New estimates as to the impact of the Covid-19 pandemic on advertising revenue in 2020 and 2021 have been issued by Magna Global, a unit of IPG Mediabrands that provides media intelligence, such as on-going estimates of worldwide advertising revenue. Magna predicts that total worldwide ad spending will end 2020 down by 7%. In the U.S., if you remove the once every four year advertising tidal wave driven by Presidential and other political campaigns, then Magna estimates that U.S. advertising revenue will be down 6% for 2020.

Other analysts generally agree with Magna’s estimates, such as Raghu Kodige, Co-Founder and Chief Product Officer of Alphonso, a TV measurement and data company based in Silicon Valley, who said, “This is a reasonable, if modest estimate, given that we’ve already logged 25% of the year in a lower-spend environment with major tentpole marketing events, like March Madness, completely shut down.”

The digital ad spend is projected to be flat year-over-year by end of 2020 worldwide and up a bit in the U.S. for 2020 at a 2% projected increase. Magna says: “The most resilient formats will be digital video, as well as social media ads.” Digital spending had a very good Q. 1 this year and there are already signs of the third and fourth quarter bouncing back.

I wrote about the falling advertising revenues caused by the Covid-19 recession last month here at Forbes.com and the new data from Magna shows clearly that traditional advertising is under a lot of pressure (particularly print and TV) and digital spending is showing some strength into the second half of 2020 and the full year of 2021.

Jonah Bloom, former Editor-in-Chief of AdAge and currently CMO of Kinship, a start-up dedicated to improving people’s friendships and networking, said there is, “a long-term, ongoing shift, that isn’t going to change regardless of market conditions,” as “brands continue to spend more on customer experience, and (related) technology and content.”

In 2021 Magna expects that advertising spend worldwide, and in the U.S., will rebound based on the GDP growth expected in 2021. Vincent Letang, Executive Vice President and Managing Partner, Global Market Intelligence at Magna, said, based on well-respected estimates of likely GDP growth in 2021, that the GDP is forecast to grow in the U.S. by 3.1% to 4.7%, according to macroeconomic forecasts issued by the Federal Reserve Bank of Philadelphia and the International Monetary Fund, respectively. These GDP estimates are likely to translate into a U.S. growth in 2021 advertising by 4% approximately, Letang estimated.

The unknowns, both in the advertising world, and across our economy, are immense as we go through this once in a lifetime event. As Josh Sternberg, editor and writer of the Media Nut, a daily media business newsletter, and a former journalist at Adweek, NBC News, Washington Post, and Digiday, said “We have no idea how bad it’s going to get.” He expressed worries to me that with the end of the stimulus, continued unemployment and a virus that is not under control yet, “it’s hard to see ad spend bouncing back.”

Though there is a lot of data and experience to back the Magna estimates, which are similar to other predictions about the next few years in the advertising industry, you still wonder if the Chinese Poet from the 6th Century BC, Lao Tzu, was wise when he said, “Those who have knowledge, don’t predict. Those who predict, don’t have knowledge.”