Drought

Craig Kelly debunks another alarmist myth (about drought)?

Claim

There is no increase in global drought as predicted by climate science. Therefore climate change is all an “alarmist myth”.

Verdict

This claim is itself a myth. Climate science doesn’t predict a significant global increase in drought, but increasing drought in some locations and increasing rainfall in others.


The claim in detail

On 7th December, Craig Kelly posted the following on Facebook:

ANOTHER ALARMIST MYTH DEBUNKED

UN Globalists and their their useful idiots supporters, try to scare gullible & naive children into believing that;

1) Droughts are getting worse, and
2) It’s all our fault for using fossil fuels, and
3) By surrender more control to UN Globalists, we can stop this trend droughts getting worse.

But it’s all a lie, a hoodwink. And anyone that claims droughts are getting worse is either liar or a fool.

Assessment

Measuring droughts

A drought is defined as a period when a drought index falls below a certain number. There are several different drought indices, which are based on (variously) precipitation, potential evapotranspiration (the amount of water that could evaporate from the ground or plants under the given conditions), temperature and/or soil moisture.

There are several different ways that droughts can be described and measured:

  • the length (duration) of drought;
  • the intensity of drought, as defined by the largest negative value of the chosen index;
  • the severity of the drought, as defined by both duration and intensity; and
  • the areal extent of the drought (the measure used in Mr Kelly’s source).

Each index and each measure will give slightly different results. Severity is the most comprehensive measure. Areal extent doesn’t measure severity well.

Climate change and droughts

As long ago as 2007 (and maybe earlier), the Intergovernmental Panel on Climate Change (IPCC) has made clear that global warming would have different effects in different parts of the world. Working Group II said: “A warmer climate, with its increased climate variability, will increase the risk of both floods and droughts.” It went on to define areas at risk:

  • “higher precipitation extremes in warmer climates are very likely to occur”, and
  • “An increase of droughts over low latitudes and mid-latitude continental interiors in summer is likely”.

This is still the prediction, and the reality. The IPCC Climate Change and Land. Summary for Policymakers (2020) says:

  • “Frequency and intensity of droughts has increased in some regions (including the Mediterranean, west Asia, many parts of South America, much of Africa, and north-eastern Asia) (medium confidence) and there has been an increase in the intensity of heavy precipitation events at a global scale (medium confidence).”
  • “The frequency and intensity of droughts are projected to increase particularly in the Mediterranean region and southern Africa (medium confidence). The frequency and intensity of extreme rainfall events are projected to increase in many regions (high confidence).”

NASA says the same (Earth’s Freshwater Future: Extremes of Flood and Drought, 2019). Researchers predict that “parts of Asia would become wetter in response to greenhouse gas emissions, while the southwestern United States, Central America and Europe would become drier.”

It is clear that while some parts of the earth are expected to experience worse droughts (longer and more severe), that isn’t expected in other locations.

So Mr Kelly’s claim is not based on actual predictions by the consensus of climate change experts.

It is a “straw man” claim. It discredits climate science based on an untruth.

Understanding the predictions

The earth is effectively a closed system for water. Very little water vapour escapes into space, so the amount of water in the world doesn’t change significantly. But global warming is changing the way that water is distributed around the world.

  • Increased temperatures are leading to more evaporation and hence drier soils.
  • But higher evaporation increases the amount of water vapour in the air, and hence increases rainfall overall.
  • Changed weather patterns mean that this rain falls in different locations and at different rates to before. In some locations, the higher rainfall compensates for the greater evaporation, and there is no increase in drought and there may be a decrease. But in other locations rainfall is lower and evaporation is increasing, so droughts become more frequent and more severe.

Studies have found century long trends in drought increasing in North America, central America, Eurasia and the Mediterranean, and soil moisture becoming wetter in the Indian subcontinent, confirming these predictions.

On some measures, drought is increasing slightly globally, but on other measures it isn’t. Drought predictions are somewhat uncertain, but generally say that while currently drought is not much increasing, if temperatures continue to rise, they will likely become more severe.

Drought in Australia

It turns out that the southeast of Australia, where most Aussies live and where most of our food is sourced, will receive less rain and experience more drought in the future. This trend is already apparent in the data (see references below) and is increasing. We will also experience more extreme flooding events when it does rain. (We can think of this as climate going to extremes, with less “normal” days.) Meanwhile, northern Australia will receive more, and more intense, rainfall and flooding in the future.

This current and projected change present problems for primary producers. Already, farm profits are down about 25% overall, and it could have been worse except for significant innovation by farmers. It will only get worse unless climate change is arrested.

The source of this misinformation

The original paper referenced in Mr Kelly’s post is Welfare in the 21st century: Increasing development, reducing inequality, the impact of climate change, and the cost of climate policies by Bjorn Lomborg. Its main topic is the economics of climate change. Bjorn accepts the reality of climate change, but believes its effects are overstated, and can be easily addressed.

In common with other of his writings, the data on drought in this paper is incomplete and misleading, for:

  • it is based on rainfall alone, and not evapotranspiration,
  • it uses global average data, and takes little account of the fact that climate science predicts that some areas will experience significant increases in drought while others won’t, and
  • the selection of areal extent as the measure of drought has likely given an unrealistic picture, because the most severe droughts are generally of lesser areal extent.

Conclusion

Craig Kelly has relied on an unreliable source to criticise a climate prediction that is NOT part of mainstream climate science. Far from him debunking a myth, he is actually perpetuating a myth.

Drought is already affecting farm profits in NSW, and will continue to do so. Globally, droughts and floods will both tend to get worse in some places, but not everywhere.

From his reference to “UN Globalists”, it appears Mr Kelly is motivated by some sort of anti-UN global conspiracy theory rather than actual climate data and predictions.

References

Global Drought
Drought in Australia

Photo: Pexels.

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