Weather and climate: weather: atmospheric conditions over a short time period (day or week, climate: composite of the variety of day-to-day weather. Climate change: long-term shift or alteration in the climate of a specific location, region, or the planet, global warming, changes in the average surface temperature. What causes climate: surface of the earth is: unequally heated by the sun. Impacts can cause droughts in some parts of the world and flooding in others. What is the evidence of climate change: since 19th century, average global temperature has increased by: 0. 6 +/- 0. 2 degrees celsius. Increase in temperature in the northern hemisphere during 20th century was the largest than any century in the past 1000 years: paleoclimate indicators: past climate indicators based on ice cores, tree rings and coral reef data. Greenhouse gases: continued to rise over the past decades, carbon dioxide and methane concentrations are higher now than ever before.