ElNino，aSpanishtermfor"theChristchild"，wasnamedbySouthAmericanfishermenwhonoticedthattheglobalweatherpattern，whichhappenseverytwotosevenyears，reducedtheamountoffishescaughtaroundChristmas．ElNinoseeswarmwater，collectedoverseveralyearsinthewesternPacific，flowbackeastwardswhenwindsthatnormallyblowwestwardsweaken，orsometimestheotherwayround．

Theweathereffects，bothgoodandbad，arefeltinmanyplaces．RichcountriesgainmorefrompowerfulNino，onbalance，thantheylose．AstudyfoundthatastrongNinoin1997helpedAmerican'seconomygrowby15billion，partlybecauseofbetteragriculturalharvests：farmersintheMidwestgainedfromextrarain．Thetotalriseinagriculturalincomesinrichcountriesisgreaterthanthefallinpoorones．

ButinIndonesiaextremelydryforestsareinflames．Amulti-yeardrought（干旱）insouth-eastBrazilisbecomingworse．ThoughheavyrainsbroughtaboutbyElNinomayrelievethedroughtinCalifornia，theyarelikelytocausesurfacefloodingandotherdisasters．

ThemostrecentpowerfulNino，in1997-98，killedaround21，000peopleandcauseddamageworth 36．But such Ninos come with months of warning，and so much is known about how they happen that governments can prepare．According to the Overseas Development Institute （ODI），however，just 12% of disaster-relief funding in the past two decades has gone on reducing risks in advance，rather than recovery and rebuilding afterwards．This is despite evidence that a dollar spent on risk-reduction saves at least two on reconstruction．

Simple improvements to infrastructure （基础设施）can reduce the spread of disease．Better sewers （下水道）make it less likely that heavy rain is followed by an outbreak of the disease of bad stomach．Stronger bridges mean villages are less likely to be left without food and medicine after floods．According to a paper in 2011by Mr Hsiang and co-authors，civil conflict is related to El Nino's harmful effects-and the poorer the country，the stronger the link．Though the relationship may not be causal，helping divided communities to prepare for d