The International Energy Agency (IEA) noted in its 2012 report that the world will face growing difficulty in reducing emissions by improving energy efficiency or by using alternative energy sources because the low - hanging fruit in these ares will soon have been picked. (scientificamerican.com)
By the seventh century, both empires were facing growing difficulties from their client states. (firstthings.com)
However, Schellenberg and von Scheve believe that the steady increase in duration and decrease in tempo that they found in their study doesn't support the idea of growing difficulties fully because it would mean our problems have increased steadily over the last fifty years. (scientificamerican.com)