Global warming is caused by the greenhouse effect, human activity, and volcanic activity. It is raising Earth's temperature and affecting the atmosphere, hydrosphere, lithosphere, and biosphere. If left unchecked, global warming could increase global temperatures by over 2°C by 2035 due to increasing CO2 levels. The Kyoto Protocol aims to reduce greenhouse gas emissions to mitigate global warming and its economic, agricultural, and health impacts. Romania has agreed to reduce its emissions 8% by 2012 to comply with the Protocol by increasing energy efficiency and developing renewable resources.