More recent reconstructions suggest far more cooling than the original CLIMAP numbers, though there is still some residual uncertainty. In order to accommodate the temperature changes implied by the land evidence, one would have needed cooling of ∼5☌, implying a larger climate sensitivity (and larger tropical sensitivity) (Rind and Peteet, 1985). By incorporating the warm CLIMAP SST values into the GCM, we showed that the global mean cooling was only 3.7☌, and implied land temperatures that did not match the data in the tropics. We (Dorothy and David) compiled terrestrial data (pollen and glacial records) around the globe that were in direct conflict with this view, indicating much colder temperatures. The prevailing view, from the CLIMAP (1976) reconstruction, was that tropical cooling was muted during the last Ice Age and that subtropical temperatures may even have been warmer than today. These issues related directly to the heart of much of GISS's efforts to constrain climate sensitivity. Both his and Jim's foresight have been vindicated in subsequent decades.Īlso in the early 1980s, Wally suggested that Dorothy Peteet and David Rind pursue the question of the tropical temperature changes during the Last Glacial Maximum with climate models. Those choice words were distinctly Wally's style. In characteristic form, Wally pushed back in a letter that “Hansen's group might be referred to as the Avis of climate modeling”, while the criticisms came from “Rent-A-Wreck”. Richard Kerr, then a Science news reporter, described in a 1989 Science Research News piece multiple criticisms and community unease related to Jim's testimony from participants at a meeting in Amherst in May of that year. Later, shortly after Jim Hansen's now famous 1988 Congressional testimony, Wally showed his support of the work done by Jim and others here at GISS. This figure superimposes (red line) the GISTEMP temperature anomaly on Fig. This tactic was complementary to the approach at GISS, where the focus was to use computers to create a simulated climate model “laboratory” (with our knowledge of the rest of the climate system built-in) to quantify and test these same concepts.Įvaluation of Broecker's 1975 projection of global warming: He was both a dreamer and experimental pragmatist for understanding mechanisms of climate change, and his strong background in geochemistry often led to insightful, zeroth-order “back of the envelope calculations” (such as the use of the Camp Century ice core “cycles” for the internal variability). Comparing the two papers points to the main differences of style Wally's ideas were often far-reaching and innovative, but slightly ad hoc. (1981), which attempted to quantify more exactly what ongoing greenhouse gas increases meant in terms of global mean temperature. Wally's paper was published six years before the landmark GISS publication of Hansen et al. In 1975, Wally published the paper “ Climatic Change: Are We on the Brink of a Pronounced Global Warming?” In this work, he deftly combined early GISS work on the climate impact of atmospheric aerosols (Rasool and Schneider, 1971) with CO 2 calculations from the NOAA Geophysical Fluid Dynamics Laboratory (Manabe and Wetherald, 1967) and threw in an estimate for natural variability from an ice core (Dansgaard et al., 1971) to predict a 1.1☌ warming in 2010 - startlingly close to the warming that actually occurred (see e.g., GISTEMP) although Wally himself said in 2017 that the agreement was "dumb luck". Over the decades, Wally's work in part covered much of the same terrain as GISS, though sometimes with a different slant. Over the years, Wally co-authored more than a dozen papers with GISS authors, but influenced far more. His fundamentally iterative approach focused on developing ideas from disparate sources of real data, testing them with models, and then rigorously examining those conclusions as more data became available and more modeling was done. Wally had an especially profound impact on the science and careers of the authors of this piece. Broecker (November 29, 1931-February 18, 2019) was a long-time collaborator, mentor, and sometimes foil to many at the NASA Goddard Institute for Space Studies (GISS), as elsewhere.
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