Dispersal capacity is an important trait enabling species to respond to climate change, particularly in fragmented landscapes, where individuals often need to move longer distances to colonise new areas. It is therefore crucial to understand species’ movement behaviour and how it is affected by environmental variables to plan effective conservation measures for a wide range of species. This thesis aimed to enhance the current understanding of the role of dispersal in enabling species to respond to global environmental change using seven species of butterflies. I identified that species and individuals with longer move bouts (step length) cross habitat boundaries more frequently. Because step length is relatively easy to measure for butterflies, it could potentially be used as a general proxy of species dispersal capacity at a landscape level. I also found a higher investment in morphological traits that enhance dispersal capacity for one out of three range-expanding species in newly colonised sites at the range margin. Differences in species dispersal capacity and habitat availability could explain why only one species showed increased investment in dispersal at the margin. Also, there was poor evidence of a relationship between movement and an associated morphological trait; wing length was not associated with increased mobility for two out of four species which suggests that increased dispersal ability may not always be linked to morphological changes during range expansion. Finally, an assessment of the relative importance of temperature, habitat quality and structure on the movements of two species within their habitats revealed no contribution of the habitat variables for one of the species, whilst temperature, habitat size, edge ratio and vegetation height significantly affected movements of the second species. Overall, this thesis highlights that responses to global environmental change are highly dependent on species and its interactions with the environment.

Coccolithophores are one of the important groups of phytoplankton in the global oceans, which makes it important to know how this group will react to changes in their environment due to climate change. Modellers already recognized their importance and included this group independently in global biogeochemical models. This study assesses the effect of light, temperature and nutrient availability on five coccolithophores, performing a range of laboratory experiments. The results of these experiments were then used to change the parameterisation of coccolithophores in the global biogeochemical model PlankTOM10. Furthermore, the model was validated in two ways, using a database of coccolithophore biomass measurements from the field and measurements of surface calcium carbonate derived from satellite data. Temperature effects on growth depend a great deal on the coccolithophore species. E. huxleyi (both, a subtropical and a temperate strain) and P. carterae grew best around 20°C, whereas G. oceanica and C. leptoporus had optimum temperatures above 25°C and still grew well at the maximum temperature tested in the experiments. E. huxleyi was the species with the highest growth rates (μmax=0.98 for the subtropical strain and μmax=0.97 for the temperate), followed closely by G. oceanica and C. leptoporus (μmax=0.91 in both species). P. carterae (μmax=0.77) had a noticeably lower maximum growth rate than the other coccolithophores. An inverse relationship with growth rate was found for all measured cellular components (POM, PIC, Chl a) as well as for cell volume in P. carterae. Coccolithophores are good competitors at high light intensities, having optimum growth light intensities above 180 μmol photons m-2 s-1. The temperate strain of E. huxleyi and the species G. oceanica showed the lowest optima at 350 μmol photon III m-2 s-1. C. leptoporus (Iopt=500 μmol photon m-2 s-1) and P. carterae (Iopt=600 μmol photon m-2 s-1) had higher optimum growth light intensities and the subtropical strain of E. huxleyi (Iopt=900 μmol photon m-2 s-1) grew best at the highest light intensity applied in this study. Only one strain of E. huxleyi showed light inhibition in its photosynthetic activity that was well above the detection limit in P-I curves up to 2000 μmol photons m-2 s-1. Apart from a well-known decrease in Chl a/C ratio with increasing light intensity, little variation in the concentration of cellular components (POM, PIC) was observed. Nutrient experiments were carried out in a chemostat with two strains of E. huxleyi and one G. oceanica. Phosphorus limitation led to an increase in cell volume (112- 157%) and particulate organic carbon (21-54%) in E. huxleyi and G. oceanica, relative to cultures grown under nitrogen limitation. Comparison of uptake rates for phosphate and nitrate with other phytoplankton groups showed that both species are very good competitors for phosphate and relatively poor competitors for nitrate. The initial PlankTOM10 model simulation overestimated biomass compared with a new observational database, and underestimated surface calcium carbonate compared with satellite data. Changing the coccolithophore parameterisation in PlankTOM10, based on the laboratory results, did not lead to significant improvements relative to the observations. However, the response of the model to the parameter changes could be explained either directly from the changed parameters, or indirectly from changes in the model ecosystem.

Science, like other realms of human activity, has its geographies. It proceeds in and through space, and participates in the construction of the political and cultural geographies by which human interactions with the nonhuman come to be known, understood and governed. The phenomenon of climate change stands at this juncture of science, politics, and the elemental materiality of the nonhuman. High-profile controversies about the physical reality, effects and management of the changing climate point to more deep-seated contestations about the place of science in modern democratic societies. This thesis engages with literatures on the historical and cultural geographies of science in order to open-up questions about the situatedness of climate change knowledges, the contested boundaries between the scientific and the political, and the spatial politics of relating epistemic claims to normative interventions in the world. The thesis proceeds through a series of linked case studies which traverse a range of emergent transnational spaces of knowledge production. It begins inside the Intergovernmental Panel on Climate Change (IPCC) and moves through the contested spaces of international climate diplomacy at the 2009 Copenhagen climate talks and through diverse cultures of knowledge authorisation in Indian climate politics. The thesis develops the notions of ‘boundary spaces’ and ‘epistemic geographies’ to capture the emergence, conjuncture and contestation of different modes of knowing and governing climate change. By following the objects of climate change knowledges – like visualisations, numerical targets, simulation models and predictions – conceptual distinctions between the spaces of knowledge production and consumption break down. Instead, a picture emerges of travelling knowledges which emphasises mutability, interpretive flexibility, and the spatial and discursive co-production of the epistemic and the normative. It is argued that by moving from ‘geographies of science’ to ‘epistemic geographies’, the hybridity of science and politics can be more effectively written-in to our accounts of contemporary knowledge politics.

We live in an era of rapid change in ecosystems and their environ- ments, that all scales up to the global. The contemporary view is that the interactions between life and the environment are bidirectional: the environment creates life and life creates the environment. However, most ecosystem models have an inbuilt rigidity such that the degrees to which they can mimic structural change in response to environmental cues is very limited. In an effort to capture the plasticity of life we present a new theoretical individual-based ecosystem model in the con- text of previous classical and experimental modelling approaches. The aim is to develop a deeper understanding of the factors determining trophic structure. The individual-based approach permits the inclusion of traits to model heritable attributes. Population-level models imple- ment a mean-�eld approximation that led to the competitive exclustion principle. The addition of a trait to de�ne speci�c feeding strategy permits the model exploration of this problem. Life history theory pre- dicts that reduced juvenile mortality selects for delayed maturity and decreased reproductive effort, and reduced adult mortality will select for the opposite. Through the inclusion of a different trait to represent relative parental investment in offspring, we explore the predictions of life history theory and hypotheses for clutch size.

Groundwater flow in permafrost is restricted to unfrozen zones, known as taliks. There is an interaction between groundwater flow and heat flow, because the permafrost distribution determines the occurrence of groundwater, but groundwater also contributes to advective heat transport influencing the distribution of permafrost. However, the advective heat flow component is small where the hydraulic gradient is low, or where recharge is limited. Conversely, where recharge is not driven by precipitation, as for example found under a wet based glacier, groundwater fluxes can be more significant. This thesis aims to improve understanding of the impacts of permafrost dynamics on Arctic groundwater flow systems for past and predicted climate change. Numerical modelling of coupled heat and fluid flow including phase change of water/ice is used to study different environments; lakes in a periglacial environment, and lakes and springs in a proglacial terrain. Results show that the transient effects of heat storage can influence the present day distribution of permafrost. This is especially pronounced underneath surface water bodies, where there are cases for which under a steady state scenario no through talik is expected, but there are through taliks under a transient scenario. In addition, heat advection by groundwater flow can influence the permafrost distribution by permafrost erosion and aggregation. The magnitude of heat advection is driven by topographically driven groundwater flow and the release of groundwater from elastic storage. The latter is significant in previously glaciated areas that have undergone a large change in hydraulic head over time. In partially frozen ground, the choice of the permafrost permeability-reduction function is crucial to quantify groundwater flow and advective heat flow. The occurrence of through taliks is influenced by the regional scale groundwater flow, but taliks also influence the regional scale hydrogeologic system by reversal of the general groundwater flow direction.

Deliberate large-scale interventions in the Earth’s climate system, known collectively as climate ‘geoengineering’, have been proposed in order to moderate anthropogenic climate change. A host of normative rationales for geoengineering has led to a growing number of appraisals to evaluate the different proposals and provide decision support. This thesis critically reviews current appraisals of geoengineering before developing and executing its own appraisal methodology in response to their limitations. These limitations concern: (1) the appraisal of geoengineering proposals in ‘contextual isolation’ of alternative options for tackling climate change; (2) inadequate methodological responses to the ‘post-normal’ scientific context in which climate change and geoengineering resides; and (3) a premature ‘closing down’ upon particular geoengineering proposals, principally stratospheric aerosol injection, through the exertion of power via framings. This thesis exhibits the findings of an ‘upstream’ participatory appraisal of geoengineering called Deliberative Mapping; an innovative analytic-deliberative methodology designed to ‘open up’ appraisal inputs and outputs to a broader diversity of framings, knowledges and future pathways. A diversity of international experts and stakeholders from across academia, civil society, industry and government, and of sociodemographically representative citizens from Norfolk (UK), were engaged using a combination of analytic Multi-Criteria Mapping specialist interviews and deliberative citizens’ panels, as well as a joint specialists-citizens workshop. The results present a radically different view to other appraisals of geoengineering, where: (1) geoengineering proposals are most often outperformed by mitigation options, with stratospheric aerosol injection ranking particularly poorly; (2) a greater diversity of perspectives and assessment criteria spanning the natural, applied and social sciences reveals considerable uncertainties in all areas of research and decision making; and (3) four propositions for governance emerge that advance sociotechnical foresight, technology control and public consent, the anticipation and alleviation of impacts, a demonstration of robustness, and ultimately, the responsible innovation of geoengineering.

The oxygen isotope excess Δ(17O) is a potential tracer of biological nitrous oxide (N2O) cycling. This study presents the first measurements of Δ(17O) in marine N2O together with details about the design and development of a custom-built Gas Chromatography-Isotope Ratio Mass Spectrometry (GC-IRMS) analytical system for δ(15N), δ(18O) and Δ(17O) of N2O. Δ(17O) values between 0.1 and 4.6 ‰ (relative to VSMOW) were observed during three field campaigns in the temperate, subtropical and tropical Atlantic Ocean, the Scotia Sea and the Weddell Sea. This indicates a biological source for oxygen isotope excess in N2O, as oceanic N2O was not in equilibrium with the atmosphere (0.9 ‰). δ(15N) values ranged from 2.3 to 25.1 ‰ (relative to Air-N2). δ(18O) measured in the Weddell Sea ranged from 44.9 to 48.8 ‰ (relative to VSMOW). The dataset from the Atlantic Ocean and the Atlantic sector of the Southern Ocean suggest nitrification and nitrifier-denitrification as the main N2O production pathway in the oxic, deep ocean. High δ(15N) values in the south Atlantic Gyre are presumably associated with a denitrification source. A novel off-the-shelf N2O analyser was tested in combination with an equilibrator for semiautonomous concentration measurements in the surface ocean. The subtropical gyres in the Atlantic Ocean were confirmed to be weak sinks ((-0.14±0.31) μmol m-2 d-1 N2O flux to the ocean in the northern, and (-0.16±0.33) μmol m-2 d-1 in the southern gyre) and the equatorial region was a source of N2O to the atmosphere (flux of 0.53 μmol m-2 d-1). New data from the Scotia Sea identified a strong source region ((2.9±2.7) μmol m-2 d-1), while the Weddell Sea was closer to equilibrium with the atmosphere ((0.9±1.0) μmol m-2 d-1).

Atmospheric trends of a series of ozone depleting substances (halons) and greenhouse gases (PFCs, SF5CF3, HFC-227ea) are reported using measurements from Cape Grim, Tasmania. A two-dimensional global atmospheric chemistry transport model is used to derive global annual emission histories of these long lived gases. Emissions of the halons are found to have decreased since peaking in the 1990s. There is still some considerable uncertainty in the remaining banks of the halons caused by uncertainties in their atmospheric lifetimes and possibly in the reported production data. The contribution of the halons to total tropospheric bromine is predicted to fall from current mixing ratios of about 8.1 ppt to about 3 ppt by 2060 assuming reported lifetimes to be correct. Emissions of the higher perfluorocarbons (PFCs) (C4F10, C5F12, C6F14 and C7F16) have decreased since peaking in the 1990s, with the exception of C7F16, emissions of which have remained stable since the 1990s. Emissions of C3F8 have also decreased since the 1990s; those of C2F6 appear to be increasing though this disagrees with recent work of other groups. However the growth rate of the radiative forcing of the atmosphere from the PFCs reported herein has been relatively constant for the past decade largely because of increasing emissions of c-C4F8. Emissions of SF5CF3 appear to have ceased in the mid-2000s seeming to confirm the source of the gas as being from production of certain fluorochemicals by the company 3M. Emissions of the hydrofluorocarbon (HFC) HFC-227ea have increased rapidly since the mid-1990s. Long term trends of six alkanes (ethane, propane, n-butane, iso-butane, n-pentane and iso- pentane) and six alkyl nitrates (methyl, ethyl, 2-propyl, 2-butyl, 2+3-pentyl and 3-methyl-2- butyl) have been derived from measurements from firn air from the two Greenland sites, NEEM and North GRIP. These suggest that alkane mixing ratios peaked in the Arctic around 1980 and that alkyl nitrate mixing ratios in the Arctic peaked in the early 1990s. A detailed chemical mechanism has been developed in a 2-D atmospheric model to investigate the tropospheric chemistry relevant to the production of alkyl nitrates. Using this model, long term emission histories of the alkanes have been derived. These suggest that alkane emissions from Europe, North America and Russia roughly halved between 1980 and the early 2000s while those from Asia roughly doubled. A historic trend of the changing photochemical age of air masses reaching the Arctic has been derived and used as a proxy for changing OH concentrations in the mid-high latitude northern hemisphere. This suggests that OH concentrations decreased from 1950 to about 1975, increased from 1975 to 1995 and have subsequently decreased again. This trend appears to correlate with the trend in the growth rate of methane in the atmosphere over the past sixty years. Using a box model the chemistry of the alkyl nitrate system both in background air and polluted air masses has been investigated, focusing on the response of the system to varying levels of atmospheric NO, OH and HO2. It appears that the observed historic trends of the alkyl nitrates are a result of both changing OH and NO concentrations.

This thesis investigates the impact of future climate change upon species vulnerability. Reports of shifts in species distributions are already numerous, but the pattern of change is not fully understood. This thesis looks to predict which species are likely to be most at risk under climate change and why? This thesis takes the equation; Vulnerability= Sensitivity + Exposure to better discover which species are most vulnerable to climate change. Additionally, this research explores how mitigation has a role in determining the degree to which species are vulnerable in the future. Determining a specie’s vulnerability to climate change required the creation of values representing each side of the equation, both a measure of sensitivity and exposure. The construction of a sensitivity measure required the creation of a life history and ecological traits database, and required the use of multiple methods of statistical analysis. Exposure was calculated using projections of future suitable climate space created using species distribution model Maxent. To explore the impact of mitigation on species vulnerability exposure was calculated under a range of climate change scenarios. The sensitivity and exposure scores are synthesised into a measure of vulnerability. The result of the equation, Vulnerability= Exposure + Sensitivity, has revealed which Mammal species are most vulnerable; those which will be exposed to a high degree of climate change and which life history and ecological traits make them sensitive. The most vulnerable species are those which are highly exposed and which have ‘slow’ life history traits, are range restricted, or, are climate specialist. The regions in which species are identified as most vulnerable include the Neotropical and Afrotropical zones. Mitigation is found to reduce potential vulnerability with early mitigation being the most beneficial. The deeper understanding gained through this research will help us prioritise species for conservation based on their vulnerability.

Sediment fingerprinting is a commonly employed technique for estimating sediment contributions from various eroding terrestrial sources to fluvial sediment load via a mixing model approach. However, there remain significant shortcomings in sediment fingerprinting practice, specifically relating to difficulties in producing high-temporal resolution apportionment estimates, inconsistencies in mixing model uncertainty representation, and a lack of attention given to organic matter provenance. Addressing these deficiencies, a combined X-ray fluorescence spectroscopy (XRFS) and diffuse reflectance infra-red Fourier transform spectroscopy (DRIFTS) approach is developed to rapidly, accurately and non-destructively analyse suspended particulate matter (SPM) geochemistry directly from sediment covered quartz fibre filter (QFF) papers at masses as low as 3 mg. An improved Bayesian source apportionment mixing model is then developed which allows for full characterisation of spatial geochemical variability, instrument precision and residual error, to yield a realistic and coherent assessment of the uncertainties associated with sediment fingerprinting estimates. Lastly, a novel application of a coupled molecular and δ2H and δ13C compound-specific isotope analysis (CSIA) of leaf wax n-alkane biomarkers is conducted to demonstrate the apportionment of plant-specific organic matter contributions to streambed sediments. Employing these developments in conjunction with automatic water samplers, high-temporal resolution SPM source apportionment estimates are derived throughout the progression of numerous storm events in a lowland agricultural catchment, revealing significant temporal variability in SPM provenance at 60- and 120-min resolution. Lower resolution, weekly, baseflow sampling is also performed, revealing distinct seasonal cycles in SPM geochemistry and sediment source apportionment over a 23-month period. Collectively, the developments presented in this thesis significantly advance sediment fingerprinting research by enabling organic and inorganic fluvial sediment fractions to be quantitatively apportioned at both low- and high-temporal resolution within realistic levels of uncertainty, thereby enhancing our understanding of sediment dynamics under a range of instream hydrological conditions.