The survey showed that six in 10 ultra high net worth US individuals - with net investable wealth of $30 million or more -  intend to give more this year than they did last.

Meanwhile, according to the Center on Philanthropy at Indiana University, big gifts are climbing. Individuals made 267 gifts of more than a million dollars during the first quarter, up 43 per cent from 186 the previous year.

The biggest of these came from James Sorenson. The inventor left his entire personal fortune to charity when he died in January. The gift, estimated at $4.5 billion, will help disadvantaged children, schools and medical facilities in Sorenson's home state of Utah.

Other notable donations include Blackstone co-founder Peter Peterson's $1 billion gift to his own foundation, which hopes to raise awareness on US high federal deficit. David Rockefeller, the only living grandchild of Standard Oil founder John Rockefeller, gave $100 million to Harvard University. The April gift was the largest the school ever received from an alumnus.

According to the Prince & Associates survey, 87 per cent of the wealthy who plan to donate more this year cited greater need as a motivation.

Most wealthy donors have the advantage of sitting on such impressive fortunes that they can peer down on today's economic storminess with relative calm. Only 13 per cent of Americans with a net worth of more than $30 million expect a significant adverse effect from the economy.

This group already accounts for a crucial and outsized portion of America's charitable giving. According to the Center on Philanthropy, the wealthiest 3 per cent of Americans account for approximately two-thirds of all household charity in the  US.

A recent study from Giving USA found that giving in the US hit $306.4 billion last year.