July 2019: a record-breaking month for fatal landslides

Yesterday, the European Union’s Copernicus Climate Change Service announced that July 2019 was the warmest month on record, continuing the long period of unsustainable global heating to which we are subjecting our planet.  The statistics are stark – last month was 1.01 C warmer than the average July temperature between 1981 and 2010. The previous record was set in July 2016.  The odds are strongly in favour of the new record being broken within the next few years.

Interestingly, last month I also recorded the highest monthly number of fatal landslides.  Regular readers will know that I have been collating this data since September 2002, a dataset that is now approaching 17 years in duration.  This has formed the basis of a number of papers over the years (e.g. Petley 2012), most recently with my post-doctoral researcher Dr Melanie Froude (Froude and Petley 2018).  The data for the period 2004-2017 can be mapped using our online tool.

In 2019 I recorded a total of exactly 100 fatal landslides, breaking the previous record by a considerable margin.  These landslides killed 358 people.  By comparison, in 2018 I recorded just 51 fatal landslides, causing 148 fatalities.  The graph below shows the cumulative total of fatal landslides, and the resulting deaths, for the year to date (correct as to 5th August 2019), but note that this data has not been subjected to the validation process that will allow it to be included in the main dataset as yet):-

The cumulative graph for fatal landslides, and the resulting fatalities, in 2019 to date.

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The black line is the number of landslides that I have recorded worldwide that have led to the loss of at least one life, whilst the grey line is the cumulative total of the number of resulting fatalities.  The dashed lines indicate the start and end of July.  The rapid acceleration in the number of fatal landslides at the start of the month is clear.  This reflects the onset of the South Asian monsoon and is the normal pattern.  However, the number of landslides recorded in unprecedented.  In this period, there have been many landslides in South Asia (most notably Nepal, India and Bangladesh), but I have also recorded events in, for example, UK, Norway, USA, Myanmar, Tajikistan, Thailand, Guinea, Switzerland, Brazil, China and elsewhere.

At this stage it is not clear as to the cause of this surprising number of fatal landslides.  It has long been suggested that increased global temperatures will lead to higher rainfall intensities (put simply, a warmer atmosphere can hold more moisture), and there is strong evidence that this is occurring.  Most of the landslides in July 2019 were triggered by short duration, high intensity rainstorms.  Whilst a single month does not prove the link by any means, July 2019 serves to illustrate once again the challenges that we will face in the future.

References

Froude, M. J. and Petley, D. N. 2018. Global fatal landslide occurrence from 2004 to 2016. Natural Hazards and Earth System Sciences, 18, 2161-2181, https://doi.org/10.5194/nhess-18-2161-2018.

Petley, D.N. 2012. Global patterns of loss of life from landslides. Geology 40 (10), 927-930.