When and how our journey started

HELBLING, E. WALTER; NARVARTE, MAITE A.; GONZÁLEZ, RAÚL A.; CABRERIZO, MARCO J.; VILLAFAÑE, VIRGINIA E.

Global change in Atlantic coastal Patagonian ecosystems: A journey through time

Springer Nature

Año: 2022; p. 1 - 9

Since its formation, our planet underwent significant alterations, from largedisplacement of land masses that resulted in the current continents andseas to an increasing oxygenation that changed the Earth?s atmosphere. Inaddition, an intense volcanism activity released huge amounts of greenhousegases (GHGs), mainly water vapor, carbon dioxide (CO2), methane (CH4),and nitrous oxide (N2O) into the atmosphere. The natural increase in GHGstriggered a key phenomenon, the ?greenhouse effect,? that allowed an increaseof surface temperature making it possible the life on Earth (Tyndall 1863). Forinstance, the mean temperature of 15 °C at present would have been minus18 °C without this effect (Mesarovic 2019). Paleoclimate investigations on icecores allowed to infer the natural variations of one of the GHGs (i.e., CO2) overgeological timescales (~800,000 years; Fig. 1a, b), evidencing changes up/down over time as large as ca. 100 ppmv within time lapses of 10?30 thousandyears. These variations in CO2 concentrations were accompanied with changesin temperature (Fig. 1c, d); hence, the Earth alternated between cold (e.g., theLittle Ice Age, nineteenth century) and warm (e.g., Medieval warm period, 800?1300 AD) periods, such as demonstrated through paleoclimate investigations(Neukom et al. 2019). Fine measurements carried out by Keeling et al. (1976)on air samples taken at the Mauna Loa Observatory in Hawaii since the late1950s showed that not only the increase of CO2 in the atmosphere reachedconcentrations far above those due to natural variations (Fig. 1a, b) ? as highas 420 ppmv in 2020 ? but also that they increased at much higher rate, thanpreviously observed, of about 100 ppmv in ca. 70 years. This higher rate ofincrease in CO2 concentration over the last decades have been coupled with aconcomitant increase of the global temperature of 1.2 °C in 120 years (Fig. 1d)