• The difference between climate and weather is time. Weather is the rain which falls over a weekend. Climate is weather averaged over a much longer period of time (at least 30 years). Normally, climate takes centuries to change. However, the climate change we are experiencing today is happening much faster, which is why it is so unnatural.
• 19 out of the 20 warmest years all have occurred since 2001.
• About 70 percent of Earth’s surface is covered by clouds at any given time. It's cloudier over sea than land.
• Heatwaves are becoming more frequent. In the 1960s, most major cities in the United States experienced heatwaves twice a year. Now, it is 6 times a year.
• Sometimes climate variability is triggered not by global warming but by regional weather cycles, like the El Niño–Southern oscillation (ENSO), the Indian Ocean Dipole (IOD), the Madden–Julian oscillation (MJO), the Northern Annular Mode (NAM) and the North Atlantic oscillation. However, even here, the extent of the variation can be influenced by climate change.
• Warm air holds more moisture. In fact, air holds about 7 percent more moisture for every 1°C rise in temperature. So, if Planet Earth heats up by 4°C, there will be around 28 percent more water vapor in the atmosphere. In other words, expect lots more rain.
• According to the United Nations Environment Programme the cost of the changes needed to adapt to a warming world is around US$ 140 billion per year. That's roughly 2 percent of global GDP.
• Climate feedbacks are mechanisms that amplify or reduce global warming. A good illustration of a positive feedback are forest fires. High temperature dries out the forest, creating tinderbox conditions. Lightning then ignites the dry forest biomass which burns down a wide expanse of forest, sending a plume of CO2 into the atmosphere. This CO2 causes more heat to be trapped in the atmosphere causing more global warming, which dries out the forest even more, and so on.
