A Global Synthesis Inversion Analysis of Recent Variability in CO Fluxes Using GOSAT and In Situ Observations.

The precise contribution of the two major sinks for anthropogenic CO emissions, terrestrial vegetation and the ocean, and their location and year-to-year variability are not well understood. Top-down estimates of the spatiotemporal variations in emissions and uptake of CO are expected to benefit from the increasing measurement density brought by recent in situ and remote CO observations. We uniquely apply a batch Bayesian synthesis inversion at relatively high resolution to in situ surface observations and bias-corrected GOSAT satellite column CO retrievals to deduce the global distributions of natural CO fluxes during 2009-2010.

Corrigendum: Recent pause in the growth rate of atmospheric CO due to enhanced terrestrial carbon uptake.

This corrects the article DOI: 10.1038/ncomms13428.

A human-driven decline in global burned area.

Fire is an essential Earth system process that alters ecosystem and atmospheric composition. Here we assessed long-term fire trends using multiple satellite data sets. We found that global burned area declined by 24.

Recent pause in the growth rate of atmospheric CO due to enhanced terrestrial carbon uptake.

Terrestrial ecosystems play a significant role in the global carbon cycle and offset a large fraction of anthropogenic CO emissions. The terrestrial carbon sink is increasing, yet the mechanisms responsible for its enhancement, and implications for the growth rate of atmospheric CO, remain unclear. Here using global carbon budget estimates, ground, atmospheric and satellite observations, and multiple global vegetation models, we report a recent pause in the growth rate of atmospheric CO, and a decline in the fraction of anthropogenic emissions that remain in the atmosphere, despite increasing anthropogenic emissions.

Large carbon release legacy from bark beetle outbreaks across Western United States.

Warmer conditions over the past two decades have contributed to rapid expansion of bark beetle outbreaks killing millions of trees over a large fraction of western United States (US) forests. These outbreaks reduce plant productivity by killing trees and transfer carbon from live to dead pools where carbon is slowly emitted to the atmosphere via heterotrophic respiration which subsequently feeds back to climate change. Recent studies have begun to examine the local impacts of bark beetle outbreaks in individual stands, but the full regional carbon consequences remain undocumented for the western US.

Agricultural Green Revolution as a driver of increasing atmospheric CO2 seasonal amplitude.

The atmospheric carbon dioxide (CO2) record displays a prominent seasonal cycle that arises mainly from changes in vegetation growth and the corresponding CO2 uptake during the boreal spring and summer growing seasons and CO2 release during the autumn and winter seasons. The CO2 seasonal amplitude has increased over the past five decades, suggesting an increase in Northern Hemisphere biospheric activity. It has been proposed that vegetation growth may have been stimulated by higher concentrations of CO2 as well as by warming in recent decades, but such mechanisms have been unable to explain the full range and magnitude of the observed increase in CO2 seasonal amplitude.

Management and climate contributions to satellite-derived active fire trends in the contiguous United States.

Unlabelled: Fires in croplands, plantations, and rangelands contribute significantly to fire emissions in the United States, yet are often overshadowed by wildland fires in efforts to develop inventories or estimate responses to climate change. Here we quantified decadal trends, interannual variability, and seasonality of Terra Moderate Resolution Imaging Spectroradiometer (MODIS) observations of active fires (thermal anomalies) as a function of management type in the contiguous U.S.

Understorey fire frequency and the fate of burned forests in southern Amazonia.

Recent drought events underscore the vulnerability of Amazon forests to understorey fires. The long-term impact of fires on biodiversity and forest carbon stocks depends on the frequency of fire damages and deforestation rates of burned forests. Here, we characterized the spatial and temporal dynamics of understorey fires (1999-2010) and deforestation (2001-2010) in southern Amazonia using new satellite-based estimates of annual fire activity (greater than 50 ha) and deforestation (greater than 10 ha).

Forecasting fire season severity in South America using sea surface temperature anomalies.

Fires in South America cause forest degradation and contribute to carbon emissions associated with land use change. We investigated the relationship between year-to-year changes in fire activity in South America and sea surface temperatures. We found that the Oceanic Niño Index was correlated with interannual fire activity in the eastern Amazon, whereas the Atlantic Multidecadal Oscillation index was more closely linked with fires in the southern and southwestern Amazon.

Climate regulation of fire emissions and deforestation in equatorial Asia.

Drainage of peatlands and deforestation have led to large-scale fires in equatorial Asia, affecting regional air quality and global concentrations of greenhouse gases. Here we used several sources of satellite data with biogeochemical and atmospheric modeling to better understand and constrain fire emissions from Indonesia, Malaysia, and Papua New Guinea during 2000-2006. We found that average fire emissions from this region [128 +/- 51 (1sigma) Tg carbon (C) year(-1), T = 10(12)] were comparable to fossil fuel emissions.

Photosynthetic control of atmospheric carbonyl sulfide during the growing season.

Climate models incorporate photosynthesis-climate feedbacks, yet we lack robust tools for large-scale assessments of these processes. Recent work suggests that carbonyl sulfide (COS), a trace gas consumed by plants, could provide a valuable constraint on photosynthesis. Here we analyze airborne observations of COS and carbon dioxide concentrations during the growing season over North America with a three-dimensional atmospheric transport model.

Continental-scale partitioning of fire emissions during the 1997 to 2001 El Niño/La Niña period.

During the 1997 to 1998 El Niño, drought conditions triggered widespread increases in fire activity, releasing CH4 and CO2 to the atmosphere. We evaluated the contribution of fires from different continents to variability in these greenhouse gases from 1997 to 2001, using satellite-based estimates of fire activity, biogeochemical modeling, and an inverse analysis of atmospheric CO anomalies. During the 1997 to 1998 El Niño, the fire emissions anomaly was 2.

Parameterization and testing of a coupled photosynthesis-stomatal conductance model for boreal trees.

A coupled photosynthesis-stomatal conductance model was parameterized and tested with branches of black spruce (Picea mariana (Mill.) B.S.

Effects of climate and atmospheric CO partial pressure on the global distribution of C grasses: present, past, and future.

C photosynthetic physiologies exhibit fundamentally different responses to temperature and atmospheric CO partial pressures (pCO) compared to the evolutionarily more primitive C type. All else being equal, C plants tend to be favored over C plants in warm humid climates and, conversely, C plants tend to be favored over C plants in cool climates. Empirical observations supported by a photosynthesis model predict the existence of a climatological crossover temperature above which C species have a carbon gain advantage and below which C species are favored.

Regulation of branch-level gas exchange of boreal trees: roles of shoot water potential and vapor pressure difference.

Effects of shoot water potential (Psi) and leaf-to-atmosphere vapor pressure difference (VPD) on gas exchange of jack pine (Pinus banksiana Lamb.), black spruce (Picea mariana (Mill.) B.

Modeling the Exchanges of Energy, Water, and Carbon Between Continents and the Atmosphere.

Atmospheric general circulation models used for climate simulation and weather forecasting require the fluxes of radiation, heat, water vapor, and momentum across the land-atmosphere interface to be specified. These fluxes are calculated by submodels called land surface parameterizations. Over the last 20 years, these parameterizations have evolved from simple, unrealistic schemes into credible representations of the global soil-vegetation-atmosphere transfer system as advances in plant physiological and hydrological research, advances in satellite data interpretation, and the results of large-scale field experiments have been exploited.

Photosynthetic Acclimation to Temperature in the Desert Shrub, Larrea divaricata: I. Carbon Dioxide Exchange Characteristics of Intact Leaves.

Larrea divaricata, a desert evergreen shrub, has a remarkable ability to adjust its photosynthetic temperature response characteristics to changing temperature conditions. In its native habitat on the floor of Death Valley, California, plants of this C(3) species when provided with adequate water are able to maintain a relatively high and constant photosynthetic activity throughout the year even though the mean daily maximum temperature varies by nearly 30 C from winter to summer. The temperature dependence of light-saturated net photosynthesis varies in concert with these seasonal temperature changes whereas the photosynthetic rate at the respective optimum temperatures shows little change.

Influence of certain environmental factors on photosynthesis and photorespiration in Simmondsia chinensis.

The response of net photosynthesis and apparent light respiration to changes in [O2], light intensity, and drought stress was determined by analysis of net photosynthetic CO2 response curves. Low [O2] treatment resulted in a large reduction in the rate of photorespiratory CO2 evolution. Lightintensity levels influenced the maximum net photosynthetic rate at saturating [CO2].