There is much discussion about the oceans warming up, ice sheets melting, and sea levels rising. NASA is an excellent source of quantitative data on these concerns.
In an earlier blog I described the AIRS (Atmospheric Infrared Sounder) satellite instrument operated by NASA. This has produced vast volumes of data since 2002.
Hartmut Aumann, working at the NASA Jet Propulsion Laboratory, has analysed this data to determine the relationship between the temperature of the ocean surface with the frequency of severe storms. Along with colleagues Ali Behrangi and Yuan Wang, Aumann published the results of the analysis in Geophysical Research Letters in December 2018.
The study analysed 15 years of data covering tropical oceans to determine the probability of the deep convective cloud (DCC) process as a function of the temperature of the sea surface. Deep convective clouds are typified by cumulonimbus clouds. These can reach an altitude of 10 km (33.000 ft).
The study found that severe storms (at least 3 mm (0.12 ins)) of rain/hour over a 25 km (16 mile) area forms when the sea surface temperature is higher than 28ºC (82ºF). The study further found that for every 1ºC (1.8ºF) rise in sea surface temperature, 21% more severe storms are formed.
Current climate models project that if carbon dioxide levels rise by 1%/year, the tropical sea surface temperature may rise by 2.7ºC (4.8ºF) by 2100. On the basis of the AIRS data study, the consequence of this would be a 60% increase in the frequency of severe storms.
Rising sea levels
There are two main factors that cause sea levels to rise:
- The addition of water from the melting of ice sheets and glaciers
- The expansion of seawater as it warms
The latest measurement from NASA indicates a rise in sea levels of 90 mm since 1993, giving an annual rate of change of 3.2 mm. This rise in sea levels, determined by satellite observations, is shown in the graph below.
Using coastal tide gauge data produced by the Commonwealth Scientific and Industrial Research Organisation (CSIRO) the rise in sea levels between 1870 and 2013 has also been calculated – graph below. This shows a total rise of c. 230 mm over this period.
These are two great examples of quantitative and verifiable data being used to demonstrate the practical effects of climate change.
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