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A safe operating space for Indigenous reindeer herders in the Circumpolar North must be the main priority for the governance of the Arctic and sub-Arctic territories in times of rapid changes on reindeer pastures. It also includes establishing reindeer herders’ adaptive capacity to these changes. Anthropogenic impact on the earth system has reached a scale where it is no longer possible to exclude abrupt global environmental change. Indigenous reindeer herders’ sustainability implies adaptive capacity that allows reindeer herders to operate safely. The Intergovernmental Panel on Climate Change highlights that the protection of grazing lands represents the most important adaptive strategy for reindeer herders under climate change. While the Arctic is rapidly integrating into the global economy, reindeer herders must face multiple socio-economic conditions and effects of assimilation past and present. This chapter addresses adaptation perspectives important for the future of reindeer husbandry and frames adaptation to rapid change for reindeer husbandry via Indigenous perspectives, insights, and knowledge.

This chapter includes transdisciplinary analysis, ethical considerations, and guidelines about co-producing research across science and Indigenous peoples’ traditional knowledge systems, particularly in the Arctic region in times of environmental and climatic change. The authors intend to reach out to many readers with different backgrounds and interests. The study employs inter- and transdisciplinary framing of the knowledge systems. This includes an implicit criticism of the typical narrowing of study to disciplinary siloes. It is claimed that traditional academic research misses the importance and positive contributions of different knowledge traditions and thought styles, and it is further claimed that inclusivity of these traditions is an ethical component of responsible research. In this sense, it is hoped that the following chapter inspires researchers to transcend institutionalized knowledge framings and opt for co-production of knowledge that is ethically responsive to rich cultural traditions in the Arctic. Any type of research done in communities should not exploit the Indigenous communities and knowledge holders.

While twentieth century sea-level rise was dominated by thermal expansion of ocean water, mass loss from glaciers and ice sheets is now a larger annual contributor. There is uncertainty on how ice sheets will respond to further warming, however, reducing confidence in twenty-first century sea-level projections. In 2019, to address the uncertainty, the Intergovernmental Panel on Climate Change (IPCC) reported that sea-level rise from the 1950s levels would likely be within 0.61–1.10 m if warming exceeds 4°C by 2100. The IPCC acknowledged greater sea-level increases were possible through mechanisms not fully incorporated in models used in the assessment. In this perspective, we discuss challenges faced in projecting sea-level change and discuss why the IPCC's sea-level range for 2100 under strong warming is focused at the low end of possible outcomes. We argue outcomes above this range are far more probable than below it and discuss how decision makers may benefit from reframing IPCC's terminology to avoid unintentionally masking worst-case scenarios. There is great uncertainty on how polar ice sheets in Greenland and Antarctica will respond to twenty-first century warming, reducing confidence in sea-level projections. The Intergovernmental Panel on Climate Change (IPCC) projects sea level in 2100 to be 0.61–1.10 m higher than 1950s levels under unabated greenhouse gas emissions. Here we explain why outcomes above this range are far more probable than below it and discuss how decision makers may benefit from reframing IPCC's terminology to avoid unintentionally masking worst-case scenarios.

This overview of climate observation, monitoring, and research for the Arctic region outlines the key elements essential to an enhanced understanding of the unprecedented climate change in the region and its global influences. The first recorded observation of sea ice extent around Svalbard date back to the whaling activities around 1600. Over the following 300 years there are periodic and inadequate observations of climate and sea ice from explorers seeking a northern sea route for sailing to Asia or reaching the North Pole. Around 1900 there were few fixed meteorological stations in the circumpolar North. During the Second World War and the following Cold War, the observation network increased significantly due to military interest. Since the 1970s the use of satellites has improved the climate and meteorological observations of Arctic areas, and advancements in marine observations (beneath the sea surface and within oceanic sediments) have contributed to a much improved network of climate and meteorological variables. Climate change in the Arctic and its possible effects within the Arctic and on global climate such as extreme weather and sea level rise were first reported in the ACIA 2005 report. Since then there has been a lot of climate-related assessments based on data from the Arctic and ongoing processes within the Arctic that are linked to global systems.

Key observational indicators of climate change in the Arctic, most spanning a 47 year period (1971–2017) demonstrate fundamental changes among nine key elements of the Arctic system. We find that, coherent with increasing air temperature, there is an intensification of the hydrological cycle, evident from increases in humidity, precipitation, river discharge, glacier equilibrium line altitude and land ice wastage. Downward trends continue in sea ice thickness (and extent) and spring snow cover extent and duration, while near-surface permafrost continues to warm. Several of the climate indicators exhibit a significant statistical correlation with air temperature or precipitation, reinforcing the notion that increasing air temperatures and precipitation are drivers of major changes in various components of the Arctic system. To progress beyond a presentation of the Arctic physical climate changes, we find a correspondence between air temperature and biophysical indicators such as tundra biomass and identify numerous biophysical disruptions with cascading effects throughout the trophic levels. These include: increased delivery of organic matter and nutrients to Arctic near‐coastal zones; condensed flowering and pollination plant species periods; timing mismatch between plant flowering and pollinators; increased plant vulnerability to insect disturbance; increased shrub biomass; increased ignition of wildfires; increased growing season CO2 uptake, with counterbalancing increases in shoulder season and winter CO2 emissions; increased carbon cycling, regulated by local hydrology and permafrost thaw; conversion between terrestrial and aquatic ecosystems; and shifting animal distribution and demographics. The Arctic biophysical system is now clearly trending away from its 20th Century state and into an unprecedented state, with implications not only within but beyond the Arctic. The indicator time series of this study are freely downloadable at AMAP.no. Key indicators of Arctic climate change: 1971–2017

This article provides a synthesis of the latest observational trends and projections for the future of the Arctic. First, the Arctic is already changing rapidly as a result of climate change. Contemporary warm Arctic temperatures and large sea ice deficits (75% volume loss) demonstrate climate states outside of previous experience. Modeled changes of the Arctic cryosphere demonstrate that even limiting global temperature increases to near 2 °C will leave the Arctic a much different environment by mid-century with less snow and sea ice, melted permafrost, altered ecosystems, and a projected annual mean Arctic temperature increase of +4 °C. Second, even under ambitious emission reduction scenarios, high-latitude land ice melt, including Greenland, are foreseen to continue due to internal lags, leading to accelerating global sea level rise throughout the century. Third, future Arctic changes may in turn impact lower latitudes through tundra greenhouse gas release and shifts in ocean and atmospheric circulation. Arctic-specific radiative and heat storage feedbacks may become an obstacle to achieving a stabilized global climate. In light of these trends, the precautionary principle calls for early adaptation and mitigation actions.

New approach proposed for defining preconditions for human development Crossing certain biophysical thresholds could have disastrous consequences for humanity Three of nine interlinked planetary boundaries have already been overstepped

A generalized vulnerability framework was used to structure an interdisciplinary and intercultural examination of factors that influence the ways in which reindeer pastoralism in Finnmark (northern Norway) may be affected by climate change. Regional and local (downscaled) climate projections included scenarios that can potentially influence foraging conditions for reindeer. None of the projections were without precedent; several climate change events in Finnmark during the last 100 years were at least as great as those projected in the next 20–30 years. Herders’ traditional responses to changes in both the natural and the socio-economic environments have depended on a flexibility in herding practice that is currently being eroded by several non-climate factors. The reduced of freedom of action resulting from loss of habitat, predation and aspects of governance (especially economic and legal constraints) potentially dwarves the putative effects of projected climate change on reindeer pastoralism. It may, however, also lead to situations in which new climatic conditions threaten the system in unprecedented ways. Developing appropriate methodologies for assessing the adaptive capacity, the vulnerability and the resilience of social–ecological systems to global changes remains a challenge. Recognition of the knowledge systems of Arctic cultures and the full engagement of local people throughout the process are key elements of the solution.

Climate change is being experienced particularly intensely in the Arctic. Arctic average temperature has risen at almost twice the rate as that of the rest of the world in the past few decades. Widespread melting of glaciers and sea ice and rising permafrost temperatures present additional evidence of strong Arctic warming. These changes in the Arctic provide an early indication of the environmental and societal significance of global consequences. The Arctic also provides important natural resources to the rest of the world (such as oil, gas, and fish) that will be affected by climate change, and the melting of Arctic glaciers is one of the factors contributing to sea level rise around the globe. An acceleration of these climatic trends is projected to occur during this century, due to ongoing increases in concentrations of greenhouse gases in the Earth's atmosphere. These Arctic changes will, in turn, impact the planet as a whole.

he potential relationships between tropical cyclones and global climate change are scientifically and socially complex, with great implications for society. The exceptional nature of the 2005 North Atlantic hurricane season alone provides great incentives for better understanding the full range of interactions and causes and effects thereof. The 2005 season saw the largest number (27) of named storms (sustained winds over 17 m s–1) and the largest number (14) of hurricanes (sustained winds over 33 m s–1), and it was the only year with three category 5 storms (maximum sustained winds over 67 m s–1). Also recorded was the most intense storm on record (Wilma, minimum pressure 882 hPa), the most intense storm ever in the Gulf of Mexico (Rita, 897 hPa), and the most costly storm on record (Katrina; some estimates put the cost of Katrina at as high as $200 billion; see information online at www.rms.com/Publications/ KatrinaReport_LessonsandImplications.pdf). (Please see www.ncdc.noaa.gov/oa/climate/research/2005/ hurricanes05.html for additional details.) The climate is in the process of a rapid warming, caused in part by human activities, including emission of greenhouse gases (GHGs) and aerosols, and changes in land use (Houghton et al. 2001; Karl and Trenberth 2003). These climate changes may well be changing the properties of tropical cyclones, yet the potential relationships between climate change and tropical cyclones and the consequences for humans have been downplayed or dismissed by a number of recent articles, testimonies, and press releases (e.g., Michaels et al. 2005;1 Pielke et al. 2005; Mayfield 2005). For example, the recent article with the allencompassing title “Hurricanes and global warming” by Pielke et al. (2005) raises several important points, yet it is incomplete and misleading because it 1) omits any mention of several of the most important aspects of the potential relationships between hurricanes and global warming, including rainfall, sea level, and storm surge; 2) leaves the impression that there is no significant connection between recent climate change caused by human activities and hurricane characteristics and impacts; and 3) does not take full account of the significance of recently identified trends and variations in tropical storms in causing impacts as compared to increasing societal vulnerability. In a similar vein, public statements and testimonies by prominent hurricane forecasters have denied or minimized important connections between global warming and tropical cyclones, attributing interannual variations in tropical cyclones only to natural variability (e.g., Mayfield 2005). It is true that society’s vulnerability to hurricane damage is increasing rapidly, predominantly because of the rise in population and property values near

Based on the experience of the U.S. National Assessment, we propose a program of research and analysis to advance capability for assessment of climate impacts, vulnerabilities, and adaptation options. We identify specific priorities for scientific research on the responses of ecological and socioeconomic systems to climate and other stresses; for improvement in the climatic inputs to impact assessments; and for further development of assessment methods to improve their practical utility to decision-makers. Finally, we propose a new institutional model for assessment, based principally on regional efforts that integrate observations, research, data, applications, and assessment on climate and linked environmental-change issues. The proposed program will require effective collaboration between scientists, resource managers, and other stakeholders, all of whose expertise is needed to define and prioritize key regional issues, characterize relevant uncertainties, and assess potential responses. While both scientifically and organizationally challenging, such an integrated program holds the best promise of advancing our capacity to manage resources and the economy adaptively under a changing climate.

Transcripts from many mitochondrial genes in kinetoplastids undergo RNA editing, a posttranscriptional process which inserts and deletes uridines. By assaying for deletion editing in vitro, we found that the editing activity from Trypanosoma brucei mitochondrial lysates (S.D. Seiwert and K.D. Stuart), Science 266:114-117,1994) sediments with a peak of approximately 20S. RNA helicase, terminal uridylyl transferase, RNA ligase, and adenylation activities, which may have a role in editing, cosediment in a broad distribution, with most of each activity at 35 to 40S. Most ATPase 6 (A6) guide RNA and unedited A6 mRNA sediments at 20 to 30S, with some sedimenting further into the gradient, while most edited A6 mRNA sediments at >35S. Several mitochondrial proteins which cross-link specifically with guide RNA upon UV treatment also sediment in glycerol gradients. Notably, a 65-kDa protein sediments primarily at approximately 20S, a 90-kDa protein sediments at 35 to 40S, and a 25-kDa protein is present at

The Arctic Climate Impact Assessment (ACIA) report to the Arctic Council in 2004 was the “first” comprehensive assessment of climate change in the Arctic. It delivered dramatic messages to the world on the changes in the Arctic climate and the critical role of this region for the future development of the global climate. These messages were confirmed in the fourth assessment report of the Intergovernmental Panel on Climate Change (IPCC) in 2007. Hence, this chapter seeks to summarize the findings of the ACIA that are increasingly viewed as foundational security issues for a sustainable future for the Arctic region and a bellwether of change for the rest of the world. Further, there follows a discussion of the Arctic Council assessments that followed the ACIA as well as an outline of a potential comprehensive follow-on assessment that is designed to assess the many elements of change, many of which have security implications for the eight Arctic countries, the peoples of the north, and for the world at large.

Several kinetoplastid mitochondrial genes cannot be expressed without RNA editing of their transcripts to create a functional open reading frame. We have examined one such mitochondrial gene, CR4, in Trypanosoma brucei EATRO164 and find extensive editing of transcripts in both bloodstream and procyclic life cycle stages. However, a consensus edited sequence for the entire mRNA occurs only in the bloodstream stage. The unedited CR4 transcript is 283 nucleotides in length, not including the poly(A) tail. A total of 325 uridines are inserted, and 40 uridines deleted, to create the mature mRNA which encodes a very hydrophobic protein.

We identified four different guide RNAs (gRNAs) that specify identical editing of Trypanosoma brucei apocytochrome b (CYb) mRNA, which indicates gRNA redundancy in T. brucei. All four gRNAs appear functional since they occur in chimeras, some of which contain an interesting gRNA 3' "extension." The gRNAs are encoded in different minicircles, rather than maxicircles as in other species. However, these gRNA genes are not between 18-base pair repeats as are the other minicircle gRNA genes in T. brucei. The three minicircles cloned contain the same gRNA genes, one of which is substantially diverged, all in the same order, indicating that they are related. CYb gRNA is less abundant in procyclic than bloodstream forms. Procyclic forms contain abundant edited CYb mRNA unlike bloodstream forms thus suggesting that CYb mRNA editing may be regulated at the level of gRNA utilization.

RNA editing adds and removes uridines at specific sites in several mitochondrial transcripts in kinetoplastid parasites probably as specified by guide RNAs (gRNAs) that are complementary to the final edited sequence. Editing has been postulated to involve transesterification which predicts (1) chimeric molecules with a gRNA covalently attached by its non-encoded oligo U tail to an internal editing site in the mRNA and (2) the corresponding truncated 5' portions of the mRNAs. We have characterized cDNAs representing a large number of both types of intermediates from Trypanosoma brucei. The lengths of both U tails and encoded gRNA sequences vary greatly in length. The majority of encoded gRNA sequences are shorter than predicted based on their minicircle coding sequences. Analysis of the predominant sites of gRNA attachment in chimeras suggests that the transesterifications that religate the truncated 5' mRNAs may proceed more rapidly at editing sites at the 5' end of an editing domain and at sites of U deletion. Partially edited sequences in the mRNA portion of chimeras and at the 3' ends of truncated 5' mRNAs also indicate a non-consecutive order of site selection during RNA editing.

The U.S. Global Change Research Program (US/GCRP) represents an integrated, government-wide scientific effort designed to document, understand, and predict changes in the global environment as the foundation for national and international policymaking. The President's budget message to the U.S. Congress for FY 1992 proposes spending $1.186 billion on the U.S. Global Change Research Program, an increase of $232 million or almost 25 percent over FY 1991. The budget details a coordinated program of research that involves nine agencies, including the addition in FY 1992 of the several units within the Department of Defense and the Smithsonian Institution.

The vulnerability framework of the Research and Assessment Systems for Sustainability Program explicitly recognizes the coupled human–environment system and accounts for interactions in the coupling affecting the system's responses to hazards and its vulnerability. This paper illustrates the usefulness of the vulnerability framework through three case studies: the tropical southern Yucatán, the arid Yaqui Valley of northwest Mexico, and the pan-Arctic. Together, these examples illustrate the role of external forces in reshaping the systems in question and their vulnerability to environmental hazards, as well as the different capacities of stakeholders, based on their access to social and biophysical capital, to respond to the changes and hazards. The framework proves useful in directing attention to the interacting parts of the coupled system and helps identify gaps in information and understanding relevant to reducing vulnerability in the systems as a whole.

Global environmental change and sustainability science increasingly recognize the need to address the consequences of changes taking place in the structure and function of the biosphere. These changes raise questions such as: Who and what are vulnerable to the multiple environmental changes underway, and where? Research demonstrates that vulnerability is registered not by exposure to hazards (perturbations and stresses) alone but also resides in the sensitivity and resilience of the system experiencing such hazards. This recognition requires revisions and enlargements in the basic design of vulnerability assessments, including the capacity to treat coupled human–environment systems and those linkages within and without the systems that affect their vulnerability. A vulnerability framework for the assessment of coupled human–environment systems is presented.

Cell survival during a severe heat stress can be enhanced when heat shock proteins are induced prior to the severe heat treatment. Induction can be accomplished either by heat or chemical treatments. The increase in survival at these severe elevated temperatures after pretreatment has been referred to as thermotolerance, which we now refer to as survival thermotolerance. It has also been shown previously that mild heat treatment allows splicing in cells subjected to a severe heat treatment, now referred to as splicing thermotolerance. The experiments shown here demonstrate that even though chemical induction of the heat shock proteins leads to survival thermotolerance, this same treatment does not induce splicing thermotolerance. These are the first results that demonstrate at least two distinct aspects of thermotolerance.

Small guide RNAs (gRNAs) may direct RNA editing in kinetoplastid mitochondria. We have characterized multiple gRNA genes from Trypanosoma brucei (EATRO 164), that can specify up to 30% of the editing of the COIII, ND7, ND8, and A6 mRNAs and we have also found that the non-translated region of edited COIII mRNA of strain (EATRO 164) differs from that of another strain. Several of the gRNAs specify overlapping regions of the same mRNA often specifying sequence beyond that required for an anchor duplex with the next gRNA. Some gRNAs have different sequence but specify identical editing of the same region of mRNA. These data indicate a complex gRNA population and consequent complex pattern of editing in T. brucei.

Thermotolerance, the ability of cells and organisms to withstand severe elevated temperatures after brief exposure to mild elevated temperatures, has been studied in numerous laboratories. Survival thermotolerance is defined as the increase in cell or organism survival at severe elevated temperatures after a pretreatment at mild elevated temperatures. This study examines splicing thermotolerance in Drosophila melanogaster, the ability to splice pre-mRNAs made at the severe temperature (38 degrees C) after a brief pretreatment at a milder temperature (35 degrees C). It is probably one of a number of mechanisms by which cells adapt to heat shock. These experiments demonstrate that pre-mRNAs synthesized at the severe temperatures in splicing thermotolerant cells, although protected in splicing-competent complexes, are not actually processed to mature mRNAs until the cells are returned to their normal temperature. We have also studied the kinetics of acquisition and loss of splicing thermotolerance. As little as 10 min of pretreatment at 35 degrees C was sufficient to provide full splicing thermotolerance to a 30-min severe heat shock of 38 degrees C. Pretreatments of less than 10 min provide partial splicing thermotolerance for a 30-min severe heat shock. Full splicing thermotolerance activity begins to decay about 4 h after the cessation of the 35 degrees C incubation and is completely lost by 8 h after the pretreatment. The kinetics experiments of pre-mRNAs synthesized during the 38 degrees C treatment in splicing thermotolerant cells indicate that one or more splicing thermotolerance factors are synthesized during the 35 degrees C pretreatment which interact with pre-mRNA-containing complexes to keep them in a splicing-competent state. These kinetic experiments also indicate that in cells which are partially splicing thermotolerant, the pre-mRNAs synthesized early during the 38 degrees C incubation are protected, whereas those synthesized late are not. In the absence of splicing thermotolerant factors, the pre-mRNA-containing complexes leave the normal splicing pathway and are allowed to exit to the cytoplasm.

Rosina M. Bierbaum was awarded the Waldo E. Smith Medal at the AGU Spring Meeting Honors Ceremony, which was held on June 2, 2000, in Washington, D.C. The medal recognizes extraordinary service to geophysics.

Jack Fellows was awarded the Edward A. Flinn III Award at the AGU Spring Meeting Honor Ceremony on May 28, 1997, in Baltimore, Md. The Flinn Award is given to individuals who personify the Union's motto, “un-selfish cooperation in research” through their facilitating, coordinating, and implementing activities. The award citation and Fellows' response are given here.

Present methods of telemetering data from the oceans by low-frequency over-water paths are unreliable and require high-powered transmitters and large platforms. The Interrogation, Recording, and Locating System (IRLS) has been developed for satellite interrogating and locating land-based moving platforms via the UHF band. This paper describes the feasibility of utilizing the IRLS system for oceanographic purposes. Included in the paper are discussions of: 1) the effects of the ocean on antenna performance, and the selection of the "best" antenna among existing and new configurations for an ocean-based system, and 2) the communication link reliability and accuracy, and the overall performance of the IRLS system, utilizing a full-scale satellite simulation experiment.

"Anthropogenic pressures on the Earth System have reached a scale where abrupt global environmental change can no longer be excluded. We propose a new approach to global sustainability in which we define planetary boundaries within which we expect that humanity can operate safely. Transgressing one or more planetary boundaries may be deleterious or even catastrophic due to the risk of crossing thresholds that will trigger non-linear, abrupt environmental change within continental- to planetary-scale systems. We have identified nine planetary boundaries and, drawing upon current scientific understanding, we propose quantifications for seven of them. These seven are climate change (CO2 concentration in the atmosphere