Abstract. The global methane (CH 4 ) budget is becoming an increasingly important component for managing realistic pathways to mitigate climate change. This relevance, due to a shorter atmospheric lifetime and a stronger warming potential than carbon dioxide, is challenged by the still unexplained changes of atmospheric CH 4 over the past decade. Emissions and concentrations of CH 4 are continuing to increase, making CH 4 the second most important human-induced greenhouse gas after carbon dioxide. Two major difficulties in reducing uncertainties come from the large variety of diffusive CH 4 sources that overlap geographically, and from the destruction of CH 4 by the very short-lived hydroxyl radical (OH). To address these difficulties, we have established a consortium of multi-disciplinary scientists under the umbrella of the Global Carbon Project to synthesize and stimulate research on the methane cycle, and producing regular (∼ biennial) updates of the global methane budget. This consortium includes atmospheric physicists and chemists, biogeochemists of surface and marine emissions, and socio-economists who study anthropogenic emissions. Following Kirschke et al. (2013), we propose here the first version of a living review paper that integrates results of top-down studies (exploiting atmospheric observations within an atmospheric inverse-modelling framework) and bottom-up models, inventories and data-driven approaches (including process-based models for estimating land surface emissions and atmospheric chemistry, and inventories for anthropogenic emissions, data-driven extrapolations). . Top-down inversions consistently infer lower emissions in China (∼ 58 Tg CH 4 yr −1 , range 51-72, −14 %) and higher emissions in Africa (86 Tg CH 4 yr −1 , range 73-108, +19 %) than bottom-up values used as prior estimates. Overall, uncertainties for anthropogenic emissions appear smaller than those from natural sources, and the uncertainties on source categories appear larger for top-down inversions than for bottom-up inventories and models.The most important source of uncertainty on the methane budget is attributable to emissions from wetland and other inland waters. We show that the wetland extent could contribute 30-40 % on the estimated range for wetland emissions. Other priorities for improving the methane budget include the following: (i) the development of process-based models for inland-water emissions, (ii) the intensification of methane observations at local scale (flux measurements) to constrain bottom-up land surface models, and at regional scale (surface networks and satellites) to constrain top-down inversions, (iii) improvements in the estimation of atmospheric loss by OH, and (iv) improvements of the transport models integrated in top-down inversions.

Abstract. The global methane (CH4) budget is becoming an increasingly important component for managing realistic pathways to mitigate climate change. This relevance, due to a shorter atmospheric lifetime and a stronger warming potential than carbon dioxide, is challenged by the still unexplained changes of atmospheric CH4 over the past decade. Emissions and concentrations of CH4 are continuing to increase making CH4 the second most important human-induced greenhouse gas after carbon dioxide. Two major difficulties in reducing uncertainties come from the large variety of diffusive CH4 sources that overlap geographically, and from the destruction of CH4 by the very short-lived hydroxyl radical (OH). To address these difficulties, we have established a consortium of multi-disciplinary scientists under the umbrella of the Global Carbon Project to synthesize and stimulate research on the methane cycle, and producing regular (~biennial) updates of the global methane budget. This consortium includes atmospheric physicists and chemists, biogeochemists of surface and marine emissions, and socio-economists who study anthropogenic emissions. Following Kirschke et al. (2013), we propose here the first version of a living review paper that integrates results of top-down studies (T-D, exploiting atmospheric observations within an atmospheric inverse-modelling framework) and bottom-up models, inventories, and data-driven approaches (B-U, including process-based models for estimating land surface emissions and atmospheric chemistry, and inventories for anthropogenic emissions, data-driven extrapolations). For the 2003–2012 decade, global methane emissions are estimated by T-D inversions at 558 Tg CH4 yr−1 (range [540–568]). About 60 % of global emissions are anthropogenic (range [50–65 %]). B-U approaches suggest larger global emissions (736 Tg CH4 yr−1 [596–884]) mostly because of larger natural emissions from individual sources such as inland waters, natural wetlands and geological sources. Considering the atmospheric constraints on the T-D budget, it is likely that some of the individual emissions reported by the B-U approaches are overestimated, leading to too large global emissions. Latitudinal data from T-D emissions indicate a predominance of tropical emissions (~64 % of the global budget,

Increasing atmospheric methane (CH 4 ) concentrations have contributed to approximately 20% of anthropogenic climate change. Despite the importance of CH 4 as a greenhouse gas, its atmospheric growth rate and dynamics over the past two decades, which include a stabilization period (1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006), followed by renewed growth starting in 2007, remain poorly understood. We provide an updated estimate of CH 4 emissions from wetlands, the largest natural global CH 4 source, for 2000-2012 using an ensemble of biogeochemical models constrained with remote sensing surface inundation and inventory-based wetland area data. Between 2000-2012, boreal wetland CH 4 emissions increased by 1.2 Tg yr −1 (−0.2-3.5 Tg yr −1 ), tropical emissions decreased by 0.9 Tg yr −1 (−3.2−1.1 Tg yr −1 ), yet globally, emissions remained unchanged at 184 ± 22 Tg yr −1 . Changing air temperature was responsible for increasing high-latitude emissions whereas declines in low-latitude wetland area decreased tropical emissions; both dynamics are consistent with features of predicted centennial-scale climate change impacts on wetland CH 4 emissions. Despite uncertainties in wetland area mapping, our study shows that global wetland CH 4 emissions have not contributed significantly to the period of renewed atmospheric CH 4 growth, and is consistent with findings from studies that indicate some combination of increasing fossil fuel and agriculture-related CH 4 emissions, and a decrease in the atmospheric oxidative sink.

Abstract. Following the recent Global Carbon Project (GCP) synthesis of the decadal methane (CH 4 ) budget over 2000, we analyse here the same dataset with a focus on quasi-decadal and inter-annual variability in CH 4 emissions. The GCP dataset integrates results from topdown studies (exploiting atmospheric observations within an atmospheric inverse-modelling framework) and bottom-up models (including process-based models for estimating land surface emissions and atmospheric chemistry), inventories of anthropogenic emissions, and data-driven approaches.The annual global methane emissions from top-down studies, which by construction match the observed methane growth rate within their uncertainties, all show an increase in total methane emissions over the period [2000][2001][2002][2003][2004][2005][2006][2007][2008][2009][2010][2011][2012], but this increase is not linear over the 13 years. Despite differences between individual studies, the mean emission anomaly of

When an earthquake occurs, a certain amount of time elapses before destructive seismic energy hits nearby population centers. Though this time is measured on the order of seconds, depending on the proximity of the rupture to a given city or town, a new public safety program in Japan is taking advantage of the fact that seismic energy travels slower than electronic communication.In this program, the Japan Meteorological Agency (JMA) rapidly determines the hypocenter (earthquake epicenter and focal depth) and magnitude of the earthquake by using real-time data from stations near the hypocenter. The distribution of strong ground shaking is anticipated quickly, and then the information is delivered immediately to government officials, representatives from various industries, members of the news media, and individuals before strong ground shaking reaches them. For example, on receiving the warning, the control room of a railway company can send an emergency notice to all train drivers to stop their trains immediately, elevators in buildings can be triggered to stop at the nearest floor and open their doors automatically, and surgeons can temporarily suspend their surgical operations to avoid risk to patients on operating tables.This innovative new service, called Earthquake Early Warning (EEW), started nationwide in Japan and became fully operational in October 2007. This service is definitely different from earthquake prediction. Although it is currently impossible to be aware of earthquakes before their occurrence (earthquake prediction), EEW operates with the assumption that it is possible to warn people located at a certain distance from the hypocenter before strong ground shaking reaches them.Even though the interval between the delivery of EEWs and the time when strong shaking reaches people is relatively short (counted in seconds), EEWs can be a useful and powerful tool for mitigating an earthquake disaster by giving people enough time to take appropriate safety measures in advance of strong shaking. Determining Hypocentral Parameters and Anticipating Seismic IntensityEarthquakes occur when stressed rock moves through brittle rupture. Two types of seismic waves are radiated from the hypocenter: One is the P wave, which travels at about 7 kilometers per second, and the other is the S wave, which travels at about 4 kilometers per second.EEW technology not only takes advantage of the relatively slow velocity of the seismic waves as compared with instantaneous electronic communication, but it also uses the difference in arrival time between P and S waves. The S wave is slower than the P wave, but the amplitude of the S wave is usually 3-10 times larger than that of the P wave. This generally means that stronger shaking is observed along the S wave.The hypocenter and magnitude of an earthquake are determined as quickly as possible using only early parts of the P waves at a few stations close to the hypocenter. Using information about the hypocenter and magnitude, the arrival time of the S waves and seismic intensit...

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Abstract. We present the application of a global carbon cycle modeling system to the estimation of monthly regional CO2 fluxes from the column-averaged mole fractions of CO2 (XCO2) retrieved from spectral observations made by the Greenhouse gases Observing SATellite (GOSAT). The regional flux estimates are to be publicly disseminated as the GOSAT Level 4 data product. The forward modeling components of the system include an atmospheric tracer transport model, an anthropogenic emissions inventory, a terrestrial biosphere exchange model, and an oceanic flux model. The atmospheric tracer transport was simulated using isentropic coordinates in the stratosphere and was tuned to reproduce the age of air. We used a fossil fuel emission inventory based on large point source data and observations of nighttime lights. The terrestrial biospheric model was optimized by fitting model parameters to observed atmospheric CO2 seasonal cycle, net primary production data, and a biomass distribution map. The oceanic surface pCO2 distribution was estimated with a 4-D variational data assimilation system based on reanalyzed ocean currents. Monthly CO2 fluxes of 64 sub-continental regions, between June 2009 and May 2010, were estimated from GOSAT FTS SWIR Level 2 XCO2 retrievals (ver. 02.00) gridded to 5° × 5° cells and averaged on a monthly basis and monthly-mean GLOBALVIEW-CO2 data. Our result indicated that adding the GOSAT XCO2 retrievals to the GLOBALVIEW data in the flux estimation brings changes to fluxes of tropics and other remote regions where the surface-based data are sparse. The uncertainties of these remote fluxes were reduced by as much as 60% through such addition. Optimized fluxes estimated for many of these regions, were brought closer to the prior fluxes by the addition of the GOSAT retrievals. In most of the regions and seasons considered here, the estimated fluxes fell within the range of natural flux variabilities estimated with the component models.

INTRODUCTIONe earthquake early warning (EEW) information provided by the Japan Meteorological Agency (JMA) is designed to enable public o cials, key safety personnel, and the general public to take advance countermeasures against the e ects of earthquake strong motion. e goal of the early warning system is earliest -wave arrival time in each subprefectural area (about a quarter to a third of one prefecture) before the strong motion arrival. For the system to be e ective, it is essential that JMA publicize the principle and purpose of the warning messages, the technical limits of EEW, and the proper actions to be taken when a warning is received. is is particularly important given the very short warning times (a few to a few tens of seconds) so that EEW can be used e ectively without causing unnecessary confusion. In this article we outline the design of the EEW system in Japan and the necessary preparatory process to start providing EEW information to the general public, summarize the performance of the system since it was launched nationwide in DESIGN OF THE EEW SYSTEMe parameters that the EEW must determine are the estimated origin time, the hypocenter location, the magnitude (in the JMA intensity scale, http://www.jma.go.jp/jma/en/ Activities/earthquake.html#S_I), and earliest arrival time (in seconds) of the strong motion for each subprefectural area.In Japan, seismic intensity has been recorded by instruments designed speci cally for this task (called "seismic intensity meters") since 1996. Seismic intensity meters observe seismic intensity at representative sites for the purposes of disaster mitigation (i.e. collect are not used for hypocenter and magnitude calculation.the acceleration a er a lter with (1/ ) 1/2 amplitude response 1996). Physically, seismic intensity is proportional to the loga--tion site per unit time. JMA has been issuing seismic intensity subprefectural area within two minutes a er the earthquake occurrence when seismic intensity of 1 or over (in JMA scale) is observed. More detailed information (seismic intensity at each observation site) promptly follows this report. Although these are "post-disaster" reports, they have been used as trigger information to start emergency responses such as directing rescue resources to an area where strong motion was observed. To integrate strong motion disaster mitigation, EEW was developed to enable countermeasures of the strong motion arrival. For EEW, seismic intensities are evaluated at -out Japan. Estimation of the seismic intensity has three steps: 1) estimation of hypocenter, 2) estimation of magnitude, and -amplitude on engineering bedrock (Si and Midorikawa 1999), 2) multiplication by the ampli cation coe cient to account conversion from velocity to seismic intensity (Midorikawa 1999). e hypocenter is the starting point of the rupture and is the earthquake, i.e., the magnitude, is predictable at the starting time of the rupture is controversial (e.g., Iio Nakatani a method that is applicable in the real-time processing environment to forecas...