Teen climate activist Greta Thunberg urged other activists to avoid public gatherings and move climate strikes online due to the coronavirus outbreak. "We young people are the least affected by this virus but it’s essential that we act in solidarity with the most vulnerable," Thunberg tweeted. "We’ll have to find new ways to create public awareness & advocate for change that don’t involve too big crowds ... So keep your numbers low but your spirits high." The 17-year-old asked followers to join "#DigitalStrike" on Fridays by posting a photo of striking and using the hashtags #ClimateStrikeOnline #fridaysforfuture #climatestrike #schoolstrike4climate. (📸: John Thys/AFP/Getty Images)