New Study: CO2 emissions reduced risk of flooding in Africa

Written by Hannah R Parker, Fraser C Lott et al.

Abstract: In 2012, heavy rainfall resulted in flooding and devastating impacts across West Africa. With many people highly vulnerable to such events in this region, this study investigates whether anthropogenic climate change has influenced such heavy precipitation events.

We use a probabilistic event attribution approach to assess the contribution of anthropogenic greenhouse gas emissions, by comparing the probability of such an event occurring in climate model simulations with all known climate forcings to those where natural forcings only are simulated.

An ensemble of simulations from 10 models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) is compared to two much larger ensembles of atmosphere-only simulations, from the Met Office model HadGEM3-A and from weather@home with a regional version of HadAM3P.

These are used to assess whether the choice of model ensemble influences the attribution statement that can be made.

Results show that anthropogenic ‘greenhouse gas’ emissions have decreased the probability of high precipitation across most of the model ensembles. However, the magnitude and confidence intervals of the decrease depend on the ensemble used, with more certainty in the magnitude in the atmosphere-only model ensembles due to larger ensemble sizes from single models with more constrained simulations.

Certainty is greatly decreased when considering a CMIP5 ensemble that can represent the relevant teleconnections due to a decrease in ensemble members. An increase in probability of high precipitation in HadGEM3-A using the observed trend in sea surface temperatures (SSTs) for natural simulations highlights the need to ensure that estimates of natural SSTs are consistent with observed trends in order for results to be robust.

Further work is needed to establish how anthropogenic forcings are affecting the rainfall processes in these simulations in order to better understand the differences in the overall effect.


Comments (1)

  • Avatar

    Carl Brehmer


    Floods have always been a component of the Earth’s natural climate. Economically advanced countries build dams and bridges to either control such flooding or allow travel above the flood waters.

    Doing so takes a lot of energy. Every facet of constructing dams and bridges to deal with flooding requires large amounts of hydrocarbon energy. How bazaar that today’s world leaders believe that flooding is now being caused by the energy that we use to deal with flooding.

    Isn’t that the meme? In order to control flooding the in Africa we must restrict the use of hydrocarbon energy worldwide because the use of hydrocarbon energy causes flooding. This is like saying that eating causes hunger and drinking water causes thirst.

Comments are closed