More from AGU

Breaching Earth’s Force Field

We live under the protection of an invisible shield of magnetic force called, appropriately enough, the magnetic field.  It keeps us safe (more or less) from particles streaming out from the Sun on the solar wind. Sometimes, however, according to scientists who study the Sun’s effect on the magnetic field, our protective force shield develops a leak or two.  This was the subject of a paper and press conference delivered today (Tuesday) at the American Geophysical Union meeting in San Francisco.

Earth’s magnetic field acts as a shield against the bombardment of particles continuously streaming from the Sun. Because the solar particles (ions and electrons) are electrically charged, they feel magnetic forces and most are deflected by our planet’s magnetic field. However, our magnetic field is a leaky shield and the number of particles breaching this shield depends on the orientation of the Sun’s magnetic field. Scientists used to think that when the Sun’s magnetic field is aligned with Earth’s, the door to our planet clangs shut and that very few particles get into our magnetic shield. The door was thought to open up when the solar magnetic field direction points opposite to Earth’s field, leading to more solar particles inside the shield.

Well, it turns out that twenty times more solar particles slip in through the cracks in our magnetic field “door” when the Sun’s magnetic field is aligned with ours. This is a result that people suspected, but they had to wait to get data from the THEMIS mission to probe the size of the leak in our magnetic field. This has what may be alarming implications for the upcoming solar cycle, when solar activity will be higher and we’ll see more affects on Earth’s magnetic field and upper atmosphere in the form of space weather (geomagnetic storms).

Abruptly Changing Climate: Will It Happen this Century?

Speaking of climate change, scientists are taking comprehensive looks at abrupt climate changes that can be spotted in the geologic (rock) record. The United States Geological Survey presented a discussion today that paints a somber picture for the United States (and clearly other countries) when climate change becomes severe.  The question they raise is whether or not society can survive as our planet’s climate changes. There are several indications that abrupt climate changes could come soon. First, simulations and models suggest that rapid and sustained September arctic sea ice loss is very likely in the 21st century.  Second, the southwestern United States may be on the verge of a peri0d  of increased drought (more so than it already experiences).  Third, it’s likely that the northward flow of warm water in the upper layers of the Atlantic Ocean (which is an important factor in the global climate regulation system) will decrease by up to 30 percent. It probably won’t collapse or weaken abruptly, but its changes will be felt.  In addition, an abrupt change in sea level could happen, but the existing models are somewhat unclear on how much or when this could happen. Finally, methane emissions will continue to occur and the pace of emissions will increase, although there won’t be abruptly large emissions of this greenhouse gas. There’s a lot we still need to figure out about how these predictions will affect us, but they do point to a world where climate change is happening and will continue to accelerate as long as we don’t do something about our greenhouse gas emissions.

IYA 2009

You may have noticed a lot of discussion about the International Year of Astronomy. It begins on January 1, 2009, which  means it’s almost upon us. The folks at AGU heard about plans for worldwide celebrations of astronomy (and you can read more about them here and here (for US readers). I’ll be participating by doing some podcasts for the 365 Days of Astronomy project and giving some IYA-related astronomy talks next year.