Japan shut down virtually all nuclear power plants after the March 11, 2011 earthquake, tsunami and nuclear power plant accident.

What has been the greenhouse gas impact of this decision? Have people merely consumed less power, or have other forms of electricity generation increased as a result? If the latter, have they been forms of electricity that have been more greenhouse gas intensive, or less greenhouse gas intensive, than nuclear power?

For the sake of simplicity, I'm asking only about Japan's decision, not about other countries that are phasing out nuclear post-Fukushima.

(As a pre-emptive reply to any criticisms: I acknowledge that nuclear power is not sustainable as it indirectly generates greenhouse gases, and there's a limited supply of nuclear material. Also, that electricity generation and electricity usage could well have changed without the shutdown of nuclear power plants)