[geo] Springtime atmospheric energy transport and the control of Arctic summer sea-ice extent : Nature Climate Change
Poster's note : cloud seeding looks like it could be a geoengineering Intervention worth investigating. It may be possible to do this over Greenland, thus replenishing the ice sheet. There will likely be secondary albedo benefits from the fresh snow thus formed. http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate1884.html Springtime atmospheric energy transport and the control of Arctic summer sea-ice extent Marie-Luise Kapsch, Rune Grand Graversen Michael Tjernström Nature Climate Change (2013) doi:10.1038/nclimate1884 Published online 28 April 2013 The summer sea-ice extent in the Arctic has decreased in recent decades, a feature that has become one of the most distinct signals of the continuing climate change. However, the inter-annual variability is large—the ice extent by the end of the summer varies by several million square kilometres from year to year. The underlying processes driving this year-to-year variability are not well understood. Here we demonstrate that the greenhouse effect associated with clouds and water vapour in spring is crucial for the development of the sea ice during the subsequent months. In years where the end-of-summer sea-ice extent is well below normal, a significantly enhanced transport of humid air is evident during spring into the region where the ice retreat is encountered. This enhanced transport of humid air leads to an anomalous convergence of humidity, and to an increase of the cloudiness. The increase of the cloudiness and humidity results in an enhancement of the greenhouse effect. As a result, downward long-wave radiation at the surface is larger than usual in spring, which enhances the ice melt. In addition, the increase of clouds causes an increase of the reflection of incoming solar radiation. This leads to the counter-intuitive effect: for years with little sea ice in September, the downwelling short-wave radiation at the surface is smaller than usual. That is, the downwelling short-wave radiation is not responsible for the initiation of the ice anomaly but acts as an amplifying feedback once the melt is started. -- You received this message because you are subscribed to the Google Groups geoengineering group. To unsubscribe from this group and stop receiving emails from it, send an email to geoengineering+unsubscr...@googlegroups.com. To post to this group, send email to geoengineering@googlegroups.com. Visit this group at http://groups.google.com/group/geoengineering?hl=en. For more options, visit https://groups.google.com/groups/opt_out.
[geo] NOAA Seminar
Note the following NOAA seminar is coming up tomorrow: Ocean Fertilization, Marine Geoengineering and the London Convention/London Protocol http://www.nodc.noaa.gov/seminars/2013/04-apr.html#OneNOAAScienceSeminars_3 0Apr2013_NODCLIB April 30, 2013; 12:00-13:00 Eastern Time; NOAA HQ SSMC-3 http://www.nodc.noaa.gov/seminars/OneNOAA_Seminar_Locations.html#SSMC Library; (Add to Google Calendar https://www.google.com/calendar/event?action=TEMPLATEtmeid=Y3B0bThyNDcyaXZ idGo0ajZrcHExbXRwbjggbm9hYS5nb3ZfNDk0NDMyMzQzNjMzMzJAcmVzb3VyY2UuY2FsZW5kYXI uZ29vZ2xlLmNvbQtmsrc=noaa.gov_49443234363332%40resource.calendar.google.com ) Mike -- You received this message because you are subscribed to the Google Groups geoengineering group. To unsubscribe from this group and stop receiving emails from it, send an email to geoengineering+unsubscr...@googlegroups.com. To post to this group, send email to geoengineering@googlegroups.com. Visit this group at http://groups.google.com/group/geoengineering?hl=en. For more options, visit https://groups.google.com/groups/opt_out.
[geo] New NRC study on Geoengineering
Dear Colleagues: The Board on Atmospheric Science and Climate is pleased to announce the formation of a new study committee, the Geoengineering Climate: Technical Evaluation and Discussion of Impacts. This committee is charged to evaluate what is currently known about the science of proposed climate geoengineering techniques, including potential risks and consequences, such as impacts, or lack thereof, on ocean acidification; describe what is known about the viability for implementation of the proposed techniques including technological and cost considerations; briefly explain other geoengineering technologies that have been proposed (beyond the selected examples); and identify research needed to provide a credible scientific underpinning for future discussions. The committee's statement of task and details about the members are available at: https://www8.nationalacademies.org/cp/CommitteeView.aspx?key=49540 Public comments may be submitted to the NRC via this site. Sincerely, Ed P.S. Apologies if you receive multiple copies of this announcement. Edward Dunlea, Ph.D. Senior Program Officer Board on Atmospheric Sciences and Climate The National Academy of Sciences 202-334-1334 edun...@nas.edumailto:edun...@nas.edu -- You received this message because you are subscribed to the Google Groups geoengineering group. To unsubscribe from this group and stop receiving emails from it, send an email to geoengineering+unsubscr...@googlegroups.com. To post to this group, send email to geoengineering@googlegroups.com. Visit this group at http://groups.google.com/group/geoengineering?hl=en. For more options, visit https://groups.google.com/groups/opt_out.
Re: [geo] New NRC study on Geoengineering
Note that there is an accompanying page on project scope: https://www8.nationalacademies.org/cp/projectview.aspx?key=49540 I think it was wise to focus on examining 3 or 4 exemplars rather than trying to define or address an exhaustive scope. I am sure the support from the U.S. Intelligence Community will no doubt set the hearts and minds of the conspiracy theorists aflutter. I condemn the torture, widespread drone attacks, etc, routinely engaged in by the U.S. Intelligence Community since 2001, and so would not participate if I did not genuinely believe that this panel will contribute to risk reduction. My understanding, based on hearsay and not solid information, is that a key risk they seek to understand is the magnitude of the threat from actors who might want to engage in rogue geoengineering projects. Project Scope An ad hoc committee will conduct a technical evaluation of a limited number of proposed geoengineering techniques, including examples of both solar radiation management (SRM) and carbon dioxide removal (CDR) techniques, and comment generally on the potential impacts of deploying these technologies, including possible environmental, economic, and national security concerns. The study will: 1. Evaluate what is currently known about the science of several (3-4) selected example techniques, including potential risks and consequences (both intended and unintended), such as impacts, or lack thereof, on ocean acidification, 2. Describe what is known about the viability for implementation of the proposed techniques including technological and cost considerations, 3. Briefly explain other geoengineering technologies that have been proposed (beyond the selected examples), and 4. Identify future research needed to provide a credible scientific underpinning for future discussions. The study will also discuss historical examples of related technologies (e.g., cloud seeding and other weather modification) for lessons that might be learned about societal reactions, examine what international agreements exist which may be relevant to the experimental testing or deployment of geoengineering technologies, and briefly explore potential societal and ethical considerations related to geoengineering. This study is intended to provide a careful, clear scientific foundation that informs ethical, legal, and political discussions surrounding geoengineering. The project has support from the National Academy of Sciences and the U.S. Intelligence Community. The approximate start date for the project is March 2013; a report is expected be issued in fall 2014. _ Ken Caldeira Carnegie Institution for Science Dept of Global Ecology 260 Panama Street, Stanford, CA 94305 USA +1 650 704 7212 kcalde...@carnegiescience.edu http://dge.stanford.edu/labs/caldeiralab @kencaldeira *Caldeira Lab is hiring postdoctoral researchers.* *http://dge.stanford.edu/labs/caldeiralab/Caldeira_employment.html* Our YouTube videos http://www.youtube.com/user/CarnegieGlobEcology/videos On Mon, Apr 29, 2013 at 1:53 PM, Rau, Greg r...@llnl.gov wrote: Dear Colleagues: The Board on Atmospheric Science and Climate is pleased to announce the formation of a new study committee, the Geoengineering Climate: Technical Evaluation and Discussion of Impacts. This committee is charged to evaluate what is currently known about the science of proposed climate geoengineering techniques, including potential risks and consequences, such as impacts, or lack thereof, on ocean acidification; describe what is known about the viability for implementation of the proposed techniques including technological and cost considerations; briefly explain other geoengineering technologies that have been proposed (beyond the selected examples); and identify research needed to provide a credible scientific underpinning for future discussions. The committee's statement of task and details about the members are available at: https://www8.nationalacademies.org/cp/CommitteeView.aspx?key=49540 Public comments may be submitted to the NRC via this site. Sincerely, Ed P.S. Apologies if you receive multiple copies of this announcement. Edward Dunlea, Ph.D. Senior Program Officer Board on Atmospheric Sciences and Climate The National Academy of Sciences 202-334-1334 edun...@nas.edu -- You received this message because you are subscribed to the Google Groups geoengineering group. To unsubscribe from this group and stop receiving emails from it, send an email to geoengineering+unsubscr...@googlegroups.com. To post to this group, send email to geoengineering@googlegroups.com. Visit this group at http://groups.google.com/group/geoengineering?hl=en. For more options, visit https://groups.google.com/groups/opt_out. -- You received this message because you are subscribed to the Google Groups geoengineering group. To unsubscribe from this group and stop receiving emails from it, send an email
[geo] membership of NRC committee on Geoengineering Climate
Project Title:Geoengineering Climate: Technical Evaluation and Discussion of Impacts PIN:DELS-BASC-12-04 Major Unit: Division of Behavioral and Social Sciences and Educationhttp://www7.nationalacademies.org/dbasse Division on Earth and Life Studies http://dels.nas.edu/ Sub Unit:Board on Environmental Change and Societyhttp://sites.nationalacademies.org/dbasse/becs Ocean Studies Board http://dels.nas.edu/osb Board on Atmospheric Sciences Climatehttp://www7.nationalacademies.org/basc RSO: Dunlea, Edward Subject/Focus Area: Earth Sciences; Engineering and Technology Committee MembershipDate Posted: 04/25/2013 *Dr. Marcia K. McNutt - (Chair) University of California, San Diego * Dr. Marcia K. McNutt is the former Director of the U.S. Geological Survey and currently has a visiting appointment at the Scripps Institution of Oceanography. She is a member of the National Academy of Sciences, the American Philosophical Society, and the American Academy of Arts and Sciences. She was awarded by the American Geophysical Union the Macelwane Medal in 1988 for research accomplishments by a young scientist and the Maurice Ewing Medal in 2007 for her significant contributions to deep-sea exploration. She holds honorary doctoral degrees from the University of Minnesota, Colorado College, Monmouth University, and Colorado School of Mines. Dr. McNutt received her Ph.D. in Earth Sciences from Scripps Institution of Oceanography. *Dr. Waleed Abdalati University of Colorado Boulder * Dr. Waleed Abdalati is a Fellow in the Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado, a Professor in the Department of Geography, and Director of the Earth Science and Observation Center (ESOC). ESOC is an interdisciplinary research and teaching center focused on the development and application of remote sensing observations in order to advance scientific understanding of the Earth. In 2011 and 2012 he was on a leave of absence from the University to serve as the Chief Scientist at NASA. In this role he oversaw the full portfolio of NASA science activities and served as advisor on agency science matters to the NASA Administrator and NASA leadership. His research has focused on the study of polar ice cover using satellite and airborne instruments. During his initial tenure at NASA from 1998-2008 held a variety of positions in the areas of scientific research, program management, scientific management, mission science oversight, etc. Prior to his joining NASA, he worked as an engineer in the aerospace industry. Dr. Abdalati received a B.S. in Mechanical Engineering from Syracuse University in 1986, a M.S. in Aerospace Engineering and a Ph.D. in Geography from the University of Colorado in 1991 and 1996 respectively. *Dr. Ken Caldeira Carnegie Institution of Washington * Dr. Ken Caldeira is a senior member of the Carnegie Institution’s Department of Global Ecology staff and a Professor, by courtesy, in Stanford’s Environmental Earth System Sciences department. Dr. Caldeira has a wide-spectrum approach to analyzing the world’s climate systems. He studies the global carbon cycle; marine biogeochemistry and chemical oceanography, including ocean acidification and the atmosphere/ocean carbon cycle; land-cover and climate change; the long-term evolution of climate and geochemical cycles; and energy technology. He was a co-author of the 2010 US National Academy America's Climate Choices report. He participated in the UK Royal Society geoengineering panel in 2009 and ocean acidification panel in 2005. He was a lead author of the 2007 U.S. “State of the Carbon Cycle Report. Caldeira was invited by the National Academy of Sciences Ocean Studies Board to deliver the 2007 Roger Revelle Lecture, “What Coral Reefs Are Dying to Tell Us About CO2 and Ocean Acidification.” In 2010, Caldeira was elected Fellow of the American Geophysical Union. *Dr. Scott C. Doney Woods Hole Oceanographic Institution * Dr. Scott Doney is a Senior Scientist in the Department of Marine Chemistry and Geochemistry at the Woods Hole Oceanographic Institution (WHOI). He graduated with a BA in chemistry from the University of California, San Diego in 1986 and a PhD in chemical oceanography from the Massachusetts Institute of Technology/Woods Hole Oceanographic Institution Joint Program in Oceanography in 1991. He was a postdoctoral fellow and later a scientist at the National Center for Atmospheric Research, before returning to Woods Hole in 2002. He was awarded the James B. Macelwane Medal from the American Geophysical Union in 2000, a Aldo Leopold Leadership Fellow in 2004, and the WHOI W. Van Alan Clark Sr. Chair in 2007. He is an AGU Fellow (2000) and a AAAS Fellow (2010). His science interests span oceanography, climate and biogeochemistry. Much of his research focuses on how the global carbon cycle and ocean ecology respond to natural and human-driven climate change. A key focus is on ocean acidification due to the
Re: [geo] RE: Biochar: Downstream effects
Excellent question! math intuition says that could have a huge albedo effect. Such an effect might be teased out from the archive of satellite ocean color observations. It should be easy to answer whether the ocean is, overall, getting darker with time. --- Fred Zimmerman Geoengineering IT! Bringing together the worlds of geoengineering and information technology GE NewsFilter: http://geoengineeringIT.net:8080 On Sun, Apr 28, 2013 at 8:43 PM, Andrew Lockley andrew.lock...@gmail.comwrote: Does it make the oceans darker? A On 21 April 2013 01:39, rongretlar...@comcast.net wrote: Greg and list: I have tried to figure out whether this paper by Jaffe et al is apt to harm or help the introduction of biochar. My perception is that Jaffe and co-authors see a fairly strong connection to biochar, but I am not so sure. There is so little biochar in place that what was being measured was almost entirely from forest fires, which char can be very different from what is now being tested . The persons at NSF who wrote up the press release (below) certainly tied this article in to biochar development. For those who don't subscribe to Science, here is what Jaffe etal said about biochar - 4 sentences in the last part of the last paragraph (with my comments on each in bold): 1. Bio-char applications to soils have been proposed as an effective means of carbon sequestration (30). RWL1: Certainly true and non controversial. (30) is J. Lehmann, J. Gaunt, M. Rondon, Mitig. Adapt. Strat. Gl. 11, 403 (2006) and is a good early background reference (at a time before biochar received its present name). 2. This activity may further enhance the translocation and export of DBC to marine systems. [RWL2: Also true - but equally true could be may not. The key is whether the material now ending up as DBC is more apt to be used by microbes and fungus - ending up mostly as CO2.Biochar literature says almost nothing about DBC, except that it is small. Char is presently used to absorb (not release) the polyaromatic compounds that I gather are being measured to compute DBC. 3. The environmental consequences of this are presently unknown but may be reflected in the reduction of DOC bioavailability and associated effects on microbial loop dynamics and aquatic food webs. [RWL3: Again, I think the key word is may. Biochar is being promoted to increase terrestrial biomass. In the Amazon, terra preta soils have double and triple the soil productivity - so maybe there will be also increased DOC bioavailability. It also seems likely that a world with much biochar will have fewer and smaller forest fires. Also char, being placed deep in soils, will generally not be found as much in surface runoff as will char from forest fires. 4. Our data suggest that we apply our existing knowledge on DOC production, storage, and movement in soils to ensure that biochar applications are implemented sustainably and managed in ways to minimize riverine DBC fluxes. [RWL4: This is a welcome offer to help investigate the biochar connection further. But I felt that DOC was being welcomed for ocean health reasons, and so if DOC and DBC are closely coupled, maybe there is a way for biochar to optimize both. Biochar is getting credit for preventing the release of excess fertilizers that are certainly harming ocean health, as well as wasting scarce farm-owner funds. Biochar's optimum temperature may be tunable to help in this tradeoff, if further research shows there is need for one. Part B Science magazine also has an introductory piece (p 287-288 ) in this same issue, by Rice University Prof. Caroline Massielo. Besides authoring five of the Jaffe etal cites, Dr. Masiello heads a biochar department at Rice and has authored numerous biochar papers. In her final four-sentence paragraph she says about the connection to biochar: 5. Jaffé et al. mention that biochar soil amendment may have unintended consequences through increased transport of DBC into aquatic and marine systems, with downstream impacts on aquatic food webs. [RWL5. It is not clear to me whether she is referencing positive or negative consequences/impacts. I am pretty sure that in most soils, the char is retaining, not releasing, dissolved carbon compounds. 6.These possibilities must be taken seriously. [RWL6: So perhaps the possibilities are mostly seen as negative - mostly thinking I guess of carcinogenic PAH compounds 7. The successful scaling-up of biochar soil amendment will require assessment of the fate of biochar carbon both in the solid and dissolved phases. [RWL7: Dr. Masiello is raising the additional topic of biochar proponents wanting long biochar lifetime - both solid and
Re: [geo] RE: Biochar: Downstream effects
List: cc Greg, Andr Fred 1. This topic is receiving viral attention in biochar circles. I understand there will be a response soon at the site www.biochar-internatonal.org I have been part of dialogs with several of the Science articles authors, and do not perceive now that great concern is warranted.by biochar proponents (like myself). I am now reading two of the author-provided background papers and will come back if I find anything new besides the following. Here is a probably pertinent quote from one of these background papers : Photo-lability of deep ocean dissolved black carbon A. Stubbins1, J. Niggemann2, and T. Dittmar2 : Biogeosciences, 9, 1661–1670, 2012 Scaling the rapid photodegradation of DBC to rates of DOC photo-mineralisation for the global ocean leads to an estimated photo-chemical half-life for oceanic DBC of less than 800 years. This is more than an order of magnitude shorter than the apparent age of DBC in the ocean. These quoted ages of the ocean DBC reassures me more about the recalcitrance of bochar. 2. Andrew asked about the color of these higher temperature carbon hydrogen compounds (there are hundreds). At this site: http://www.indianalivinggreen.com/polycyclic-aromatic-hydrocarbons/ was this sentence: The color of PAHs can vary from colorless to yellow-green. I cite this mainly to hope others on this list can provide more authoritative color data. This is a new topic in the biochar world. 3. Fred asked about learning something abut biochar by looking at a time-history of ocean color. Maybe, but there has been so little biochar added to soil and we think such a small fraction ever makes it to the ocean, that it should be difficult to tie anything historical to biochar. Biochar will be placed more carefully below surface (for economic reasons) than will occur for most lightning-generated char. 4. One of the biochar analysts looking at this today noted the issue of soil erosion. This next sentence came from a Wiki Each year, about 75 billion tons of soil is eroded from the land—a rate that is about 13-40 times as fast as the natural rate of erosion. Biochar proponents claim that biochar will help prevent erosion by improving tilth. This erosion release probably increased ocean albedo - but do we want that? 5. My guess (nothing more at this point) is that this will not be a show-stopper for biochar. But I welcome hearing other opinions, as this topic has already been used negatively. That was not the intent of the authors. Ron - Original Message - From: Fred Zimmerman geoengineerin...@gmail.com To: Andrew Lockley andrew.lock...@gmail.com Cc: Ronal Larson rongretlar...@comcast.net, Greg Rau r...@llnl.gov, geoengineering geoengineering@googlegroups.com Sent: Monday, April 29, 2013 6:33:46 AM Subject: Re: [geo] RE: Biochar: Downstream effects Excellent question! math intuition says that could have a huge albedo effect. Such an effect might be teased out from the archive of satellite ocean color observations. It should be easy to answer whether the ocean is, overall, getting darker with time. --- Fred Zimmerman Geoengineering IT! Bringing together the worlds of geoengineering and information technology GE NewsFilter: http://geoengineeringIT.net:8080 On Sun, Apr 28, 2013 at 8:43 PM, Andrew Lockley andrew.lock...@gmail.com wrote: Does it make the oceans darker? A On 21 April 2013 01:39, rongretlar...@comcast.net wrote: Greg and list: I have tried to figure out whether this paper by Jaffe et al is apt to harm or help the introduction of biochar. My perception is that Jaffe and co-authors see a fairly strong connection to biochar, but I am not so sure. There is so little biochar in place that what was being measured was almost entirely from forest fires, which char can be very different from what is now being tested . The persons at NSF who wrote up the press release (below) certainly tied this article in to biochar development. For those who don't subscribe to Science, here is what Jaffe etal said about biochar - 4 sentences in the last part of the last paragraph (with my comments on each in bold): 1. Bio-char applications to soils have been proposed as an effective means of carbon sequestration (30). RWL1: Certainly true and non controversial. (30) is J. Lehmann, J. Gaunt, M. Rondon, Mitig. Adapt. Strat. Gl. 11, 403 (2006) and is a good early background reference (at a time before biochar received its present name). 2. This activity may further enhance the translocation and export of DBC to marine systems. [RWL2: Also true - but equally true could be may not. The key is whether the material now ending up as DBC is more apt to be used by microbes and fungus - ending up mostly as CO2. Biochar literature says almost nothing about DBC, except that it is small. Char is presently used to absorb (not release) the polyaromatic
[geo] Warming-induced increase in aerosol number concentration likely to moderate climate change
Warming-induced increase in aerosol number concentration likely to moderate climate change * Pauli Paasonenhttp://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#auth-1, * Ari Asmihttp://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#auth-2, * Tuukka Petäjähttp://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#auth-3, * Maija K. Kajoshttp://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#auth-4, * Mikko Äijälähttp://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#auth-5, * Heikki Junninenhttp://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#auth-6, * Thomas Holsthttp://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#auth-7, * Jonathan P. D. Abbatthttp://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#auth-8, * Almut Arnethhttp://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#auth-9, * Wolfram Birmilihttp://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#auth-10, * Hugo Denier van der Gonhttp://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#auth-11, * Amar Hamedhttp://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#auth-12, * András Hofferhttp://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#auth-13, * Lauri Laaksohttp://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#auth-14, * Ari Laaksonenhttp://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#auth-15, * W. Richard Leaitchhttp://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#auth-16, * Christian Plass-Dülmerhttp://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#auth-17, * Sara C. Pryorhttp://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#auth-18, * Petri Räisänenhttp://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#auth-19, * Erik Swietlickihttp://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#auth-20, * Alfred Wiedensohlerhttp://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#auth-21, * Douglas R. Worsnophttp://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#auth-22, * Veli-Matti Kerminenhttp://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#auth-23 *Markku Kulmalahttp://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#auth-24 * Affiliationshttp://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#affil-auth * Contributionshttp://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#contrib-auth * Corresponding authorhttp://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#corres-auth Nature Geoscience (2013) doi:10.1038/ngeo1800 Received 01 October 2012 Accepted 14 March 2013 Published online 28 April 2013 Atmospheric aerosol particles influence the climate system directly by scattering and absorbing solar radiation, and indirectly by acting as cloud condensation nuclei1http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#ref1, 2http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#ref2, 3http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#ref3, 4http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#ref4. Apart from black carbon aerosol, aerosols cause a negative radiative forcing at the top of the atmosphere and substantially mitigate the warming caused by greenhouse gases1http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#ref1. In the future, tightening of controls on anthropogenic aerosol and precursor vapour emissions to achieve higher air quality may weaken this beneficial effect5http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#ref5, 6http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#ref6, 7http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#ref7. Natural aerosols, too, might affect future warming2http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#ref2, 3http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#ref3, 8http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#ref8, 9http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#ref9. Here we analyse long-term observations of concentrations and compositions of aerosol particles and their biogenic precursor vapours in continental mid- and high-latitude environments. We use measurements of particle number size distribution together with boundary layer heights derived from reanalysis data to show that the boundary layer burden of cloud condensation nuclei increases exponentially with temperature. Our results confirm a negative feedback mechanism between the continental biosphere, aerosols and climate: aerosol cooling effects are strengthened by rising biogenic organic vapour emissions in response to warming,
