Limitations on Anthropogenic Global Warming

22 05 2009

by Leonard Weinstein, ScD
March 1, 2009

reposted from The Air Vent
It is not obvious what the ideal temperature and CO2 level should be for mankind. We tend to assume that the average of whatever has occurred in the recent past is the ideal level, since we have adjusted to that level, and changes from that level can cause disruptions in living conditions and activities. Significant temperature and CO2 increases in recent years have raised the issue of whether these were possibly related and were due to human activity, and whether this is a potentially significant problem.

Earth’s temperature has only been directly measured at enough locations to give a reasonably accurate global average for about the last 150 years, with the greatest accuracy (from satellites) only going back about 30 years. The “reliable” CO2 background level has only been directly continuously measured at one location (Mauna Loa) for about 50 years, and at a much larger number of locations for about 30 years. Some other direct and indirect CO2 measurements were made prior to 50 years ago, and the measurements thought to be most reliable were used to extend the CO2 curve back to 1850.

Figure 1 is a commonly used figure to show smoothed global variations of the temperature and CO2 concentration data from 1850 through 2000 AD. This data indicates the Earth’s surface has warmed about 0.7OC (1.3 OF) and the atmospheric CO2 appears to have increased by over 30%. These two pieces of information are the basis for the present “Anthropogenic Global Warming issue”.

Figure 1. Variation of global average temperature and CO2 concentration over last 150 years Read the rest of this entry »


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Categories : Carbon dioxide, climate_change

The Guardian Appears Ready to Power Glasgow 100% From Wind (Part 2)

22 05 2009
By Steven Goddard
In Wednesday’s Guardian, their lead environmental story made this bold claim about The Whitelee Wind Farm:
Europe’s largest onshore wind farm, which is already powerful enough to meet Glasgow’s electricity needs

There was no discussion in the article about how Glasgow would handle extended periods of cold and calm winds, such as was often seen this past winter.   Read the rest of this entry »


Comments : 208 Comments »

Categories : energy

A look at human CO2 emissions -vs- ocean absorption

22 05 2009

Steve Fitzpatrick writes in with a short essay:

Graphic by NASA
Ocean CO2 absorption

On May 11 you reposted a blog from Dr. Roy Spencer, where he suggests that much of the increase in atmospheric CO2 could be due to warming of the oceans, and where he presents a few graphs that he claims are consistent with ocean surface temperature change contributing more than 80% of the measure increase in CO2 since 1958.  Dr. Spencer’s suggestion is contradicted by many published studies of absorption of CO2 by the ocean, with some studies dating from the early 1960’s, long before “global warming” was a political issue.  In this post I offer a simple model that shows why net absorption of CO2 by the ocean is most likely the main ocean effect.

If the rise in CO2 is being driven by human emissions, then the year-on-year increase in atmospheric CO2 ought to be a function of the rate of release of CO2, less any increase in the rate of removal of CO2 by increased plant growth and by absorption and chemical neutralization of CO2 by the ocean.  Both ocean absorption and plant growth rates should increase with increased CO2 concentration in the atmosphere.  To simplify things, I focus here only on ocean absorption.

On the other hand, surface temperature changes ought to have a relatively rapid effect, because the surface of the ocean is in contact with the atmosphere and so can quickly absorb or desorb CO2 as the water temperature changes.  In fact, the ocean surface continuously absorbs CO2 where the temperature is falling, mostly at high latitudes, and emits CO2 where the water is warming, mostly at lower latitudes.  Cold upwelling water from the deep ocean warms at the surface and desorbs CO2, while very cold water at high latitudes absorbs CO2 before it falls to the deep ocean.  An increase in average ocean surface temperature will cause more CO2 to be emitted from surface water, but this effect is limited to a very small volume fraction of the ocean.  Effects due to rapid temperature changes (annual time scale and less) are limited to a relatively thin layer, while the gradual absorption/neutralization process takes place at a rate controlled by ocean circulation and replacement of the surface water with upwelling (and “very old”) deep ocean water.

Any change in sea surface temperature should add to or subtract from the atmosphere’s CO2. Read the rest of this entry »


Comments : 188 Comments »

Categories : Carbon dioxide, oceans