Why is everyone talking about 1.5 degrees?

The media are full of reports about the omi­nous tem­pe­ra­tu­re of 1.5°C. Why is this like that? An expl­ana­ti­on in simp­le terms.

The 1.5 degree tar­get or limit deno­tes a thres­hold at which the con­se­quen­ces of cli­ma­te chan­ge can still be reason­ab­ly mana­ged. If this limit is excee­ded, this will have serious unfo­re­seeable and irrever­si­ble con­se­quen­ces for lar­ge parts of man­kind. The­se seve­re con­se­quen­ces are e.g. long-las­ting droughts, heat extre­mes, hea­vy rain events or floods. How such events look like is not only shown by the flood dis­as­ter in the Ahr val­ley, but also by the cur­rent heat wave in India and Paki­stan with tem­pe­ra­tures of 50°C.

The choice of 1.5°C is not an arbi­tra­ri­ly cho­sen tem­pe­ra­tu­re, but this goes back to a spe­cial report of the Inter­go­vern­men­tal Panel on Cli­ma­te Chan­ge, which lists the bene­fits that com­pli­ance with this limit would mean. This tem­pe­ra­tu­re refers to the avera­ge tem­pe­ra­tu­re from befo­re indus­tria­liza­ti­on, which occur­red in the years 1850–1900. This is refer­red to as man-made cli­ma­te chan­ge.

Why is the empha­sis on “man-made” important? Quite sim­ply, if it has been cau­sed by humans, humans can also coun­ter­act it. The­re are now many, many stu­dies from the sci­en­ti­fic com­mu­ni­ty that can pro­ve that human actions have cau­sed the cli­ma­te to chan­ge.

Now the World Meteo­ro­lo­gi­cal Orga­niza­ti­on (WMO) has published a report that says the avera­ge glo­bal tem­pe­ra­tu­re could reach the 1.5‑degree mark for the first time as ear­ly as 2026. Tha­t’s four years from now.

Some sci­en­tists speak of a “tip­ping point” at which our eco­sys­tem chan­ges so much that irrever­si­ble effects occur. The­se include, for exam­p­le, rising sea levels and the mel­ting of lar­ge gla­ciers.

It is empha­si­zed that excee­ding the 1.5‑degree limit once is not the same as excee­ding it per­ma­nent­ly. This report is a remin­der to all of us, but espe­ci­al­ly to poli­ti­ci­ans and indus­try, that action must final­ly be taken. Green­house gas emis­si­ons must be redu­ced now. And in a cle­ar­ly noti­ceable amount. The cli­ma­te is not wai­ting for poli­ti­ci­ans to finish their dis­cus­sions.

By the way: Ger­ma­ny has alre­a­dy used up all its resour­ces on May 04. At least theo­re­ti­cal­ly, becau­se this is indi­ca­ted by Earth Over­load Day, which is a day of action by the Glo­bal Foot­print Net­work orga­niza­ti­on. This is to point out that we con­su­me more resour­ces than our earth can pro­vi­de us humans.

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