The projected timing of climate departure from recent variability

ABSTRACT

Ecological and societal disruptions by modern climate change are critically determined by the time frame over which climates shift beyond historical analogues. Here we present a new index of the year when the projected mean climate of a given location moves to a state continuously outside the bounds of historical variability under alternative greenhouse gas emissions scenarios.

Using 1860 to 2005 as the historical period, this index has a global mean of 2069 (±18 years s.d.) for near-surface air temperature under an emissions stabilization scenario and 2047 (±14 years s.d.) under a ‘business-as-usual’ scenario. Unprecedented climates will occur earliest in the tropics and among low-income countries, highlighting the vulnerability of global biodiversity and the limited governmental capacity to respond to the impacts of climate change. Our findings shed light on the urgency of mitigating greenhouse gas emissions if climates potentially harmful to biodiversity and society are to be prevented.

Figure 1: Estimating the projected timing of climate departure from recent variability.

a, Mean annual temperatures of an example grid cell (small square on map) exceed historical climate bounds (grey area) for three consecutive years starting in 2012 (blue arrow) and for 11 consecutive years after 2023 (green arrow);

Figure 2: The projected timing of climate departure from recent variability.

a, b, Projected year when annual (a) or monthly (b) air temperature means move to a state continuously outside annual or monthly historical bounds, respectively. c, Absolute change in mean annual air temperature

Figure 3: The projected timing of climate departure from recent variability in global biodiversity hotspots.

These plots indicate the difference between the average year in which the climate exceeds bounds of historical variability for each hotspot and the estimated global averages

ORIGINAL: Nature
By Camilo Mora,
Abby G. Frazier,
Ryan J. Longman,
Rachel S. Dacks,
Maya M. Walton,
Eric J. Tong,
Joseph J. Sanchez,
Lauren R. Kaiser,
Yuko O. Stender,
James M. Anderson,
Christine M. Ambrosino,
Iria Fernandez-Silva,
Louise M. Giuseffi
& Thomas W. Giambelluca

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Nature 502, 183–187 (10 October 2013)
doi:10.1038/nature12540 Received
25 April 2013 Accepted
06 August 2013 Published online
09 October 2013
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