Global climate indicators
The global climate indicators provide an overview of changes in the climate system!The setof interlinked physical indicators presented here connect the changing compositionoftheatmosphere with changes in energyin the climate system and the response of land,ocean,andice.
The global indicators are based on a wide range of data sets which comprise data frommultiple observing systems including satellitesandin situ networks (for details on data setsusedin the report,see Data set and methods).
Changes to the physical climate,measured herebykey indicators,can have cascadingimpacts on national development and progress toward the UN SustainableDevelopmentGoals (SDGs).²For example,changes in the acidityor temperature oftheocean can affectmarine life,potentially impacting coastal communitiesthat may depend on the local catchfor their livelihood or food security.Onthe other hand,climate science has acriticalrole toplayinfacilitating sustainable development.Asdemonstrated bythe 2023 Unitedin Sciencereport,weather,climate,and water-relatedsciences support the achievement of manyof theSDGs.³Recognizing the interconnectionsbetween climate and development canthereforelead to synergisticaction-an increasing necessity as the world getsfurther off-track fromachieving both the SDGs and the Paris Agreement goals.4
BASELINES
Baselinesare periodsof time,usuallyspanningthree decades ormore,thatare used as afixedbenchmark against whichcurrent conditions can be compared.For scientific,policy andpractical reasons,several different baselines are usedin thisreport,andthese are specifiedin the textandfigures.Where possible,the mostrecent WMO climatologicalstandardnormal,
1991-2020,is used forconsistent reporting.
Forsome indicators,however,itis not possible to use the standardnormal owingto a lackofmeasurements during the early part of the period.There are alsotwo specific exceptions.First,forthe global meantemperaturetime series-and only for the global mean series-a referenceperiodof1850-1900 is used.Thisisthe baselineused in IPCCAR6 WGlas a reference periodforpre-industrial conditions and is relevant forunderstanding progress inthe contextof theParis Agreement.Second,greenhouse gas concentrations can be estimated much furtherback in time usinggas bubbles trappedin ice cores.Therefore,the year 1750 is used in thisreport to representpre-industrial greenhouse gas concentrations.
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