The eastward winds that form each winter in the Arctic stratosphere are intermittently disrupted by planetary-scale waves propagating up from the surface in events known as stratospheric sudden warmings. It is shown here that following roughly half of these sudden warmings, the winds take as long as three months to recover, during which time the polar stratosphere evolves in a robust and predictable fashion. These extended recoveries, termed here Polar-night Jet Oscillation (PJO) events, are relevant to understanding the response of the extratropical troposphere to forcings such as solar variability and climate change. They also represent a possible source of improvement in our ability to predict weather regimes at seasonal timescales. Four projects are reported on here. In the first, the approximation of stratospheric radiative cooling by a linear relaxation is tested and found to hold well enough to diagnose effective damping rates. In the polar night, the rates found are weaker than those typically assumed by simplified modelling studies of the extratropical stratosphere and troposphere. In the second, PJO events are identified and characterized in observations, reanalyses, and a comprehensive chemistry-climate model. Their observed behaviour is reproduced well in the model. Their duration correlates with the depth in the stratosphere to which the disruption descends, and is associated with the strong suppression of further planetary wave propagation into the vortex. In the third, the response of the zonal mean winds and temperatures to the eddy-driven torques that occur during PJO events is studied. The collapse of planetary waves following the initial warming permits radiative processes to dominate. The weak radiative damping rates diagnosed in the first project are required to capture the redistribution of angular momentum responsible for the circulation anomalies. In the final project, these damping rates are imposed in a simplified model of the coupled stratosphere and troposphere. The weaker damping is found to change the warmings generated by the model to be more PJO-like in character. Planetary waves in this case collapse following the warmings, confirming the dual role of the suppression of wave driving and extended radiative timescales in determining the behaviour of PJO events.

This dissertation presents the results of an investigation of rural households’ ability to adapt to changing environmental and climatic conditions. It presents soil degradation arising from worsening soil erosion, leaching, depletion of nutrients due to years of uninterrupted cultivation and low levels of use of fertilizers; uncontrolled deforestation leading to loss of biodiversity; and climate variability seen through longer dry seasons as well as delayed and falling levels of precipitation as key issues leading to the vulnerability of households in Kakemega District in Western Province of Kenya. An enquiry has been made into the adaptation strategies of the rural households and a composite household adaptive capacity index (HACI) developed which is then used in hypothesis testing. Despite a situation laden with serious soil degradation and fears that credit taken by rural households often end up in low-return necessity-based enterprises or in consumption expenditure, the dissertation shows that the use of credit positively contributes to the HACI as does regular and optimal use of farm inputs. Diversification into non-agricultural activities, on-farm planting of trees and migration with remittances were some of the adaptation strategies observed among households with relatively high adaptive capacity indices while a secondary school level of education alongside the possession of non-land and non-livestock assets were key factors clearly associated with high adaptive capacity indices. Regarding adaptation decision making, the household head was observed to be the single most important actor in a process which was often characterized by authoritarianism. The household head’s level of information or awareness of environmental changes and open options proved to be important for adaptation. It was revealed that membership to groups and networks as well as government and NGO-activities were the most important factors in informing the household heads. Given small land sizes and a high incidence of other negative shocks, household heads tended to adopt and implement only tried and tested adaptation actions. During the study behind this dissertation, pioneers in the implementation of new strategies were observed to be better informed household heads or beneficiaries of incentives from the promoters of such strategies. Newer efforts aimed at the promotion of adaptability would therefore gain wider acceptance and adoption if preceded by a pilot phase carefully designed to include committed opinion shapers who would provide a demonstration effect. / In dieser Dissertation wurden ländliche Haushalte bezüglich ihrer Anpassungsfähigkeit an den Umwelt- und Klimawandel untersucht. Desweiteren geht die Dissertation unter anderen der Frage über Strategien nach, die von ländlichen Haushalten angesichts der Auswirkungen von Umweltproblemen eingesetzt werden. Die Feldforschung wurde unter den Haushalten im Kakamega Distrikt in Kenia getätigt. Eine Abnahme der Bodenproduktivität ist durch Erosion, einem Auslaugen und einer ununterbrochenen Kultivierung in Kakamega entstanden. Desweiteren führt eine unkontrollierte Abholzung mit resultierendem Verlust von heimischer Flora und Fauna sowie längeren Trockenperioden mit verspätetem Einsatz von Regenfällen und einer damit verbundenen Niederschlagsminimierung zu einer schwierigen Lebenssituation für die ländlichen Haushalte, die hauptsächlich durch Landwirtschaft ihre Existenz sichern. Diese Situation (gekennzeichnet durch Abholzung, Verlust der Artenvielfalt, Verminderung der Bodenqualität und unregelmäßige und wechselhafte Niederschlag) wird in dieser Arbeit als Umweltwandel (Environmental Change oder Environmental Stress) bezeichnet. Es konnte unter anderem als eines der Ergebnisse der Arbeit festgestellt werden, dass die ländlichen Haushalte aufgrund schlechten Bodens, unkontrollierten Abholzungen, längeren Trockenzeiten und sinkenden Niederschlagsmengen sehr anfällig sind. Durch den Einsatz des zusammengesetzten Haushalt-Anpassungsfähigkeitsindex (Household Adaptive Capacity Index = HACI), der im Rahmen dieser Dissertation entwickelt wurde, konnten die Bedenken gemindert werden, dass Kredite, die an ärmeren ländlichen Haushalten vergeben werden, oft für Notgründungen und Konsumausgaben eingesetzt werden. Es hat sich herauskristallisiert, dass die optimale und regelmäßige Nutzung von Düngemitteln sowie der Einsatz von Krediten, die HACI positiv beeinflusst. Als weitere Ergebnisse konnte beobachtet werden, dass Haushalte mit höheren Anpassungsfähigkeitsindexen Anpassungstrategien wie Diversifizierung in nicht-agra Aktivitäten, Aufforstung und Migration verwenden, und, dass ein Sekundarschulabschluss und der Besitz von Wirtschaftsgütern mit hohen Haushalt-Anpassungsfähigkeitsindexen assoziiert sind. Zum Anpassungsentscheidungspozess konnte festgestellt werden, dass Haushaltoberhäupter, die wichtigste Akteure sind. Entscheidungsweisen dieser Haushaltoberhäupten lassen oftmals autoritäre Züge erkennen. So entscheiden die Haushaltoberhäupter häufig auch, in welcher Art und Weise Haushalte sich anpassen dürfen. Von daher ist das Wissen des Haushaltoberhauptes über die herrschenden Umweltbedingungen und die offenen Strategien oder Handlungspielräume von Bedeutung. Die Feldforschung zeigte, dass die Zugehörigkeit zu einzelnen Gruppen sowie die Bemühungen von der Regierung und den Nichtregierungsorganisationen wichtig für die Erhöhung des Wissens von Haushaltoberhäupten sind. Da der durchschnittliche Haushaltgrundstückbesitz sinkt und andere negative Ereignisse wie Krankheit und Tod zunehmend Angst verbreiten, setzen Haushaltsoberhäupter häufig nur dann empfohlene Strategien zur Anpassung ein, wenn sie beispielsweise einen Erfolg bei einem Nachbar verzeichnen können. Oftmals werden Anpassungsstrategien auch bei finanziellen Anreizen, zum Beispiel von Förderern, umgesetzt. Es würden mit hoher Wahrscheinlichkeit mehr Anpassungstrategien von ländlichen Haushalten umgesetzt werden, wenn diese Strategien Pilotprojekte beinhalten würden, die Haushalten das Zusammenspiel von Anpassung und Ernteertrag präsentieren.

The eastward winds that form each winter in the Arctic stratosphere are intermittently disrupted by planetary-scale waves propagating up from the surface in events known as stratospheric sudden warmings. It is shown here that following roughly half of these sudden warmings, the winds take as long as three months to recover, during which time the polar stratosphere evolves in a robust and predictable fashion. These extended recoveries, termed here Polar-night Jet Oscillation (PJO) events, are relevant to understanding the response of the extratropical troposphere to forcings such as solar variability and climate change. They also represent a possible source of improvement in our ability to predict weather regimes at seasonal timescales. Four projects are reported on here. In the first, the approximation of stratospheric radiative cooling by a linear relaxation is tested and found to hold well enough to diagnose effective damping rates. In the polar night, the rates found are weaker than those typically assumed by simplified modelling studies of the extratropical stratosphere and troposphere. In the second, PJO events are identified and characterized in observations, reanalyses, and a comprehensive chemistry-climate model. Their observed behaviour is reproduced well in the model. Their duration correlates with the depth in the stratosphere to which the disruption descends, and is associated with the strong suppression of further planetary wave propagation into the vortex. In the third, the response of the zonal mean winds and temperatures to the eddy-driven torques that occur during PJO events is studied. The collapse of planetary waves following the initial warming permits radiative processes to dominate. The weak radiative damping rates diagnosed in the first project are required to capture the redistribution of angular momentum responsible for the circulation anomalies. In the final project, these damping rates are imposed in a simplified model of the coupled stratosphere and troposphere. The weaker damping is found to change the warmings generated by the model to be more PJO-like in character. Planetary waves in this case collapse following the warmings, confirming the dual role of the suppression of wave driving and extended radiative timescales in determining the behaviour of PJO events.

Climate related problems such as droughts, heat waves, increased levels of precipitation and storms threaten the functionality of several infrastructural systems. This thesis focus on infrastructure that provides for water and sanitation services because it has been identified as being particular at risk when the climate is changing. The identification and mapping of the vulnerability of a system can improve the prerequisites to choose more appropriate measures to facilitate the situation at hand. In this study a set of GIS based methodologies using indicators (simple and composite) of vulnerability are proposed and assessed. “Physical” vulnerability is used as a measure combining the intrinsic characteristics of a system and the climate related hazard resulting in a measure for physical vulnerability. GIS software is used to manage the spatial data sets and to combine the indicators into indexes of physical vulnerability. The assessed systems and related climate hazards are: - Water and sewage pipe network and an increased risk of pipe breakage due to increased frequencies of landslides and – An increased risk for ground and surface water supplies related to pollution from the point sources sewage infiltration and polluted ground”. The resulting GIS applications are tested on pilot areas located in the Stockholm region and GIS based sensitivity analyses are performed. The availability and accessibility of relevant digital spatial data is also assessed and discussed.

The background state and changes associated with the El Niño-Southern Oscillation (ENSO) in the tropical Pacific Ocean influence climate patterns all over the world. Understanding how the tropical Pacific will be impacted by climate change is therefore critical to accurate regional climate projections. However, sparse historical data coverage and strong natural variability in the basin make it difficult to assess the response of the tropical Pacific to anthropogenic climate change. Further, climate models disagree regarding the response of the basin to continued anthropogenic forcing into the future. Building off of the limited instrumental record, high-resolution records from coral and lake sediment archives can be used to assess the response of the tropical Pacific to past climate changes and to compare and assess climate model projections. In the present study, I use high-resolution coral and lake records from the equatorial Pacific to assess climate model projections and the response of the coupled ocean-atmospheric climate system in the basin (ocean temperature, salinity, winds, precipitation) to natural and anthropogenic forcing. Using a simple model of how climate is recorded by corals, we compare historical climate data and climate model simulations with coral paleoclimate records to assess climate model projections and address uncertainties in the historical data, models and paleoclimate records. We demonstrate that this simple model is able to capture variability and trend observed in the coral records, and show that the both sea surface temperature and salinity contribute to the observed coral trend. However, we find major discrepancies in the observed and climate model simulated trends in the tropical Pacific that may be attributed to uncertainties in model simulated salinity. We then assess 20th-century variability and trends in SST and salinity in the central tropical Pacific using replicated coral δ¹⁸O and Sr/Ca records from the Republic of Kiribati and the central Line Islands. We find that the coral records from these sites display a warming and freshening trend superimposed on strong interannual and low-frequency variability. Further, we demonstrate an apparent strengthening of the E-W SST gradient across the dateline (between 173°E and 160°W) and a slight weakening of the N-S SST gradient due to enhanced warming along the equator and west of the dateline relative to other sites. However, we find no evidence of increased variability in the central Pacific, suggesting that there has not been an increase in central Pacific style ENSO events. Finally, we show that the salinity response to climate change may be very patchy within the basin. Using a new ~90 year coral Mn/Ca record from the central Pacific, we investigate variability and trends in tropical Pacific trade winds. First, we demonstrate a strong association between westerly wind anomalies and coral skeletal Mn/Ca, which recorded all of the major historical El Niño events of the 20th century. In this new long Mn/Ca record, we find a reduction in the amplitude and frequency of Mn/Ca pulses between 1893 and 1982, suggesting a decrease in westerly wind anomalies in the western equatorial Pacific Ocean. Finally, we use a sediment record from Bainbridge Crater Lake, Galápagos Archipelago to assess variability in the eastern tropical Pacific over the past ~6 thousand years. Based on results from long-term monitoring of the lake, we propose a new climate interpretation of the sediment record and find further evidence reduced mid-Holocene ENSO variability and a ramp up of ENSO variability starting around 1775 cal. years BP.

Pacific salmon (Oncorhynchus spp.) production strongly influences the ecosystems, cultures and economies of the Northeast Pacific. Historical variability in population sizes is complex, reflecting natural and human drivers. The nature and extent of such ‘exogenous’ controls on salmon and their nursery ecosystems are poorly understood, a significant impediment to sustainable fisheries management. Novel applications of paleolimnology demonstrate that past sockeye salmon abundances and nursery system ecology can be reconstructed from lake sediments. This thesis focuses on employing these techniques to establish the forcing mechanisms underlying salmon population and ecosystem dynamics, and determine the effects and interactions of fisheries management. I provided the first reconstruction for a southern North American stock, which demonstrated the influences of both conspicuous (e.g. commercial fishery, main-stem damming) and uncertain human impacts (e.g. local damming) on endangered salmon declines. By reconstructing ecological variability at multiple trophic levels, I established that rehabilitative management (e.g. fish stocking) may have permanently altered nursery lake rearing capacity, a change potentially reinforced by recent atmospheric changes. This work highlights significant impediments to ongoing recovery efforts. I extended my analysis of salmon management by exploring the interactive impacts of exotic salmon stocking on a remote northern lake. I demonstrated the utility of long-term data in pre-emptively understanding the complex impacts of stocking by documenting the long-term trajectories in limnological conditions. Integrating modeling, limnological and paleolimnological analyses, I determined that climate change and salmon introductions compound to alter chemical, physical and biological lake variables, ultimately altering ecosystem structure and functioning. Finally I reconstructed salmon abundances over the past six millennia, the longest record and the first Canadian example to date, demonstrating salmon production is cyclical and far more variable than observed in the monitoring record. My analyses established that North Pacific salmon production is forced by ocean-atmospheric teleconnections ultimately linked to climatic variability in the tropical Pacific. Further analyses provided the first evidence for a possible solar forcing of Holocene salmon production on both orbital and higher frequency time scales. Cumulatively this research improves our understanding of the processes underlying variability in Pacific salmon and their natal ecosystems, important to ecologically-informed future management. / Thesis (Ph.D, Biology) -- Queen's University, 2008-09-27 02:41:54.576

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Submitted by Lucienne Costa (lucienneferreira@ufcg.edu.br) on 2018-08-14T14:56:36Z No. of bitstreams: 1 DANIELLE CAGLIARI DE LIMA – DISSERTAÇÃO (PPGMET) 2017.pdf: 3778584 bytes, checksum: 74013e9f2e77f7e02dbb6be83101aaf0 (MD5) / Made available in DSpace on 2018-08-14T14:56:36Z (GMT). No. of bitstreams: 1 DANIELLE CAGLIARI DE LIMA – DISSERTAÇÃO (PPGMET) 2017.pdf: 3778584 bytes, checksum: 74013e9f2e77f7e02dbb6be83101aaf0 (MD5) Previous issue date: 2017-08-29 / Capes / Estudos recentes mostram que o ciclo solar influencia os sistemas meteorológicos estratosféricos e troposféricos, proporcionando assim um novo quadro conceitual que reconsidera a evidência da influência solar no clima. Portanto, a principal proposta desse trabalho é investigar os possíveis efeitos dos ciclos solares nas anomalias da Temperatura da Superfície do Mar (ATSM). Para tanto, utilizou-se dados do número de manchas solares (NMS), proveniente do Royal Observatory of Belgium, de ATSM das áreas dos Niños 1+2, 3, 3.4 e 4, no Pacífico, e das áreas do Atlântico Tropical Norte e Sul, obtidos nos sites do CPC/NCEP/NOAA e do ESRL/NOAA, respectivamente, e de Oscilação Decenal do Pacífico (ODP), do ESRL/NOAA, todos dados mensais no período de dezembro/1949 a janeiro/2017. Objetivando filtrar as oscilações de escala intrasazonal, foi realizada a média móvel de três meses, com valor centrado no mês intermediário para todas as séries. Empregou-se o método dos quantis para classificar os períodos frios, neutros e quentes de cada área, considerando os 25% menores valores como períodos frios, os 25% intermediários como neutros e os 25% superiores como quente. Foram calculadas as médias e os desvios padrões do NMS para cada período e realizado o teste t de Student para comparar estas médias. Dessa forma verificou-se que, nos períodos de máximos do NMS, as ATSM no Pacífico e Atlântico Norte tendem para as condições neutras e as do Atlântico Sul para as frias. Para se verificar detalhes da relação entre as séries de ATSM e NMS, aplicou-se a análise espectral de transformadas Ondaletas Contínuas, Cruzadas e de Coerências, tendo como base a Ondaleta de Morlet. Os resultados demostraram haver influências dos ciclos solares de Hale (256 meses), de Schwabe (128 meses) e do seu segundo harmônico (64 meses) no comportamento das ATSM. Também foi observado que as ATSM nos oceanos Pacífico e Atlântico respondem de forma diferente ao forçante solar. Concluiu-se que os efeitos dos ciclos solares sobre as ATSM se dá de forma não linear, pois ocorreram mudanças de fases entre as séries ao longo do tempo. Quanto à diferença de resposta das ATSM do Pacífico e do Atlântico, ao forçante solar, acredita-se que seja devido à Anomalia Geomagnética do Hemisfério Sul e a fenômenos atmosféricos associados, mas não houve estudos contundentes a esse respeito, tanto que se sugerem pesquisas sobre a influência dos ciclos solares na circulação atmosférica, principalmente, para a região do Atlântico Sul. / Recent studies show that the solar cycle influences stratospheric and tropospheric meteorological systems, thus providing a new conceptual framework that reconsiders the evidence of solar influence on climate. Therefore, the main proposal of this work is to investigate the possible effects of solar cycles on Sea Surface Temperature Anomalies (SSTA). In order to do so, we used data of sunspot number (SN) from the Royal Observatory of Belgium, SST anomalies in the areas of Niños 1 + 2, 3, 3.4 and 4 in the Pacific, and North Atlantic and South Atlantic, in the Atlantic, obtained from the CPC/NCEP/NOAA and ESRL/NOAA sites, respectively, and Pacific Decadal Oscillation (PDO), from the ESRL/NOAA, all monthly data during the period of December/1949 to January/2017. A three-month moving average filter was applied on all series to remove the intraseasonal oscillations. The quantile method was used to classify the cold, neutral and warm periods of each area, considering the 25% lower values as cold periods, the 25% intermediate as neutral and the 25% higher as warm. The means and standard deviations of the SN were calculated for each period and Student's t-test was performed to compare these means. It was verified that, in periods of SN maxima, the SSTA in the Pacific and North Atlantic tended to neutral conditions and those from the South Atlantic to the cold. In order to verify details of the relation into the series of SSTA and SN, the spectral analysis of the Continuous Wavelet Transform, Cross-Wavelet Transform and Wavelet Coherence was used, based on Morlet wavelet. The results showed that there were influences of solar cycles of Hale (256 months), Schwabe (128 months) and its second harmonic (64 months) in the behavior of SSTA. It has also been observed that the SSTA in the Pacific and Atlantic oceans respond differently to the solar forcing. It was concluded that the solar cycles effects on SSTA occur in a non-linear way, as there were phase changes between the series over time. As for the difference in the response of the Pacific and Atlantic SSTA to the solar forcing, it is believed to be due to the Southern Hemisphere Geomagnetic Anomaly and associated atmospheric phenomena, but there have been no conclusive studies on this matter, so much so that researches are suggested on the influence of solar cycles on the atmospheric circulation, most importantly for the South Atlantic region.

The present work focused on the interdecadal variability of precipitation in the Western Brazilian Amazon in order to help improve this knowledge and, in addition, to analyze, study and evaluate the low-frequency variability of the hydrological cycle in this region. To this end, we used data collected from conventional rain gauge stations 5, available at the National Climatic Data Center (NCDC), reanalysis data of the following meteorological variables: long-wave radiation emerging (ROLE), temperature of the sea surface (SST) , vertical motion (Omega), zonal wind, as well as data series of the climate index of the Pacific Decadal Oscillation (ODP), and rainfall data of the project at the University of Delaware (UDEL), available at the Climate Diagnostic Center / National Oceanic and Atmospheric Administration (CDC / NOAA). Related to the local climate and the global level, particularly with the El Nino-Southern Oscillation (ENSO) and Pacific Decadal oscillation (ODP). It was noted that at the crucial stage of the ODP was a 8.1% increase in precipitation over the cold phase, mainly in the south-central axis of the western Amazon, while in the northwest basin of Rio Negro, it was noticed that at the hot rained 5.9% less when compared to the cold phase. Evidence indicates that since 1999, the ODP has entered into a new cold phase. Then, we analyzed the SST of the Pacific Ocean for the period 1999-2008 and observed the new configuration should last for 20 years, possibly causing significant changes in rainfall in this region. / Fundação de Amparo a Pesquisa do Estado de Alagoas / No presente trabalho dissertou-se sobre a variabilidade interdecadal da precipitação na Amazônia Ocidental Brasileira com o objetivo de contribuir para melhorar esse conhecimento e, em adição, analisar, estudar e avaliar a variabilidade de baixa freqüência no ciclo hidrológico dessa região. Para tal, foram utilizados dados observados de 5 estações pluviômetricas convencionais, disponíveis no site do National Climatic Data Center (NCDC), dados de reanálises das seguintes variáveis meteorológicas: radiação de ondas longas emergente (ROLE), temperatura da superfície do mar (TSM), movimento vertical (Omega), vento zonal, como também dados da série do índice climático da Oscilação Decadal do Pacífico (ODP), e dados de precipitação do projeto da University of Delaware (UDEL), disponíveis no site do Climate Diagnostic Center/National Oceanic and Atmospheric Administration (CDC/NOAA). Relacionou-se o clima local com o global, em particular com o fenômeno El Nino-Oscilação Sul (ENOS) e a Oscilção Decadal do Pacifico (ODP). Notou-se que na fase quente da ODP houve um aumento de 8,1% na precipitação em relação a fase fria, principalmente no eixo centro-sudoeste da Amazônia ocidental, enquanto no noroeste, bacia do Rio Negro, percebeu-se que na fase quente choveu 5,9% a menos quando comparado a fase fria. Evidências, indicam que desde 1999, a ODP tenha entrado em uma nova fase fria. Então, analisou-se a TSM do Oceano Pacifico para o período 1999-2008 e observou-se a nova configuração que deve perdurar pelos próximos 20 anos, possivelmente provocando mudanças significativas no regime pluviométrico desta região.

Doctor of Philosophy / Division of Biology / Brett K. Sandercock / Impacts of climate change on biological systems include shifts in seasonal phenology. How do migratory animals adjust reproductive decisions as they shift timing of breeding? I investigated patterns of climate change at a network of Arctic sites in Alaska and Canada, and examined the impacts of climate change on the breeding phenology, reproductive performance, and trophic interactions of Arctic-breeding shorebirds. First, I compared the breeding performance of three species, Western Sandpiper, Semipalmated Sandpiper, and Red-necked Phalaropes, at Nome, Alaska, across a 14-year interval. I found that shorebirds responded to a decreasing temperature during laying by delaying timing of breeding. Delayed breeding shortened the incubation duration for two biparental species but extended incubation for a uniparental species. Despite a short Arctic summer, the breeding windows of three sympatric species were temporally distinct. The three species often nested within several meters from each other, but bred under different temperature regimes and adjusted their reproductive output to different sets of environmental factors. Shifts in breeding phenology can disrupt trophic interactions, especially the phenological match between peak prey availability and hatching of shorebirds. Comparing the extent of phenological mismatch between six shorebirds and their invertebrate prey at ten Arctic sites, peak demand of shorebird broods occurred on average 3.8 days (± 13.8) later than local food peaks, and population demand curves overlapped with food curves by 47% (± 14%). Latitudinal and longitudinal gradients in the extent of trophic mismatch were mediated through geographic variation in the seasonal phenology of invertebrates and shorebirds. For individual nests, both more northerly and easterly sites showed greater phenological mismatch with annual food peaks. Delayed emergence of food peaks at more northerly and easterly sites alleviated the extent of phenological mismatch. My multi-site study provides the first evidence that large-scale geographic processes can determine the extent of phenological mismatch in a bitrophic system. Trends of climate change are sensitive to breeding stages and also vary along a longitudinal gradient. Variability in climatic trends in the Arctic, combined with species-dependent responses to local climate change, indicate that it will be challenging to predict the impacts of future climate change.