Glacial Climate in the Tropics

“variation; temperature and especially rainfall were highly variable at low latitudes (Broecker, 1996).”

“In the tropics, rainfall was highly variable (Broecker 1996)3.”

“Such a redistribution in atmospheric moisture could produce large and abrupt changes in global climate (Broecker, 1996) by altering the high-latitude surface ocean salinity "eld and structure of the oceanic thermohaline circulation (Kerr, 1998).”

“Quantification of glacial SSTs in tropical regions is still controversial, with much debate whether temperatures were similar to modern-day values or decreased by 5–6 °C; ref”

“In South American tropical areas, temperatures during the LGM (Last Glacial Maximum) seem to have been 2o to 6oC (4o š 2) lower than today (van der Hammen and Absy, 1994; Broecker, 1996).”

“As the montane climate descended only 500±900 m during the Pleistocene (Holloway, 1986; Broeker, 1996), the montane habits of this species group make their dispersal during the Pleistocene unlikely; the group probably achieved its present distribution during the Tertiary.”

“, in Broecker (1996)). New measurements also indicate a partly ice-free north Atlantic during glacial summer periods (Weinelt et al., 1996). To account for these critics on 3. Results and discussion CLIMAP SSTs we have performed an additional glacial sensitivity experiment with cooler tropical 3.1. Present climate 3.1…”

“0% ascribed to ice volume changes during the last deglaciation [Broecker, 1996], and (2) a 0.”

“Holocene weather extremes have quite significant effects on organisms (Lamb, 1977).”

“In particular, oxygen isotope data confirm cooler seas during glacials and interstadials, and suggest that tropical seas were ∼5–6◦C cooler than today (e.g., Rind and Peteet, 1985; Chappell, 1994; Stute et al., 1995; Broecker, 1996; Bush and Philander, 1998; McCulloch et al., 1999; Lea et al., 2000).”

“This difference of 3� C is similar to the 2–3� C general cooling found for interglacial-glacial temperature change within the tropical-subtropical band [CLIMAP Project Members, 1976, 1981], (information about glacial temperatures in the tropics can be found in the work of Broecker [1996] ).”

“This estimate must be taken as a min ecause cooler temperatures reduce the saturation vapo ure of the atmosphere, which should decrease snowfa ncrease the elevation of snowline (Broecker, 1996).”

“Average temperature changes of 101 per century (and, in some cases, significant changes per decade) have been inferred (Anklin & Barnola, 1993; Broecker, 1996; Ditlevsen, Svensmark, & Johnsen, 1996; Lehman, 1993).”

“Reducing greenhouse gases reduces the effective emitting height of the atmosphere and cools the PA4024 LOVING AND VALLIS: GLACIAL CLIMATE VARIABILITY 2 of 19 PA4024 climate, and in our model increasing the planetary emissivity (e) is a parameterization for this.”

“The debate regarding meltwater as playing the dominate role in initiating YD climate change also continues (Alley et al. 1993a; Lowell et al. 1995; Thompson et al. 1995; Broecker 1996; Bard et al. 1997).”

“Although sea-surface temperature (SST) in the western tropical Pacific may have cooled only 2-3'C, SST in the western tropical Atlantic cooled at least 5-6?C (Broecker, 1996). Thompson et al. (1995) suggest South American continental cooling of 5-80C, and provide evidence for highelevation (6,000 m) neotropical coolin…”

“In this context, Broecker (1996) postulated that the southern Polar Front, rather than the Equator, could form the boundary between the ‘‘southern’’ (i.e. Antarctic) and ‘‘northern’’ climate modes.”

“5°C during the Last Glacial Maximum (Broecker 1996).”

“Millennial-scale climate changes20 associated with Northern Hemisphere Heinrich Stadials (HSs) are thought to have a near global-footprint due to the transmission of the signal via the atmospheric and oceanic circulation (e.g. Alley et al., 1999; Hostetler et al., 1999; Broecker, 1996).”

“…with increasing representation of cool and dry climate taxa during colder climatic intervals pre 10.5 kyr, similar to global records, which suggest that prior to the Holocene, temperatures were cooler and conditions were more arid (e.g., Thompson et al., 1995; Broecker,1996; Lea et al., 2000).”

“At present, it is not clear if this difference reflects regional differences in the extent of cooling, or if one group of proxies is misleading (Broecker 1996).”