<div dir="ltr"><div class="gmail_quote"><div dir="ltr"><div><div>There are a wide range of different climate models that can be referenced to study anthropogenic climate change, and I often find that discussion of the issue does not comprehensively include most or all of these climate models. <br>
<br>Consider how often we hear that 1998 was the warmest year in the modern temperature record for global average temperatures, which from what I have gathered is often sourced from the Hadley Center model of global average temperature, despite the fact other credible temperature models do not show 1998 to be the warmest. This claim is often linked with discussion of a slow down in global warming, despite the fact that it is unequivocal that 2000-2010 global average temperatures are significantly warmer than 1990-2000, and short term variations of less than a decade are quite expected due to natural variability and human climate forcings, some of which are cooling Earth's climate, human and natural sourced aerosols, which are masking global warming to some extent, as these sources indicate:<br>
<a href="http://www.colorado.edu/news/releases/2013/03/01/volcanic-aerosols-not-pollutants-tamped-down-recent-earth-warming-says-cu">http://www.colorado.edu/news/releases/2013/03/01/volcanic-aerosols-not-pollutants-tamped-down-recent-earth-warming-says-cu</a></div>
<div><a href="http://news.bbc.co.uk/2/hi/science/nature/8108100.stm">http://news.bbc.co.uk/2/hi/science/nature/8108100.stm</a></div><div> </div><div>Consider this research from the Proceedings of the National Academy of Sciences, which points out that switching to clearer burning natural gas to avoid coal power will slow the human sourced aerosal pollution, thus lowering some of the aerosal global warming masking effect. Ironic, yes?</div>
<div> </div><div><a href="http://www.pnas.org/content/105/38/14245.full">http://www.pnas.org/content/105/38/14245.full</a></div><div><strong><font size="4">On avoiding dangerous anthropogenic interference with the climate system: Formidable challenges ahead</font></strong></div>
<div>"Switching from coal to “cleaner” natural gas will reduce CO<font><sub>2</sub> emission and thus would be effective in minimizing future increases in the committed warming. However, because it also reduces air pollution and thus the ABC masking effect, it may speed up the approach to the committed warming of 2.4°C (1.4–4.3°C)."</font></div>
<div><font>-----------------------------------------------<br>NASA's Goddard Institute for Space Studies has shown 2005 to be warmer than 1998, and thus if this reference is used to construct a graph of global warming over the past 20 years, a different curve results than when 1998 is shown as the warmest.<br>
<br>
This article from "New Scientist' discusses these issues and the errors in assuming global warming has stopped over the past decade or so:</font></div><font><div><br><font size="4">Climate myths: Global warming stopped in 1998</font><br>
</div></font><div><a href="http://www.newscientist.com/article/dn14527-climate-myths-global-warming-stopped-in-1998.html" target="_blank">http://www.newscientist.com/article/dn14527-climate-myths-global-warming-stopped-in-1998.html</a><br>
----------------------------------<br>The MIT Integrated Global System
Model–Community Atmosphere Model (IGSM-CAM) as far as I know is unique, and stands apart from IPCC climate models, which appear to receive a lot of attention, both from skeptics of the magnitude of anthropogenic climate change and from those accepting that the risks of extreme climate change are great.<br>
</div></div><div>
<div><div>A recent publication frrom MIT using the MIT climate model makes for interesting reading:</div><div><br><a href="http://globalchange.mit.edu/research/publications/2425" target="_blank">http://globalchange.mit.edu/research/publications/2425</a><br>
<br><a href="http://globalchange.mit.edu/files/document/MITJPSPGC_Rpt245.pdf" target="_blank">http://globalchange.mit.edu/files/document/MITJPSPGC_Rpt245.pdf</a><br>
</div><h2>Climate Change Impacts on Extreme Events in the United States: An Uncertainty Analysis</h2><div>
by Monier, E. and X. Gao (May)</div><p><a href="http://globalchange.mit.edu/research/publications/reports/all" target="_blank">Joint Program Report Series</a>, 14 p., 2013 </p><p>(<a href="http://globalchange.mit.edu//research/publications/reports/summary_245" target="_blank">Three questions with Erwan Monier</a>)</p>
<h3>Abstract</h3><p>Extreme weather and climate events, such as heat waves, droughts
and severe precipitation events, have substantial impacts on ecosystems
and the economy. However, future climate simulations display large
uncertainty in mean changes. As a result, the uncertainty in future
changes of extreme events, especially at the local and national level,
is large. In this study, we analyze changes in extreme events over the
US in a 60-member ensemble simulation of the 21st century with the
Massachusetts Institute of Technology (MIT) Integrated Global System
Model–Community Atmosphere Model (IGSM-CAM). Four values of climate
sensitivity, three emissions scenarios and five initial conditions are
considered. The results show a general intensification of extreme daily
maximum temperatures and extreme precipitation events over most of the
US. The number of rain days per year increases over the Great Plains but
decreases in the northern Pacific Coast and along the Gulf Coast.
Extreme daily minimum temperatures increase, especially over the
northern parts of the US. As a result, the number of frost days per year
decreases over the entire US and the frost-free zone expands northward.
This study displays a wide range of future changes in extreme events in
the US, even simulated by a single climate model. Nonetheless, it
clearly shows that under a reference emissions scenario with no climate
policy, changes in extreme events reach dangerous levels, especially for
large values of climate sensitivity. On the other hand, the
implementation of a stabilization scenario drastically reduces the
changes in extremes, even for the highest climate sensitivity
considered.</p><div>
</div><p><a href="http://globalchange.mit.edu/files/document/MITJPSPGC_Rpt245.pdf" target="_blank">Link to full document</a> (8859 kB PDF)</p></div></div></div>
</div><div><br>---------------------------------------</div><div>Vision2020 Post: Ted Moffett</div></div>