Monday, January 8, 2007

Twenthith century sea level change

Here is an example of a really nice abstract. I can just copy and paste it because most everyone can understand it.

GEOPHYSICAL RESEARCH LETTERS, VOL. 34, L01602, doi:10.1029/2006GL028492, 2007

On the decadal rates of sea level change during the twentieth century


Nine long and nearly continuous sea level records were chosen from around the world to explore rates of change in sea level for 1904–2003. These records were found to capture the variability found in a larger number of stations over the last half century studied previously. Extending the sea level record back over the entire century suggests that the high variability in the rates of sea level change observed over the past 20 years were not particularly unusual. The rate of sea level change was found to be larger in the early part of last century (2.03 ± 0.35 mm/yr 1904–1953), in comparison with the latter part (1.45 ± 0.34 mm/yr 1954–2003). The highest decadal rate of rise occurred in the decade centred on 1980 (5.31 mm/yr) with the lowest rate of rise occurring in the decade centred on 1964 (−1.49 mm/yr). Over the entire century the mean rate of change was 1.74 ± 0.16 mm/yr.

Now there is a well written piece of science.

This research extends the sea level record back to 1904 and shows that recent sea level variability is not unusual and that recent sea level change is not greater than at other recent time periods.

How will this impact the climate change question?

It is counter intuitive, considering glacier melt and thermal expansion, that sea level change was greater in the early part of the twentieth century rather than the later. This finding seems to further cloud the waters (yes, pun intended) as to what the dynamics of sea level change are. What is the impact of warming and glacier melt on sea level? What other influences are there that could make oceans rise more quickly in the frist half of the century? This, as the saying goes, requires further study.

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Friday, January 5, 2007

Milankovitch is spot-on

This looks like a very interesting article. From reading the abstract the author makes a logical argument that, with respect to Milankovitch forcing (The change in incoming solar radiation due to changes in how the Earth is situated relative to the sun), one should consider ice volume dynamics (changes in ice volume) rather than ice volume total. In doing so the Milankovitch forcing is revealed without lag (there is often thousands of years of lag between forcing change and equivalent ice volume change). The author also finds that variations in CO2 appear to lag the rate of change in ice volume which gives CO2 a secondary role in ice volume change.

This finding helps make sense of the role that orbital changes play in ice volume. Up to this point there has been some confusion since ice volume has not always followed orbital parameters with any consistency. With this finding we see that orbital parameters play a role in how quickly the ice volume changes.

That CO2 has a secondary role to orbital parameters has been known to climate scientists for some time. The role of CO2 has been considered one of a positive feedback to orbital parameters with increased warming form changes in solar energy leading to more CO2 which leads to more warming.

Further research:

The impact of this research on how understanding of climate sensitivity.

GEOPHYSICAL RESEARCH LETTERS,VOL. 33, L24703, doi:10.1029/2006GL027817,2006

In defense of Milankovitch

Gerard Roe
Department of Earth and Space Sciences, University of Washington, Seattle, Washington, USA

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Thursday, January 4, 2007

Good news about global warming

Well sort of. An interesting finding written up in the Journal of Geophysical Research (JGR). Using climate models the investigators looked at what the impact of climate change would be on particulate matter and tropospheric (bad) ozone. Seems that due to the increase in water vapor associated with climate change both these pollutants decrease. Particulate matter due to rain out and ozone due to increased reactive gases (OH) derived from water vapor.


Sensitivity of global tropospheric ozone and fine

JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 111, D24103, doi:10.1029/2005JD006939, 2006

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