<div><b style="font-size:13px;color:rgb(34,34,34);font-family:arial,sans-serif;background-color:rgb(255,255,255)">Plants moderate climate warming</b></div><div><br style="color:rgb(34,34,34);font-family:arial,sans-serif;font-size:13px;background-color:rgb(255,255,255)">
</div><div><span class="date">Apr. 28, 2013</span> — As temperatures warm, plants 
release gases that help form clouds and cool the atmosphere, according to 
research from IIASA and the University of Helsinki.</div><div><p id="first"></p><p>The new study, published in <em>Nature Geoscience</em>, identified a negative 
feedback loop in which higher temperatures lead to an increase in concentrations 
of natural aerosols that have a cooling effect on the atmosphere.</p><p>Full article:</p><p><a href="http://www.sciencedaily.com/releases/2013/04/130428144921.htm" target="_blank" style="font-size:13px;color:rgb(17,85,204);font-family:arial,sans-serif;background-color:rgb(255,255,255)">http://www.sciencedaily.com/releases/2013/04/130428144921.htm</a></p>
<p><span style="font-family:Arial,sans-serif"><br></span></p><p><span style="font-family:Arial,sans-serif">-
- - - BASED ON THIS STUDY:</span></p><p></p><p class="MsoNormal"></p><p></p><p></p><h1 class="article-heading"><span style="font-size:small">Warming-induced increase in aerosol number 
concentration likely to moderate climate change</span></h1><p></p><p></p><a name="_GoBack"></a><span style="font-family:'Times New Roman',serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/abs/ngeo1800.html#auth-1"><span class="fn"><span style="font-family:Arial,sans-serif">Pauli Paasonen</span></span></a></span><span class="comma"><span style="font-family:Arial,sans-serif">,</span></span>^{<span style="font-family:Arial,sans-serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#a1">1</a>,<span class="apple-converted-space"> </span><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#a2">2</a>,<span class="apple-converted-space"> </span><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#a17">17</a></span>}<span style="font-family:Arial,sans-serif"> </span><span style="font-family:'Times New Roman',serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/abs/ngeo1800.html#auth-2"><span class="fn"><span style="font-family:"Arial","sans-serif"">Ari Asmi</span></span></a></span><span class="comma"><span style="font-family:Arial,sans-serif">,</span></span>^{<span style="font-family:Arial,sans-serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#a1">1</a>,<span class="apple-converted-space"> </span><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#a17">17</a></span>}<span style="font-family:Arial,sans-serif"> </span><span style="font-family:'Times New Roman',serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/abs/ngeo1800.html#auth-3"><span class="fn"><span style="font-family:"Arial","sans-serif"">Tuukka Petäjä</span></span></a></span><span class="comma"><span style="font-family:Arial,sans-serif">,</span></span>^{<span style="font-family:Arial,sans-serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#a1">1</a></span>}<span style="font-family:Arial,sans-serif"> </span><span style="font-family:'Times New Roman',serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/abs/ngeo1800.html#auth-4"><span class="fn"><span style="font-family:"Arial","sans-serif"">Maija K. Kajos</span></span></a></span><span class="comma"><span style="font-family:Arial,sans-serif">,</span></span>^{<span style="font-family:Arial,sans-serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#a1">1</a></span>}<span style="font-family:Arial,sans-serif"> </span><span style="font-family:'Times New Roman',serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/abs/ngeo1800.html#auth-5"><span class="fn"><span style="font-family:"Arial","sans-serif"">Mikko Äijälä</span></span></a></span><span class="comma"><span style="font-family:Arial,sans-serif">,</span></span>^{<span style="font-family:Arial,sans-serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#a1">1</a></span>}<span style="font-family:Arial,sans-serif"> </span><span style="font-family:'Times New Roman',serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/abs/ngeo1800.html#auth-6"><span class="fn"><span style="font-family:"Arial","sans-serif"">Heikki Junninen</span></span></a></span><span class="comma"><span style="font-family:Arial,sans-serif">,</span></span>^{<span style="font-family:Arial,sans-serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#a1">1</a></span>}<span style="font-family:Arial,sans-serif"> </span><span style="font-family:'Times New Roman',serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/abs/ngeo1800.html#auth-7"><span class="fn"><span style="font-family:"Arial","sans-serif"">Thomas Holst</span></span></a></span><span class="comma"><span style="font-family:Arial,sans-serif">,</span></span>^{<span style="font-family:Arial,sans-serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#a3">3</a></span>}<span style="font-family:Arial,sans-serif"> </span><span style="font-family:'Times New Roman',serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/abs/ngeo1800.html#auth-8"><span class="fn"><span style="font-family:"Arial","sans-serif"">Jonathan P. D. Abbatt</span></span></a></span><span class="comma"><span style="font-family:Arial,sans-serif">,</span></span>^{<span style="font-family:Arial,sans-serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#a4">4</a></span>}<span style="font-family:Arial,sans-serif"> </span><span style="font-family:'Times New Roman',serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/abs/ngeo1800.html#auth-9"><span class="fn"><span style="font-family:"Arial","sans-serif"">Almut Arneth</span></span></a></span><span class="comma"><span style="font-family:Arial,sans-serif">,</span></span>^{<span style="font-family:Arial,sans-serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#a5">5</a></span>}<span style="font-family:Arial,sans-serif"> </span><span style="font-family:'Times New Roman',serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/abs/ngeo1800.html#auth-10"><span class="fn"><span style="font-family:"Arial","sans-serif"">Wolfram Birmili</span></span></a></span><span class="comma"><span style="font-family:Arial,sans-serif">,</span></span>^{<span style="font-family:Arial,sans-serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#a6">6</a></span>}<span style="font-family:Arial,sans-serif"> </span><span style="font-family:'Times New Roman',serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/abs/ngeo1800.html#auth-11"><span class="fn"><span style="font-family:"Arial","sans-serif"">Hugo Denier van der Gon</span></span></a></span><span class="comma"><span style="font-family:Arial,sans-serif">,</span></span>^{<span style="font-family:Arial,sans-serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#a7">7</a></span>}<span style="font-family:Arial,sans-serif"> </span><span style="font-family:'Times New Roman',serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/abs/ngeo1800.html#auth-12"><span class="fn"><span style="font-family:"Arial","sans-serif"">Amar Hamed</span></span></a></span><span class="comma"><span style="font-family:Arial,sans-serif">,</span></span>^{<span style="font-family:Arial,sans-serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#a8">8</a></span>}<span style="font-family:Arial,sans-serif"> </span><span style="font-family:'Times New Roman',serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/abs/ngeo1800.html#auth-13"><span class="fn"><span style="font-family:"Arial","sans-serif"">András Hoffer</span></span></a></span><span class="comma"><span style="font-family:Arial,sans-serif">,</span></span>^{<span style="font-family:Arial,sans-serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#a9">9</a></span>}<span style="font-family:Arial,sans-serif"> </span><span style="font-family:'Times New Roman',serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/abs/ngeo1800.html#auth-14"><span class="fn"><span style="font-family:"Arial","sans-serif"">Lauri Laakso</span></span></a></span><span class="comma"><span style="font-family:Arial,sans-serif">,</span></span>^{<span style="font-family:Arial,sans-serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#a10">10</a>,<span class="apple-converted-space"> </span><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#a11">11</a></span>}<span style="font-family:Arial,sans-serif"> </span><span style="font-family:'Times New Roman',serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/abs/ngeo1800.html#auth-15"><span class="fn"><span style="font-family:"Arial","sans-serif"">Ari Laaksonen</span></span></a></span><span class="comma"><span style="font-family:Arial,sans-serif">,</span></span>^{<span style="font-family:Arial,sans-serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#a8">8</a>,<span class="apple-converted-space"> </span><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#a10">10</a></span>}<span style="font-family:Arial,sans-serif"> </span><span style="font-family:'Times New Roman',serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/abs/ngeo1800.html#auth-16"><span class="fn"><span style="font-family:"Arial","sans-serif"">W. Richard Leaitch</span></span></a></span><span class="comma"><span style="font-family:Arial,sans-serif">,</span></span>^{<span style="font-family:Arial,sans-serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#a12">12</a></span>}<span style="font-family:Arial,sans-serif"> </span><span style="font-family:'Times New Roman',serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/abs/ngeo1800.html#auth-17"><span class="fn"><span style="font-family:"Arial","sans-serif"">Christian Plass-Dülmer</span></span></a></span><span class="comma"><span style="font-family:Arial,sans-serif">,</span></span>^{<span style="font-family:Arial,sans-serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#a13">13</a></span>}<span style="font-family:Arial,sans-serif"> </span><span style="font-family:'Times New Roman',serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/abs/ngeo1800.html#auth-18"><span class="fn"><span style="font-family:"Arial","sans-serif"">Sara C. Pryor</span></span></a></span><span class="comma"><span style="font-family:Arial,sans-serif">,</span></span>^{<span style="font-family:Arial,sans-serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#a14">14</a></span>}<span style="font-family:Arial,sans-serif"> </span><span style="font-family:'Times New Roman',serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/abs/ngeo1800.html#auth-19"><span class="fn"><span style="font-family:"Arial","sans-serif"">Petri Räisänen</span></span></a></span><span class="comma"><span style="font-family:Arial,sans-serif">,</span></span>^{<span style="font-family:Arial,sans-serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#a10">10</a></span>}<span style="font-family:Arial,sans-serif"> </span><span style="font-family:'Times New Roman',serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/abs/ngeo1800.html#auth-20"><span class="fn"><span style="font-family:"Arial","sans-serif"">Erik Swietlicki</span></span></a></span><span class="comma"><span style="font-family:Arial,sans-serif">,</span></span>^{<span style="font-family:Arial,sans-serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#a15">15</a></span>}<span style="font-family:Arial,sans-serif"> </span><span style="font-family:'Times New Roman',serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/abs/ngeo1800.html#auth-21"><span class="fn"><span style="font-family:"Arial","sans-serif"">Alfred Wiedensohler</span></span></a></span><span class="comma"><span style="font-family:Arial,sans-serif">,</span></span>^{<span style="font-family:Arial,sans-serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#a6">6</a></span>}<span style="font-family:Arial,sans-serif"> </span><span style="font-family:'Times New Roman',serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/abs/ngeo1800.html#auth-22"><span class="fn"><span style="font-family:"Arial","sans-serif"">Douglas R. Worsnop</span></span></a></span><span class="comma"><span style="font-family:Arial,sans-serif">,</span></span>^{<span style="font-family:Arial,sans-serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#a1">1</a>,<span class="apple-converted-space"> </span><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#a8">8</a>,<span class="apple-converted-space"> </span><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#a10">10</a>,<span class="apple-converted-space"> </span><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#a16">16</a></span>}<span style="font-family:Arial,sans-serif"> </span><span style="font-family:'Times New Roman',serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/abs/ngeo1800.html#auth-23"><span class="fn"><span style="font-family:"Arial","sans-serif"">Veli-Matti Kerminen</span></span></a></span>^{<span style="font-family:Arial,sans-serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#a1">1</a></span>}<span style="font-family:Arial,sans-serif"> &<span class="apple-converted-space"> </span></span><span style="font-family:'Times New Roman',serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/abs/ngeo1800.html#auth-24"><span class="fn"><span style="font-family:"Arial","sans-serif"">Markku
Kulmala</span></span></a></span>^{<span style="font-family:Arial,sans-serif"><a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#a1">1</a></span>}<br><br>Nature Geoscience Year published: (2013)<br>
<p></p><p></p><div id="first-paragraph" class="first-paragraph-abs">
<p>Atmospheric aerosol particles influence the climate system directly by 
scattering and absorbing solar radiation, and indirectly by acting as cloud 
condensation nuclei^{<a id="ref-link-3" title="Forster, P. et al. in Climate Change 2007: The Physical Science Basis (eds Solomon, S. et al.) 129-234 (Cambridge Univ. Press, 2007)." href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#ref1">1</a>, <a id="ref-link-4" title="Carslaw, K. S. et al. A review of natural aerosol interactions and feedbacks within the Earth system. Atmos. Chem. Phys. 10, 1701-1737 (2010)." href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#ref2">2</a>, <a id="ref-link-5" title="Arneth, A. et al. Terrestrial biogeochemical feedbacks in the climate system. Nature Geosci. 3, 525-532 (2010)." href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#ref3">3</a>, <a id="ref-link-6" title="Mahowald, N. Aerosol indirect effects on biogeochemical cycles and climate. Science 334, 794-796 (2011)." href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#ref4">4</a>}. 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 gases^{<a id="ref-link-7" title="Forster, P. et al. in Climate Change 2007: The Physical Science Basis (eds Solomon, S. et al.) 129-234 (Cambridge Univ. Press, 2007)." href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#ref1">1</a>}. In the 
future, tightening of controls on anthropogenic aerosol and precursor vapour 
emissions to achieve higher air quality may weaken this beneficial effect^{<a id="ref-link-8" title="Arneth, A., Unger, N., Kulmala, M. & Andreae, M. O. Clean the air, heat the planet. Science 326, 672-673 (2009)." href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#ref5">5</a>, <a id="ref-link-9" title="Mickley, L. J., Leibensperger, E. M., Jacob, D. J. & Rind, D. Regional warming from aerosol removal over the United States: Results from a transient 2010-2050 climate simulation. Atmos. Environ. 46, 545-553 (2012)." href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#ref6">6</a>, <a id="ref-link-10" title="Makkonen, R. et al. Air pollution control and decreasing new particle formation lead to strong climate warming. Atmos. Chem. Phys. 12, 1515-1524 (2012)." href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#ref7">7</a>}. Natural 
aerosols, too, might affect future warming^{<a id="ref-link-11" title="Carslaw, K. S. et al. A review of natural aerosol interactions and feedbacks within the Earth system. Atmos. Chem. Phys. 10, 1701-1737 (2010)." href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#ref2">2</a>, <a id="ref-link-12" title="Arneth, A. et al. Terrestrial biogeochemical feedbacks in the climate system. Nature Geosci. 3, 525-532 (2010)." href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#ref3">3</a>, <a id="ref-link-13" title="Quinn, P. K. & Bates, T. S. The case against climate regulation via oceanic phytoplankton sulphur emissions. Nature 480, 51-56 (2011)." href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#ref8">8</a>, <a id="ref-link-14" title="Kulmala, M. et al. A new feedback mechanism linking forests, aerosols, and climate. Atmos. Chem. Phys. 4, 557-562 (2004)." href="http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo1800.html#ref9">9</a>}. 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, which in turn enhance condensation on particles and their 
growth to the size of cloud condensation nuclei. This natural growth mechanism 
produces roughly 50<span class="mb">%</span> of particles at the size of cloud 
condensation nuclei across Europe. We conclude that biosphere–atmosphere 
interactions are crucial for aerosol climate effects and can significantly 
influence the effects of anthropogenic aerosol emission controls, both on 
climate and air quality.</p></div><p></p><p>The article is at: <a href="http://www.nature.com/ngeo/journal/vaop/ncurrent/abs/ngeo1800.html">http://www.nature.com/ngeo/journal/vaop/ncurrent/abs/ngeo1800.html</a></p><p><br>
</p><p><br></p><p><br></p><p></p><div><div>Patricia S. De Angelis, Ph.D.</div><div>Botanist, Division of Scientific Authority-US Fish & Wildlife Service-International Affairs</div><div>Chair, Medicinal Plant Working Group-Plant Conservation Alliance</div>
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