Drought In The Horn Of Africa - Exposing Another 'Attribution' Study Which Claims It's Our Fault

World Weather Attribution and Imperial College London just keep them coming: the ‘scientific’ studies which purport to demonstrate that man-made climate change is the cause of bad weather occurring across the world. Floods in China, storms in Florida, heatwaves in South America, wildfires in Australia and the western US, now droughts in Africa - it’s all your bloody fault for selfishly using a car and keeping warm in winter using gas or oil-fired central heating, and eating meat, and drinking milk, and all the other reckless, planet-destroying stuff which you do day after day on account of living normally and not like some hermit in a cave.

The latest offering from World Weather Attribution, now based at Imperial College London (where else?) has of course been immediately picked up by the climate fanatical Graun:

The devastating drought in the Horn of Africa would not have happened without the human-made impact of the climate crisis, new science has shown.

The drought has affected about 50 million people in the Horn of Africa directly and another 100 million in the wider area. About 20 million people are at risk of acute food insecurity and potentially famine.

The region has been suffering its worst drought in 40 years since October 2020, with extended dry conditions punctuated by short intense rainfall that has often led to flash flooding. There have been five consecutive seasons of rainfall below normal levels.

At least 4.35 million people are in need of humanitarian assistance, and at least 180,000 refugees have fled Somalia and South Sudan for Kenya and Ethiopia, which have also been affected by the drought.

According to a study by the World Weather Attribution group of scientists published on Thursday, the ongoing drought would not have happened without human actions that have changed the climate.

That is because a lack of rainfall, but also higher temperatures driven by global heating have made the soil and pasture of the region much drier than they would normally be by increasing the evaporation of moisture from the earth and plants.

The study found that the recent rainfall conditions would not have led to drought in a world that was 1.2C cooler, and that by a conservative estimate climate change had made droughts such as the current one about 100 more times likely to occur.

Friederike Otto, a senior lecturer in climate science at the Grantham Institute for climate change and the environment at Imperial College London said: “This study shows very strongly that drought is much more than just the lack of rain, and that the impacts of climate change strongly depend on how vulnerable we are. One of the main findings from the recently published Intergovernmental Panel on Climate Change synthesis report is that we are way more vulnerable than we thought.”

Yup, Friederike Otto, the Wonder Woman of Extreme Weather Attribution, is at it again, telling us that ‘drought is not just a lack of rainfall’, it’s other stuff too, all wrapped up with the ‘impacts of climate change’. But as usual, if you want to know what the study really says and why it says it, you have to read the study itself, not rely upon the Graun or even one of the contributing authors to tell you what it’s about, because they’re in the business of promoting the Net Zero agenda, nothing else, and they use ‘science’ distorted through the lens of commissioned funded research and media bias in order to do it.

As it happens, the Guardian article presents a fair summary of the findings of the paper, but it leaves so much qualifying detail out. It is that qualifying detail which reveals this WWA attribution study to be basically rubbish, junk, not fit for purpose (unless that purpose is to communicate gossip masquerading as science to the mainstream media that ‘it was climate change wot dunnit’, with regard to the occurrence of yet another impactful weather event). This is how they get away with it, because they know very few people will go to the paper itself, let alone try to read it and analyse its findings in relation to exaggerated and hyped mainstream media reporting. But I’m pleased to oblige. I read this crap so you don’t have to.

So, here we go. The study outlines the occurrence of the meteorological drought as follows:

The Southern part of the Horn of Africa, covering parts of southern Ethiopia, southern Somalia, and eastern Kenya (see figure 1), saw below average rainfall for the short rains (October-December) in 2020, 2021 and 2022 as well as the long rains (March-May) in 2021 and 2022.

Here’s what they attempted to do:

In order to identify whether human-induced climate change was a driver of the low rainfall, i.e the meteorological drought, we analysed rainfall over the most impacted region in the Southern Horn of Africa, covering parts of southern Ethiopia, southern Somalia, and eastern Kenya, for 24 consecutive months, from January 2021 to December 2022, as well as just the individual 2022 March-May and October-December seasons separately.

This is what they discovered:

We find that in today’s climate, which has been warmed about 1.2°C by human-induced greenhouse gas emissions, the below-average rainfall in the March-May season is a 1 in 10 year event, a 1 in 5 year event in the short rains. For the entire 24-month period there is a 5% chance in every year for such an event to develop.
Using two observation-based rainfall products we find there is a trend towards less rainfall in the long rains but not over the short rains, which show the opposite, a wettening. There is no trend when looking at the short and long rains combined over 24 months.

The alleged climate changed drought, remember, is a shortage of rains in both seasons over the period 2020-22. But they find that this is hardly a ‘rare’ event; it can be expected to occur once every 20 years. Also, they find, looking at weather records for the region, that there is only a trend towards drier conditions in the long rains (March to May). There is the opposite trend in the short rains, i.e. the October-December season has been getting gradually wetter. So 2020-22, as far as the short rains is concerned, bucks the long term trend which means it is problematic to attribute it to long term warming of the climate. Finally, looking at the long and short rains combined, there is no statistical drying trend averaged over 24 months. I’ll say that again: there is no trend, which means also that attributing this 24 month drought to long term warming is also problematic. But the authors don’t let such minor details get in the way of a good yarn.

The years of the drought also saw consecutive La Niña conditions. There is a high correlation between below-average short rains and La Niña, but there is no correlation with the long rains. When taking into account the effect of La Niña there is a trend towards wetter conditions in the short rains.
To formally attribute these trends to climate change and to try to quantify its contribution to the drought, we used climate models and looked at similarly low rainfall events over the same region in the model data. We found that the models show similar results to the observations: low rainfall events like those currently observed in the long rains have become about twice as likely due to human-induced climate change, while there is no attributable change when short and long rains are combined. In the short rains, models where the effect of La Niña is taken into account show that a low rainfall season like the one observed has become less likely, making the increased rainfall in the short rains attributable to human-induced climate change.

The first bold writing sounds confusing. First they state that there’s a high correlation between below average short rains and La Nina, then they say, taking into account La Nina, that there is a trend towards wetter short rains. I can only imagine that, over the period of observations, there must have been less La Ninas happening generally, therefore resulting in a trend towards wetter short rains, because when La Nina does occur (as in 2020-22) the short season is significantly drier. The second bold passage appears to be reasonable: they found a drying trend in the long rains in both the observations and the models, which could not be explained by La Nina, so they attributed this drying trend to long term climate change. But they could find no attributable trend in the combined long and short rains, i.e. no drying trend or wetting trend, so they could not attribute the 24 month drought in the Horn to climate change using climate models.

The authors then go on to make the following bizarre claim: after admitting that the models show a wetting trend in the short rains when taking La Nina (a natural weather event) into account, they conclude that dry short rains - like 2020-22 - have therefore become less likely. But they don’t credit La Nina with this wetting trend; they claim it is because of man-made climate change! How odd.

In the short rains, models where the effect of La Niña is taken into account show that a low rainfall season like the one observed has become less likely, making the increased rainfall in the short rains attributable to human-induced climate change.

In their statistical analysis of the effect of increasing GMST (global mean surface temperature), the authors admit that natural variability plays a large part in the observed precipitation trends:

On comparing the above results with the fitted trends using only GMST as covariate, we find that the response to GMST is weaker when the ENSO effect is not taken into account (see left-hand panel, Fig. A6), possibly due to confounding effects of ENSO (as demonstrated in Table A1): in particular, the occurrence of three consecutive La Niña years at the end of the time series masks the underlying GMST trend to some extent. La Niña is known to exert substantial influence on OND rainfall in EA, and has been associated with most recent intense drought events in EA (e.g., 2010-2011; Funk, 2011, 2016; Uhe et al., 2017). Furthermore, co-occurrence of La Niña with the negative phase of the Indian Ocean Dipole (IOD) has been found to exacerbate drought conditions (Schubert et al., 2016). The IOD phase was negative in the most part of 2021 and 2022 (BOM, 2022).

But the main point here is, the models cannot be used with confidence to attribute the observed low rainfall in both the long and short rains over this 24 month period. They just can’t. So the authors try something else. Here is what they do:

In order to understand whether climate change influenced not only the meteorological drought (i.e. low rainfall), but also other aspects of the drought, including the agricultural drought which influences how much water is available for plants, we also looked at the role of temperature. To do this we combined the rainfall assessment with an assessment of changes in potential evapotranspiration, i.e. how much water evaporates from soil and plants because of higher temperatures, in a multivariate analysis for the 24 months of drought.
We found that, as a result of human-induced climate change, the combination of low rainfall and high evapotranspiration as unusual as the recent conditions would not have led to drought at all in a 1.2°C cooler world (see figure 2). In today’s climate the same event is now classified as an exceptional drought (D4, dark red in fig. 1), with major crop and pasture losses and widespread water shortages. This change in drought severity is primarily due to the strong increase in evaporative demand caused by higher temperatures.

You see what they did? They couldn’t attribute the meteorological drought to human-induced climate change, so they claimed that the increase in evapotranspiration (the agricultural drought) was caused by climate change because of the higher temperatures experienced in the Horn of Africa in a 1.2C warmer world. It’s not the first time they’ve resorted to this sleight of hand either, when they found they could not attribute the lack of rainfall to climate change. Here is what WWA said about a recent drought in central South America:

• In order to identify whether the reduced rainfall is a real trend beyond natural variability that can be attributed to climate change, we looked at once in 20-year low rainfall events over the same region in climate models and found that the models show that low rainfall events decrease – ie they become wetter; the opposite of the trend observed in most weather records – although this trend is again not significant and is compatible with natural variability. Thus, we cannot attribute the low rainfall to climate change.

• This does not rule out that climate change affected other aspects of the drought. To investigate whether the high temperatures, which are in part attributable to climate change, led to a deficit in water availability, calculated as potential evapotranspiration subtracted from the rainfall, we repeated the analysis for this indicator.

• The results show that, in climate models, the increase in temperature does partly compensate for the increase in rainfall but only to offset the wettening, and does not lead to a significant climate change signal in effective precipitation..

• However, higher temperatures in the region, which have been attributed to climate change, decreased water availability in the models in late 2022, indicating that climate change probably reduced water availability over this period in the observations too, thus increasing agricultural drought, although the study cannot quantify this effect.

• This means even though the reduced rainfall is within the natural variability, consequences of drought are becoming more severe due to the strong increase in extreme heat.

This is little more than guessing. They’re assuming that the modest increase in mean temperature can be attributed to ‘climate change’ and then they are assigning an increase in the rate of evaporation from the soil surface and transpiration from the leaves of plants solely to this increase in temperature, although they can’t quantify the magnitude of the effect. Of course they can’t. Evapotranspiration is a complex phenomenon affected by more than just air temperature:

Factors influencing evapotranspiration

There are five major factors that affect evapotranspiration. These include both climatic and physical properties of the region, plus the specific physiology of the plant involved. Here’s a description of each of them, and how they play a role.

• The Soil – Soil composition determines its water retention and thus its ET properties. High sand or gravel soils retain the least water and will lose more water to evaporation than loamy or clay soils, for example.

• The Air – One of the most obvious factors influencing evaporation is air temperature. This affects the carrying capacity of the air, as well as the energy imparted into water that contributes to its rate of phase change to vapor. As such, a higher temperature typically results in an increased rate of ET.Wind speed will also affect the rate of evaporation, as increased air movement will provide contact surfaces with more available transportation of vapor, increasing the rate of ET.

• The Sun – Solar radiation is more than just the thermal effects of the sun. Frequency, energy, and albedo all vary depending on the location and time of day, and all affect the rate of ET. These are factors that are useful to consider but difficult to measure accurately without advanced technology.

• Water – The relative humidity (RH) of the air determines how much vapor can be held in it. With high humidity, there is less absorption of new vapor and ET is reduced. Low humidity means the air can carry more vapor, thus ET is increased.Increased rainfall can increase humidity and decrease transpiration. Rain typically increases RH

• The Plant – Different plants have different adaptations to their climate. Some are more capable of retaining their water during dry spells, others transpire more rapidly. The age and health of the plant also play a role. Some will have deeper roots, allowing them to reach water for longer without rainfall or irrigation. The physiology of the plant will play a large role in the rate of ET and therefore different plants will need different irrigation schedules.

Air temperature is just a small part of a complex interplay of factors influencing evapotranspiration rates. A significant influence is the nature of the soil, the character of land management/farming and the nature of the predominant vegetative land cover. In this respect, the authors of the study point out the following significant changes in land use and management in the Horn of Africa:

7.4 Environmental degradation and land-use changes
Over the past decades, the land across the HoA has undergone significant changes which has fueled vulnerability to climate change and the recurring droughts (Prieto-Garcia et al., 2022; Warsame & Sarkodie, 2022). Environmental degradation, unsustainable land-use practices and harvesting, the overexploitation of grazing land and other pastoral activities, deforestation, urbanisation, as well as ongoing conflict have altered the microclimate in the area, causing changes in precipitation patterns that further exacerbate drought conditions, impacting the terrestrial ecosystem, and increasing vulnerability of local communities (Galaty, 2013; Prieto-Garcia et al., 2022). For example, several indigenous plants have been declining including the Yeheb plant, a small tree endemic to the drylands of Ethiopia and Somalia which contains high nutritional and economic value (Prieto-Garcia et al., 2022). Also the large influx of refugees e.g. into Kenya over the years has increasingly stretched the little resources available, contributing further to environmental degradation (OCHA, 2023). Land grabbing, which involves the conversion of forests lands and grazing lands into large-scale commercial agriculture, biofuel production, or mining operations, has had severe negative impacts on the environment and livelihoods of communities across Sub-Saharan Africa (Borras et al., 2011). Pastoralists are particularly vulnerable to land grabbing due to insecure land rights and inadequate legislative protection, as well as stereotypical views held by policy-makers that tend to justify attempts to grab land in the name of development and for other, more 'productive' uses, such as promises of conservation, preservation of natural resources, national development, and progress (Galaty, 2013).

All of these changes in land use and plant vegetation will affect rates of evapotranspiration over the long term. But the authors completely ignore them in order to concentrate on just one factor which they attribute to human-caused climate change - temperature. They then make this bold, completely unsubstantiated statement:

Combining lines of evidence from the synthesis results of the past climate, results from future projections and physical knowledge we communicate that the drought severity has increased dramatically because of human-induced climate change. This is primarily driven by the very strong increase in temperature and thus PET, but there is also evidence that this is augmented by drying of the long rains.

Which does the trick, because then the media just take over and spread this bullshit across the world:

https://duckduckgo.com/?t=ffab&q=horn+of+africa+drought&ia=web