Climate change,human impacts,and the resilience of coral reefs

The diversity, frequency, and scale of human impacts on coral reefs are increasing to the extent that reefs are threatened globally. Projected increases in carbon dioxide and temperature over the next 50 years exceed the conditions under which coral reefs have flourished over the past half-million years. However, reefs will change rather than disappear entirely, with some species already showing far greater tolerance to climate change and coral bleaching than others. International integration of management strategies that support reef resilience need to be vigorously implemented, and complemented by strong policy decisions to reduce the rate of global warming.     

西吉气候变化及其对马铃薯产量的影响

结合西吉1961-2008年的气象资料和同期的马铃薯产量资料,分析了西吉气候变化的主要特征以及马铃薯产量与不同气候因子的相关关系.结果表明:近50年来,西吉地区的年平均气温与地温均有不同幅度的升高,10℃初日明显提前、积温增加,降水则呈下降趋势,相对湿度变化不显著,日照时数与平均风速变化较小.除发芽期的日照时数对马铃薯...     

气候变化对粳稻安全齐穗和安全成熟期的影响

应用江苏省南通市1951—2010年9—11月份逐日日平均温度资料,根据有关界限温度指标,推测保证率为50%、80%和90%的安全齐穗期和安全成熟期,发现1991—2010年这20年水稻安全齐穗期和安全成熟期较之前两个20年均有不同程度延迟;80%保证率的安全齐穗期分别推迟8 d、9 d,80%保证率的安全成熟期分别推迟10 d、5 d;同时发现采用的以20℃作为安全齐穗的指标在气候变暖形势下,已经难以发挥指导生产实际的作用;进而提出以齐穗至成熟期有效积温为参考指标,通过安全成熟期向前累加活动积温(≥10℃)的方法来修正安全齐穗期,使得修正后的安全齐穗期较原推测日期提早25 d左右,即80%保证率安全齐穗期在9月6日左右。     

Robots in agriculture: prospects,impacts, ethics,and policy

Agriculture is both the site of development of important new technologies and a key area of application of technologies developed elsewhere. It is little wonder, then, that many thinkers believe that progress in the science and engineering of robotics may soon change the face of farming. This paper surveys the prospects for agricultural robotics, discusses its likely impacts, and examines the ethical and policy questions it may raise. Along with the environmental and economic impacts of robots, political, social, cultural, and security implications of the introduction of robots that have received little attention in the larger literature on agricultural robotics are considered. Key policy choices necessary to meet the ethical challenges likely to arise as agricultural robots start to become used more widely, and to maximise the social, environmental, and economic benefits of robotics in agriculture, are highlighted.

     

European seasonal and annual temperature variability, trends, and extremes since 1500

Multiproxy reconstructions of monthly and seasonal surface temperature fields for Europe back to 1500 show that the late 20th- and early 21st-century European climate is very likely (>95% confidence level) warmer than that of any time during the past 500 years. This agrees with findings for the entire Northern Hemisphere. European winter average temperatures during the period 1500 to 1900 were reduced by approximately 0.5 degrees C (0.25 degrees C for annual mean temperatures) compared to the 20th century. Summer temperatures did not experience systematic century-scale cooling relative to present conditions. The coldest European winter was 1708/1709; 2003 was by far the hottest summer.     

Private agrifood governance: conclusions,observations and provocations

This paper concludes the special issue of Agriculture and Human Values devoted to private governance of global agri-food systems. Rather than aiming to summarize the findings of the various papers that make up the issue, it highlights a number of cross-cutting issues relating to the increasing role of private governance. Key issues that are discussed include the legitimacy of private governance of agri-food systems and the scope for trade-off between its various dimensions, private governance in a global context and the motivation for firms to engage in governance. Throughout, the major focus is on unresolved issues and on-going controversies with the intention of stimulating further research in this area.     

Take your choice: ice ages, quakes, or impacts

If you are looking for a coherent, tidily packaged program, do not bother with the meetings of the American Geophysics Union. Its name suggests at least certain constraints, but in practice there are almost none. This past December's meeting was typical: it included anything natural and nonliving within the gravitational influence of the sun. For good measure the marine biology of the American Society of Limnology and Oceanography was thrown in as well. Here are some selections.     

Atmospheric warming and the amplification of precipitation extremes

Climate models suggest that extreme precipitation events will become more common in an anthropogenically warmed climate. However, observational limitations have hindered a direct evaluation of model-projected changes in extreme precipitation. We used satellite observations and model simulations to examine the response of tropical precipitation events to naturally driven changes in surface temperature and atmospheric moisture content. These observations reveal a distinct link between rainfall extremes and temperature, with heavy rain events increasing during warm periods and decreasing during cold periods. Furthermore, the observed amplification of rainfall extremes is found to be larger than that predicted by models, implying that projections of future changes in rainfall extremes in response to anthropogenic global warming may be underestimated.     

Arctic air pollution: origins and impacts

Notable warming trends have been observed in the Arctic. Although increased human-induced emissions of long-lived greenhouse gases are certainly the main driving factor, air pollutants, such as aerosols and ozone, are also important. Air pollutants are transported to the Arctic, primarily from Eurasia, leading to high concentrations in winter and spring (Arctic haze). Local ship emissions and summertime boreal forest fires may also be important pollution sources. Aerosols and ozone could be perturbing the radiative budget of the Arctic through processes specific to the region: Absorption of solar radiation by aerosols is enhanced by highly reflective snow and ice surfaces; deposition of light-absorbing aerosols on snow or ice can decrease surface albedo; and tropospheric ozone forcing may also be contributing to warming in this region. Future increases in pollutant emissions locally or in mid-latitudes could further accelerate global warming in the Arctic.     

Climate change, keystone predation, and biodiversity loss

Climate change can affect organisms both directly via physiological stress and indirectly via changing relationships among species. However, we do not fully understand how changing interspecific relationships contribute to community- and ecosystem-level responses to environmental forcing. I used experiments and spatial and temporal comparisons to demonstrate that warming substantially reduces predator-free space on rocky shores. The vertical extent of mussel beds decreased by 51% in 52 years, and reproductive populations of mussels disappeared at several sites. Prey species were able to occupy a hot, extralimital site if predation pressure was experimentally reduced, and local species richness more than doubled as a result. These results suggest that anthropogenic climate change can alter interspecific interactions and produce unexpected changes in species distributions, community structure, and diversity.     

Vegetation, Climate, and Coastal Submergence in Connecticut

Pollen analysis of a coastal marsh sediment at Guilford, Connecticut, indicates that there was a period of warmth and dryness preceding 3000 years ago. The subsequent increase of conifers at the expense of oak indicates a reversal that could account for decreasing rates of ice melt and rise of sea level. The record of herbaceous vegetation (grasses vs. sedges) suggests that the rise in the water table has been pulsating in character.     

Nuclear waste: increasing scale and sociopolitical impacts

The article argues that insufficient attention has been paid to the operational aspects of the U.S. radioactive waste management system when it grows to the scale necessary to handle wastes produced by a fully deployed plutonium economy. Without such information, many of the unsettling speculations which have become part of the public debate and are summarized herein cannot be clearly addressed. The article then outlines the types of information necessary to begin estimating the costs and consequences of radioactive waste management. Finally, an index of social exposure to radioactive hazard is proposed to improve the basis for policy decisions in this area.     

Montmorillonite: electron-optical observations

Fine-grained micas are consistent impurities in Camp-Berteaux (Morocco) and Wyoming montmorillonities. These micas give selected-area electron diffraction spot patterns with triclinic, monoclinic, and hexagonal symmetries similar tO those reported previously for monmorillonites. Camp-Berteaux montmorillonite appears as folded and flexible polycrystalline aggregates with pronounced texturing along the [02],[11], and[1ī] directions. Wyoming montmorillonite displays better crystallinity and larger crystallite size, and its structure is no longer truly "turbostratic".