Dear Dr. Staff: I was reading a newspaper, and it said that global warming may increase the temperature by 3.5 degrees Fahrenheit in the next thirty years. I wanted to see how that would affect Europeans, so I converted it to Celsius. But I was surprised to discover that +3.5 degrees Fahrenheit is -15.8 degrees Celsius. Does this mean that the temperature will go up 3.5 degrees in Fahrenheit and down 16 degrees in Celsius? How can this be?

--Confused by Temperatures

Dear Confused: What you've discovered is the difference between a conversion formula and a conversion factor. To convert from one unit distance to another, such as from feet to inches, you use a factor--such as 12. For every foot you have, you have twelve inches. (Since most people have two feet, they also have 24 inches, but that's another matter.) But temperature doesn't work that way. The formula to convert Celsius to Fahrenheit is much more complicated, involving an advanced mathematical concept referred to as multi-term computation, which is too complex to get into now.

If you look at a map, you'll see that Great Britain is about as far north as Minnesota. Yet, you probably know that winters in London are nothing like the icy monstrosities of Minnesota. Britain has been as warm as it is now only since the nineteenth century, when it switched from Fahrenheit to Celsius. It did this to promote global warming. Since water freezes at 32 degrees Fahrenheit, but 0 degrees Celsius, when the temperature is between 0 and 32, water is frozen in Fahrenheit, but liquid in Celsius. So England, which uses Celsius, doesn't get nearly as much snow as Minnesota, which uses Fahrenheit.

But the global climate does not turn on a dime. The global warming you hear so much about these days is the continued warming of the earth from the leftover momentum caused by countries changing to Celsius to make their winters less severe.

The United States and Jamaica are the only countries left in the world to use Fahrenheit, because if a country as big as the United States were to change now, global warming would get much worse and Jamaica works so much with the United States that they use the same system we do. (Together, these two countries make up what's called the thermocouple, but that's another topic too complex to get into.) While converting to Celsius would result in a better climate for all Americans, the US will probably wait to switch to Celsius until the global climate has adjusted to the warming left over from the conversion of the rest of the world to Celsius. --Thermal Wizard