Category: 2013

Ranga Myneni announces new coauthored article.

November 18th, 2013 in 2013, 2013, Faculty, November-13, Publications, Ranga Myneni

Professor Ranga Myneni announced today the publication of a new coauthored article in the journal Remote Sensing.

The article, “Recent Changes in Terrestrial Gross Primary Productivity in Asia from 1982 to 2011” was coauthored by Prof. Myneni and eight other authors from Japan, Korea, and China.

Kazuhito Ichii of Fukushima University in Kanayagawa, Fuhushima, Japan is the lead author of the paper.

The article can be read online at this address.

To see more of Prof. Myneni’s publications go to the publications section of our website.

Ranga Myneni Announces New Coauthored Article

November 14th, 2013 in 2013, 2013, Faculty, November-13, Publications, Ranga Myneni

Professor Ranga Myneni announced today the publication of a new coauthored article in the journal Remote Sensing.

The article, “A production efficiency model-based method for satellite estimates of corn and soybean yields in the midwestern US,” was coauthored by Prof. Myneni and six other authors from China, California, Australia, and Nebraska.

Qinchuan Xin and Peng Gong of Tsinghua University, Beijing, China were the article’s lead authors.

The article can be read online at this address.

To see more of Prof. Myneni’s publications go to the publications section of our website.

Dave Marchant publishes new article in Icarus

November 7th, 2013 in 2013, 2013, Dave Marchant, Faculty, November-13, Publications

E&E Professor Dave Marchant announced the publication of a new co-authored paper today.

Along with James Fastook from the University of Maine and James Head from Brown University, Marchant co-authored a paper titled “Formation of Lobate Debris Aprons on Mars: Assessment of Regional Ice Sheet Collapse and Debris-cover Armoring.”

The article will be published in the January edition, volume 228, of Icarus.

To see the early online publication of the article click here.

To see Dave Marchant’s other publications from the past two years click here.

IPCC Working Group I Assessment Report released online: Prof. Ranga Myneni one of lead authors on Chapter 6 “Carbon and Other Biogeochemical Cycles”

October 30th, 2013 in 2013, 2013, Faculty, October-13, Publications, Ranga Myneni

The Intergovernmental Panel on Climate Change (IPCC) has released an online version of Working Group I’s (WGI) section of the Fifth Assessment Report (AR5). Professor Ranga Myneni was a lead authors on Chapter Six “Carbon and Other Biogeochemical Cycles.”

The IPCC Fifth Assessment Report (AR5) assess the state of our current knowledge of climate change and provides scientific information to better equip policy makers on the future of climate change. Material from WGI’s portion of AR5 was used to prepare a Summary for Policy Makers (SPM) which was vetted by representatives of all governments involved and adopted as an official statement of The Physical Science Basis of Climate Change at this point. The SPM was released in late September 2013. Cambridge University Press will release print copies of WGI’s report, “Climate Change 2013: The Physical Science Basis,” in the coming months.

IPCC will also release the remaining sections of AR5, Working Group II, Working Group III, and a Synthesis Report, in the coming months. For more information on IPCC and AR5 visit IPCC’s website.

Ranga Myneni publishes new article in International Journal of Remote Sensing

October 28th, 2013 in 2013, 2013, Faculty, Juri Knjazihhin, October-13, Publications, Ranga Myneni

Professor Ranga Myneni and Research Professor Yuri Knyazikhin have published a new article entitled “Using hyperspectral vegetation indices to estimate the fraction of photosynthetically active radiation absorbed by corn canopies” in the International Journal of Remote Sensing. Changwei Tan of Yangzhou University of Yangzhou, China was lead author on the paper.

To read this article click here or see a list of all of Professor Myneni’s recent publications.

Professor Myneni coauthored a paper in PNAS on the dynamics of Amazon Droughts

October 22nd, 2013 in 2013, 2013, Faculty, October-13, Publications, Ranga Myneni

A paper titled “Increased dry-season length over southern Amazonia in recent decades and its implication for future climate projection” by Fu et al. appeared in an early edition of the journal “Proceedings of the National Academy of Sciences of the United States of America” (PNAS) on Tuesday October 21st, 2013. This paper addresses the question of whether the dry-season length will increase as that will determines the fate of the rainforests over Amazonia and future global atmospheric CO2 concentration. The authors show observationally that the dry-season length over southern Amazonia has increased significantly since 1979. Although the causes for this change are unknown, it resembles the effects of anthropogenic climate change. The global climate models that were presented in the Intergovernmental Panel on Climate Change’s fifth assessment report seem to substantially underestimate the variability of the dry-season length. Such a bias implies that the future change of the dry-season length, and hence the risk of rainforest die-back, may be underestimated by the projections of these models. The paper can be downloaded from http://www.pnas.org/content/early/2013/10/15/1302584110

A press release accompanying the publication can be found at http://www.jsg.utexas.edu/news/2013/10/risk-of-amazon-rainforest-dieback-is-higher-than-ipcc-projects/

Prof. Baldwin and Sue Wing Forecast U.S. CO2 Emissions to Exceed Official Estimates in Recent Journal of Regional Science Paper

September 25th, 2013 in 2013, 2013, Faculty, Ian Sue Wing, James Baldwin, Publications, September-13

Recent developments in U.S. climate change policy have seen the first tentative steps toward legislating a binding aggregate emission cap and implementing curbs on GHGs at the state and regional levels.1 This state and regional level policy action has been identified as both a critical element in U.S. emissions reductions and as a force to shape national climate change mitigation policy (Byrne et al., 2007; Lutsey and Sperling, 2008; Rabe, 2008). Consequently, the resulting economic effects of these policies is the subject of intense recent interest (Grainger and Kolstad, 2009; Hassett et al., 2009; Sue Wing, 2010). The first step in making any such assessment, and one incorporated or mandated in all state climate action plans (EPA, 2012), is to forecast how states’ baseline emissions are likely to evolve. Prerequisite to such projections is the ability to characterize the geographic variations in the precursors of GHGs—particularly CO2—based on an understanding of their historical evolution.

In this paper we investigate how the driving forces behind U.S. carbon dioxide emissions have evolved over the period 1963–2008. We take an explicitly spatial approach, quantifying in detail the interregional variations in CO2 precursors that are largely absent in the literature. While several recent papers have exploited state-level databases on the prices and quantities of fuel use, their focus has been quantifying the aggregate effects of drivers such as income and prices.2 The unfortunate consequence is that the substantial interregional heterogeneity underlying these results, which is interesting in its own right, has largely been ignored. An important exception to this general trend is Metcalf’s (2008) inquiry into the drivers of the energy intensity of U.S. states, which he disaggregates into intrasectoral changes in energy efficiency and intersectoral changes in the structure of economic activity. This paper’s key feature is the use of index number decomposition analysis, which is a popular technique for apportioning the time-evolution of a composite variable into contributions associated with movements in its constituent factors.3 We build on this approach, developing an extended decomposition framework which attributes the evolution of CO2 emissions over space and time to five precursors: the emissions intensity of energy use, the energy intensity of economic activity, the composition of states’ output, per capita income and population. Click to read entire paper…

Prof. Myneni’s recent paper in PNAS on CO2 growth rates and tropical temperature

September 9th, 2013 in 2013, 2013, Faculty, Publications, Ranga Myneni, September-13

Abstract

Previous studies have highlighted the occurrence and intensity of El Niño–Southern Oscillation as important drivers of the interannual variability of the atmospheric CO2 growth rate, but the underlying biogeophysical mechanisms governing such connections remain unclear. Here we show a strong and persistent coupling (r2 ≈ 0.50) between interannual variations of the CO2 growth rate and tropical land–surface air temperature during 1959 to 2011, with a 1 °C tropical temperature anomaly leading to a 3.5 ± 0.6 Petagrams of carbon per year (PgC/y) CO2 growth-rate anomaly on average. Analysis of simulation results from Dynamic Global Vegetation Models suggests that this temperature–CO2 coupling is contributed mainly by the additive responses of heterotrophic respiration (Rh) and net primary production (NPP) to temperature variations in tropical ecosystems. However, we find a weaker and less consistent (r2 ≈ 0.25) interannual coupling between CO2 growth rate and tropical land precipitation than diagnosed from the Dynamic Global Vegetation Models, likely resulting from the subtractive responses of tropical Rh and NPP to precipitation anomalies that partly offset each other in the net ecosystem exchange (i.e., net ecosystem exchange ≈ Rh − NPP). Variations in other climate variables (e.g., large-scale cloudiness) and natural disturbances (e.g., volcanic eruptions) may induce transient reductions in the temperature–CO2 coupling, but the relationship is robust during the past 50 y and shows full recovery within a few years after any such major variability event. Therefore, it provides an important diagnostic tool for improved understanding of the contemporary and future global carbon cycle. Click for complete PNAS article…

Prof. Myneni’s recent paper in NATURE on asymmetric daytime and night-time warming on vegetation growth

September 9th, 2013 in 2013, 2013, Faculty, Publications, Ranga Myneni, September-13

Temperature data over the past five decades show faster warming of the global land surface during the night than during the day1. This asymmetric warming is expected to affect carbon assimilation and consumption in plants, because photosynthesis in most plants occurs during daytime and is more sensitive to the maximum daily temperature, Tmax, whereas plant respiration occurs throughout the day2 and is therefore influenced by both Tmax and the minimum daily temperature, Tmin. Most studies of the response of terrestrial ecosystems to climate warming, however, ignore this asymmetric forcing effect on vegetation growth and carbon dioxide (CO2) fluxes3, 4, 5, 6. Here we analyse the interannual covariations of the satellite-derived normalized difference vegetation index (NDVI, an indicator of vegetation greenness) with Tmax and Tmin over the Northern Hemisphere. After removing the correlation between Tmax and Tmin, we find that the partial correlation between Tmax and NDVI is positive in most wet and cool ecosystems over boreal regions, but negative in dry temperate regions. In contrast, the partial correlation between Tmin and NDVI is negative in boreal regions, and exhibits a more complex behaviour in dry temperate regions. We detect similar patterns in terrestrial net CO2 exchange maps obtained from a global atmospheric inversion model. Additional analysis of the long-term atmospheric CO2 concentration record of the station Point Barrow in Alaska suggests that the peak-to-peak amplitude of CO2 increased by 23 ± 11% for a +1 °C anomaly in Tmax from May to September over lands north of 51° N, but decreased by 28 ± 14% for a +1 °C anomaly in Tmin. These lines of evidence suggest that asymmetric diurnal warming, a process that is currently not taken into account in many global carbon cycle models, leads to a divergent response of Northern Hemisphere vegetation growth and carbon sequestration to rising temperatures. Click for complete article…

Rita Cabral – First Author In Nature Paper

August 19th, 2013 in 2013, 2013, August-13, Graduate students, Publications

Anomalous Sulphur Isotopes in Plume Lavas Reveal Deep Mantle Storage of Archaean Crust

Basaltic lavas erupted at some oceanic intraplate hotspot volcanoes are thought to sample ancient subducted crustal materials1, 2. However, the residence time of these subducted materials in the mantle is uncertain and model-dependent3, and compelling evidence for their return to the surface in regions of mantle upwelling beneath hotspots is lacking. Here we report anomalous sulphur isotope signatures indicating mass-independent fractionation (MIF) in olivine-hosted sulphides from 20-million-year-old ocean island basalts from Mangaia, Cook Islands (Polynesia), which have been suggested to sample recycled oceanic crust3, 4. Continue reading at Nature.com…