Dr Catherine Hirst

Assistant Professor in the Department of Earth Sciences

What do you do?

I am an Assistant Professor in the Department of Earth Sciences. I am a geologist and geochemist by trade. I apply this geoscience toolbox to understand the impact of climate change on soil and river waters in Arctic and Antarctic landscapes. I’ve been fortunate to conduct fieldwork and work alongside fantastic scientists in Sweden, Siberia, Belgium, Alaska, and the UK. I am passionate about nurturing an inter-disciplinary, intergenerational, inclusive, and fun, workplace.

How are you involved in this area of science? 

Amplified climate change in polar regions is warming permafrost soils and exposing ancient organic carbon. If a portion of carbon is released to the atmosphere as greenhouse gases then permafrost thaw can further amplify warming – the permafrost carbon feedback.

Policy makers want to know how much greenhouse gas will be released from thawed permafrost and include this estimate in their climate mitigation strategy. To inform policy makers, we must determine the processes controlling organic carbon fate today.

I investigate the mechanistic role(s) that minerals play in mediating soil organic carbon transport through high latitude landscapes. I collect soil, soil water and river water samples from permafrost-dominated regions. I apply a geochemical tool kit, including non-traditional stable isotopes (like iron and silicon), to investigate the mineral-associated organic carbon in these samples. I place my geochemical findings in context with hydrological and organic geochemistry data.

What do you love about this topic?

I love working on a wide range of polar scales – pinning down environmental processes at a nanoscale and conveying their importance on a global scale. I love the inter-disciplinary nature of polar science – bringing together people with complementary and fascinating insights, from organic geochemistry to hydrology to geophysics.

I love visiting wild and beautiful field sites – it is a real privilege to observe these fragile environments and work alongside local people. Living in wild places is what inspired me to become a scientist – and it is what I love most about this topic.

How does this work deliver real-world impact?

As a community, we want to determine if permafrost thaw will be a ‘tipping point of no return’ for Earth's climate. We will do this by understanding the processes driving permafrost thaw and permafrost soil organic carbon loss to the atmosphere, rivers and ocean. We aim to include these numbers in reports that advise governments on climate change mitigation strategies (e.g., the IPCC report).