Monsoon systems influence the water supply and livelihoods of over half of the world. Observations are too short to provide estimates of monsoon variability on the multi-year timescale relevant to the future or to identify the causes of change on this timescale. The credibility of future projections of monsoon behavior is limited by the large spread in the simulated magnitude of precipitation changes. Past climates provide an opportunity to overcome these problems. This project will use annually-resolved palaeoenvironmental records of climate variability over the past 6000 years from corals, molluscs, speleothems and tree rings, together with global climate-model simulations and high-resolution simulations of the Indian, African, East Asia and South American monsoons, to provide a better understanding of monsoon dynamics and interannual to multidecadal variability (IM). We will use the millennium before the pre-industrial era (850-1850 CE) as the reference climate and compare this with simulations of the mid- Holocene (MH, 6000 years ago) and transient simulations from 6000 year ago to ca 850 CE. We will provide a quantitative and comprehensive assessment of what aspects of monsoon variability are adequately represented by current models, using environmental modelling to simulate the observations. By linking modelling of past climates and future projections, we will assess the credibility of these projections and the likelihood of extreme events at decadal time scales. The project is organized around four themes: (1) the impact of external forcing and extratropical climates on intertropical convergence and the hydrological cycle in the tropics; (2) characterization of IM variability to determine the extent to which the stochastic component is modulated by external forcing or changes in mean climate; (3) the influence of local (vegetation, dust) and remote factors on the duration, intensity and pattern of the Indian, African and South American monsoons; and (4) the identification of palaeo-constraints that can be used to assess the reliability of future monsoon evolution.

There is a recognised gap in the communication of information generated by climate scientists and evidence needed by policy makers, in part because influencing policy through research is complex and requires skills that might not be valued or common in research systems. The current situation of our Earth's system, together with the social movements for climate justice, urge a step change in how policy and scientists approach Climate Change. Through this fellowship, I will develop new routes for impact in palaeoclimatology and will lead a vital step change in my field of research. Annual to decadal climate predictions may offer important information to Climate Services and Environmental Agencies, which would help guide short- and medium-term climate change strategies. For example, a better knowledge of the frequency and magnitude of floods in the UK. Decadal climate predictions are skilful for surface temperature, but confidence in projections of atmospheric pattern and the associated ecosystem response are less robust. This is, in part, because the amplitude of the decadal climate response is difficult to verify by the available instrumental data (reanalyses), which only goes back a century or two, and the impact of superimposed low-frequency variability might not be well represented. One way to provide more information on the decadal climate response is to include high-temporal resolution palaeoclimate timeseries in reanalyses. So far, the availability of proxy data suitable for this purpose is limited by the nature of the data (qualitative vs quantitative), chronological constrains (dating uncertainty and time-resolution of the proxy records) and geographical location of the proxy records (i.e limited to specific climate regions as ice-cores and corals), hence the study of decadal climate variability in the past is still in its infancy. In order to make developments in this field, I will lead an international research team that integrates palaeoclimatologists and climate modellers. We will combine emerging methodological approaches in proxy developments, chronological constraints, statistical tools and data-model comparison to provide advanced information of past decadal climate variability in the North Atlantic-European region such as shifting atmospheric circulation and occurrence of extreme weather events; and we will develop emergent constraints based on past climate scenarios to be applied to decadal prediction systems. Beyond the scientific goals, the fellowship aims at a better integration of palaeo evidence into climate policy to create a step change in how long-term climate data are viewed and used by policy and stakeholders. We will create a network of policy advisers, policy makers and other end users willing to engage. A co-development model of research will be adopted to develop shared understanding to design the research outputs, and ensure the research contributes to the specific and current needs of the decision makers across various sectors. The ultimate challenge is to create a leading centre for Palaeo Evidence for Policy at Royal Holloway University of London to: (1) build a palaeo-climate service feeding policy makers with evidence to assist decision-making; (2) support palaeoclimatologists in the UK and overseas to make impact cases studies; (3) train the next generation of early career researchers in policy skills. The fellowship will also explore art-based methods for impact. In particular, creative writing to promote climate science literacy for young children.

Green-energy transition technologies such as carbon storage, geothermal energy extraction, hydrogen storage, and compressed-air energy storage, all rely to some extent on subsurface injection or extraction of fluids. This process of injection and retrieval is well known to industry, as it has been performed all over the world, for decades. Fluid injection processes create mechanical disturbances in the subsurface, leading to local or regional displacements that may result in tremors. In the vast majority of cases, these tremors are imperceptible to humans, and have no effect on engineered structures. Nonetheless, in recent years, low magnitude induced seismic events have had profound consequences on the social acceptance of subsurface technologies, including the halting of natural gas production at the Groningen field in the Netherlands, halting of carbon storage experiments in Spain, halting of geothermal energy projects in Switzerland, and the moratorium on UK onshore gas extraction. In light of the seismic events of increasing severity recently measured during geothermal mining in Cornwall, the need to develop a rigorous fundamental understanding of induced seismicity is clear, significant, and timely, in order to prevent induced seismicity from jeopardising the ability to effectively develop the green energy transition. Most mathematical models that are used to predict and understand tremors rely on past observations of natural tremors and earthquakes. However, fluid-driven displacement in the subsurface is a controlled event, in which the properties of the injected fluids and the conditions of injection can be adjusted and optimised to avoid large events from happening. This project aims to develop a fundamental understanding of how the conditions of subsurface rocks, and the way in which fluid is injected in these rocks, affect the amount of seismicity that may be produced. We will analyse in detail the behaviour of fluid-driven seismic events, and will develop a physically realistic model based on computer simulations, novel laboratory experiments, and comprehensive field observations. Our model will characterise the relationships between specific subsurface properties, the nature of the fluid injection, and the severity of the seismic event. These findings will be linked to hazard analysis, to identify the conditions under which processes such as carbon storage, deep geothermal energy extraction, and compressed-air energy storage, are more or less likely to create tremors. We will also investigate how to best share our scientific findings with regulators and the general public, so as to maximise the impact of this work. This project will lead to an improved understanding of the processes and conditions that underpin the severity of induced seismic events, with a vision of developing strategies that will improve our ability to prevent and control these events. This project will also provide the scientific basis to improve precision and cost-effectiveness of scientific instruments that are used to monitor the subsurface, so that we can identify tremors as they occur, and better interpret what is causing them as we observe them. In the short term, we need to develop these models so that regulators and decision-makers can develop policies based on scientific evidence, using a variety of analysis tools that inter-validate each other, thereby ensuring that their predictions are robust. This is an important step in supporting the ability of developing a resilient, diversified, sustainable, and environmentally responsible energy security strategy for the UK. In the long term, by creating confidence in the understanding of these subsurface events, and demonstrating evidence of our ability to control them, we will lead the UK into an era where humans understand why certain seismic events have occurred, allowing them to potentially develop mechanisms to forecast their occurrence, and reduce their severity.

Nuclear power is low-carbon and green energy. It presently provides about 10% of the world's electricity and 20% of the UK's electricity, contributing enormously to global Net Zero emissions. Nuclear power will continue to play an important role in the global transition to a low carbon economy. However, one major disadvantage of nuclear power is that its generation process produces radioactive waste that can remain hazardous for hundreds of thousands of years. Over the past more than 60 years' utilisation of nuclear power in the UK and worldwide, many radioactive wastes have accumulated, most of which are stored temporarily in storage near nuclear power plants. It is vital for us to deal with the waste to protect human health and the environment. A global consensus has been reached in this area, that is to isolate radioactive waste that is incompatible with surface disposal permanently in suitable underground rock formations (i.e., host rocks) by developing a geological disposal facility (GDF). As also set out in the 2014 White Paper, the UK Government is committed to implementing geological disposal, with work on developing this led by Radioactive Waste Management Ltd (RWM). Developing a GDF relies on a stable rock formation to ensure mechanical stability and barrier function of host rocks. It is therefore essential to understand factors that influence the integrity of rocks. This is challenging partially because of the complexity of rock fractures that are widespread in the Earth upper crust. Although rock mechanical behaviour has a long record of study, attempts to understand the role of fractures on rock deformation still has unresolved issues. For example, natural rock fractures are often dealt with crudely; almost all previous studies of this problem assume rock fractures to be continuous, with zero or very small cohesion that can be neglected. However, it is almost a ubiquitous feature that natural rock fractures in the subsurface are incipient and heterogeneous, with considerable tensile strength and cohesion. This is either due to secondary minerals having recrystallised, bonding fracture surfaces together, or due to rock bridges. This INFORM project will focus on mineral-filled fractures (i.e., veins) that are frequently seen in the subsurface but often ignored or less researched so far. The aim of INFORM is to increase confidence in the design, construction, and operation of GDFs, by developing a mechanics-based multi-scale framework to understand the influence of fracture heterogeneity on the integrity and deformation behaviour of rocks across scales. The framework will integrate imaging analysis, laboratory experiments, numerical modelling, and field observations, to (1) determine factors contributing to fracture heterogeneity across scales, (2) understand the shear and triaxial deformational behaviour of veined rocks considering natural fracture geometry and heterogeneity, and (3) develop a field-scale model for repository structures considering fracture heterogeneity. Unlike most previous studies, which have focused on the influence of mechanical fractures on rock behaviour, INFORM will for the first time investigate the influence of natural veins, and will consider and implement these observations in the modelling of veined rock behaviour applied to a GDF. INFORM will "inform" a wide range of audiences with new insights through correlating micro-scale observations and macro-scale deformation of heterogenous veined and fractured rocks. This will be possible with the strong support of our academic and industrial partners (RWM, UK; Jacobs, UK; Northeastern University, China; GFZ, Germany; Stanford University, USA) and the help of our well-designed outreach and publication plans. INFORM will lead to a more accurate and reliable examination of fracture heterogeneity, which will not only directly benefit GDF R&D, but also broader rock engineering applications (e.g., tunnelling, cavern construction).

The discovery of the Subsurface LithoAutotrophic Microbial Ecosystem (SLiME) in basalt formations in 1995, seemingly using hydrogen formed from water rock interactions, was of great significance as this anaerobic community could be independent of surface photosynthesis, both organic matter and oxygen. This potentially significant energy supply might also explain the surprisingly large numbers of prokaryotes found in subsurface terrestrial environment (at least to 3 km depth), despite extreme conditions and lack of obvious energy supply. It also has profound astrobiological significance as a mechanism for subsurface life in planets even with surface conditions that are unsuitable for life. However, the significance of this hydrogen generation is controversial having being criticized as being a negligible reaction in the environment (conditions too alkaline, restricted by limited reduced iron concentrations in minerals and by its dependence on the production of fresh reactive surfaces). However, hydrogen formation has also been detected at depth in earthquake fault zones and there is indirect evidence that this is used by subsurface prokaryotes to produce methane. The mechanism of hydrogen formation in this case is thought to be due to mechanochemistry as a result of subsurface fracturing of rocks in earthquake zones. If this is true then with some greater than 20,000 earthquakes a year any rock type could potentially produce hydrogen making a substantial SLiME community distinctly more possible. In addition, we have demonstrated that some prokaryotes may actually speed-up hydrogen formation from minerals in sediment slurries, including hydrogen generation from pure silica sand. As silicates make up ~95% of the Earth's crust this could potentially be a significant source of hydrogen. We intend to investigate further these mechanisms of hydrogen formation by testing a range of common minerals and conditions for hydrogen generation, including at increasing temperatures to simulate the heating that occurs due to sediment burial. We will determine whether microbial processes are stimulated by hydrogen formation and identify and culture the microbes involved. These enriched microbes will then be used with pure minerals to investigate their involvement and ability to use the mineral as an energy source in more detail. Some high pressure experiments will enable temperatures up to 150oC to be investigated. This is too high for microbes (max ~120oC) but may produce hydrogen and other compounds which can diffuse upwards to feed the base of the biosphere. Novel sealed rock crushing experiments will also be conducted (30 - 120oC) to test whether just cracking of rocks can produce enough hydrogen to feed a microbial population.