Satellite evidence for significant biophysical consequences of the “Grain for Green” Program on the Loess Plateau in China

Afforestation has been implemented worldwide as regional and national policies to address environmental problems and to improve ecosystem services. China\u27s central government launched the “Grain for Green” Program (GGP) in 1999 to increase forest cover and to control soil erosion by converting agricultural lands on steep slopes to forests and grasslands. Here a variety of satellite data products from the Moderate Resolution Imaging Spectroradiometer were used to assess the biophysical consequences of the GGP for the Loess Plateau, the pilot region of the program. The average tree cover of the plateau substantially increased because of the GGP, with a relative increase of 41.0%. The GGP led to significant increases in enhanced vegetation index (EVI), leaf area index, and the fraction of photosynthetically active radiation absorbed by canopies. The increase in forest productivity as approximated by EVI was not driven by elevated air temperature, changing precipitation, or rising atmospheric carbon dioxide concentrations. Moreover, the afforestation significantly reduced surface albedo, leading to a positive radiative forcing and a warming effect on the climate. The GGP also led to a significant decline in daytime land surface temperature and exerted a cooling effect on the climate. The GGP therefore has significant biophysical consequences by altering carbon cycling, hydrologic processes, and surface energy exchange and has significant feedbacks to the regional climate. The net radiative forcing on the climate depends on the offsetting of the negative forcing from carbon sequestration and higher evapotranspiration and the positive forcing from lower albedo

When and how to dismantle nuclear weapons

This paper first derives revenue-maximizing auctions with identity-specific externalities among all players (seller and buyers). Our main findings are as follows. Firstly, a modified second-price sealed-bid auction with appropriate entry fees and reserve price is revenue-maximizing. Secondly, seller may physically destroy the auctioned item if the item is unsold or use destroying the item as nonparticipation threat. Thirdly, the revenue-maximizing auction induces full participation of buyers. Fourthly, each losing buyer's payment includes an externality-correcting component that equals the allocative externality to him. These components eliminate the impact of externalities on strategic bidding behavior. The paper further studies revenue-maximizing auctions with financial externalities. One-to-one correspondences between revenue-maximizing auctions for settings with and without financial externalities are established through incorporating externality-correcting payments. This result provides a general method for designing revenue-maximizing auctions in different settings of financial externalities, since revenue-maximizing auctions can be obtained through transforming the revenue-maximizing auctions for the regular settings without externalities.Auctions design; Endogenous participation; Externality

Endogenous entry and auctions design with private participation costs

This paper studies endogenous entry and ex ante revenue-maximizing auctions in an independent private value setting where potential bidders have private-information entry costs. The contribution of this paper is four-fold. First, we show that any equilibrium entry can be characterized through a set of continuous and monotonic shutdown curves that separate the bidders' types into participating and nonparticipating categories. Second, the expected winning probability of a participant does not depend on his private entry cost. Furthermore, the expected winning probabilities of the participating types are given by the slopes of the shutdown curves. Third, symmetric entry equilibria (shutdown curves) implemented by the classes of ex post efficient or ex post revenue-maximizing mechanisms are completely characterized. Fourth, within these two classes of mechanisms, a modified Vickrey auction with uniform reserve price and entry subsidy is ex ante revenue-maximizing. The desired entry subsidy and reserve price are determined by the lower end of the corresponding shutdown curve.Auctions Design; Ex Post Efficiency; Endogenous Participation; Multidimensional Screening; Vickrey Auction

Drought effects on large fire activity in Canadian and Alaskan forests

Fire is the dominant disturbance in forest ecosystems across Canada and Alaska, and has important implications for forest ecosystems, terrestrial carbon dioxide emissions and the forestry industry. Large fire activity had increased in Canadian and Alaskan forests during the last four decades of the 20th century. Here we combined the Palmer Drought Severity Index and historical large fire databases to demonstrate that Canada and Alaska forest regions experienced summer drying over this time period, and drought during the fire season significantly affected forest fire activity in these regions. Climatic warming, positive geopotential height anomalies and ocean circulation patterns were spatially and temporally convolved in causing drought conditions, which in turn enhanced fuel flammability and thereby indirectly affected fire activity. Future fire regimes will likely depend on drought patterns under global climate change scenarios

Estimating risk aversion from ascending and sealed-bid auctions: the case of timber auction data

Estimating bidders’ risk aversion in auctions is a challeging problem because of identification issues. This paper takes advantage of bidding data from two auction designs to identify nonparametrically the bidders’ utility function within a private value framework. In particular, ascending auction data allow us to recover the latent distribution of private values, while first-price sealed-bid auction data allow us to recover the bidders’ utility function. This leads to a nonparametric estimator. An application to the US Forest Service timber auctions is proposed. Estimated utility functions display concavity, which can be partly captured by constant relative risk aversion.Risk Aversion; Nonparametric Identi.cation; Nonparametric and Semipara-metric Estimation; Timber Auctions

Contest design and optimal endogenous entry

This paper derives the effort-maximizing contest rule and the optimal endogenous entry in a context where potential participants bear fixed entry costs. The organizer is allowed to design the contest under a fixed budget with two strategic instruments: he sets the value of the prize purse, and arranges a monetary transfer (entry subsidy or fee) for each participating contestant. In other words, the budget can either be used to subsidize participation or an entry fee can be charged to fund the prize purse. The results show that the optimally designed contest attracts exactly two participating contestants in its unique subgame perfect equilibrium (when there is a positive fixed entry cost) and extracts all the surplus from participating contestants. The study also shows that the direction and amount of the monetary transfer depend on the magnitude of the entry cost: the contest organizer subsidizes entry when contestants bear substantial entry costs, but charges an entry fee to fund the prize purse whenever the entry cost is sufficiently low.Contest; Endogenous Entry; Entry Cost; Subsidy; Entry Fee

Unifying Contests: from Noisy Ranking to Ratio-Form Contest Success Functions

This paper proposes a multi-winner noisy-ranking contest model. Contestants are ranked in a descending order by their perceived outputs, and rewarded by their ranks. A contestant's perceivable output increases with his/her autonomous effort, but is subject to random perturbation. We establish, under plausible conditions, the equivalence between our model and the family of (winner-take-all and multi-winner) lottery contests built upon ratio-form contest success functions. Our model thus provides a micro foundation for this family of often studied contests. In addition, our approach reveals a common thread that connects a broad class of seeming disparate competitive activities and unifies them in the nutshell of ratio-form success functions.Multi-Winner Contest; Contest Success Function; Noisy Ranking

The beauty of "bigness" in contest design: merging or splitting?

This paper studies in a multiple-winner contest setting how the total efforts may vary between a grand contest and a set of subcontests. We first show that the rent-dissipation rate increases when the numbers of contestants and prizes are "scaled up". In other words, the total efforts of a contest exhibit a striking "increasing return to scale" property: when the numbers of contestants and prizes scale up proportionally, the total efforts of the contest increase more than proportionally. Thus, the total efforts must increase when a set of identical subcontests are merged into a grand contest. Equivalently, the total efforts decrease when a grand contest is evenly divided. We further allow the grand contest to be split into uneven subcontests. We show that under a mild and plausible condition (regular contest technology), the grand contest generates more efforts as compared to any split contests.Contests; Multiple-winners; Efforts; Size; Replication