Another sign of Graves' disease is hyperthyroidism, i.e., overproduction of the thyroid hormones T3 and T4. Normal thyroid levels are also seen, and occasionally also hypothyroidism, which may assist in causing goitre (though it is not the cause of the Graves' disease).
Without this greenhouse effect, the average surface temperature would be 255 degrees kelvin (-18 degrees Celsius or 0 degrees Fahrenheit); a temperature so low that all water on Earth would freeze, the oceans would turn into ice and life, as we know it, would not exist.
With no atmosphere, Venus would have a surface temperature of 130oC. With global clouds (which are present) but no greenhouse effect, Venus would have a surface temperature of minus 50oC. With global clouds and the actual greenhouse effect, Venus's real surface temperature averages at 470oC.