Now show this to the Tokyo city office

"We hear you! More cars it is!"

No one tell Paris

When you make an urban park, you have to accept two things though. First, locally the city becomes more expensive. And second, it will occupy more space over potentially natural zones (over suburban area actually, that themselves will grow over peri-rural, that will push these, etc.)

If your goal is wildlife preservation or carbon capture, you probably want one more hectare in a forest rather than an hectare in a park inside a city.

Don't get me wrong, I wanted more trees when I was living in a city. But the choice is between livable big cities or trying to make the cities as small impact as possible.

It can be an easy thing to test yourself, depending on local geography. Go for a walk in a forested area, even lightly, and then walk in an open field, then walk on a street. The temperature difference is easy to notice.

There's a trail nearby that goes from lightly forested to pavement next to a road, and then back to lightly forested. There's easily a 5-10*c difference when on the pavement, it's like hitting a wall of heat.

Edit: this is to say: there should be no doubt about the effectiveness and necessity of urban tree cover. Green walls/roofs, light coloured roofs, green covered parking lots, etc. Solar panels also work well to block the sun, and provide extra power as well.