Yang, Tian et al. published a new paper on “Century-scale patterns and trends of global pyrogenic carbon emissions and fire influences on terrestrial carbon balance” in Global Biogeochemical Cycles.

 

Abstract

Fires have consumed a large amount of terrestrial organic carbon and significantly influenced terrestrial ecosystems and the physical climate system over the past century. Although biomass burning has been widely investigated at a global level in recent decades via satellite observations, less work has been conducted to examine the century-scale changes in global fire regimes and fire influences on the terrestrial carbon balance. In this study, we investigated global pyrogenic carbon emissions and fire influences on the terrestrial carbon fluxes from 1901 to 2010 by using a process-based land ecosystem model. Our results show a significant declining trend in global pyrogenic carbon emissions between the early 20th century and the mid-1980s but a significant upward trend between the mid-1980s and the 2000s as a result of more frequent fires in ecosystems with high carbon storage, such as peatlands and tropical forests. Over the past 110?years, average pyrogenic carbon emissions were estimated to be 2.43?Pg?C?yr^?1 (1?Pg?=?10¹⁵?g), and global average combustion rate (defined as carbon emissions per unit area burned) was 537.85?g?C?m^?2 burned area. Due to the impacts of fires, the net primary productivity and carbon sink of global terrestrial ecosystems were reduced by 4.14?Pg?C?yr^?1 and 0.57?Pg?C?yr^?1, respectively. Our study suggests that special attention should be paid to fire activities in the peatlands and tropical forests in the future. Practical management strategies, such as minimizing forest logging and reducing the rate of cropland expansion in the humid regions, are in need to reduce fire risk and mitigate fire-induced greenhouse gases emissions.

 

 

To read the full article, please go to Global Biogeochemical Cycles.

 

The recent paper “Climate extremes dominating seasonal and interannual variations in carbon export from the Mississippi River Basin” led by Dr. Tian found that climate variability and extreme events such as drought and flood , were the primary factor responsible fro seasonal and interannaul variations in carbon export from the MS River Basin. The article was published in Global Biogeochemical Cycles.

 

Abstract

Knowledge about the annual and seasonal patterns of organic and inorganic carbon (C) exports from the major rivers of the world to the coastal ocean is essential for our understanding and potential management of the global C budget so as to limit anthropogenic modification of global climate. Unfortunately our predictive understanding of what controls the timing, magnitude, and quality of C export is still rudimentary. Here we use a process-based coupled hydrologic/ecosystem biogeochemistry model (the Dynamic Land Ecosystem Model) to examine how climate variability and extreme events, changing land use, and atmospheric chemistry have affected the annual and seasonal patterns of C exports from the Mississippi River basin to the Gulf of Mexico. Our process-based simulations estimate that the average annual exports of dissolved organic C (DOC), particulate organic C (POC), and dissolved inorganic C (DIC) in the 2000s were 2.6?±?0.4?Tg?C?yr^?1, 3.4?±?0.3?Tg?C?yr^?1, and 18.8?±?3.4?Tg?C?yr^?1, respectively. Although land use change was the most important agent of change in C export over the past century, climate variability and extreme events (such as flooding and drought) were primarily responsible for seasonal and interannual variations in C export from the basin. The maximum seasonal export of DIC occurred in summer while for DOC and POC the maximum occurred in winter. Relative to the 10?year average (2001–2010), our modeling analysis indicates that the years of maximal and minimal C export cooccurred with wet and dry years (2008: 32% above average and 2006: 32% below average). Given Intergovernmental Panel on Climate Change-predicted changes in climate variability and the severity of rain events and droughts of wet and dry years for the remainder of the 21st century, our modeling results suggest major changes in the riverine link between the terrestrial and oceanic realms, which are likely to have a major impact on C delivery to the coastal ocean.

To read the full article go to Global Biogeochemical Cycles.

The new article entitled “Anthropogenic and climatic influenced on carbon fluxes from eastern North America to the Atlantic Ocean: A process-based modeling study” led by Dr. Tian was published in JGR-Biogeosciences.

 

Abstract:

The magnitude, spatiotemporal patterns, and controls of carbon flux from land to the ocean remain uncertain. Here we applied a process-based land model with explicit representation of carbon processes in streams and rivers to examine how changes in climate, land conversion, management practices, atmospheric CO₂, and nitrogen deposition affected carbon fluxes from eastern North America to the Atlantic Ocean, specifically the Gulf of Maine (GOM), Middle Atlantic Bight (MAB), and South Atlantic Bight (SAB). Our simulation results indicate that the mean annual fluxes (±1 standard deviation) of dissolved organic carbon (DOC), particulate organic carbon (POC), and dissolved inorganic carbon (DIC) in the past three decades (1980–2008) were 2.37?±?0.60, 1.06?±?0.20, and 3.57?±?0.72?Tg?C?yr^?1, respectively. Carbon export demonstrated substantial spatial and temporal variability. For the region as a whole, the model simulates a significant decrease in riverine DIC fluxes from 1901 to 2008, whereas there were no significant trends in DOC or POC fluxes. In the SAB, however, there were significant declines in the fluxes of all three forms of carbon, and in the MAB subregion, DIC and POC fluxes declined significantly. The only significant trend in the GOM subregion was an increase in DIC flux. Climate variability was the primary cause of interannual variability in carbon export. Land conversion from cropland to forest was the primary factor contributing to decreases in all forms of C export, while nitrogen deposition and fertilizer use, as well as atmospheric CO₂ increases, tended to increase DOC, POC, and DIC fluxes.

 

To read the full article, go to JGR-Biogeosciences.

March 2014

AUBURN – Dr. Tian published a new paper entitled “North American terrestrial CO2 uptake largely offset by CH4 and N2O emissions: toward a full accounting of the greenhouse gas budget” in Climatic Change. The paper highlight the greenhouse warming potential (GWP) of North American terrestrial ecosystems during 2001-2010. Dr. Tian pioneering work was also featured in North American Carbon Program.

30 April 2014

AUBURN – Dr. Susan Pan published a new paper on “Modeling and Monitoring Terrestrial Primary Production in a Changing Global Environment: Toward a Multiscale Synthesis of Observation and Simulation” in Advances in Meteorology. The paper focuses on 3 major approaches to monitoring an predicting terrestrial NPP: ground based measurements, satellite observations, and process-based models and highlight the importance of incorporating socioeconomic component into terrestrial ecosystem models for accurately estimating and predicting terrestrial NPP in a changing global environment.