Education. If you want to become an optometrist, you'll need about eight years of education. Depending on how fast you work, you might be able to graduate sooner if you take on additional credit hours or complete coursework during the summer.
Although the results for the Earthâs temperature are usually given as anomalies, climate scientists have used the measured temperature data to calculate average temperatures. NOAAâs result for the 20th century average land-ocean Earth surface temperature is 13.9 Â°C. The 2011 NOAA surface temperature anomaly of 0.51 Â°C, gives an average Earth temperature of 14.4 Â°C for 2011. To find out more about how the Earth is warmed and the greenhouse gases that are responsible, see How Atmospheric Warming Works and Greenhouse Gases.
Today's global temperature is typically measured by how it compares to one of these past long-term periods. For example, the average annual temperature for the globe between 1951 and 1980 was around 57.2 degrees Fahrenheit (14 degrees Celsius). In 2015, the hottest year on record, the temperature was about 1.8 degrees F (1 degree C) warmer than the 1951â1980 base period. That calculation comes from NASA and NOAA. Other agencies may come up with a slightly different number because there are several techniques for calculating a global average, depending on how one accounts for temperatures above the data-sparse oceans and other poorly sampled regions.