I would think that much could be debated in the mere premise of the topic. I am not entirely sure that one could make the argument in an effective manner suggesting that our civilization is on a path of decline. There are some elements that are quite scary. The threat of political instability all over the world, and the willingness to use wanton violence to achieve such ends are examples of this. The strikingly high amount of poverty in the world is another element that poses fear in our civilization. Yet, I think that there are enough realities that are evident to make the case that we are not necessarily in decline, but rather represent some of the strongest elements of a civilization on the rise. Technology proliferation in so many forms, along with advanced scientific inquiry in so many realms are elements that have to be reconciled in understanding our civilization as not one on the decline. Even the development of nuclear weapons, something that one could see as a potential example of decline, would have to be seen as something of a representation of a society or civilization that has strength. The development of the nuclear capacity through the work by Dr. Oppenheimer and others in Los Alamos represent one of the best examples of a civilized humanity that uses reason and problem solving to come to a solution. The growth of nuclear weapons and its corresponding desire to control the presence of these weapons in a rational and a manner where discourse with many agents is another example of a civilization that seeks to use discourse and thought to solve problems. I do concede that there are aspects of our society that could bring into question why we are in decline, but there are many more that illuminate our successes and ideas for strength.
Before answering the question, I would like to define civilisation with a quote:
Civilization is social order promoting cultural creation. Four elements constitute it: economic provision, political organization, moral traditions and the pursuit of knowledge and the arts. It begins where chaos and insecurity end. For when fear is overcome, curiosity and constructiveness are free, and man passes by natural impulse towards the understanding and embellishment of life. - Will Durant
Now if we look at the above parameters we see that in spite of the technical advancement, the world economy is on the decline and poverty is increasing. political systems are falling apart and there is unrest the world over. Moral values are going down the drain. Now instead of being caring about our nearest and dearest ones, I am referring to parents, we limiting it to a day in the year by celebrating Father's and Mother's Day. The number of single parents is on the increase and living together has become norm of the day. Prostitution and gay marriages are being legalised in the name of personal liberties.
The only thing that is being cared for the ppursuit of knowledge and the arts. The are also benefiting only who have abundant resources. Others are so tied up with earning of their bread and butter, that they can hardly any advantage of the technological development. Art is the only thing that is available to all in form of music only.
Chaos and insecurity has increased. Threats from more powerful are increasing, specially in Muslim states, that can be subjected to aggression in the name of false alarm of WMDs as happened to Iraq and in the name of war on terror to Afghanistan. Who knows Iran may be the next!
I don't think that with 3 main elements gone and insecurity on the increase, one can conclude that the civilisation is not on the decline.