Sun and climate

Does the Sun change the climate?

Since the Sun is responsible for creating the Earth's climate, any changes in the Sun might be expected to cause changes on Earth. The extent to which that happens and the way it happens is not understood yet. However, some data suggest that the Sun is more active now that it has been for 1000 years, and we know that a mini-ice age happened when the Sun was very quiet and there were no sunspots for a very long time. Have a look at the section on sunspots to find out more. The Sun does effect the Earth's climate, but not enough to explain the temperature increases over the past 30 years. This is due to a man made increase in green house gasses, such as carbon dioxide.

Are there any changes on Earth that suggest a change in climate is happening now?

Yes, indeed. One such change is seen in the Antarctic. Because of rising temperatures, huge chunks of the Antarctic ice shelf (more that 40 miles, 70 km, wide) are falling off into the sea. This is being studied by the British Antarctic Survey.

Did sunspots sink the Titanic?

The Titanic sank on the evening of April 14th, 1912. The surface temperature of the seas was lower then and large icebergs were often seen floating in the Arctic and drifting southwards. The Titanic hit a very large iceberg and sank.

If you look at this plot you can see that there is a correlation between the surface temperature of the sea (SST) and the sunspot number. So, it seems that even if sunspots didn't leap out and hit the Titanic, they may have helped to sink it.

How does the radiation fron the Sun change?

The radiation from the Sun changes with solar activity. It increases when there are a lot of Sunspots. The increase in the visible is quite small, but the increase in the ultraviolet and X-ray radiation is much larger.

Here are some X-ray images of the Sun taken with the YOHKOH spacecraft. They go from solar minimum (no sunspots) on the right to solar maximum (lots of sunspots) on the left. Notice how dramatically the strength of X-rays from the Sun changes. We don't fully understand what effect the ultraviolet and X-ray radiation has on the Earth's climate.