Warming but not thawing of the cold permafrost in northern Alaska during the past 50 years

Climate warming has not resulted in measurable thawing of the cold (-5°C to -10°C) permafrost in northern Alaska during the last half century. The maximum depths of summer thaw at five locations near Barrow, Alaska, in 2005 were within the ranges of the depths obtained at those same locations during the early 1950s. However, there has been a net warming of about 2°C, after a cooling of 0.4°C during 1953-1960, at the upper depths of the permafrost column at two of the locations. Thawing of permafrost from above (increase in active layer thickness) is determined by the summer thawing index for the specific year; any warming, or cooling, of the upper permafrost column results from the cumulative effect of changes in the average annual air temperatures over a period of years, assuming no change in surface conditions. Theoretically, thawing from the base of permafrost should be negligible even in areas of thin (about 100-200 m) permafrost in northern Alaska. The reported shoreline erosion along the northern Alaska coast is a secondary result from changes in the adjacent ocean ice coverage during the fall stormy period, and is not directly because of any "thawing" of the permafrost.     

气候变暖条件下,中(高)亚洲地区不稳定型冻土的巨大挑战和创新解决方案:——来自首届亚洲冻土大会及会后青藏高原考察的总结报告

首届亚洲冻土大会于2006年8月5~16日在兰州、青藏线和拉萨顺利召开.大会讨论主要包括以下5个议题:1)冻土工程;2)山区和高原冻融灾害及冰缘环境;3)冰冻圈的气候与环境条件;4)冻土水文、寒区水资源及土地利用,和;5)冻土监测、制图及模拟.国内论文大多集中于青藏铁路各种科技创新和工程(示范)建设方面.中亚冻土分类、制图和监测研讨会明确了制定统一的中亚地区冻土图的计划和实施方案.会议期间,国内主要新闻媒体对全球15位著名冻土学家进行了联合采访.大约80位中外代表参加了青藏(公)铁路沿线考察,并于8月15日在拉萨举行青藏铁路工程和环境问题讨论会.专家一致认为,青藏铁路所采取的冻土工程措施基本上是恰当、有效的,能够保证青藏铁路路基的长期稳定性.但是,沿线寒区环境保护问题还任重道远,需要尽快进行综合管(治)理,以达到青藏地区社会经济和谐、持续发展的目标.     

气候变化对拉萨河谷冬小麦主要生育期的影响分析

了解气候变化对冬小麦生育期的影响,可为农业应对气候变化、调整农作物种植结构提供科学依据。本文利用1996—2022年近26 a拉萨冬小麦生育期以及逐日平均气温（T_m）、最高气温（T_max）、最低气温（T_min）、气温日较差（DTR）、相对湿度（RH）、降水量（Pr）、日照时数（S）和≥0 ℃积温（∑T₀）等资料,采用线性倾向估计、Pearson相关系数和优势分析方法等,分析了拉萨河谷冬小麦生育期变化特征以及影响的主导气象因子。结果表明：(1)近26 a拉萨河谷冬小麦营养生长期（Vegetative Growth Period,VGP）、生殖生长期（Reproductive Growth Period,RGP）和全生育期（Whole Growth Period,WGP）的T_m均呈上升趋势,T_min升温率大于T_max的升温率,DTR、RH呈减小趋势,∑T₀、Pr和S趋于增加。(2)冬小麦拔节前各生育期提早,提早率为0.47~6.75 d/10 a;拔节后各生育期推迟,推迟率为3.17~7.03 d/10 a;VGP、WGP延长,RGP缩短。(3)拉萨河谷10月、1月T_min和2月T_m的升高,是冬小麦出苗、分蘖和返青期提前的主要因素,导致冬小麦拔节后生育期推迟的重要因素则是4—5月S增加及6月RH减少。     

A natural hydrate dissolution experiment on complex multi-component hydrates on the sea floor

Dissolution of natural hydrate cores was measured using time-lapse photography on the seafloor at Barkley Canyon (850 m depth and 4.17 °C). Two types of hydrate fabrics in close contact with one another were studied: a “yellow” hydrate stained with condensate oil and a “white” hydrate. From thermogenic origins, both fabrics contained methane as well as heavier hydrocarbons. These multi-component hydrates were calculated to be well within p-T stability conditions (<200 m water depth needed at 4.17 °C). While stable in pressure and temperature, the hydrates were bathed in under-saturated seawater, which promoted dissolution. The flux of gas from the shrinking yellow hydrate core was 0.15 ± 0.01 mmol gas/m² s, while the white hydrate dissolved faster at 0.25 ± 0.02 mmol gas/m² s. To determine the controlling mechanism for the observed changes in the hydrate cores, experimental results were compared with an engineering correlation for convective mass transfer. Using water velocity as a fitting parameter, the correlation agreed well with results from a previous dissolution experiment on well-characterized synthetic hydrates. Even with a number of other unknowns, when applied to the natural hydrate, the mass transfer correlation predicted the dissolution rate within 20%. This seafloor-based experiment, along with visual observations of seafloor hydrate dissolution over a 3-day period, were used to further understand the fate of natural seafloor hydrates exposed on the seafloor. By showing that mass transfer is the rate-controlling mechanism for dissolution of these natural hydrate outcrops, proper hydrodynamic calculations can be employed to give a refined estimate on hydrate dissolution rates.     

The WTO and the Kyoto Protocol: interaction issues

Abstract

This article builds upon the broad survey of climate-trade interactions in Part 1, by focusing upon the specific issues in the interaction of the WTO and the Kyoto Protocol.¹ It classifies the various issues into three groups according to their potential to cause problems and relative urgency. The article gives special attention to issues that are problematic because of the likelihood of occurrence of specific conflicts and the significance of their economic and/or political consequences. It concludes that although there are many interactions that are not problematic and some that offer the potential for win—win outcomes, the possibility of offsetting border measures that could be applied against energy-intensive imports from the USA may become a particularly nettlesome issue.     

Development and deployment of a precision underwater positioning system for in situ laser Raman spectroscopy in the deep ocean

The field of ocean geochemistry has recently been expanded to include in situ laser Raman spectroscopic measurements in the deep ocean. While this technique has proved to be successful for transparent targets, such as fluids and gases, difficulty exists in using deep submergence vehicle manipulators to position and control the very small laser spot with respect to opaque samples of interest, such as many rocks, minerals, bacterial mats, and seafloor gas hydrates. We have developed, tested, and successfully deployed by remotely operated vehicle (ROV) a precision underwater positioner (PUP) which provides the stability and precision movement required to perform spectroscopic measurements using the Deep Ocean Raman In situ Spectrometer (DORISS) instrument on opaque targets in the deep ocean for geochemical research. The positioner is also adaptable to other sensors, such as electrodes, which require precise control and positioning on the seafloor. PUP is capable of translating the DORISS optical head with a precision of 0.1 mm in three dimensions over a range of at least 15 cm, at depths up to 4000 m, and under the normal range of oceanic conditions (T, P, current velocity). The positioner is controlled, and spectra are obtained, in real time via Ethernet by scientists aboard the surface vessel. This capability has allowed us to acquire high quality Raman spectra of targets such as rocks, shells, and gas hydrates on the seafloor, including the ability to scan the laser spot across a rock surface in sub-millimeter increments to identify the constituent mineral grains. These developments have greatly enhanced the ability to obtain in situ Raman spectra on the seafloor from an enormous range of specimens.     

Qualitative Methods for Research on Mapmaking and Map Use

Contemporary cartographic research on mapmaking and map use has a broad mandate and, as a consequence, researchers need a broad suite of methods. Consistent with research developments in other geographic subdisciplines, cartographic researchers now use qualitative methods. They offer the advantage of bringing research closer to the problem‐solving realms of mapmakers and map users. Our purpose here is to discuss an array of qualitative methods for mapmaking and map use. Questionnaires, interviews, and protocol methods are used to gather verbal data about mapmaking and map use. Ethnographies produce data from direct observation of mapmakers and users. Maps also are sources for document analysis. We use examples of published cartographic research to elaborate on each of these methods.     

A replacement for the Dobson spectrophotometer?

Pure and Applied Geophysics -