Projections of future sea level rise rely on ice sheet models that are highly tuned to simulate the geometry and flow of the modern ice sheets despite uncertainties in the surface mass balance and unknown basal processes. Overfitting these models to the present day means that the sensitivity of the ice sheet to future warming is untested and unconstrained. Recent advances in cosmogenic dating (a method to measure how long glacially eroded rocks have been exposed to the sun) as well as ice sheet modeling and statistical uncertainty quantification now make it feasible to use reconstructions of past ice sheet changes to test and improve coupled climate-ice sheet models. While many ice sheets have been reconstructed with great detail, the deglaciation of the Cordilleran Ice Sheet that covered the Rocky Mountains in North America during the last ice age is poorly constrained. Yet, this ice sheet offers great potential to constrain models due to its similarities to modern ice sheets, such as the southern Greenland Ice Sheet (mountainous, high accumulation and strong precipitation gradients, marine/land terminating). The Cordilleran Ice Sheet is also thought to have played a key role in rapid sea level and climate changes during the last deglaciation (a transition 21-7 thousand years ago that took us out of the last ice age), but evidence of this is limited. Our team of researchers, with a proven track record in reconstructing and modeling deglacial ice sheets and climate, will produce the first 3-D reconstruction of Cordilleran Ice Sheet collapse during the last deglaciation based on a robust empirical-modeling approach. We will undertake a carefully designed field campaign across this large and mountainous region to apply the "glacial dipstick" approach, generating 135 Be-10 ages along ~15 vertical transects. Using a statistical Uncertainty Quantification approach, we will combine the field data with modeling of the Cordilleran and western Laurentide Ice Sheets with a complex yet efficient coupled climate-ice sheet model used for future projections. This will produce an ensemble of plausible reconstructions for the deglaciation of the Cordilleran Ice Sheet.

A comprehensive understanding of the interactions between the biosphere and the atmosphere is crucial for: (i) Earth System science (ii) predicting the impact of future climate change. Isoprene is the most important biogenic volatile organic compound (VOC) in the atmosphere, with its emissions accounting for 1/3 of the global total VOC emissions (i.e. natural and anthropogenic combined). Through its degradation chemistry, isoprene impacts ozone and the formation of aerosols, which together impact global warming and the atmosphere's ability to cleanse itself of pollutants. Recent model studies show that the calculated impact of isoprene on ozone is critically dependent on the model isoprene chemical scheme, in particular the way the isoprene derived nitrates are treated. There is considerable uncertainty over how much of these nitrates are formed and what subsequently happens to them. Of particular importance is whether the nitrogen oxides, which are tied up in the nitrates, are later recycled or are lost from the atmosphere. This then impacts the amount of ozone that can be subsequently formed. Virtually everything that is known about isoprene nitrate chemistry is based on theoretical calculations, with most observational constraints based on measurements of either groups of nitrates as totals, or degradation products that come from more than one reaction and precursor species. For any substantial scientific progress to be made comprehensive measurement of individual nitrates is required, in laboratory studies to properly understand the chemistry of individual nitrates, and in the field to determine the true impact of isoprene on ozone and aerosol. Studies of isoprene degradation chemistry have been greatly limited by measurement techniques and their inability to identify and quantify individual organic nitrates. We therefore propose to: 1. Develop an analytical gas chromatography mass spectrometry instrument capable of detecting and identifying individual isoprene derived nitrates 2. Synthesise 18 individual isoprene derived nitrates to enable their unambiguous detection and identification and for their concentrations to be quantified down to atmospheric levels. The final products of this "Technology Led" proposal will be novel synthesis protocols and an analytical system that will allow calibrated measurements of 18 individual isoprene nitrates at concentrations down to atmospheric levels. The system can then subsequently be used in both laboratory and field studies. Such an analytical system will be unique and will enable isoprene chemistry to be studied at the level of individual reactions and products. This will facilitate a major advancement in the evaluation of model chemical mechanisms used to predict air quality and climate. It will enable a step change in the ability to constrain these mechanisms by allowing quantification of the rates and products of individual branches of these reaction schemes. Further it will allow the concentrations of individual isoprene nitrates to be measured in the real atmosphere and models tested against these data. Altogether this will enable the impact of isoprene nitrates on nitrogen oxide recycling and ozone to be quantified with well constrained models. The elevated ozone in England during the 2003 heatwave was attributed, in part, to elevated concentrations of isoprene. Future changes in climate and land-use are likely to affect isoprene emissions so understanding how isoprene impacts nitrogen oxide recycling is important for predicting future ozone concentrations. The potential advancements in scientific understanding that can be made following the development of the technology within this proposal are therefore essential for policy makers developing emission control strategies.

Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.

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