As interest grows in mitigating atmospheric carbon dioxide (CO2) concentrations, there is an increasing need to understand the factors that determine fluxes of carbon (C) to and from the atmosphere. This project quantifies the natural and anthropogenic sources and sinks of atmospheric CO2 on a county scale. In collaboration with the Hubbard Brook Research Foundation's (HBRF's) Sciencelinks Carbon Group, a net C budget for Chittenden County, Vermont has been created, with key C sources and sinks categorized in terms of land use. The primary goal of the budget is to provide up-to-date and accurate decisionmaking information to planners and policy-makers in the county, allowing the most tangible benefits to be gained from mitigation efforts. This project creates and tests a methodology that is easily replicable in any county in the United States. This methodology will facilitate the process of developing county-level C balance data beyond Vermont and the Northeast. This study suggests that Chittenden County is a net sink for C; 1.12 Tg C accumulate per year in the county's biomass and soils while 0.418 Tg C are emitted each year through anthropogenic activity within the county. C emitted in the manufacture of imported products is not considered. This work contributes to a larger ongoing study by the HBRF which compares C emissions and sequestration among seven counties representing different patterns of land use.

Forests play an integral role in regulating the exchange of carbon between the atmosphere and the terrestrial biosphere. These ecosystems only cover for about 30% of the land surface, forests account for almost half of the annual carbon uptake. The amount of carbon sequestered by forest ecosystems is largely dependent upon favorable climate conditions that promote increases in growth. Under the lowest emissions scenario, the United States is projected to undergo an almost 2˚C increase in temperature by the end of the century and it is important that we assess the contemporary climate-growth relationships of multiple forest types to better evaluate the stability and persistence of this vital carbon sink. Tree rings have been used to assess forest response to macroclimate conditions, but often the trees sampled for these analyses are only the most dominant individuals in the forest. This excludes individuals found in the understory of complex forest systems, such as those in the temperate forests of the eastern United States, and climate-growth relationships calculated from only dominant individuals may not be representative of the entire stand. Recent studies have shown that structural complexity of the forest canopy can significantly alter the microclimate conditions at which understory trees grow. Altered growth responses of the understory trees could increase the resilience of complex forest systems to the changes in temperature that are expected by the end of the century. Here, I apply dendrochronology methods to quantify climate-growth relationships of canopy strata in temperate forests of the eastern United States. Many different forest types are found in this region and have been the focus of numerous species-specific studies on climate growth relationships. However, the integrated response of co-occurring species within canopy units is not often investigated, despite measures of productivity being an integration of ecosystem processes. I present research that investigates the differential climate sensitivities of canopy strata, and I present a means to more accurately represent biomass estimates calculated from tree-ring data. The first study quantifies the climate sensitivities of different canopy strata from five temperate forests in the eastern US. We used a generalized additive model (GAM) to assess the influence that growing season mean temperature, growing season precipitation, and tree size have on dominant (uppermost), intermediate, and understory (lowermost) canopy strata. We found that differential climate sensitivities do exist between canopy strata, causing each canopy class to respond to extreme climate conditions in a different manner. For example, during the hottest and wettest years dominant and intermediate trees show slight increases in growth, whereas understory trees show significant decreases in growth. These results suggest that the climate and competitive environments created within stratified canopy layers may provide an added degree of ecosystem stability in the face of changing climate conditions. The second study assesses the spatial coherence of climate-growth relationships between canopy layers from the eastern temperate forest region. We collected increment cores from sites in Missouri, Indiana, Ohio, Michigan, Massachusetts, and Maine and we found that site groupings were relatively consistent between canopy layers. Dominant and intermediate trees showed a strong correlation with temperature that also coincides with the forest types and species distributions that are observed across the region. However, understory trees show stronger relationships with precipitation. Sites from the northeast US and Michigan displayed muted climate relationships, likely due to having both coniferous and hardwood species present. The midwest sites, composed of mostly hardwood species, showed relatively strong, negative temperature relationships in the dominant and intermediate canopy layers, but understory trees displayed strong positive relationships with temperature. These results suggest that although macroclimate conditions influence species distributions and affect the dominant trees, understory trees are likely responding to microclimate conditions. This also suggests that regions with increased functional diversity and complex canopy structure may be better buffered against changing climate conditions. Finally, we identify four main sources of uncertainty in estimating aboveground biomass from tree-ring data. Tree rings are being used more frequently to estimate the annual uptake of biomass by forested ecosystems. However, these calculations require several steps and assumptions that affect the overall accuracy of the biomass estimates. The error range around tree-ring estimates of aboveground biomass is seldom reported. We illustrate how increment upscaling, allometric, stand density, and mortality uncertainties can affect biomass estimates from a well-studied site in the Valles Caldera in northern New Mexico. We found that dominant sources of uncertainty change depending upon whether cumulative or incremental biomass is calculated. At the cumulative level, choice of allometric equation and tree mortality estimates dominate the uncertainty, whereas inter-annual variability in the tree-ring record dominates incremental biomass estimates. Despite the calculations that are required to translate linear ring-width measurements into biomass quantities, the underlying climate-growth relationships recorded within the tree rings are not significantly altered. Tree-rings provide a means for non-destructively quantifying the aboveground biomass in a forest and reporting the accompanying uncertainties will facilitate more accurate comparisons between disparate forest types.

A boreal forest wetland (L979) was flooded in 1993 at the Experimental Lakes Area, Ontario to imitate a hydroelectric reservoir and to study the effects of flooding on greenhouse gas production and emission. Flooding initially caused CO₂ and CH4 emission rates to increase and changed the wetland from a small, natural carbon sink to a large source of carbon. The increased production of greenhouse gases in the peatland also caused the majority of the peat to float to the surface creating floating peat islands, within 4 years of flooding. The floating peat islands are a larger source than the central pond of CH4 to the atmosphere due to the high water table and small oxidation zone as compared to the earlier undisturbed peatland. The floating peat islands had an average flux of 202 ± 66 mg C-CH4/m²/day comparable to rates measured in 1995. Methane flux rates are spatially and temporally variable ranging from ?117 to 3430 mg C-CH4/m²/day. The variability is partly due to episodic releases of gas bubbles and changes in overlying pressure from the water table. The development of floating peat islands created an underlying water pocket. The water pocket increased water movement between the central pond and the peatland and led to increased peat temperatures and methane oxidation, and removal of debris from the water pocket. DIC, CH4, and O₂ concentrations, and δ13C-DIC, δ13-CH4, and δ18O-O₂ values in the water pocket were similar to values in the central pond. Before flooding, the δ13C-CH4 values from the peatland ranged between ?36 and ?72? indicating that about 65 to 90% of the methane was oxidized before flooding. After flooding, the median δ13C-CH4 value from the floating peat islands was ?52? indicating that about 30% of the methane was oxidized before it was emitted to the atmosphere. Since the floating islands are now vegetated, photosynthesis and transport via plants allow the movement of oxygen into the peat islands Methane oxidation in the central pond was similar in 2001 and 2002. DIC and CH4 isotope mass budgets from June 3 to September 23, 2002 indicate that inputs were smaller than outputs at L979. Calculated net DIC and CH4 production in the central pond was 8490 and 432 kg C, with δ13C-DIC of -18. 5 ? and δ13C-CH4 of -32. 5?. Decomposition of peat was the source of DIC and CH4. O₂ saturation levels indicate that the pond is always undersaturated and that respiration dominates the system; however, the δ18O-O₂ also indicates that photosynthesis is an important process in the central pond of L979. The peat islands contributed about 90% of the total CH4 flux, whereas the open water areas contributed 10%. This indicates that formation of peat islands in a hydroelectric area can significantly affect the greenhouse gas emissions to the atmosphere. The average flux of CH4 from the entire wetland in 2002 was 202 ± 77 mg C-CH4/m²/day, equivalent to 44 ± 17 g C-CH4/m²/year (year = 220 days). This is higher than preflood values of 0. 5 g C-CH4/m²/year in 1992, and the early post-flood value of 8. 9 g C-CH4/m²/year in 1993/1994. The wetland continues to emit methane after ten years of flooding at higher than preflood rates.

A boreal forest wetland (L979) was flooded in 1993 at the Experimental Lakes Area, Ontario to imitate a hydroelectric reservoir and to study the effects of flooding on greenhouse gas production and emission. Flooding initially caused CO₂ and CH4 emission rates to increase and changed the wetland from a small, natural carbon sink to a large source of carbon. The increased production of greenhouse gases in the peatland also caused the majority of the peat to float to the surface creating floating peat islands, within 4 years of flooding. The floating peat islands are a larger source than the central pond of CH4 to the atmosphere due to the high water table and small oxidation zone as compared to the earlier undisturbed peatland. The floating peat islands had an average flux of 202 ± 66 mg C-CH4/m²/day comparable to rates measured in 1995. Methane flux rates are spatially and temporally variable ranging from ?117 to 3430 mg C-CH4/m²/day. The variability is partly due to episodic releases of gas bubbles and changes in overlying pressure from the water table. The development of floating peat islands created an underlying water pocket. The water pocket increased water movement between the central pond and the peatland and led to increased peat temperatures and methane oxidation, and removal of debris from the water pocket. DIC, CH4, and O₂ concentrations, and δ13C-DIC, δ13-CH4, and δ18O-O₂ values in the water pocket were similar to values in the central pond. Before flooding, the δ13C-CH4 values from the peatland ranged between ?36 and ?72? indicating that about 65 to 90% of the methane was oxidized before flooding. After flooding, the median δ13C-CH4 value from the floating peat islands was ?52? indicating that about 30% of the methane was oxidized before it was emitted to the atmosphere. Since the floating islands are now vegetated, photosynthesis and transport via plants allow the movement of oxygen into the peat islands Methane oxidation in the central pond was similar in 2001 and 2002. DIC and CH4 isotope mass budgets from June 3 to September 23, 2002 indicate that inputs were smaller than outputs at L979. Calculated net DIC and CH4 production in the central pond was 8490 and 432 kg C, with δ13C-DIC of -18. 5 ? and δ13C-CH4 of -32. 5?. Decomposition of peat was the source of DIC and CH4. O₂ saturation levels indicate that the pond is always undersaturated and that respiration dominates the system; however, the δ18O-O₂ also indicates that photosynthesis is an important process in the central pond of L979. The peat islands contributed about 90% of the total CH4 flux, whereas the open water areas contributed 10%. This indicates that formation of peat islands in a hydroelectric area can significantly affect the greenhouse gas emissions to the atmosphere. The average flux of CH4 from the entire wetland in 2002 was 202 ± 77 mg C-CH4/m²/day, equivalent to 44 ± 17 g C-CH4/m²/year (year = 220 days). This is higher than preflood values of 0. 5 g C-CH4/m²/year in 1992, and the early post-flood value of 8. 9 g C-CH4/m²/year in 1993/1994. The wetland continues to emit methane after ten years of flooding at higher than preflood rates.

Sea-level change during the Quaternary has had significant impacts on the geology of the Bahamas and the global carbon budget. During periods of low sea-level position conduit caves form in the Bahamas as a function of their respective water budgets. These conduit caves can then collapse and if this collapse reaches the surface a progradational collapse blue hole can be made. Upon subsequent sea-level rise these blue holes can become sediment inilled. Tidal pumping through these sedimentilled blue holes can result in the formation of whitings. Whitings are formed when the tidally pushed water warms and degasses CO2, driving the precipitation of CaCO3. Whitings are also formed on the shallow banks by resuspension by fish. As sea-level fluctuates the amount of land in the Bahamas and other carbonate regions increases or decreases with sea-level fall or rise, respectively. As the amount of land increases in the Bahamas and other carbonate regions, there is a decrease of carbonate rock exposure at high latitudes due to glaciation. The loss of high latitude carbonates is made up for in the gain of low latitude carbonates in terms of rates of inorganic carbon drawdown associated with karst processes. Additionally, this inorganic carbon draw down from karst processes represents approximately 16% of the unknown carbon sink as reported by the IPCC. This study is significant in that it contributes to the understanding of sea-level fluctuations in relation to the geology of the Bahamas and the global carbon budget.

Syftet med examensarbetet har varit att studera kol i mindre vattendrag med hjälp av jämviktsmodellering i PHREEQC. Fokus har varit dynamik av löst icke organiskt kol (DIC) samt att förstå hur mycket koldioxid (CO2) som avges från mindre vattendrag och om den mängden har signifikant inverkan på den globala kolbalansen. Med hjälp av provtagen data från Krycklans avrinningsområde år 2003-2007 och 2009 har modellering av DIC och pCO2 utförts med målet att se förändring både över säsong och nedströms i ytvattensystemet. För att utvärdera modellen har tillhandahållen data över uppmätt pCO2 använts. Målet var att jämföra modellerade och tillhandahållna pCO2-värden för att se hur väl modellen kunde beskriva verkligheten och om den fungerade bättre för någon plats eller under vissa delar av året. Analysen visade att pCO2-värden för modellen följer uppmätta pCO2-värden förhållandevis bra. Avvikelserna var störst för en av provpunkterna (provpunkt 6). Modellerade pCO2-värden följde de uppmätta pCO2-värden bäst under vårfloden. Modellen och analys av data visade tydliga indikationer på en avgång av CO2 från vattendraget. / The purpose of this Master thesis has been to study carbon flux in creeks. Chemical equilibrium models were produced to this end using PHREEQC. Specifically, dissolved inorganic carbon (DIC) quantities have been studied in order to understand the discharge of carbon dioxide (CO2) from the creek headwaters and how that affects the global carbon balance. Modeling of DIC and pCO2 was conducted using data from 2003-2007 and 2009 sampled at two points in the Krycklan research catchment located in northern Sweden. Seasonal variation of DIC and pCO2 in the two sample points was studied as well as the difference of these quantities between the two points. Evaluation of the model was done in part by comparing predicted pCO2 values with actual values stemming from a previous study leading to an assessment of the validity of the model. One of the sample points showed larger discrepancies between predictedand actual values than the other. Studying the seasonal variation of discrepancies, they were at the minimum during the spring flood. Finally, the analysis showed clear indications of a net CO2 discharge from the creekstretch between the two sample points.

In 2008, the so-called Climate Change Act went through the UK Parliament. The bill was a commitment to radically reduce carbon emissions. During the same period of time, a third runway was planned at the London Heathrow airport. The aim with this paper is to analyse the controversy that occurs over how the expansion of civil aviation can be connected or disconnected from the politics of climate change. The specific case of Heathrow expansion brings to the fore how certain domains and economic spheres are contested, as they become subjects for incorporation with climate change policy as a discursive practice. In focus of the study are debates in the UK Parliament, as well as contestations in the form of direct actions by the activist network “Plane Stupid”. A disparity in the debate exists between “carbon budget” and “technological enframing”: two competing programmes of government. The distinction between these programmes derives from a difference of relativising and absolutising rationalities. The parliament’s decision over Heathrow is an attempt to mitigate the conflict between conflicting policies. In the direct actions by Plane Stupid the issue is however demonstrated as a conflict, and absolute connections between the question of Heathrow and climate change are visualised. By making contestations of programmes and techniques of government, the practice of resistance relates to and utilise the productive powers of governmentality. The conflict of Heathrow touches upon dynamics of discursive modifications. The control and capacity to define the character of a problem are productive powers that are subjects for continuous negotiations, contestations and conflicts.

In 2008, the so-called Climate Change Act went through the UK Parliament. The bill was a commitment to radically reduce carbon emissions. During the same period of time, a third runway was planned at the London Heathrow airport. The aim with this paper is to analyse the controversy that occurs over how the expansion of civil aviation can be connected or disconnected from the politics of climate change. The specific case of Heathrow expansion brings to the fore how certain domains and economic spheres are contested, as they become subjects for incorporation with climate change policy as a discursive practice. In focus of the study are debates in the UK Parliament, as well as contestations in the form of direct actions by the activist network “Plane Stupid”. A disparity in the debate exists between “carbon budget” and “technological enframing”: two competing programmes of government. The distinction between these programmes derives from a difference of relativising and absolutising rationalities. The parliament’s decision over Heathrow is an attempt to mitigate the conflict between conflicting policies. In the direct actions by Plane Stupid the issue is however demonstrated as a conflict, and absolute connections between the question of Heathrow and climate change are visualised. By making contestations of programmes and techniques of government, the practice of resistance relates to and utilise the productive powers of governmentality. The conflict of Heathrow touches upon dynamics of discursive modifications. The control and capacity to define the character of a problem are productive powers that are subjects for continuous negotiations, contestations and conflicts.

A simple rule for the optimal global price of carbon is presented, which captures the geophysical, economic, and ethical drivers of climate policy as well as the effect of uncertainty about future growth of consumption. There is also a discussion of the optimal carbon budget and the amount of unburnable carbon and stranded fossil fuel reserves and a back-on-the-envelope expression are given for calculating these. It is also shown how one can derive the end of the carbon era and peak warming. This simple arithmetic for determining climate policy is meant to complement the simulations of large-scale integrated assessment model, and to give analytical understanding of the key determinants of climate policy. The simple rules perform very well in a full integrated assessment model. It is also shown how to take account of a 2 °C upper limit on global warming. Steady increases in energy efficiency do not affect the optimal price of carbon, but postpone the carbon-free era somewhat and if technical progress in renewables and economic growth are strong leads to substantially lower cumulative emissions and lower peak global warming.

Climate change is now more of a reality than ever. Carbon budget provides an upper limit on the amount of carbon that can be emitted, for the earth to be within an accepted temperature rise. People are aware that eating less meat, flying less and reducing product consumption would decrease their emission, but they are not sure on how much less. Existing studies show that people are quite willing to accept the concept of carbon budget but there is no tool that visualises this information at an individual level.  This study investigated the features that must be included in a carbon budget tool when visualising an individual’s information to create awareness. An exploratory design approach was used in this study where the design was iteratively developed from user feedback. Four preliminary designs were first developed and discussed in a focus group. With the feedback from the focus group, one design was finalised and redesigned as a carbon budget tool. This was tested in a one-on-one user testing where users had to complete tasks using the tool. The study results provided evidence that personalised information, effective text, labels, interactive features, and clear and simple layout are important features that must be included when designing a tool to visualise an individual’s carbon budget. The participants also rated an increase in awareness of carbon budget concept after using the tool. / Klimatförändringarna är nu mer verkliga än någonsin. En koldioxidbudget anger en övre gräns för mängden utsläpp av klimatgaser som kan släppas ut för att hålla ökningen av jordens medeltemperaturen inom en acceptabel gräns. Många människor är medvetna om att lägre köttkonsumtion, färre flygresor och en minskad konsumtion av saker skulle minska deras utsläpp, men de är inte säkra på hur mycket varje ändring påverkar utsläppen. Befintliga studier visar att människor accepterar begreppet koldioxidbudget i sig, men det finns idag inga verktyg för att visualisera en koldioxidbudget på individuell nivå.  Denna studie undersöker vilka funktioner som behöver ingå i ett verktyg för visualisering av en individuell koldioxidbudget, med syfte att skapa medvetenhet hos användaren. En utforskande designmetod användes där verktygets design utvecklades iterativt med feedback från användare. Först utvecklades fyra preliminära designprototyper som diskuterades i en fokusgrupp. Med feedback från fokusgruppen vidareutvecklades en av prototyperna till en slutgiltig version. Detta testades i en användartestning där användare utförde uppgifter med verktyget. Studieresultaten visade att personlig information, effektiv text, etiketter, interaktiva funktioner och tydlig och enkel layout är viktiga funktioner som måste inkluderas när man utformar ett verktyg för att visualisera en koldioxidbudget för individuell användning. Deltagarna bedömde också att de uppnått en ökad medvetenhet om konceptet koldioxidbudget efter att ha använt verktyget.