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Home > Research > Researchers > Nick Hewitt
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Nick Hewitt supervises 5 postgraduate research students. Some of the students have produced research profiles, these are listed below:

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Professor Nick Hewitt

Professor

Nick Hewitt

LEC Building

Lancaster University

Bailrigg

Lancaster LA1 4YQ

United Kingdom

Tel: +44 1524 593931

Location:

Research Interests

Research Interests

EMISSIONS OF BIOGENIC REACTIVE TRACE GASES AND THEIR ROLES IN THE EARTH SYSTEM

The biosphere is by far the largest source of reactive trace gases to the Earth’s atmosphere. These compounds provide protection against abiotic and biotic stresses and allow plant-to-plant and plant-to-insect communication. Some of these compounds are highly reactive in the gas phase, and some are emitted in enormous, but unknown, quantities. The combination of high reactivity and large mass emission rates means these compounds play major roles in the physics and chemistry of the atmosphere. They mediate in the formation of ozone, hydroxyl and other oxidants, so controlling the oxidizing capacity of the atmosphere, which in turn controls the lifetime of methane and other radiatively-active “greenhouse” gases. They also form secondary organic aerosol (SOA) particles, which can directly influence the radiative balance of the atmosphere. SOA may activate cloud condensation nuclei (CNN), and by modifying cloud formation and properties can have indirect effects on climate. As well as their effects on radiative forcing, both ozone and aerosol particles have detrimental effects on human health and ecosystem functioning, and hence bVOCs play a role not only in the Earth’s climate system but also in air quality.

My research on biogenic volatile organic compounds (bVOCs) spans scales from the cell to the globe and includes both experimental and modelling work. I was PI of a large NERC consortium project studying the role of bVOCs in atmospheric composition and chemistry above a tropical rain forest in Malaysia (the “OP3” project – see OP3 special issue in ACP and other papers, including our 2009 paper in PNAS). In this project we showed that large-scale land use change in the tropics – specifically the conversion of tropical rain forest to oil palm plantations – causes changes in atmospheric composition and chemistry. Using measurements and models we showed that the management of the emissions of reactive nitrogen species is essential to prevent formation of damaging levels of ground-level ozone in these regions.

In our paper in Nature Climate Change in 2013 we similarly showed that the large-scale conversion of farm land in Europe to the production of poplar or willow (now grown as biofuels) will likely exacerbate ground-level ozone pollution, with detrimental effects on human mortality and crop yields.

In 2013-2014 we have been measuring the fluxes of the important bVOC, isoprene, at a remote site in Amazonia. We have obtained a unique nine-month record of isoprene fluxes and are currently writing this up for publications

In 2013-2014 we also developed the ability to measure hydrocarbon fluxes from the surface to the atmosphere at the landscape scale using a mass spectrometer on a light airplane (the NERC ARSF Dornier 228). We flew over London and SE England and obtained the first airborne flux measurements of benzene, toluene and isoprene in Europe. These data are also currently being written up for publication.

CLIMATE-SOCIETY FEEDBACKS AND THE AVOIDANCE OF CLIMATE CHANGE

I have become very interested in how both individual actions and societal choices might influence atmospheric composition and hence climate. Having discovered the work of William Jevons and his paradox (his 1865 book “The Coal Question” is available on the web) I have been collaborating with Andy Jarvis at Lancaster on climate–society feedbacks and the avoidance of climate change. In our 2012 paper in Nature Climate Change we showed that effective climate mitigation will require establishing a meaningful climate-society feedback to arrest the growth in global CO2 emissions through decarbonising global primary energy sources.

In our current joint work we are exploring how the global energy system and CO2 emissions have co-evolved. Although still at an early stage, it appears that global CO2 emissions have grown at ~3/4 the rate of the growth in primary energy use. Similarly final energy use has grown at ~3/4 the rate of the growth in primary energy use. We hypothesis that this may be because the growth in energy use is regulated in part by the architecture of the network along which it is distributed into the three dimensional space in which humans operate.

We have also been attempting to construct 'Business-As-Usual' forecasts of global primary energy use (and CO2 emissions) based simply on the observed behaviour of these metrics over the last 160 years. We argue that this gives a better prediction of future energy use and CO2 emissions than do scenarios, as used by the IPCC. This work is currently available as a discussion paper in Earth System Science Discussions.

I have also recently attempted to quantify the influence of realistic dietary choices on greenhouse gas emissions.

I am a Royal Society Wolfson Research Merit Award holder.

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