use Net::Google::Calendar;
use Data::Dumper;

my $username = 'MEINE_EMAIL_BEI_GOOGLE';
my $password = 'MEIN_PASSWORT_FUER_GOOGLE';

my $cal = Net::Google::Calendar->new;
$cal->login($username, $password);

my @calendars = $cal->get_calendars;

foreach(@calendars){
  print Dumper $_."\n-----------------------------\n";
}

403 Forbidden at /usr/local/share/perl/5.20.2/Net/Google/Calendar.pm line 629, <DATA> line 1.

sub get_feed {
    my ($self, $feed, %opts) = @_;
    if (ref($feed)){
        return $feed if $feed->isa('XML::Atom::Feed');
        if ($feed->isa('URI')) {
            my %params = ($self->{_auth}->auth_params('GET', $feed), %opts);
            my $r   = $self->{_ua}->get("$feed", %params);

            my $redirect_tries = 0;
            while ($r->code == 302 || $r->code == 301) {
                my $location = $r->header('location');
                %params = ($self->{_auth}->auth_params('GET', $location), %opts);
                $r   = $self->{_ua}->get($location, %params);
                $redirect_tries++;
                die "Too many redirects ($redirect_tries)" 
                  if $redirect_tries > $REDIRECT_MAX;
            }

      -->   die $r->status_line unless $r->is_success;
            $feed = $r->content;
        }
    }
    return XML::Atom::Feed->new(\$feed);
}