From jimr@gps.caltech.edu Tue Oct 23 22:14:35 2001 Date: Sun, 30 Sep 2001 22:11:40 -0500 From: Jim Randerson To: nacp@python.as.harvard.edu, nacp@io.harvard.edu Cc: oxelson@ucar.edu Subject: comments/text on NACP - fossil fuels, atm. strategy, wetlands Dear Steve, Here is some text for possible incorporation into the next draft, and some comments to add to the ongoing dialogue on the website. Sincerely, Jim Fossil emissions (adding to text from Marland and Harriss): An error of only 10% in fossil fuel emission estimates may have comparable size to the terrestrial carbon sink for North America. Errors in fossil emissions, particularly their spatial and seasonal distributions, need to be reduced by an order of magnitude for efficient use of aircraft and remote atmospheric observations of carbon sinks. Achieving this will require forging new collaborations between energy industries and the scientific community over the next decade. Several aspects of fossil fuel emissions currently limit our understanding of the carbon cycle, including their spatial distribution, time evolution, and chemical composition. In many regions of North America, the bulk of emissions may occur in the free troposphere from aircraft. On a seasonal basis, it is not clear if the northern part of Canada and Alaska have higher emissions in summer (from greater economic activity) or winter (from greater heating demand). The chemical composition of fossil fuels affects the use of oxygen and carbon isotopes as tracers of terrestrial and oceanic carbon sinks, yet we know little about how the chemical composition changes spatially or seasonally over the North American continent. These types of information are also of immense interest to those studying regional pollution and deposition of compounds such as nitric acid (which affect ecosystem function). It is insufficient to know only the combination of fuel types (oil, gas, and coal) as in the past; the chemical and isotopic composition of each of these components can vary widely depending on the particular deposit or oil field. For phase 1 of the North American Field Campaign, gridded monthly products are required for the entire North American continent, possibly at the county level. Other useful products would include a mean diurnal cycle of emission at a regional scale, high resolution isotope products, and the stochiometery of C,H,O,N,S for assessing the contribution of fossil fuels to changes in atmospheric oxygen. Developing a collaboration with energy industries will be critical for components of the North American carbon program that extend over longer timeframes. It is critical that as we develop a long-term carbon plan, we have the mechanisms in place for near real time transfer of emissions data to scientists and policy makers. Without this information, design of conservation (efficiency more bland) measures will be hindered, and estimates by the scientific community of biological sinks may be limited in their accuracy. Attribution of mechanism would also be compromised. For example, if temperatures during the North American summer field campaign were anomalously high, increased use of air-conditioning across the central U.S. could be falsely attributed to greater metabolic activity from soil microbes. Comments on Atmospheric Sampling Strategy With respect to the current design of the North American Carbon Program and the INEX program described by Jacob, much of the effort seems to be going towards building a fencepost along the two coasts of the U.S. While the jet stream over North America proceeds from west to east, its seems like almost all of the back trajectory calculations at the surface (presented at the NACP meeting) show strong entrainment of air from Canada and Alaska in the northern part of the U.S., and from the Gulf of Mexico in the southern part of the U.S. I would just like to reiterate one of the points made at the meeting: that our communities need to carefully evaluate mass transfer into and out of the lowest levels of the atmosphere over the North America continent before resources are committed to different regional aircraft campaigns. We need to solicit the atmospheric community for information on the following questions: how does mass enter and leave the lowest levels of the atmosphere each month over the continent and how do these flows change during different phases of ENSO and the NAO. Fence posts across the width of Canada and Mexico may provide a more interesting and meaningful story. Text for Wetlands section (building on comments from Roulet and Crill) About one-third of the carbon in the U.S. resides in Alaska (A.D.McGuire, personal communication). Much of this carbon resides in wetlands and other poorly drained ecosystems such as those with underlying permafrost. Changes in the hydrologic status of these ecosystems will determine carbon storage or loss over the next century. Because fire and other disturbances (building roads) have such a profound influence on the surface energy balance and thus drainage characteristics of these ecosystems, they may be one of the primary agents that precipitate change.