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SUMMARY:Methane and the Paris Agreement - Professor Euan Nisbet\, Royal Ho
 lloway and NERC Project MOYA
DTSTART:20180226T141500Z
DTEND:20180226T151500Z
UID:TALK99739@talks.cam.ac.uk
CONTACT:Paul Griffiths
DESCRIPTION:Atmospheric methane began rising rapidly and unexpectedly in 2
 007\, after the global burden had been stable for some years. Sustained me
 thane growth took place between 2007-2013 at about 6 ppb yr-1. Then\, for 
 the three years 2014\, 2015 and 2016\, growth increased again at over 10 p
 pb yr-1. This growth continues in 2017. Total growth from 2007-present has
  been about 70 ppb (Nisbet et al.\, 2016 and submitted). Methane growth ha
 s been accompanied by a significant negative shift in the δ13CCH4 ratio o
 f the methane burden\, reversing the positive trend that has been sustaine
 d through the 20th century. The causes of the rise and shift are not under
 stood. The isotopic shift may indicate an increase in biogenic emissions\,
  especially in the tropics and subtropics (Schaefer et al\, 2016\, Nisbet 
 et al. 2016)\, or perhaps a decline in methane destruction by OH (Turner e
 t al.\, 2017\, Rigby et al. 2017). Biomass burning may have declined\, or 
 the proportion of fossil fuel emissions may have dropped. Possible factors
  driving increased biogenic emissions are warmer\, wetter tropical wetland
 s and increases in emissions from cattle\, perhaps as the inter-tropical c
 onvergence zone expands its range. However\, models suggest methane’s li
 fetime may be changing also: the ‘sources vs sinks’ debate focuses on 
 the time-scale of the isotopic shift.\n\nThe 2015 UNFCCC Paris Agreement a
 mbitiously sought to hold the increase in the global average temperature b
 elow 2°C above pre-industrial levels\, and\, going beyond that\, to striv
 e for 1.5°C. There has been optimism that this very ambitious goal may be
  feasible\, though the roadmap has steep hills and depends heavily on a sh
 arp near-future cut in the methane burden. But the recent methane increase
  makes this increasingly difficult. Methane growth\, if sustained at curre
 nt rates\, would lead to warming well above the Paris target (Nisbet et al
 .\, submitted). However\, although methane’s recent rise appears to be f
 rom factors that are not directly anthropogenic\, most methane emissions d
 o indeed come directly from human activities\, including leaks from the en
 ergy industry (Schwietzke et al.\, 2017)\, emissions from landfills\, and 
 output from agricultural ruminants\, especially cows. Thus for Paris targe
 ts to be achieved\, anthropogenic emissions must be cut back urgently\, an
 d more importance given to proactive removal from the atmosphere.\n\nThe d
 ebate about the causes of methane’s rise cannot be solved until better t
 ropical data\, especially isotopic measurements\, are available. The ongoi
 ng changes in the methane budget are the focus of project MOYA (Methane Ob
 servations and Yearly Assessments)\, which is a multi-partner UK consortiu
 m supported from 2016-2020 by the Natural Environment Research Council. Th
 e project is global in scope and includes measurement\, field campaigns\, 
 and modelling work: http://moya.blogs.bris.ac.uk/project-moya-nercs-study-
 of-the-global-methane-budget/ . At the core of MOYA is a network of in sit
 u observations\, including planned continuous CO2 and CH4 measurement on A
 scension Is.\, E. Falkland Is. Halley Bay\, Antarctica\, and the Atlantic-
 crossing ships RRS JC Ross and Cap San Lorenzo\, as well as flask or bag s
 ampling from many other locations. Ascension is the only remote equatorial
  station worldwide with continuous measurement of greenhouse gases\, but u
 nfortunately the collapse of the Ascension runway has made it difficult to
  sustain measurement.\n\nNisbet\, E.G.\, et al. (2016) Glob. Biogeochem. C
 ycles\, 30\, 1356-1370 \n\nNisbet\, E.G. et al. (submitted). Atmospheric M
 ethane & the Paris Accord \n\nRigby\, M. et al. (2017) PNAS\, 114\, 5373-5
 377\n\nSchaefer\, H.\, et al.\, (2016) Science\, 352\, 80-84\n\nSchwietzke
  et al. (2017) Nature 538\, 88-91\n\nTurner\, A.J.\, et al. (2017) Proc. N
 atl. Acad.  Sci. USA. 114\, 5367–5372
LOCATION:Pfizer Lecture Theatre\, Department of Chemistry
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