Current warming trend is linked to human activities.
Climate change in past was entirely natural, and could've been caused by:
- subtle variations in the earth's orbit.
- slight changes in its tilt towards the sun.
- variations in the global pattern of ocean currents, which moves heat around the world.
El Nino effect is a periodic 'blip' in the usual global climate. Found off the west coast of S Ameria - caused by a short-term reduction in the intensity of the cold ocean currents. Results in unusual patterns of temperature and rainfall, and…