However, Mr Campbell warned delegates against "crude anti-Americanism".
"There is such a thing as finite resources," Norbert Röttgen, the German environment minister, warned delegates.
The Indonesian president, Susilo Bambang Yudhoyono, warned delegates that the conflict threatened to "radicalise the Muslim world".
Toomas Hendrik Ilves, the president of Estonia and an enthusiastic advocate for more tech-savvy government, warned delegates in Dublin not to erect "another wall in the BRICs".
Last July Smith warned delegates at Republic's annual conference against portraying the Queen's death as "an opportunity" for anti-monarchists.
London's transport commissioner also warned delegates at the conference in Birmingham that new plans for segregated cycle lanes in the capital could be toned down after criticism.
In his conference address, Mr Cable warned delegates of the tough decisions ahead, and urged them to engage with the "painful economic realities".
Admitting that recent polls, which have consistently predicted a SNP landslide at the expense of Scottish Labour, have made for pleasant reading, and that some "have given me altitude sickness", she warned delegates to take nothing for granted.
Just hours after Nick Clegg, the Liberal Democrat home affairs spokesman, warned delegates against doing the "spade work" for opposition parties by turning on their leader, Sir Menzies inadvertently became the one doing the digging.
Mr Khosla, the venture capitalist, warned delegates at the conference in San Jose that they needed technologies that are "unconditionally cheaper" than fossil fuels: "If it ain't cheaper, it doesn't scale".For the time being, however, keeping pace with demand is more of a worry.
