CHICAGO (CBS) — It’s a little cold to have a picnic, but that’s exactly what people are doing outside the Shedd Aquarium on this Earth Day.

This is the second year for the lakefront tourist attraction to participate in Picnic for the Planet – this time as part of an effort to set a world record for the largest outdoor picnic in a 24-hour period.

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Lesley Spraggins, with the Nature Conservancy, says the Shedd is one of roughly 3,000 picnic sites across the globe — including Australia — to work for the record.

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People gathered at picnic tables — under a tent on the patio of the Shedd, which sheltered them a little from the chilly lake breeze — sitting and eating for at least 10 minutes, so as to be properly recorded for the attempt.

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Some 7th graders visiting Chicago from New Orleans were happy to participate – enjoying the snack of fruit, veggies and salmon.

Spraggins says the point of the picnic is to get people thinking about how they must take care of their food and water sources.

She says as more of us live in big cities, we find it harder to connect with nature.

However, Spraggins says she frequently sees people having picnics in Millennium Park in downtown Chicago.

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The event runs through 6 p.m. Sunday. Organizers don’t expect to know the global tally for a couple of weeks.