State of the Arctic October 2006

This State of the Arctic Report presents a review of recent data by an international group of scientists who developed a consensus on the information content and reliability. The report highlights data primarily from 2000 to 2005 with a first look at winter 2006, providing an update to some of the records of physical processes discussed in the Arctic Climate Impact Assessment (ACIA, 2004, 2005). Of particular note: • Atmospheric climate patterns are shifting (Fig. 1). The late winter/spring pattern for 2000–2005 had new hot spots in northeast Canada and the East Siberian Sea relative to 1980–1999. Late winter 2006, however, shows a return to earlier climate patterns, with warm temperatures in the extended region near Svalbard. • Ocean salinity and temperature profiles at the North Pole and in the Beaufort Sea, which changed abruptly in the 1990s, show that conditions since 2000 have relaxed toward the pre-1990 climatology, although 2001–2004 has seen an increase in northward ocean heat transport through Bering Strait (Fig. 2), which is thought to impact sea ice loss. • Sea ice extent continues to decrease. The sea ice extent in September 2005 was the minimum observed in summer during the satellite era (beginning in 1979), marking an unprecedented series of extreme ice extent minima beginning in 2002 (Fig. 3). The sea ice extent in March 2006 was also the minimum observed in winter during the satellite era. • Tundra vegetation greenness increased, primarily due to an increase in the abundance of shrubs. Boreal forest vegetation greenness decreased, possibly due to drought conditions (Fig. 4). • There is increasing interest in the stability of the Greenland ice sheet. The velocity of outlet glaciers increased in 2005 relative to 2000 and 1995, but uncertainty remains with regard to the total mass balance. • Permafrost temperatures continue to increase. However, data on changes in the active layer thickness (the relatively thin layer of ground between the surface and permafrost that undergoes seasonal freezing and thawing) are less conclusive. While some of the sites show a barely noticeable increasing trend in the thickness of the active layer, most of them do not. • Globally, 2005 was the warmest year in the instrumental record (beginning in 1880), with the Arctic providing a large contribution toward this increase. Many of the trends documented in the ACIA are continuing, but some are not. Taken collectively, the observations presented in this report indicate that during 2000–2005 the Arctic system showed signs of continued warming. However, there are a few indications that certain elements may be recovering and returning to recent climatological norms (for example, the central Arctic Ocean and some wind patterns). These mixed tendencies further illustrate the sensitivity and complexity of the Arctic physical system. They underline the importance of maintaining and expanding efforts to observe and better understand this important component of the climate system to provide accurate predictions of its future state.

RB32-266 Cooling Milk on Nebraska Farms

The desire of Nebraska people to continue the improvement of living conditions and to secure more healthful foods has been responsible for many changes in methods of caring for milk. One of the important factors in keeping milk sweet and of good quality is the process of cooling and keeping it cool until used. Three of these processes are as follows: placing containers of warm milk in any quantity of still water or still air at temperatures ranging from freezing to within a few degrees of the temperature of the milk, placing the containers in such positions that air or water are circulated around them, and causing the milk to flow in such manner that a thin film comes in contact with a surface which is cooled by air or liquids varying in temperature from 10 degrees Fahrenheit to a few degrees below that of the milk. After some of the heat has been removed the milk is stored under conditions very similar to those found in cooling processes. This 1932 research bulletin discusses why milk is cooled, why milk sours, how bacteria grows, and the many ways that milk can be cooled.

EC33-136 Corn in Nebraska

Corn is Nebraska's most important crop. Of the nearly 19 million acres under cultivation in the state, over 10 million acres or more than 50 percent is normally planted to corn. This is three times the acreage of wheat, four times that of oats, and ten times that of barley. The 10-year average acre yield of corn for this state is 25.8 bushels compared with 26.9 bushels for the entire United States. Nebraska, with an average annual crop of approximately 258 million bushels, usually ranks third among all states in the total production of corn, being exceeded by Iowa and Illinois. This 1933 extension circular discusses the importance of corn, seed, varieties of corn, freezing injury, testing seed corn, hybrid corn, soil fertility and rotation, cultural practices, harvesting and storing corn, power machinery in relation to costs in corn production, corn diseases and insects, and utilization of corn.

Long-term recovery patterns of arctic tundra after winter seismic exploration

In response to the increasing global demand for energy, oil exploration and development are expanding into frontier areas of the Arctic, where slow-growing tundra vegetation and the underlying permafrost soils are very sensitive to disturbance. The creation of vehicle trails on the tundra from seismic exploration for oil has accelerated in the past decade, and the cumulative impact represents a geographic footprint that covers a greater extent of Alaska’s North Slope tundra than all other direct human impacts combined. Seismic exploration for oil and gas was conducted on the coastal plain of the Arctic National Wildlife Refuge, Alaska, USA, in the winters of 1984 and 1985. This study documents recovery of vegetation and permafrost soils over a two-decade period after vehicle traffic on snow-covered tundra. Paired permanent vegetation plots (disturbed vs. reference) were monitored six times from 1984 to 2002. Data were collected on percent vegetative cover by plant species and on soil and ground ice characteristics. We developed Bayesian hierarchical models, with temporally and spatially autocorrelated errors, to analyze the effects of vegetation type and initial disturbance levels on recovery patterns of the different plant growth forms as well as soil thaw depth. Plant community composition was altered on the trails by species-specific responses to initial disturbance and subsequent changes in substrate. Long-term changes included increased cover of graminoids and decreased cover of evergreen shrubs and mosses. Trails with low levels of initial disturbance usually improved well over time, whereas those with medium to high levels of initial disturbance recovered slowly. Trails on ice-poor, gravel substrates of riparian areas recovered better than those on ice-rich loamy soils of the uplands, even after severe initial damage. Recovery to pre-disturbance communities was not possible where trail subsidence occurred due to thawing of ground ice. Previous studies of disturbance from winter seismic vehicles in the Arctic predicted short-term and mostly aesthetic impacts, but we found that severe impacts to tundra vegetation persisted for two decades after disturbance under some conditions. We recommend management approaches that should be used to prevent persistent tundra damage.