Oregon Chapter
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Meeting Minutes

April 10th, 2012

“The Scientific Case for Human Influence on Global Climate: What We Learn From Analyzing ALL The Evidence.”

Video of entire meeting, courtesy: Erik Holm, Oregon AMS Member - Click here

Steve Pierce opened the meeting with a welcome to everyone in attendance. President Pierce thanked our co-sponsor of the event, Columbia-Willamette Sigma Xi Chapter, Portland State University and local media. Additionally Pierce announced future meetings and outlined the meetings ground rules(same as for the January meeting) for decorum due to the highly politicized topic. The audience enjoyed his humor of the guidelines . powerpoint (.pps) or (.pdf)

 

Secretary Mark Nelsen, Nominations Committee Chair, called for final nominations with the annual elections of officers. Election ballots will be sent to current members.

 

After chapter business was completed, the educational portion began with a speaker panel format that consisted of Dr. Phil Mote, Oregon State Climatologist, Director of the Oregon Climate Change Research Institute and Professor of Oceanic and Atmospheric Sciences at Oregon State University. Andreas Schmittner, Associate Professor of Oceanic and Atmospheric Sciences, Oregon State University. Dr. Christina Hulbe, Professor of Geology, Portland State University.

Speaker Panel Presention with annotations, click here for .pdf (note 20mb file size)

Dr. Phil Mote began the panel presentation  with some general remarks outlining the difference between weather and climate, and discussing the differences between personal observation and scientific/empirical analysis as ways of knowing something.

Dr. Mote explained that  climate change is happening over long time scales (decades to centuries) we cannot rely only on personal experience to understand it but we must use objective empirical analysis, which is often abstract and more difficult to absorb and retain.

Additionally he explained that despite the complexity of the climate system and the fact that there are still many unknowns that are subject of new research, we DO KNOW that there are greenhouse gases in the atmosphere (H2O, CO2, CH4, and others) that warm the surface. We also know that human activities have increased the concentrations of these gases recently, which has contributed to the 0.8 deg C increase in global surface temperatures observed during the past 100 years. Although global surface temperatures have not increased during the past 10 years, this does not mean that the warming has stopped. In fact observations of deep ocean heat content show continued and uninterrupted warming of the climate system.

Dr. Christina Hulbe who presented next, showed observations of decreasing Arctic sea ice area, shrinking of mountain glaciers worldwide and increasing sea levels.

Dr. Hulbe explained that an important reason for the observed warming is the raising CO2 concentrations as observed at the Mauna Loa Observatory in Hawaii since 1958. Analysis of the global carbon cycle shows that only about half of the carbon emitted by humans remains in the atmosphere. Oceans and vegetation (and soils) on land take up the rest by about equal amounts. Atmospheric CO2 concentrations can be reconstructed precisely using measuring bubbles of air trapped in Antarctic ice cores. From these measurements we know that CO2 was very constant (280 ppm) during the last 1000 years and that it fluctuated between 180 and 280 during the ice age cycles of the past 800,000 years.

Dr. Andreas Schmittner, who presented last, outlined Earth’s global energy budget by distinguishing between solar (visible wavelengths) and terrestrial (infrared wavelengths) radiation. Whereas Earth’s atmosphere is transparent for solar radiation it is opaque for terrestrial radiation, most of which is absorbed by greenhouse gases and clouds. The back-radiation from these gases and clouds toward the surface increases surface temperatures. Increasing CO2 concentrations since pre-industrial times alone have led to a reduction of outgoing infrared radiation at the top-of-the-atmosphere by 1.7 W/m2 (radiative forcing). This reduced heat loss to space causes warming. Feedbacks can amplify or reduce the heating caused by CO2 changes alone. Warming leads to more evaporation and increased water vapor in the atmosphere. Since water vapor is a greenhouse gas this leads to additional warming. This is a positive feedback effect (more warming).

Dr. Schmittner stated that other important feedback effects are the ice-albedo effect and changes of clouds. Cloud feedbacks are currently the least understood which contributes to uncertainty about future climate projections. Dr. Schmittner continued with a discussion of paleoclimate evidence from the Last Glacial Maximum (20,000 years ago). During that time CO2 was 180 ppm (compared to 280 ppm during the Late Holocene), huge ice sheets covered large parts of North America and northern Europe, sea level was 120 m lower than today and vegetation was much different in many regions. Surface temperature reconstructions from pollen and ocean microorganisms found in sediment cores show that land temperatures were much colder (10 – 20 deg F) at mid latitudes (e.g. in the US and Europe) but ocean surface temperatures were only 4 deg F cooler and global average surface air temperatures were only 7 deg F. This suggests that small changes in global average temperatures, which are dominated by the ocean, are amplified over land and at mid- and high latitudes.

Dr Schmittner explained that the strong correlation between CO2 and climate over the last 800,000 years implies that CO2 is important. Climate models that do not include CO2 or that have a very low sensitivity to CO2 changes cannot reproduce the observed cooling during the ice ages. Models in best agreement with the observations have a moderate sensitivity (2-3 deg warming for a doubling of atmospheric CO2).
Dr. Mote subsequently discussed various ways that have been used to confuse people, like cherry picking data. An example of cherry picking data was a graph shown by Dr. Fulks in his Jan 25th presentation, in which observed upper ocean heat content changes from 2003 to 2009 were shown (no trend), but it did not show the full record which goes back more than 50 years, which shows a clear increasing trend. Another graph that Fulks showed contained bad data of contaminated atmospheric CO2 concentrations.

The panel stated that scientists have examined other explanations for the observed recent warming trend. E.g. changes in El Nino do not show a multi-decadal trend and therefore cannot explain the long-term warming. Moreover, the ocean has gained heat during the last 50 years: an observation inconsistent with a proposed (e.g. by George Taylor during his Jan. 25 presentation) ocean heat loss as an explanation for atmospheric warming. Satellites have measured solar irradiance precisely since 1978. It shows an 11-year solar cycle (sunspot cycle) but no long-term trend. Thus the recent solar variability cannot explain the observed multi-decadal warming. Also the solar forcing is much smaller (0.25 W/m2) compared to the forcing from CO2 increases (1.7 W/m2). Both simple statistical and complex climate models can reproduce the observed recent temperature changes only if they account for an important contribution from human activities (mainly increased greenhouse gas concentrations).

At the conclusion of the speaker panel presentation, panel memebers interacted with the audience in a Question and Answer session where written and oral questions presented and answered.

 

Microsoft Powerpoint (.pps file extension) viewer download (click here)