How to promote reduction of carbon footprint for conference participation? Researchers need to get together with each other in conferences to give talks, listen to talks, discuss with others, network, etc.  But travel to conferences is expensive and adds substantially to one's carbon footprint.

How can this kind of academic interaction be accomplished remotely, i.e. without traveling?  How can remote participation in conferences be set up so as to approach the effectiveness of in-person attendance?

Edit:

I would like to see someone discuss the choice of location.  I got this idea from the answer that mentioned Energy Star.  I once visited the Canary Islands and saw political graffiti saying "no more concrete."  I wonder if holding a conference in an area with poor urban planning, with explosive building patterns, would have a disproportional effect on local climate, species diversity, populations abandoning traditional farming and migrating to the city and underemployment... these are thoughts that are just starting to form.  I hope someone with a better understanding of these things can weigh in.  For example, is there a way to relate these factors to the technical component "carbon footprint"?

What about how much food needs to be flown in?  For example, a conference held on an island that doesn't lend itself to producing fresh fruit, vs. a venue that can source more locally grown food?

Then there's fuel for heating and air conditioning, and gasoline for getting from the airport to the hotel.  I wonder whether conference organizers ever think about any of these considerations....

But I would still like to understand how remote participation can be shaped to yield similar benefits to in-person attendance.  Maybe it would help to form some small interest-based subgroups?
Personal, disputable view follows.

Even if you avoid a conference, you save only a few kilograms of carbon. There's millions of other fliers that don't care about it and are travelling at the same time.

The best way to protect the environment is through technological advances: planes that work with eco-friendly fuel, are faster or more effective, better virtual reality technology that allows one to avoid travels, maybe even quantum teleportation and all that kind of stuff. 

How do we advance technology? Through scientific research. How do we get it earlier? By advancing scientific knowledge as fast as we can, in the most efficient way. So go to that conference, don't worry about that minor O(1) saving, and do your part to obtain the O(n) or O(n^2) one later on in the history of humanity. Maybe that theorem in homological algebra that you are presenting today is going to be instrumental to quantum teleportation in 100 years.