Michael R. Raupach (1950-2015)
Mike Raupach’s contribution to carbon cycle research has been exceptional.
Trained in physical sciences, Mike initially focused on understanding turbulent flows in vegetation canopies and the transport of heat, water, carbon dioxide and trace gases. He quickly recognized the great benefits that could come from coupling the carbon and water cycles. His work contributed to the recent recognition of the role of semi-arid regions in driving the large interannual variability of atmospheric CO2.
Mike pioneered research showing how global carbon emissions have tracked the most carbon– intensive scenarios of the Intergovernmental Panel on Climate Change up to recently. He also identified how a century-old decline in the carbon intensity of the global economy ceased as emerging economies took center stage in the growth of the global economy.
Mike reconciled the views of several researchers who had published conflicting evidence on the influence of climate change on recent trends in the land and ocean carbon sinks. For decades this question had been informed by the so-called ‘airborne fraction’, the fraction of CO2 emissions that remained in the atmosphere. However, trends in the airborne fraction are influenced by a number of factors that are difficult to disentangle, in particular the natural climate variability, the uncertain fraction of emissions from land-use change, and the influence of emissions trajectory on growth in atmospheric CO2. Mike provided a formal decomposition of the contribution of each factor and showed that the land and ocean carbon sinks have already responded to climate change in a way that reduces their capacity to take up CO2.
Mike also tackled one of today’s most difficult climate policy questions: how to share a finite quota of cumulative carbon emissions in order to limit average global warming to below 2°C. His analysis quantifies the sharing options available to inform practical policy decisions with, on the one hand, a full equity world, and on the other hand, continuation of the status quo. It thus provides a framework for policymakers to ask: ‘if others acted consistently with our proposed share of the carbon quota (i.e. in the same way as us), would the global outcome be acceptable to us?’ It also contributed to making explicit the gap between the cumulative carbon quota available and fossil fuel reserves at the global and local scales.
Mike provided intellectual leadership both in research and in making scientific research more relevant for society. One of his most important contributions to carbon cycle research was as co-founder of the Global Carbon Project in the early 2000s, which he co-Chaired between 2000 and 2008, designing and implementing its science framework. Mike also edited (with Chris Field) the book The Global Carbon Cycle: Integrating Humans, Climate, and the Natural World (2004), which provided a new, more extensive interdisciplinary framework to align research on the natural carbon cycle in the context of its human drivers.
Beyond his scientific contributions, Mike was an example of integrity, clarity of purpose, and humility, from which we all benefited. His kindness and approachability made him a wonderful person to work and be with; he inspired and touched many colleagues and friends.
(March 2016, C. Le Quéré)