Study Finds Little Change In Global Rainfall Patterns

By Paul Homewood

   

  

While floods are in the news, it is worth taking a look at a paper, “Changes in annual precipitation over the Earth’s land mass excluding Antarctica from the 18th century to 2013”, published last month by Wijngaarden and Sneyd.

 

 

Its main findings were summarised:

 

Highlights

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Over 1½ million monthly precipitation totals observed at 1000 stations in 114 countries analysed.

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Data record much longer than 3 recent conflicting studies that analysed a few decades of data.

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No substantial difference found for stations located at northern, tropical and southern latitudes.

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No substantial difference found for stations experiencing dry, moderate and wet climates.

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No significant global precipitation change from 1850 to present.

 

 

 

 

Summary

Precipitation measurements made at nearly 1000 stations located in 114 countries were studied. Each station had at least 100 years of observations resulting in a dataset comprising over 1½ million monthly precipitation amounts. Data for some stations extend back to the 1700s although most of the data exist for the period after 1850. The total annual precipitation was found if all monthly data in a given year were present. The percentage annual precipitation change relative to 1961–90 was plotted for 6 continents; as well as for stations at different latitudes and those experiencing low, moderate and high annual precipitation totals. The trends for precipitation change together with their 95% confidence intervals were found for various periods of time. Most trends exhibited no clear precipitation change. The global changes in precipitation over the Earth’s land mass excluding Antarctica relative to 1961–90 were estimated to be: −1.2 ± 1.7, 2.6 ± 2.5 and −5.4 ± 8.1% per century for the periods 1850–2000, 1900–2000 and 1950–2000, respectively. A change of 1% per century corresponds to a precipitation change of 0.09 mm/year.

http://www.sciencedirect.com/science/article/pii/S0022169415008744

 

What is most striking, apart from the fact that it finds very little in the way of trends, is other studies claiming to find changes only used a few decades of data. This is of course a trick often employed by the Met Office.