You have missed meta_value
parameter.
You can use like this :
$today=date('Y-m-d');
$args = array(
'numberposts' => 10,
'post_type' => 'events',
'meta_key' => 'event_date',
'meta_value >=' => $today
);
// get results
$the_query = new WP_Query( $args );