I layer over Pole. theSouth Molina’s tireless that avast holehadappeared intheozone osol cans, accelerated by thediscovery of the momentum forthe phasingoutof CFCs inaer- scientific diplomacy. These efforts created and policymakers was Molina’s initiationinto olet (UVB)lightto penetrate to Earth’s surface. ozone, allowing ultravi harmfulhigh-energy There thegas cancatalyse thedestructionof for introducing chlorineto thestratosphere. atmosphere, where they become aTrojan horse prevents oxidation removing them from the valuable asrefrigerants andpropellants also 1974). Thechemical inertnessthatmadeCFCs M. MolinaandF. Rowland Nature threat posed by CFCs to theatmosphere (see where hebuilthiscareer. Berkeley, brought him to the United States, attheUniversitychemistry of California(UC), Freiburg, Germany. Doctoral studies inphysical city, atthe University andappliedchemistry of Autonomous University of Mexico, inhishome He studied chemical engineeringattheNational Molina went to boarding school in Switzerland. US president Barack Obama. States and Mexico, he was a trusted adviser to wide. A treasured public figure in the United improved thequalityof life formillionsworld- quality inmegacities, andonclimate change, implementation, andMolina’s later work onair successful international agreement to date”. Its described thetreaty as“perhapsthesinglemost 2003, former UN secretary-general Kofi Annan and theozone holehasbegunto recover. In reduced stratospheric chlorineandbromine, Nations treaty to achieve universal ratification, 7 October, aged 77. work onstratospheric chemistry. He diedon the Dutch chemist Paul Crutzen for their his formeradviser F. Rowland Sherwood and shared the1995 with NobelPrize inChemistry and otherozone-depleting chemicals.Molina international agreement to phase outCFCs Substances thatDeplete theOzone Layer, an bring aboutthe1987 Montreal Protocol on advocacy helpedto andscientific diplomacy Ozone-hole Nobelwinner, Montreal Protocol advocate, presidents’ adviser. (1943–2020) Mario Molina Obituary Communicating this work to the media Born inMexico City, thesonof adiplomat, The Montreal Protocol, United thefirst At UC Irvine, heandRowlandAt UCIrvine, calculated the at theBritishAntarctic Survey reported ospheric ozone. Adecade later, scientists fluorocarbons (CFCs) could deplete strat- predict that global emissions of chloro n themid-1970s, MarioMolinahelpedto 249 , 810–812; , 810–812; - - “His work on air quality work“His onairquality the JetPropulsion inPasadena, Laboratory stratospheric chlorineisstored intherelatively Pole.South Duringthedark,cold polarwinter, observed during thewinter(PSCs) over the ‘mother of pearl’polarstratospheric clouds of ice particles thatmakeistry upthebeautiful over Pole, theSouth andseasonal? unanswered: why was theozone holelocalized Protocol. However, basic questions remained ozone hole,andconcluded withtheMontreal face predicted thatchlorineactivation would of hydrogen ice sur chloridewith a crystalline - processes. Calculations based onthereactions such anefficient catalyst forthese stratospheric returns inthepolarspring. leads to intense ozone depletionwhensunlight Antarctic polarvortex dueto such reactions chlorine. Thewinter build-upof thegas inthe and chlorinecompounds ledto therelease of reactions particles: between icePSC surfaces California, didcreative experiments to mimic hypochlorous acidandhydrogen chloride. formsof gas-phaseinert chlorinenitrate, the quality oflife for millions worldwide.” in megacities improved Molina found the answer in the surface chem Molina andhisresearch group, thenat A mystery remained asto why ice shouldbe ©
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A l l r i g h t s r e s e r v e d . - ten millioninhabitants)in the global south. mega Tan Molina,began work onairqualityin then-wife and long-time collaborator, Luisa between 1989 and2004, Molinaandhis To steer policy, theMexico CityProject com and thatitplayed apartinactivating chlorine. ospheric temperatures induced such disorder, that hydrogenconfirming chloride at low strat Cambridge, hisresearch group did experiments Massachusetts Institute of Technology (MIT)in surface layer, or quasi- that thedifference mightbedueto adisordered lab orintheenvironment. Molinasuggested be much less efficient than is observed in the e-mail: [email protected] The Journal A. of Physical Chemistry 2015 co-edited his Festschrift special issue in a symposium in his honour in 2014, and in MIT from 2000 to 2004. She co-organized New York. Molina was her PhD adviser at environmental science at Columbia University, of chemical engineering and departments V. Faye McNeill is a professor in the transmission of SARS-CoV-2 inMexico. passionately for mask-wearing to reduce the com/2hzsB1). months,headvocated In his final Extreme Climate Change’ (see go.nature. Policies to Protect People andthePlanetfrom ‘Well Under 2 Degrees Celsius: Fast Action three popesandco- Pontifical Academy of Sciences, headvised Mexico, and,asamemberof theVatican’s advisera scientific to several presidents of credibility. andscientific macy Heserved as a technical issue to anyone, with gentle diplo for theAdvancement of Science. we‘What know’, fortheAmericanAssociation public-outreach initiative onclimate change, Diego.UC San In2014, hespearheadedamajor but remained aninspirational facultymemberat last decades,hespentincreasing timeinMexico, ment, athinktankbased inMexico City. In his Strategic andtheEnviron StudiesonEnergy and founded the Mario Molina Center for air qualityinhisbeloved homecity. holder engagement. Thiswork improved the scientists, analysis with in-depth and stake hoods, involving hundreds of international inurbanof atmosphericneighbour chemistry bined unprecedented large-scale studies field Nature |Vol 587 |12 November 2020 |193 While hewas institute professor atMIT Molina could communicate theessence of In 2004, Molinarelocated to Diego UCSan cities (broadly, those with more than authored the2017 report liquid layer, on ice. At the ------
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