is to model the three stable isotopes in tree rings for boreal forests both inside (Siberia, Canada, Alaska) and outside (Finland, Sweden, Norway) of the permafrost zone. This modeling process aims to simulate the depth of permafrost thaw and assess the adaptive abilities of forest ecosystems under changing climate conditions. Furthermore, the researchers aim to identify triggers, such as stratospheric volcanic eruptions, that have led to decreased vapor elasticity and reduced sunshine duration over the past 1500 years.
Funding for this study was provided by the Russian Science Foundation (21-17-00006), and SibFU is actively implementing the Centre for Low-carbon Development and Climate Policy strategic project as part of the Priority 2030 program.
By shedding light on the interplay between tree ring data and climate change, this research underscores the urgency of addressing and mitigating the effects of climate change. The insights gained from reconstructing past climate patterns and forecasting future ones will contribute to the development of effective climate models and policies. Through continued scientific exploration and collaboration, we can strive towards a more sustainable future and combat the challenges posed by a rapidly changing climate.
