Sunspots disappearing from the sun. The last time this happened it coincided with "The Little Ice Age." For a good part of the 20th century, "solar influence was significant. Studies show that by the end of the 20th century the Sun's activity may have been at its highest for more than 8,000 years." Further,
Other solar parameters have been changing as well, such as the magnetic field the Sun sheds, which has almost doubled in the past century. But then things turned. In only the past decade or so the Sun has started a decline in activity, and the lateness of cycle 24 is an indicator.The past decade has been warmer than previous ones. It is the result of a rapid increase in global temperature between 1978 and 1998. Since then average temperatures have held at a high, though steady, level. Many computer climate projections suggest that the global temperatures will start to rise again in a few years. But those projections do not take into account the change in the Sun's behaviour. The tardiness of cycle 24 indicates that we might be entering a period of low solar activity that may counteract man-made greenhouse temperature increases. Some members of the Russian Academy of Sciences say we may be at the start of a period like that seen between 1790 and 1820, a minor decline in solar activity called the Dalton Minimum. They estimate that the Sun's reduced activity may cause a global temperature drop of 1.5C by 2020. This is larger than most sensible predictions of man-made global warming over this period.
It's something we must take seriously because what happened in the 17th century is bound to happen again some time. Recent work studying the periods when our Sun loses its sunspots, along with data on other Sun-like stars that may be behaving in the same way, suggests that our Sun may spend between 10 and 25 per cent of the time in this state. Perhaps the lateness of cycle 24 might even be the start of another Little Ice Age. If so, then our Sun might come to our rescue over climate change, mitigating mankind's influence and allowing us more time to act. It might even be the case that the Earth's response to low solar activity will overturn many of our assumptions about man's influence on climate change. We don't know. We must keep watching the sun.
Just don't tell Gore, though. Remember, to him -- the "debate [about climate change] is ended." And he's the Nobel to "prove" it.