Not even Central Park has been safe from shadows. In 1987, hundreds of people formed a line through the park and opened black umbrellas on cue in a symbolic protest of the Time Warner Center in Columbus Circle, whose design was ultimately tweaked. More recently, in 2014, a series of towers planned along West 57th Street prompted the local community board’s Central Park Sunshine Task Force.

The city does assess the impact of shadows from new construction, but only when a zoning change is required, prompting many to call for a more comprehensive policy that reviews the effects of all tall buildings.

After Michael Kwartler, an architect and shadows consultant who wrote a 1991 proposal on preserving sunlight in parks, found that the huge towers rising in Hudson Yards would block much of the sunlight on a boulevard and park planned as part of the development, changes were made, but not enough to prevent extensive shadows.

“It’s an issue that really needs to be solved, and not on a case-by-case basis,” he said.

Greenacre Park, a space so small (6,360 square feet) that it is called a “vest pocket park,” was pieced together from three lots once occupied by a store, a garage and part of a synagogue. Today, it feels like the terrace of a grand country estate, with Knoll chairs and tables beside vibrant flower beds, a trellis with heat lamps for the chill, and cascading water drowning out the urban din. It has an average of 700 visitors daily.

As part of the rezoning plan, which is meant to maintain the east side of Midtown Manhattan as a world-class commercial corridor, the city conducted a shadows study showing no significant adverse impact on Greenacre Park. Rachaele Raynoff, a spokeswoman for the planning department, said “projected incremental development” from the proposed zoning changes would create “no more shadow on the space than buildings that can be built today.”

The rezoning plan, which requires approval by the Planning Commission and the City Council, aims to expand the city’s tax base, attract more jobs and finance improvements to subway stations, streets and sidewalks.

The Greenacre Foundation commissioned its own shadows study. Jacob Dugopolski, with the firm WXY, found that development on six sites could cast the entire park into shadow. The foundation has called for height limits on those sites, or at the very least a public review of their shadow impact on the park.