Global atmospheric measurements of CO2, CH4, CO, H2, N2O, SF6, and isotopic ratios in several of those species. Numerical models of atmospheric transport. Field measurements of air-sea gas exchange.
Pieter Tans has been actively interested in mankind's influence on climate since he was a student. Convinced that man-made climate change was a problem certain to grow in importance over time, he changed direction from solid state physics to Earth sciences. His PhD study used carbon-14 and carbon-13 in tree rings to reconstruct the increase of atmospheric carbon dioxide since the late 19th century. As part of this work he developed a new way to calculate the behavior of CO2 isotopic ratios, separating the influence of net exchange of total carbon between Earth reservoirs from pure isotopic exchange in which 12CO2 and 13CO2 molecules are exchanged between air and water, for example, without changing total carbon in either reservoir. This formalism to deal with isotopic exchange is now universally followed in the field.
Pieter led the National Oceanic and Atmospheric Administration (NOAA) Carbon Cycle Greenhouse Gases group from 1985 until 2019. He discovered the existence of a very large sink (uptake) of CO2 by terrestrial ecosystems at mid-latitudes in the northern hemisphere, partially offsetting the emissions caused by the burning of coal, oil, and natural gas. Over four decades the carbon cycle group has maintained what we now call NOAA鈥檚 (GGGRN), producing the most widely used data of atmospheric CO2, CH4, and several other greenhouse gases.
Since 1991, and still ongoing, we have had a very close collaboration between the NOAA GGGRN and INSTAAR's Stable Isotope Laboratory. This resulted in global measurements of 13C/12C and 18O/16O ratios in CO2 and 13C/12C and D/H ratios in CH4, which can unravel the contribution of different source types to the observed trends. In 2004 a similar cooperation started between GGGRN and INSTAAAR's AMS Radiocarbon Preparation & Research Lab for measurements of the 14C/total C ratio in atmospheric CO2, which uniquely separates the recent emissions of fossil fuel CO2 from other sources.
GGGRN is also active in the development of , a global measurement and modeling system developed to keep track of sources (emissions to the atmosphere) and sinks (removal from the atmosphere) of carbon dioxide around the world. A version of CarbonTracker for methane (CH4) has also been developed, as well as CarbonTracker-Lagrange (CT-L), a regional inverse modeling framework designed for estimating North American greenhouse gas emissions and uptake fluxes.
Inspired by the observation that 90 year old air was present near the bottom of the firn layer at South Pole, despite being in contact with today鈥檚 atmosphere, Pieter invented the AirCore in 2002. It is a 100-150 m long coiled tube hoisted by balloon to 30 km altitude. One side is open, the other end is closed. It is initially filled with a known reference gas that streams out from the open end during ascent to lower pressures. During the subsequent descent by parachute, atmospheric air streams back in, providing a continuous sample from 30 km to the surface.
Education
- PhD: University of Groningen, 1978
Awards
- Fellow, American Association for the Advancement of Science (AAAS), 2011
- Roger Revelle Medal, American Geophysical Union, 2010
- Fellow, American Geophysical Union (AGU), 2004
- Corresponding Member, Royal Netherlands Academy of Arts and Sciences, 1995
