How does the sun affect our climate?

Our sun is the source of most of the energy that drives the biological and physical processes in the world around us—in oceans and on land it fuels plant growth that forms the base of the food chain, and in the atmosphere, it warms air which drives our weather.

The rate of energy coming from the sun changes slightly day to day. Over many millennia the earth-sun orbital relationship can change the geographical distribution of the sun’s energy over the earth’s surface. It has been suggested that changes in solar output might affect our climate—both directly, by changing the rate of solar heating of the earth and atmosphere, and indirectly, by changing cloud forming processes.
Over the time-scale of millions of years, the change in solar intensity is a critical factor influencing climate (e.g., ice ages).  However, changes in the rate of solar heating over the last century cannot account for the magnitude of the rise in global mean temperature since the late 1970s.

Scientists have considered the sun-climate hypothesis to explain the earth’s rapid warming. The evidence collected shows that the sun noticeably affects our climate over millions of years, but it is not the cause of recent warming.
The rate at which energy from the sun reaches the top of earth’s atmosphere is called “total solar irradiance” (or TSI).  TSI fluctuates slightly from day to day and week to week. In addition to these rapid, short-term fluctuations, there is an 11-year cycle in TSI measurements related to “sunspots” (a part of the sun’s surface that is temporarily cooler and darker than its neighboring regions).
Two different hypotheses have been proposed to test whether solar radiation can explain climate change. 

Increase in emissions and climate change 

During the last two decades, aerosol emissions increased in some countries and decreased in others. Research shows that the impact of these particles on global average surface temperature over this time period is small.
What is causing increases in the Earth’s average temperature, and how do we know this?
We do know with a good degree of certainty that between 1750-2011, or since the beginning of the industrial period until today, the average increase in energy hitting a given area of the atmosphere (radiative forcing, measured in a unit called watts per square meter) due to heat-trapping gases is 56 times greater (~ 2.83 watts per square meter) than the increase in radiative forcing from the small shift in the sun’s energy (~0.05 watts per square meter).
In its Fifth Assessment Report, IPCC scientists evaluated simulations of historical climate variables using a number of numerical models. They first assumed no increase in heat-trapping gases since 1750, so that the temperatures calculated were those that would have been achieved if only solar variability, volcanic eruptions, and other natural climate drivers were included.
The temperature results were similar to observed temperatures only for the first half of the century, but the models did not accurately show the general warming trend that has been recorded during the second half of the twentieth century.
When computer models include human-induced heat-trapping gases, they accurately reproduce the observed warming during the twentieth and twenty-first centuries.
The evidence shows that although fluctuations in the amount of solar energy reaching our atmosphere do influence our climate, the global warming trend of the past six decades cannot be attributed to changes in the sun.

Solar energy and pollution 

Solar energy is provided free by the sun and comes in two forms; light and heat. Special technology is needed to capture this energy. Heat from the sun can be used to heat water in our homes and buildings and light from the sun can also produce electricity. Energy technologies utilizing the sun have great potential to benefit the world, and new emerging processes, like Sliver Cells, will ultimately help drive costs down. They can diversify energy supply, reduce dependence on fossil fuels, improve the quality of the air we breathe, offset greenhouse gas emissions, and stimulate economies by creating jobs in the manufacturing and installation of systems. Technology using the sun focussed in dish concentrators has been around for some time, although the technology is evolving and already replacing some fossil fuel power requirements.

Energy Independence and solar power
Have you thought about a DIY heating system using the sun? In many climates, a system can provide a very high percentage (50 to 75%) of domestic hot water energy. Total Solar Energy has some great tips and advice for the do-it-yourself project. If you are in a rural environment you might also want to consider using solar water pumps. 

For more information relating to going solar, don't forget to visit our solar blog section for more handy guides and articles.

If you want to move into the future and join the solar revolution, or if you want to find out what solar panels are right for you, go to HahaSmart.com and try our price checker tool. You can see how much a system will cost, and how much you can save over the next 20 years.