The new study finds that satellite measurements have likely been underestimating the Warming of the lower levels of the atmosphere over the last 40 years. Basic physics equations govern the relationship between temperature and moisture in the air, but many measurements of temperature and moisture used in climate models diverge from this relationship. The study was published in Journal Climate.
Ben Santer, a climate scientist at Lawrence Livermore National Laboratory in California and the lead author said that Satellite measurements of the troposphere have underestimated its temperature or overestimated its moisture. It is very hard to determine which interpretation is more credible. The study reveals that several observational datasets, particularly those with the smallest values of ocean surface Warming and tropospheric Warming appear to be at odds with other, independently measured complementary variables. Complementary variables are those with a physical relationship to each other.
In models, these ratios are strictly defined based on physical laws governing moisture and heat. It takes more energy to Warming up moist air than dry air because water sucks up heat efficiently. Warming air can also hold more moisture than cooler air, a phenomenon that is visible in morning dew as the air cools overnight, it sheds water. The researchers found that the satellite observations didn’t stick to these supposedly well-defined rules. They fell within a wide range, depending on which dataset the researchers used.