Global cooling

This winter has been rather cold. It almost feels like we're entering a new ice age. Now, don't laugh. This statement isn't as crazy as it seems. Yes, global warming is a, uh, hot topic these days, but more and more scientists are considering the possibility of global "cooling" occurring soon. This would result in the average temperatures on Earth dropping. It has happened in the past, and it will happen again in the future. Earth is warm now, but that's not always the case. In the past, large parts of the planet were covered in ice. We call these periods ice ages. Note the plural. There wasn't just one ice age. There have been several. During the recent past, we experienced the Little Ice Age. It lasted almost 500 years, from around, say, 1300 to 1800. The ice pack in the Arctic Ocean grew larger and moved south. Glaciers in the European Alps and on Greenland grew bigger and advanced southward. Temperatures dropped all over the northern hemisphere. Winters were longer, summers were shorter, and summer rains were heavier. There were numerous famines since the cold and rain frequently destroyed crops. Why did this ice age and others like it happen? One theory claims that Earth's orbit caused them. Earth's orbit changes slightly over time, so the northern hemisphere receives less sunlight on those occasions. This reduces temperatures. It's possible that an orbital change caused the major ice ages. In case you're curious, the last such ice age happened around 20,000 years ago. How often does Earth's orbit change? No one knows for sure. Scientists estimate it changes between every 20,000 to 50,000 years. There's also a second possible reason for global cooling. This relates to decreased solar activity. The presence or lack of sunspots can affect temperatures here on Earth. During the Little Ice Age, there were significantly fewer sunspots. For instance, in one 30-year period, astronomers spotted a few dozen sunspots. Normally, they would have seen tens of thousands of them. With less solar activity, some believe temperatures on Earth decreased, thereby resulting in colder weather.