evidence: According to an ongoing temperature analysis led by scientists at NASA’s Goddard Institute for Space Studies (GISS), the average global temperature on Earth has increased by at least 1.1° Celsius (1.9° Fahrenheit) since 1880. The majority of the warming has occurred since 1975, at a rate of roughly 0.15 to 0.20°C per decade. [...] As the maps show, global warming does not mean temperatures rise everywhere at every time by same rate. Temperatures might rise 5 degrees in one region and drop 2 degrees in another. For instance, exceptionally cold winters in one place might be balanced by extremely warm winters in another part of the world. Generally, warming is greater over land than over the oceans because water is slower to absorb and release heat (thermal inertia). Warming may also differ substantially within specific land masses and ocean basins. [...] The leveling off of temperatures in the middle of the 20th century can be explained by natural variability and by the cooling effects of aerosols generated by factories, power plants, and motor vehicles in the years of rapid economic growth after World War II. Fossil fuel use also increased after the war (5 percent per year), boosting greenhouse gases. Cooling from aerosol pollution happened rapidly. In contrast, greenhouse gases accumulated slowly, but they remain in the atmosphere for a much longer time. According to former GISS director James Hansen, the strong warming trend of the past four decades likely reflects a shift from balanced aerosol and greenhouse gas effects on the atmosphere to a predominance of greenhouse gas effects after aerosols were curbed by pollution controls.