Let us climate-declare all products, starting with the most important ones.
The best approach to really get the steam up (no pun intended) on lowering CO2 emission would be to put a tax on fossil fuels, any kind, any place and for whatever purpose they are used. But politicians always say that will not work if not done on a supranational level, preferably global. So: nothing happens – no-one can agree, and when responsibility is shared, it is always the others that should begin.
But climate-declaring products can be done at the national level. It is only about influencing choices. So let us start with the most important ones; just a few examples;
Airplanes and flight-travel: When someone buys a ticket they should be told that the airplane of choice emitted x tons of CO2 while being constructed, and the flight you are about to take will emit another x tons. This should be compared to the national average emission per capita, the global average being about 5 tons.
Beef: the production of this kind of imported beef resulted in emitting x tons of CO2 from birth to butcher’s shop, again comparing it to the national average.
Of course any other product, also products that emit less CO2 should be declared, so that we all can choose wisely, forcing business to choose wisely.