Solar Activity, Greenhouse Gas Levels and Climate Change on Our Earth

Reader Contribution by Richard Hilderman and Ph.D.

Growing up in the wide open spaces of Montana I spent a great deal of my time in the vast outdoors and developed an appreciation and understanding of nature and the environment.  Over the years, as a scientist, I have become concerned about the possible impact global warming could have not only on humans but all creatures great and small.

A major goal of this blog will be to explain how the planet has maintained a stable temperature for life for billions of years.  Next we will discuss how human-induced forces are making the job of the planet more difficult.  Then we will discuss how the planet attempts to adapt to these human induced forces through climate change and what the potential consequences of this climate change are.  We will also look at current weather events in the context of climate change. 

It is my hope that this blog will stimulate meaningful discussions on climate change so that individuals can make informed decisions pertaining to global warming.  I will also be writing an article for the MOTHER EARTH NEWS magazine on climate change that will appear late next year.  Thus I would appreciate reader comments not only on my blogs but also thoughts for the magazine article. My first post for this blog appears below: 

Solar Activity, Greenhouse Gas Levels and Climate Change on Our Earth

Two main mechanisms, the fluctuations in solar activity and the fluctuations in the atmospheric level of greenhouse gases have been proposed to explain current changes in our global climate, a topic much in the news these days as we become more concerned about global warming.  In this first blog posting, let’s consider these mechanisms in the context of how the planet regulates its temperature.  In actuality, both of the mechanisms do play a role in the planet’s climate.

It is well established that fluctuations in the intensity of solar activity trigger glacial and interglacial periods.  However, the change in solar intensity is too small to explain the different global temperatures seen during glacial and interglacial periods.  There must be additional forces involved in regulating global temperature.  In future postings we will examine some of these.

Low concentrations of greenhouse gases in the atmosphere help maintain a stable temperature on the planet.  Greenhouse gases are carbon dioxide, methane, nitrous oxide and water vapor. The Earth is warmed by incoming high energy, short-wave length solar radiation from the Sun.  This radiation reaches the planet’s surface and is converted to heat and lower energy in the form of long-wave radiation.  Eventually this long-wave radiation is reradiated from the Earth’s surface into outer space.  If all the radiation that strikes the planet’s surface was reradiated into outer space, the planet would become extremely cold and uninhabitable because the Earth receives solar radiation only during daylight hours. 

The planet utilizes an important characteristic of the greenhouse gases to ensure a stable temperature.  The greenhouse gases allow short-wave radiation from the Sun to pass through the atmosphere to warm the planet and they also reflect some of the long-wave radiation that is to be reradiated into outer space back to the Earth’s surface. 

Reflecting this long-wave radiation back to the surface helps maintain a stable temperature.  The Earth must balance the incoming and outgoing radiation otherwise the planet would get progressively warmer or colder. If the Earth’s heat budget is balanced, the Earth is said to be in thermal equilibrium. 

The Earth has been in existence for about 4.5 billion years.  Natural cycles of ice ages have come and gone with fluctuations in solar activity, temperature and greenhouse gases.  However, it is extremely important to keep in mind that these previous natural cycles took place prior to the emergence of modern humans.  Humans are the only species on the planet that has the capability of profoundly altering the planet. 

Humans had little impact on the planet prior to the industrial revolution.  Burning of fossil fuels started with the industrial revolution and this combustion of fossil fuel generated greenhouse gases, mainly carbon dioxide.  Fossil fuel release of greenhouse gases should be considered “unnatural emission” because greenhouse gases released from combustion of fossil fuels is not part of the natural cycle of the planet.

We must be extremely cautious in comparing current global climate changes to the climate changes of the past natural cycles since the burning of fossil fuels was not part of the previous natural cycles.  We do not know how the planet would have reacted to these unnatural additions. 

Will the continued increase in the unnatural greenhouse emissions into the atmosphere have a negative impact on the Earth’s thermal equilibrium?  I would suggest so.  Future blogs will address this question by discussing how the planet controls the amount of atmospheric carbon dioxide.