multiple warnings when I log out

Whenever I log out of my wordpress account, I get a screen full of warnings like this:

Warning: Cannot modify header information – headers already sent by (output started at /home/obscured/public_html/wp-content/themes/WP1/functions.php:12) in /home/obscured/public_html/wp-login.php on line 287

Warning: Cannot modify header information – headers already sent by (output started at /home/obscured/public_html/wp-content/themes/WP1/functions.php:12) in /home/obscured/public_html/wp-login.php on line 299

Warning: Cannot modify header information – headers already sent by (output started at /home/obscured/public_html/wp-content/themes/WP1/functions.php:12) in /home/obscured/public_html/wp-includes/pluggable.php on line 689

Warning: Cannot modify header information – headers already sent by (output started at /home/obscured/public_html/wp-content/themes/WP1/functions.php:12) in /home/obscured/public_html/wp-includes/pluggable.php on line 690

Warning: Cannot modify header information – headers already sent by (output started at /home/obscured/public_html/wp-content/themes/WP1/functions.php:12) in /home/obscured/public_html/wp-includes/pluggable.php on line 691

Warning: Cannot modify header information – headers already sent by (output started at /home/obscured/public_html/wp-content/themes/WP1/functions.php:12) in /home/obscured/public_html/wp-includes/pluggable.php on line 692

Warning: Cannot modify header information – headers already sent by (output started at /home/obscured/public_html/wp-content/themes/WP1/functions.php:12) in /home/obscured/public_html/wp-includes/pluggable.php on line 693

Warning: Cannot modify header information – headers already sent by (output started at /home/obscured/public_html/wp-content/themes/WP1/functions.php:12) in /home/obscured/public_html/wp-includes/pluggable.php on line 694

Warning: Cannot modify header information – headers already sent by (output started at /home/obscured/public_html/wp-content/themes/WP1/functions.php:12) in /home/obscured/public_html/wp-includes/pluggable.php on line 697

Warning: Cannot modify header information – headers already sent by (output started at /home/obscured/public_html/wp-content/themes/WP1/functions.php:12) in /home/obscured/public_html/wp-includes/pluggable.php on line 698

Warning: Cannot modify header information – headers already sent by (output started at /home/obscured/public_html/wp-content/themes/WP1/functions.php:12) in /home/obscured/public_html/wp-includes/pluggable.php on line 699

Warning: Cannot modify header information – headers already sent by (output started at /home/obscured/public_html/wp-content/themes/WP1/functions.php:12) in /home/obscured/public_html/wp-includes/pluggable.php on line 700

Warning: Cannot modify header information – headers already sent by (output started at /home/obscured/public_html/wp-content/themes/WP1/functions.php:12) in /home/obscured/public_html/wp-includes/pluggable.php on line 703

Warning: Cannot modify header information – headers already sent by (output started at /home/obscured/public_html/wp-content/themes/WP1/functions.php:12) in /home/obscured/public_html/wp-includes/pluggable.php on line 704

Warning: Cannot modify header information – headers already sent by (output started at /home/obscured/public_html/wp-content/themes/WP1/functions.php:12) in /home/obscured/public_html/wp-includes/pluggable.php on line 705

Warning: Cannot modify header information – headers already sent by (output started at /home/obscured/public_html/wp-content/themes/WP1/functions.php:12) in /home/obscured/public_html/wp-includes/pluggable.php on line 706

Warning: Cannot modify header information – headers already sent by (output started at /home/obscured/public_html/wp-content/themes/WP1/functions.php:12) in /home/obscured/public_html/wp-includes/pluggable.php on line 865

What is wrong? my site is obscured-reflections.net and I would appreciate any help :]