One More Blog Post About Global Warming

I admit to be being concerned about global warming, its many impacts, present and future, on human welfare, and the insidious fact that those least responsible for global warming and the resultant climate change are likely to suffer the most serious impacts.

I also admit to anger at my fellow humans, both scientific and political, who continue to deny the scientific basis for concern about global warming when the consensus among scientists is overwhelming, an unusual situation in science. It is a failure for which the deniers and minimizers should be held accountable.

In retrospect it is easy to reflect on human history and find examples where numbers of people, some highly educated and well respected, were wrong about important events and changes in society. Certainly many were sincere in their ultimately incorrect beliefs, based on limited available information and their life experiences and inevitable mental filters for processing that information. Others were undoubtedly self-serving opportunists who perhaps knew better but compromised their integrity. In this latter category I include those scientists and other well-informed people who denied the link between smoking and serious health effects, and more recently those who deny global warming or minimize its impacts. In my mind they are people who have sold their souls for filthy lucre.

What is so hard to understand about global warming? It is the same physical process that occurs in a car on a hot day that we all experience. The visible light rays from the sun, distributed in a spectrum determined by the sun’s surface temperature (about 5,500C) easily penetrate the car’s glass windows and are absorbed by the car’s interior which gets warm and often hot to the touch. These warm or hot surfaces then reradiate in a spectrum different from the sun’s radiative spectrum because of their vastly different surface temperatures. The basic physics is the same – Planck’s Law, first proposed in 1900, determines the spectral distribution and intensities of the radiation emitted by a black body at temperature T.

In a car the reradiated heat from the interior surfaces is mostly in the infrared region which the glass is not as transparent to as it is to the visible radiation from the sun. This trapping of the reradiated heat causes the car’s interior temperature to rise until enough reradiated infrared radiation gets through the glass due to the interior’s now higher temperature to provide a balance between the energy of the incoming and outgoing radiation streams. This is exactly what happens in the earth’s atmosphere, with gases in the atmosphere playing the role of the glass windshield and determining the atmosphere’s transmission characteristics. Important global warming gases are CO2, largely from combustion of fossil fuels, and natural gas (methane), and a few others. The earth’s current temperatures, hospitable to life, reflect such an energy balance between the sun and the earth. Venus is an example of where the equilibrium temperature reached by the planet to achieve an energy balance with the sun is much higher.

Read more: Lapsed Physicist

Leave a Reply

%d bloggers like this: