The Sun has become quite testy. Like a giant cosmic toddler, it's throwing a fit, apparently for no better reason than the toddler does: because it can. Scientists have spotted the first X class solar flare coming from the sun, with more on the way. 2013 is expected to be a tumultuous year in terms of solar activity.
Solar dynamics are poorly understood, mainly because it is difficult to predict how plasmas behave. When you have a lot of superheated gas twisting and roiling in its own magnetic field, it is very difficult to predict the outcome. Astrophysicists can only predict the sun's behavior in general terms.
It could be worse. A solar storm the likes of the 1859 Carrington Event would devastate our civilization. Smaller flares and solar storms may not be quite as violent, but they can still have an effect on Earth. Highly charged particles can interfere with satellites and cause brilliant aurorae far away from the poles. Radio transmissions might be disrupted. It is theorized, although admittedly unproven, that high levels of flare activity can heat up the Earth's surface.
Now we just have to see if the sun really does go cold and quiet after the storm, as some think it might. That would truly be a catastrophe.