IPCC Summary for Policymakers - Observed Changes
Read the content under the heading "Past and recent drivers of climate change" and "Attribution of climate changes and impacts" (Click on 1.2 and 1.3 on the left of the screen). (46 minutes)
The Intergovernmental Panel on Climate Change (IPCC)
Click https://ar5-syr.ipcc.ch/topic_observedchanges.php link to open resource.