PARENT SESSION
Contributed Oral Session 157: Climate Dynamics: Temperature Effects; Modeling
Friday, August 12, 8:00 AM - 11:30 AM, Meeting Room 516 D, Level 5, Palais des congrès de Montréal

Where will no-analog climates likely occur in the future?

Williams, John^*,1, ¹ Department of Geography, Madison, WI, USA

ABSTRACT- By the end of the 21st century, the Earth system will very likely include climate regimes with no modern analog and, possibly, no good analog to any Quaternary climate regimes. No-analog climates challenge ecological forecasting, because model parameterizations are primarily based upon observations drawn from the currently realized environmental space. In order to identify areas that may experience novel climates, I analyzed GISS and GFDL climate scenarios for the fourth IPCC assessment report, using a emissions scenario of 1% annual increases in CO₂ to 2x pre-industrial levels, followed by CO₂ stabilization. Regionally novel climatic conditions were identified by 1) calculating standardized Euclidean dissimilarities between each end-state gridpoint (model years 211-240) and the set of all initial-state grid points (model years 1-30) from the same region, and 2) retaining the smallest dissimilarities. Climate was represented as mean monthly temperatures for JJA and DJF, and mean daily precipitation for JJA and DJF. Surprisingly, despite significant warming over Northern Hemisphere continents (GFDL: 5 to 6°C DJF warming in circum-Arctic regions), future climates for North America and Eurasia generally have good analogs in the initial climate space, whereas climatic conditions with no good modern analogs are most prevalent in Australia, Africa, and South America. This pattern reflects two main influences. First, high-latitude climate change is mainly limited to DJF temperatures, whereas low-latitude surface-energy budgets cause a strong negative coupling between precipitation and temperature, resulting in synchronous changes in multiple climate dimensions. Secondly, larger continents have a larger pool of potential climatic analogs and reduced likelihood of finding no good modern analog. The probability of future novel species assemblages may therefore be highest in low-latitude regions and smaller continents.

Key words: climate, no-analogs, IPCC