On what authority are carbon credits issued? Carbon Credits are a weird thing. Businesses can buy and sell them, and having enough carbon credits to offset your CO2 output suddenly makes you a Green Business. That being said, who issues Carbon Credits, and on what authority? Is a Carbon Credit a promise to remove an amount of CO2 from the atmosphere? 

Last I checked that was a massively expensive technology still in it's infancy, but Carbon Credits have been around for quite some time.  Does it work like a Futures market ("When the tech becomes available I promise to remove 30 bln tons of C02")?
Carbon credit accreditation is a process done by independent accrediting agencies. It is comparable to the way that universities are accredited by various agencies saying that their degrees are legit. You sign up to do a project to reduce carbon output, and then the accrediting agency confirms that you did just that.

Carbon offsetting isn't a future's market, it is a (financial) commitment to a project right now that is dedicated to lowering greenhouse gasses. Here is a list of potential projects, and here is a map showing projects in progress with a certain company. 

I'm actually really glad you asked this question, because I just assumed that carbon offsets were effective proven means, like planting trees. But looking at some of these projects is bringing up some doubt in my mind. I don't see how burning methane into CO$_2$ is doing anything except turning a larger short-term problem into a smaller long-term problem. Or how to measure the exact number of tons of carbon you are saving by changing domestic behavior.