Subject: NACP report Date: Mon, 24 Sep 2001 15:13:14 -0400 From: Gregg Marland To: nacp@io.harvard.edu CC: harriss@ucar.edu Bob, here is my first cut at a summary of our working group report to the plenary from Boulder. I send it to you and Steve simultaneously because I am leaving on travel on Wednesday. Please feel free to tinker as you will. Steve, I add the last paragraph advisedly. Do with it as you wish, discard it if you like, it just kind of caught my fancy once the idea passed by. Cheers, Gregg North American Carbon Plan Workshop Boulder, Colorado September 4-7, 2001 Working Group Meeting on the Human Aspects of the Global Carbon Cycle A group of 8 met to discuss the human components of the global carbon cycle. Human activities have become an important part of the global carbon cycle and understanding the current carbon balance of North America requires a detailed understanding of the contribution of human activities, particularly CO2 emissions from fossil fuel combustion, but including emissions of methane and carbon monoxide. There are two major aspects to understanding the role of humans in the global carbon cycle. One is a detailed understanding of the spatial and temporal distribution of carbon emissions. Two is a detailed understanding of how activities undertaken to reduce emissions will impact the net flux of greenhouse gases to the atmosphere once full-system impacts are considered. It is the first of these that is of particular interest in the context of the North American Carbon Plan. What is needed is a set of spatially and temporally resolved data bases for human sources of CO2, CH4 and CO. To use these data bases in resolving other questions about the North American carbon cycle will require emissions time series at the finest possible spatial and temporal scales. Emissions from fossil fuel use should include the mix of fuels involved in order to be able to derive the isotopic signature of emissions. We also need a better description of the uncertainties in these values. Discussants felt the issues should be confronted in 3 phases, with phase 1 focusing on emissions data on a scale on the order of monthly and U. S. counties. Phases 2 and 3 would provide further insight into the diurnal and weekly cycles and into understanding the linkages between human-system emissions and the climate system. It is clear, for example, that hot summer days are related to increased use of air conditioning. Can we describe the climate related linkage to emissions, the Q10 of humans? Intensive campaigns will probably require time and site-specific evaluation of human sources of greenhouse gases. Emissions from large point sources, for example, can be highly variable on small temporal and spatial scales as power plants are taken down for maintenance and adjusted to meet load demand. In the context of specific focused campaigns to understand the functioning of the North American carbon cycle, it may be possible to think in terms of human emissions as a variable that might be manipulated. And, just as a wild idea from me, humans are involved at a significant scale in moving carbon from one place to another. That is, crops photosynthesize in one place and humans respire in quite another. Is this translocation important? If the city of Chicago has 2.9 million people and an area of 228 square miles (60,000 hectares), and if people respire at an average rate of 1 kg CO2/person/day (depending, of course, on diet, health, activity, temperature, etc.), this amounts to a net average flux, from human respiration, of 5 t C/ha/yr for the city of Chicago. ---------------------------------------------------------------------- Gregg Marland 865-241-4850 phone Environmental Sciences Division 865-574-2232 fax Oak Ridge National Laboratory gum@ornl.gov Oak Ridge, TN 37831-6335 USA