• by Wayne Friedman , July 20, 2010

ZenithOptimedia has raised its worldwide advertising growth estimate again -- this time to a 3.5% hike in 2010 over the year before.

The big media-buying group says strong growth in North America and Europe, as well as higher revenues from Internet, mobile and social media, is driving its estimates higher. Zenith says 2010 is estimated to hit $448 billion.

This is the third time ZenithOptimedia has pushed up its numbers. The most recent growth rate sat at 2.2%.

There is better news for 2011, where global ad spending is expected to climb 4.5% from a 4.1% previous estimate. Outer years will climb at better rates; 2012 will see 5.3% growth.

Zenith expects developed markets will grow by 2.4% in 2011 and 2.9% in 2012. Developing markets will grow much more substantially. They were expected to grow by 9.1% and 9.8%, mostly from Asia-Pacific and Latin America regions.

All this will be a reversal from 2009, which had a 10.3% decline.

Worldwide television is expected to get to a 40.8% share of the global ad market in 2012, up from 39.2% in 2009.

Internet ad spending will continue to be the biggest medium after TV and newspapers. In 2010, it will grow 13.1% in 2010 and gain another 16.1% in 2011. By 2012, there will be another big gain: 17.1%. Zenith notes that Internet ad spending was at 12.7% in 2009.

In North America, the agency is forecasting a 1.3% growth in 2010 -- up from an earlier estimate that pegged the market at a 1.5% decline. ZenithOptimedia now expects a 2.2% growth in Western Europe, up from 0.4% previous estimate.