Double Jeopardy: understanding the combined impacts of climate change and pollution on Arctic ecosystems

Rachael Treharne


Start Year: 2014, 1st cohort

Host University: The University of Sheffield

Department: Animal & Plant Sciences

Supervisors: Dr Gareth Phoenix, Dr Jarle W Bjerke, Dr Lisa Emberson 

Twitter: @RachaelTreharne

Rachael Treharne

Academic profile


MBiolSci Biology 1st Class Hons, University of Sheffield, UK, 2010-2014

Work experience

Field assistant for an NERC-funded project: Carbon Cycle Linkages in Permafrost Systems (CYCLOPS, @project_cyclops), June-September, 2013 & 2014.

Skills and relevant qualifications

CO2 flux measurements: Using a LiCor LI6400 to measure Net Ecosystem Exchange, Ecosystem Respiration, Gross Primary Productivity and branch and leaf level photosynthesis and respiration.

PP Systems EGM4 to measure Net Ecosystem Exchange and Ecosystem Respiration;

Chlorophyll fluorescence measurements: Using an LI6400 and LiCor fluorometer and a Mini-Pam fluorometer;

Remote sensing: Techniques for vegetation analysis using ArcGIS, ENVI5.2, and R;

Basic modelling: Parameterisation and basic use of a coupled photosynthesis-stomatal conductance model;


ACCE Ph.D. Research topic

Double Jeopardy: understanding the combined impacts of climate change and pollution on Arctic ecosystems

The Arctic is warming at twice the rate of the rest of the world and simultaneously receiving an increasing amount of atmospheric pollution. The tendency for Arctic vegetation to respond to this warming by becoming more productive, known as ‘Arctic greening’, is one of the most well-established trends in Arctic climate change ecology.

However, evidence of vegetation damage is increasing in some Arctic regions. This ‘Arctic browning’ is driven by climatic and biological extreme events, such as sudden, short-lived warm periods in winter. As these events become more frequent with continuing climate change, their impacts could increasingly attenuate the effects of trend climate change. In addition, initial observations suggest extreme event-driven browning is exacerbated by pollution. This creates major uncertainty as to the future anticipated greening of the Arctic.

This project will use a multi-scaled approach to assessing Arctic browning in Northern Norway. Remote sensing will be used to assess the extent and drivers of vegetation damage. Methods will also be developed for upscaling plot-level measurements of key carbon fluxes, enabling the consequences of Arctic browning for landscape carbon balance to be estimated for the first time.