[Vision2020] May 2013: MIT: Science and Policy of Global Change: "Climate Change Impacts on Extreme Events in the United States: An Uncertainty Analysis"

[Ted Moffett]

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.

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:
http://www.colorado.edu/news/releases/2013/03/01/volcanic-aerosols-not-pollutants-tamped-down-recent-earth-warming-says-cu
http://news.bbc.co.uk/2/hi/science/nature/8108100.stm

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?

http://www.pnas.org/content/105/38/14245.full
*On avoiding dangerous anthropogenic interference with the climate system:
Formidable challenges ahead*
"Switching from coal to “cleaner” natural gas will reduce CO2 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)."
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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.

This article from "New Scientist' discusses these issues and the errors in
assuming global warming has stopped over the past decade or so:

Climate myths: Global warming stopped in 1998
http://www.newscientist.com/article/dn14527-climate-myths-global-warming-stopped-in-1998.html
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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.
A recent publication frrom MIT using the MIT climate model makes for
interesting reading:

http://globalchange.mit.edu/research/publications/2425

http://globalchange.mit.edu/files/document/MITJPSPGC_Rpt245.pdf
Climate Change Impacts on Extreme Events in the United States: An
Uncertainty Analysis
by Monier, E. and X. Gao (May)

Joint Program Report
Series<http://globalchange.mit.edu/research/publications/reports/all>,
14 p., 2013

(Three questions with Erwan
Monier<http://globalchange.mit.edu//research/publications/reports/summary_245>
)
Abstract

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.

Link to full document<http://globalchange.mit.edu/files/document/MITJPSPGC_Rpt245.pdf>(8859
kB PDF)

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Vision2020 Post: Ted Moffett
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