Long-term Climate Trends Research Articles

Small ponds and big landscapes: the challenge of invertebrate spatial and temporal dynamics for European pond conservation

1. Present understanding of the ecology and conservation of European ponds is built upon two traditions: first, extensive surveys of many ponds, often based on one visit and second, intensive experiments usually restricted to one site but over longer periods. Neither approach adequately captures the long-term spatial and temporal dynamics of pond invertebrates. 2. Over the last decade the significance of landscape, land use and species turnover between ponds has been highlighted both for the conservation of pond wildlife and as a key factor in the ecology of pond invertebrates. These large-scale spatial patterns and the resulting heterogeneity of ponds and their wildlife are not effectively addressed by the tradition of intensive, single-site experiments. Longer-term databases, sufficient to allow analysis of species turnover, show considerable annual temporal variation in species' distributions, a phenomenon not adequately addressed by extensive, single-year surveys. 3. The limited number of studies that combine landscape spatial scale with inter-annual time scales all suggest that important invertebrate dynamics occur at these levels. Species and metacommunities show spatial variation and inter-annual turnover. Data from a 10-year study of small, experimental ponds show temporal and spatial variation in species distributions and community measures responding to scales from the individual pond up to long-term climate trends, e.g. the North Atlantic Oscillation. 4. The ecological integrity of ponds requires the conservation of this potential for variation, change and heterogeneity. Copyright © 2005 John Wiley & Sons, Ltd.

Long-term climatic trend and body size variation in teal Anas crecca

A general warming of climate in the future may profoundly affect wildlife populations in terms of numbers, distribution and characteristics of the individuals, therefore leading to new challenges in terms of management and conservation. The effects of global warming can already be detected through the analysis of long-term databases, but insights into these processes can also be acquired by studying changes in wildlife populations during periods with clear trends in climatic changes. We analysed ringing data from more than 38,000 teal Anas crecca caught at the Station Biologique de la Tour du Valat in the Camargue, Southern France, between September 1954 and April 1971. Temperature in the Camargue clearly decreased over the ringing period. There was no correlation between average annual body mass and temperature in any age or sex class, nor a significant effect of temperature on the age ratio of the population. In adults, there were more males when average daily maximum winter temperature increased, while the opposite trend was found for juveniles. The clearest pattern we observed was a positive relationship between temperature and wing length of the individuals: in all sex and age classes, birds tended to get smaller as temperature decreased. It is unlikely that this pattern was related to harsh climate affecting teal feather growth. Rather, we hypothesise that climate affected the distribution of the individuals in Europe: as temperature got colder, small birds found it still more difficult to remain in northern areas and increasingly used the Camargue as a refuge. Reversing the observed pattern suggests that a global warming of climate in the future may have profound consequences for the distribution of wintering teal in Europe, as more and more birds will become able to remain in northern areas closer to their breeding grounds.

Latitude gradients in the natural variance in stratospheric conductivity – Implications for studies of long-term changes

Stratospheric electrical conductivity measurements have been made from high altitude research balloons at various locations around the world for more than 40 years. In the stratosphere, conductivity changes may indicate changes in aerosol or water vapor content. In this paper, we will compare the short term variation amplitude in data taken at several latitudes from equatorial to polar cap. Short term variations that occur on time scales of weeks to months (10 5–10 7 s) can be attributed to Forbush decreases, geomagnetic storms, aerosol injections by volcanos and forest fires, etc. Variations with time scales of minutes to days (10 3–10 5 s) can have amplitudes of a factor of ∼2 or more at high magnetic latitude. The variance at equatorial latitude is much smaller. The sources of these fluctuations and the latitude gradient remain unknown. Variations of all origins completely obscure any long-term climatic trend in the data taken in the previous four decades at both mid and high latitude.

Should light wind and windy nights have the same temperature trends at individual levels even if the boundary layer averaged heat content change is the same?

[1] Long-term climate trends of surface air temperature should not be expected to have the same trends for light wind and stronger wind nights, even if the trends in the boundary layer heat fluxes were the same. Parker (2004) segmented observed surface temperature data into lighter and stronger wind terciles in order to assess whether the reported large-scale global-averaged temperature increases are attributable to urban warming. We conclude, however, that trends at an individual height depend on wind speed, thermodynamic stability, aerodynamic roughness, and the vertical gradient of absolute humidity. We present an analysis to illustrate why temperature values at specific levels will depend on wind speed, and with the same boundary layer heat content change, trends in temperature should be expected to be different at every height near the surface when the winds are light, as well as different between light wind and stronger wind nights. This introduces a complexity into the assessment of long-term surface temperature trends that has not been previously recognized.

Acceleration technique for Milankovitch type forcing in a coupled atmosphere-ocean circulation model: method and application for the Holocene

A method is introduced which allows the calculation of long-term climate trends within the framework of a coupled atmosphere-ocean circulation model. The change in the seasonal cycle of incident solar radiation induced by varying orbital parameters has been accelerated by factors of 10 and 100 in order to allow transient simulations over the period from the mid-Holocene until today, covering the last 7,000 years. In contrast to conventional time-slice experiments, this approach is not restricted to equilibrium simulations and is capable to utilise all available data for validation. We find that opposing Holocene climate trends in tropics and extra-tropics are a robust feature in our experiments. Results from the transient simulations of the mid-Holocene climate at 6,000 years before present show considerable differences to atmosphere-alone model simulations, in particular at high latitudes, attributed to atmosphere-ocean-sea ice effects. The simulations were extended for the time period 1800–2000 AD, where, in contrast to the Holocene climate, increased concentrations of greenhouse gases in the atmosphere provide for the strongest driving mechanism. The experiments reveal that a Northern Hemisphere cooling trend over the Holocene is completely cancelled by the warming trend during the last century, which brings the recent global warming into a long-term context.

Climate Effects of the Deep Continental Stratus Clouds Generated by the Tibetan Plateau

Evidence is presented to show that the maximum annual mean cloud optical depth between 60°S and 60°N is located on the lee side of the Tibetan Plateau. This largest cloud optical depth is produced by persistent deep stratus clouds (primarily the nimbostratus and altostratus) during winter and spring. These deep stratus clouds are generated and maintained by the frictional and blocking effects of the Tibetan Plateau. The plateau slows down the overflow, inducing downstream midlevel divergence; meanwhile it forces the low-level flows to converge downstream, generating sustained large-scale lifting and stable stratification that maintain the thick stratus clouds. These stratus clouds produce extremely strong cloud radiative forcing at the top of the atmosphere, which fundamentally influences the local energy balance and climate change. Analysis of the long-term meteorological station observations reveals that the monthly mean anomalous cloudiness and surface temperature vary in tandem. In addition, the surface warming leads to destabilization and desaturation in the boundary layer. This evidence suggests a positive feedback between the continental stratus clouds and surface temperature through changing lower-tropospheric relative humidity and stratification. It is shown that the positive feedback mechanism is more robust during the period of the surface cooling than during the surface warming. It is suggested that the positive climate feedback of the continental stratus cloud may be instrumental in understanding the long-term climatic trend and variations over East Asia.

Differences in Responses of Chinook Salmon to Climate Shifts: Implications for Conservation

Understanding how organisms respond to climate is critical for focusing the debate about ways to recover imperiled or manage exploited species. However, efforts to understand climate effects on biota are complicated by differences among species in life history and physiology. Even within a species it is not clear if different populations will react similarly to large-scale climate trends. Climate regimes exhibit basin-wide effects similar to the El Ni no Southern Oscillation but persist for decades. In the North Pacific Ocean, two regime shifts (abrupt changes from one regime to another) occurred in 1976–1977 and 1989–1990 and had wide ranging effects on many species. We examined the response of chinook salmon from 9 evolutionary significant units (ESUs) to the regime shifts. While there was an average decline in spawner numbers associated with the regime shifts, ESUs did not respond in a uniform manner: some ESUs declined, some did not respond and one may have increased. Four ESUs currently listed under the Endangered Species Act may have declined more across regime boundaries than did the five non-listed ones. Interpretation of this result depends on two ESUs: the Snake River spring/summer run and the Central Valley fall run. The Snake River ESU had the largest decline and most sampling effort. If this ESU was excluded from the analysis, there was no evidence that listed and non-listed stocks responded differently to the regimes. The Central Valley ESU is currently a candidate for listing. If this ESU is considered to be a threatened or endangered, then listed ESUs declined more on average than did non-listed ESUs across the regime boundaries regardless of the Snake River ESU. As a whole, these results suggest that long-term climate trends are important to the dynamics of chinook populations and that sub-units of a species (here ESUs) can respond differently to these regimes.

Community Production Practices and Desertification in the Sahelo-Sudanian Region of Cameroon at the Turn of the Millennium

The Sahelo-Sudanian region of Cameroon extends over 10 million hectares. Varied flora and soil types, a complex mosaic of vegetation and plant communities and a diversified wild animal population are the major natural resources of this region. Desertification in the region can be related to two major known causes: a. short or long-term drought due to short-term or long-term climatic trends toward aridity; b. human activities which degrade the biological environment. Globally, humans generally have less effect on desertification than climatic change in the short run. The only strategy to fight against this situation particularly in the developing countries is to withdraw populations from the areas and to settle them elsewhere. However, most local or regional desertification processes in general, and in the Sahelo-Sudanian region in particular, are due to the misuse or unsound exploitation of natural resources by humans and their animals. Often, comprehension of the complexity of even small interactions between parameters affecting our local environment remains limited. Poor economic assessments of the long-term benefits of proper natural resource conservation and management increase the extent of the exploitation, in turn increasing the degradation process. Yet ecologically sound management of natural resources integrating indigenous knowledge and basic population interest and concern can secure restoration in several areas and sustained productivity of Sahelo-Sudanian lands.

Do Diatom, Chironomid, and Pollen Records Consistently Infer Holocene July Air Temperature? A Comparison Using Sediment Cores from Four Alpine Lakes in Northern Sweden

The aim of this study is to assess the performance of diatom, chironomid, and pollen transfer functions for inferences of July air temperature during the Holocene using sediments from four alpine lakes in an area with low human impact in northern Sweden. The study demonstrates that diatom, chironomid, and pollen assemblages in the sediment cores contain climate information so that present-day temperature at each lake can be inferred with reasonable confidence for most proxies. Most proxy records from the sites consistently infer a long-term decreasing trend in July air temperature from ca. 6000 cal yr BP until the present. However, there are also large variations in the temporal patterns of the inferred temperatures during some periods, especially before 7000 cal yr BP, when there are also nonsynchronous changes in loss-on-ignition in the four lakes. This variability indicates that local conditions in the catchments (influence of snowfields, soil-forming processes) had a large impact on the organism assemblages in the early Holocene.Long-distance transport of pollen into high alpine lakes makes temperature inferences from pollen transfer functions unreliable. Due to the uncertainties of the methods, predictive errors of the transfer functions, and variability caused by local catchment/lake characteristics, only long-term trends in climate can be inferred. High-resolution studies using diatoms, chironomids, and pollen for climate reconstruction are probably not meaningful during periods with small changes in climate (<1°C). Future research should concentrate on low-resolution, multiproxy, and multilake studies to further understand the relationship between the proxies and climate.

An analysis of Skukuza climate data

Data from the climate station at Skukuza, which has been open from 1912 to the present, are analysed. This exercise was done to provide the South African Regional Science Initiative (SAFARI-2000) experimental program with long-term climate statistics and trends. Climate parameters analysed are rainfall, temperature, humidity and sunshine. In the case of rainfall and temperature, the data was first tested for homogeneity and in only three out of 36 monthly cases, the data proved not to be homogeneous. No monthly rainfall trends proved to be significant (at the 5 % level), with five months indicating slightly negative trends and seven slightly positive. Only the monthly maximum temperature series for June proved to be non-homogeneous. The June maximum temperature trend and the February, March, May, July and December minimum temperature trends were significantly positive. The annual time series for minimum temperature were also significantly positive. The monthly results were reiterated by the seasonal results, with the winter maximum temperature trend and the autumn and summer minimum temperature trends significantly positive. Ten months showed negative temperature diurnal range trends with only March being significant. All long-term statistics of rainfall, temperature, humidity and sunshine were found to be typical of a savanna type climate in the southern hemisphere, although average monthly sunshine hours were somewhat less than the norm, due to frequent influx of moist air from the Mozambique Channel.

Late Cretaceous to early Paleocene climate and sea-level fluctuations: the Tunisian record

Climate and sea-level fluctuations across the Cretaceous–Tertiary (K–T) transition in Tunisia were examined based on bulk rock and clay mineralogies, biostratigraphy and lithology in five sections (El Melah, El Kef, Elles, Ain Settara and Seldja) spanning from open marine to shallow inner neritic environments. Late Campanian to early Danian trends examined at El Kef and Elles indicate an increasingly more humid climate associated with sea-level fluctuations and increased detrital influx that culminates at the K–T transition. This long-term trend in increasing humidity and runoff in the Tethys region is associated with middle and high latitude cooling. Results of short-term changes across the K–T transition indicate a sea-level lowstand in the latest Maastrichtian about 25–100 ka below the K–T boundary with the regression marked by increased detrital influx at El Kef and Elles and a short hiatus at Ain Settara. A rising sea-level at the end of the Maastrichtian is expressed at Elles and El Kef by deposition of a foraminiferal packstone. A flooding surface and condensed sedimentation mark the K–T boundary clay which is rich in terrestrial organic matter. The P0–P1a transition is marked by a sea-level lowstand corresponding to a short hiatus at Ain Settara where most of P0 is missing and a period of non-deposition and erosion in the lower part of P1a (64.95 Ma). At Seldja, P0 and possibly the topmost part of CF1 are missing. These sea-level fluctuations are associated with maximum humidity. These data suggest that in Tunisia, long-term environmental stresses during the last 500 ka before the K–T boundary and continuing into the early Danian are primarily related to climate and sea-level fluctuations. Within this long-term climatic trend the pronounced warm and humid event within the latest Maastrichtian Zone CF1 may be linked to greenhouse conditions induced by Deccan volcanism. The absence of any significant clay mineral variations at or near the K–T boundary and Ir anomaly suggests that the bolide impact had a relatively incidental short-term effect on climate in the Tethys region.

1300-year tree-ring width and density series based on living, dead and subfossil black spruce at tree-line in Subarctic Quebec, Canada

Living, dead and subfossil trees of black spiruce (Picea mariina [Mill.] BSP were used to build a 1300-year chronology based on ring width and wood density. All density sariables (maximcum, minimum, earlywood and latewood densities) among the three types of trees were simlilar, whereas ring width was significantly Higher in liviing trees thani in deacd and subfossil trees. Correlition of the indexed series from liviing and dead trees and from dead and subfossil trees that grew during the samiie periods were higher for Maximum density (r = 0.70, 0.63) and mean latewood density (r = 0.65, 0.66) than for Minimum density (r = 0.16. 0.35 and ring with (r=0.15, 0.49). respctively. Maximum density and mean latewood density were significantly correlated with all temperature variables: mean annual (January-December) and growing season (May September) temperatures, sum of degree days and frost-free days. Accordingly, Maximum and latewood density in tree-rings of spruce stem at tree-linec can be conisidered as a function Of summner-temnperature distributions and different types of trees can be combined for the reconstruction of long-term climatic trends due to theii synchronous variations.

Seasonal changes in sea surface temperature and salinity during the Little Ice Age in the Caribbean Sea deduced from Mg/Ca and 18O/16O ratios in corals

Abstract The oxygen isotopic composition ( δ 18 O) of coral skeletons reflects a combination of sea surface temperature (SST) and the δ 18 O of seawater, which is related to sea surface salinity (SSS). In contrast, the magnesium/calcium (Mg/Ca) ratio of a coral skeleton reflects SST independent of salinity. By using the relationships among coral Mg/Ca ratios, coral δ 18 O, seawater δ 18 O and SST, it is possible to determine past SST and SSS uniquely. Such determinations were made and calibrated using the Mg/Ca ratio and the δ 18 O of the modern part of a 3 m long coral core ( Montastrea faveolata ), collected from the southwest coast of Puerto Rico in the Caribbean Sea where both SST and SSS changes seasonally and the seawater δ 18 O measured at the coral site. Our results yielded three relationships (coral Mg/Ca–SST, δ 18 O coral – δ 18 O water -SST, and δ 18 O water –SSS). With these calibration equations seasonal changes in SST and SSS during the little ice age (LIA) in the Caribbean Sea were reconstructed. The δ 18 O and Mg/Ca ratio of the coral skeleton between 1699 and 1703 suggests that the SST during the LIA was approximately 2°C cooler than present with the SSS showing greater seasonal changes as well. These results are in good agreement with climate-based reconstruction from corals based on oxygen isotopes, although the possibility of some uncertainty remain in our estimation including long-term decadal scale trends in climate.

Reconstruction of remote climate changes from borehole temperatures

Data from temperature measurements in drillholes are indicators of the temperature variations associated with past climate change. The aim of this paper is to investigate the maximum extent of ground temperature history which can be extracted from geothermal data. We discuss ground surface temperature histories reconstructed from borehole temperature measurements in twelve deep holes (∼ 700 to 6000 m) in the Czech Republic. The study has identified climatic episodes back to the last glaciation period. The reconstructed climatic histories exhibit features similar to those extracted from borehole temperature logs by other inversion techniques and also found by independent climate reconstruction methods. Results confirm the possibility to identify long-term climatic trends from the borehole temperature-depth profiles and to integrate it into the assemblage of traditional paleoclimatological records.

The ‘natural’ vegetation of the Mexican Bajío: Archival documentation of a 16th-century Savanna environment

Neo-ecologists make assumptions about a ‘natural’ or potential vegetation when they argue whether a particular landscape is in secondary and degraded condition. Similarly, paleoecologists attempt to infer a three-dimensional biotic mosaic from a core taken in a low-lying wetland. Yet with millennia of human disturbance, climatic fluctuation, biotic response to long-term climatic trends or catastrophic ‘events’, and co-evolution between Holocene vegetation and human land-use, ‘natural ecosystems’ have not been in equilibrium. While past vegetation changes can be traced, efforts to reconstruct potential vegetation are probably unrealistic. This paper assembles 16th century landscape descriptions of the Bajio of Central Mexico from archival repositories, to characterise the landscape at the time of Spanish intrusion. Attention is focused on five major landscape elements: (1) Riparian woodlands of mesquite, bald cypress and willow, with reed stands; (2) Level, vertisolic plains, with a low-tree savanna (mesquite-acacia-grass); (3) Steeper piedmont plains with stony substrates, probably favoring xeric, thorn-bush associations; (4) Rough uplands with a mix of mesquite-acacia woodland, scrub oak, and thorn bush; and (5) Mountains dominated by live and deciduous oak woodlands. The biotic mosaic of the 16th century appears similar to that of the modern spontaneous vegetation in physiognomic terms, despite changes in structure. Areas of older indigenous settlement were affected by local vegetation disturbance, with partial deforestation near lakes Cuitzeo and Yuriria. While Spanish-Criollo intrusion (1540–1640) brought new, potentially destructive landuse methods, there is no evidence of additional landscape degradation in the Bajio until well into the 18th century. Dramatic changes in hydrology and riparian vegetation are quite recent. Archival documentation provides a complementary methodology to re-examine the interplay of edaphic variation, climate and cumulative land-use in understanding contemporary vegetation, and it can assist in converting proxy data into a three-dimensional landscape.

Effects of climate on chemical_ weathering in watersheds

Climatic effects on chemical weathering are evaluated by correlating variations On solute concentrations and fluxes with temperature, precipitation, runoff, and evapotranspiration ( ET) for a worldwide distribution of sixty-eight watersheds underlain by granitoid rock types. Stream solute concentrations are strongly correlated with proportional ET loss, and evaporative concentration makes stream solute concentrations an inappropriate surrogate for chemical weathering. Chemical fluxes are unaffected by ET, and SiO 2 and Na weathering fluxes exhibit systematic increases with precipitation, runoff, and temperature. However, warm and wet watersheds produce anomalously rapid weathering rates. A proposed model that provides an improved prediction of weathering rates over climatic extremes Os the product of linear precipitation and Arrhenius temperature functions. The resulting apparent activation energies based on SiO 2 and Na fluxes are 59.4 and 62.5 kJ · mol -1, respectively. The coupling between temperature and precipitation emphasizes the importance of tropical regions On global silicate weathering fluxes, and suggests it is not representative to use continental averages for temperature and precipitation On the weathering rate functions of global carbon cycling and climatic change models. Fluxes of K, Ca, and Mg exhibit no climatic correlation, implying that other processes, such as ion exchange, nutrient cycling, and variations On lithology, obscure any climatic signal. The correlation between yearly variations On precipitation and solute fluxes within individual watersheds Os stronger than the correlation between precipitation and solute fluxes of watersheds with different climatic regimes. This underscores the significance of transport-induced variability On controlling stream chemistry, and the importance of distinguishing between short-term and long-term climatic trends. No correlation exists between chemical fluxes and topographic relief or the extent of recent glaciation, implying that physical erosion rates do not have a critical influence on chemical weathering rates.

Transformation of a subtropical river into a hyperhaline estuary: the Casamance River (Senegal)—paleogeographical implications

Located in the South of Senegal, in the transitional Guineo-Congolian/Soudanian zone, the Casamance system is composed of a small river, supplied by a narrow drainage basin and followed by a 250 km long estuary. The continuous rainfall decrease experienced by the region since the beginning of the century drastically affected the Casamance river. This climatic change suddenly accelerated during 1968–1970, which led to a four-stage succession: • - before 1968–1970 (stage 1, rainfall ⩾ 1300 mm), the Casamance estuary showed the customary negative upstream salinity gradient; • - between 1968–1970 and 1978 (stage 2, rainfall ⩽ 1000 mm), under decreasing rainfall, the Casamance estuary shifted to a hyperline “inverse estuary”. It showed well-defined physical, chemical and biological zonations. Fresh groundwater resources, supplying the upper reaches of the river during the dry season, were progressively depleted. • - between 1978 and 1986–1987 (stage 3), the salinity peak of the end of the dry season progressively rose and shifted upward. The ecological zonation showed the increasing marine influence until 1986; • - between 1986–1987 and 1990 (stage 4), the dry season fresh water input had weakened with the depletion of groundwater resources. A slight increase in rainfall was insufficient to repulse the hyperhaline waters and the restricted area extended upstream and downstream. The physical, chemical and biological zonations strongly widened and flattened. In the future, the return to stage 1 conditions, by an increase in average rainfall, would take decades. Inevitably it will be much longer than the transformation into a hyperhaline estuary. Thus a slight decrease of the average rainfall in the region provoked a drastic change of the hydrological and biological patterns of the ria. The result seems to be a major crisis in the region, and might be recorded in the fossil records. We discuss these observations in terms of possible misreadings of paleoenvironments, and in relation with long-term climate trends.

Stratigraphic and Lateral Variations of Source Rock Attributes of the Pematang Formation, Central Sumatra: ABSTRACT

The Pematang Formation of the Central Sumatra basin has been shown to be the primary, if not the sole, source for the basin's 10+ billion barrels of recoverable oil. This lacustrine unit, which is restricted to a series of Paleogene half-grabens, typifies the variability present in many rift source rock systems. Differences in organic facies (i.e., level of organic enrichment, kerogen composition, bitumen and product character) occur both stratigraphically and laterally as a result of a series of complex interactions. The stratigraphic controls on organic facies within the Pematang appear to be: (1) the changing relationship between subsidence and sedimentation; (2) long-term climate trends influencing both lake level and regional vegetation patterns; and (3) the evolution of the lake basin's nutrient pool. These controls result in an increase in the level of organic enrichment and oil-proneness toward the top of the unit. Superimposed on this pattern are changes in organic matter content (carbon content) and character (palynofacies, biomarker and isotopic compositions) caused by short-term climatic oscillations. Lateral controls on organic facies can be examined at two different scales - basinal and sub-basinal_ Basinal variations can be related to: (1) different relative subsidence rates among the various sub-basins; and (2) variations in lake water chemistry as a result of the nature of the paleodrainage basin. On a sub­ basinal scale organic facies appear to be controlled by: (1) hydrodynamic processes and basin circulation; and (2) variations in water depth. These lateral variations are manifested in the level of organic enrichment, the relative proportions of oil- and gas-prone kerogen, and variations in oil composition.

Dangers of multiyear averaging in analyses of long-term climate trends

Multiyear averaging in studies seeking long-term trends can be risky and misleading. It is shown here that a change of 1 year in the starting point of the averaging done in generating a multiyear-average sequence can make a dramatic difference in the appearance of the sequence, even including whether the apparent trend is upward or downward. An example is given in which the same time series, when grouped to 3-year averages by starting in turn at the first, second, and third points of the series, yields one 3-year-average sequence that is monotonically increasing, a second 3-year-average sequence that is monotonically decreasing, and a third 3-year-average sequence that has constant values. Furthermore, it is proven in general that such series can be created for n-year averages for any integer n > 2, and can be extended to exceed any desired length. Finally, historical sea-ice data from Iceland are used to illustrate with a long-term climate data set the misrepresentation of climate statistics which can occur through selective multiyear averaging.

Earthwatch. Sensing of the Earth and its climate from space

Satellites can observe more than ballistic missiles and clouds; an appropriately equipped satellite can be used to monitor long-term trends in the Earth's climate and ecology