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An Empirical Review of Recent Trends in the Greenhouse Effect

By Robin Pittwood, Kiwi Thinker

Abstract

The core of the human caused global warming proposition is that an increasing level of greenhouse gases acts to reduce heat loss from the planet making the atmosphere here warmer. The amount of warming anticipated by the IPCC models is from about one to several degrees C for a doubling of CO2 concentration.

But a conundrum has arisen lately: While CO2 has continued rise significantly the temperature has not. There has been no global warming since about 1997. Scientists on both sides of the debate have noticed this and have offered something like 55 explanations as to why this could be so. Some of those explanations lock into the dogma built into the IPCC models, taking for certain that the greenhouse effect is increasing, but because there is no atmospheric temperature rise, they then have to explain the retained heat is somewhere else.

Is the greenhouse effect occurring as the IPCC models propose?

This study analysed two important factors directly associated with the greenhouse effect, atmospheric temperature and outgoing radiation and finds that outgoing radiation has not declined. The missing heat has gone back to space as usual. But more importantly the (lack of a) trend observed in an empirical derivation of the Stefan Boltzmann relative emissivity factor directly contradicts the greenhouse theory built into the IPCC models.

Article

Regular readers at any of the main climate change blogs will be aware that since about 1997 there has been nearly no global temperature rise. And they will know too, that this is despite atmospheric CO2 concentration continuing to rise. To date there are some 55 ideas to explain this slowdown in global warming. Some of the ‘explanations’ presume the so-called ‘greenhouse effect’ must still be increasing as the IPCC models calculate; it’s just that the heat has been hidden elsewhere, maybe deep in the ocean.

This study, based on 34 years of satellite data; outgoing long-wave infrared radiation (OLWIR) and temperature, demonstrates otherwise.

I used three data sets, OLWIR from NOAA, and the average of both UAH and RSS for global temperature.

I obtained monthly average OLWIR (W/m2) for each 2.5 degree latitude by 2.5 degree longitude area of the globe. After converting the netCDF files to Excel, I scaled each 2.5*2.5 area’s OLWIR to account for the varying size of its area, resulting in a global average OLWIR. (There was some missing data mid 1994 to early 1995. I populated this by a linear interpolation). The resulting annual average OLWIR is shown in the graph below for the years 1979 to 2012. A linear regression fit shows a generally increasing trend in OLWIR over this period.

The temperature data is also plotted on the graph below. A linear regression fit shows a generally increasing trend for the years 1979 to 2012.

The relationship between temperature and emitted radiation follows a universal law of physics, Stefan Boltzmann’s law states the emitted radiation is the product of the fourth power of absolute temperature and an emissivity factor. A reduction in the emissivity factor means less outgoing radiation for a given temperature. That would indicate a stronger greenhouse effect. An increase in the emissivity factor means more outgoing radiation for a given temperature. That would indicate a more transparent atmosphere. The study derived earth’s emissivity factor for each of the 34 years and the results displayed.

Using an average global temperature of 287 Kelvin added to the temperature anomaly, the relative emissivity has been derived for each year using the formula:

j / (k*T^4)

where j is OLWIR, k is the Stefan Boltzmann constant, and T is the temperature.

If the greenhouse effect was increasing, relative emissivity should be declining. A quick look at the graphs shows clearly this is not the case.

Our planet’s relative emissivity has been flat-lining, despite increasing CO2 concentration over the study period. The derived emissivity factor, being basically constant, directly contradicts all of the IPCC models. No increased greenhouse effect is observed.

Findings:

The two primary findings of this empirical study are:

Outgoing radiation has not declined over this period as expected by IPCC models. The missing heat has gone back to space – as usual and as per Stefan Boltzmann’s law, via OLWIR, and,



The increasing greenhouse effect expected by IPCC models, has not exposed itself. There has been no increased greenhouse effect over this period. [A closer inspection of the relative emissivity trend shows the atmosphere is even becoming a little more transparent – though little should be made of this given the variability of the data].

Conclusion:

The core of the human caused global warming proposition is that an increasing level of greenhouse gases acts to reduce heat loss from the planet making the atmosphere here warmer. But is the greenhouse effect occurring as the IPCC models propose? This study analysed two important factors directly associated with the greenhouse effect, atmospheric temperature and outgoing radiation and finds that outgoing radiation has not declined. The missing heat has gone back to space as usual.

But more importantly the (lack of a) trend observed in an empirical derivation of the Stefan Boltzmann relative emissivity factor directly contradicts the greenhouse theory built into the IPCC models.

The original post on this study may be found here.

Data Table: