Is there a Connection between Global Warming and Solar Radiation?

In the last twenty years, climate change skeptics have posited several theories about why our planet has been registering warmer air and sea temperatures, none of which factor in human involvement in these temperature changes. One of the most pervasive of these alternate theories is that global warming and solar radiation are linked, that increasing solar activity is to blame for Earth’s climate changing.

Solar Cycles

In order to understand the relationship between global warming and solar radiation, it’s necessary to understand how the sun and the Earth relate to one another in space. The Earth, like most planets, follows an orbit that subtly changes shape over time. These orbital “wobbles” or fluctuations are referred to as Milankovich cycles, and are thought to be responsible for the appearance and disappearance of ice ages during the Earth’s history. In this sense, global warming and cooling is a purely natural phenomenon that has always occurred during certain periods.

Radiation Output

The sun itself experiences an approximate 11-year cycle of warming and cooling. During cooler periods, solar radiation output does decrease - but scientists say that this change is only about 1/10 of a percent, and nothing that could account for the dramatic climactic changes seen on Earth. Global warming and solar radiation are connected, but even historically cold periods such as the “Little Ice Age” of Medieval Europe would not have been dramatic enough to counteract the temperature increases seen today.

Fossil Fuel Use

The human use of fossil fuels has led to a dramatic increase in average planetary temperatures on Earth; carbon dioxide and other greenhouse gases trap the heat generated by the rays of the sun, and as we produce more of them the planet gets hotter and hotter. Never in the Earth’s history have temperatures risen so quickly and so dramatically. For this reason, the scientific consensus is that while the heat of the sun is responsible for global warming in a general sense, current global warming and solar radiation trends are not related.

Solar Activity

Some theorize that increases in solar activity (such as sun spots or solar flares) account for Earth’s temperature variances, pointing out that sunspot activity has reached a thousand-year high at the beginning of this most recent millennium. However, it must be pointed out that solar radiation has been on a downward trend in the past four decades, while Earth’s temperatures have been rising—thus destroying any links between the two events. Note that interest in this theory has fallen off since about 2007, when this evidence was posted online.

What Statistics Tell Us

Most scientists estimate that global temperatures are expected to rise anywhere from 2 to 11 degree Fahrenheit by the year 2100. This is almost twice as high an increase as any previous instance of climate change in the Earth’s entire history. For this reason alone, it seems absurd to postulate that there is a direct connection between global warming and solar radiation. The sun has always been present while fossil fuels are the new arrival on the scene. An increase of even 4 degrees will lead to extreme changes in weather patterns, local climates, and sea levels.

Scientists agree that global warming and solar radiation today are not directly connected to one another. The sun is actually expected to enter into a period of very low solar radiation output in the next few years. Global temperatures continue to rise, and the fault lies quite largely in the activities of humans for producing excessive amounts of greenhouse gases and depletion of the ozone layer.