Carbon credits are, like most government regulations, a well-meaning attempt at dealing with a tragedy of the commons - the polluting of a common resource (the atmosphere) that no one person or country owns and yet we all depend on.

A brief rundown in case you're not aware - a tragedy of the commons is a type of market failure - where the free market fails to price something (fossil fuels) high enough to accurately reflect all the negative costs it has on market participants (or innocent bystanders).

In my opinion governments stepping in to raise the price of carbon emissions won't go as planned (stakeholders will corrupt the process somewhat), but we should attempt to achieve a net positive result.

As for climate "always changing", time frames are important. What do you mean that when you were growing up we were heading for a mini ice age? According to indicators like tree-rings and ice layers the planet's climate has been fairly stable since the last mini ice age in the 16-1700s.