Prof Chris Funk
In the last six years in Madagascar, five years have seen bad or very bad rainy seasons.
My colleagues and I were able to track this using the satellite gauge precipitation data we developed – the Climate Hazards Group (CHIRPS) Infrared Rainfall System with Stations – to monitor droughts in areas like southern Madagascar. My work has focused on the sea temperatures between Australia and Hawaii – the Indo-Pacific – and the impacts of variations on southern and eastern Africa.
Our data suggests that since 2015, with the exception of the 2018-2019 rains, seasonal rainfall (which typically falls from October to May in southern Madagascar) has been low. This is among the driest 10 percent years since 1981.
Other data suggests that the past six years have also been unusually warm. Warmer air can hold more water vapor, resulting in vapor deficits. These deficits can exacerbate droughts by drying out vegetation because the drier air removes moisture from the plants.
Thinking back to the temperatures of the Indo-Pacific Sea, I have been really struck by the extreme conditions since 2014.
The Indo-Pacific is dominated by three types of extreme weather events; El Niño, La Niña and the Indian Ocean Dipole. All of this happens when parts of the ocean get unusually warm. El Niño is influenced by the Eastern Pacific, La Niña by the Western Pacific and the Indian Ocean Dipole by the Western Indian Ocean.
When these events occur, the wind pattern changes to withstand heavy precipitation in any extremely hot region. These changes, in turn, can disrupt rainfall conditions over eastern and southern Africa.
Every year since 2014, there has been either a La Niña or an El Niño, except from 2019 to 2020. But that year has been an exceptionally strong dipole event in the Indian Ocean.
This is consistent with my view that climate change increases “climate volatility” by increasing the frequency of extreme sea surface temperatures. Because extreme sea surface temperatures create these extreme weather events.
Repeated shaking caused severe stress on the vegetation.
Although I have no expertise as a food security analyst, the Famine Early Warning Systems Network is monitoring conditions in Madagascar very closely. They report lower-than-average production of rice, corn and legumes in the main production areas of the highlands as well as in eastern and southern Madagascar. There is also a very poor production of cassava, a staple food.
Our satellite imagery confirms it: we can see that the droughts have really dried out the vegetation.
In general, this type of persistent water stress weakens the resilience of poor households. It can also lead to higher food prices.
Lack of rain has been linked to climate change. Why?
In my work on climate risks, it has become clear that we need to recognize how and when climate change exacerbates natural climate and weather extremes.
The specific links between sea surface temperature conditions and recent dry conditions in Madagascar are not well understood, but the link between climate change and more extreme Indo-Pacific sea surface temperatures is fairly clear.
Our research, supporting famine early warning, for example, has described how climate change amplifies the magnitude of natural variations, such as El Niños and La Niñas. This contributed to the post-2014 increase in food insecurity in eastern and southern Africa.
From 2019 to 2021, we saw exceptionally warm ocean conditions in the Indian Ocean and the Western Pacific. And, as mentioned earlier, warmer air can hold more water vapor, resulting in deficits.
In two recent papers, one focusing on an analysis of global drought and the other on East Africa, we argue that these warmer temperatures have amplified the impact of precipitation deficits, especially in the regions. arid regions.
Data for southern Madagascar suggests that sharp increases in atmospheric water demand due to warmer air temperatures have occurred there during many recent droughts.
The just released report of the Intergovernmental Panel on Climate Change suggests short-term and persistent climate change similar to that of El Niño. This could be associated with warmer conditions in the eastern Pacific Ocean, warmer air temperatures and more frequent droughts in southern Madagascar.
My take on “projections”, however, is that we must reject the idea that climate change is an “external” process. There is no physical process that causes all sea surface temperatures and air temperatures to slowly heat up at very similar rates.
Energy builds up in the ocean and atmosphere, then converges to specific places, creating more extreme weather and climate conditions.
I think we can safely project that what we see happening will continue. We will continue to see increased Indo-Pacific volatility which will lead to more frequent and stronger El Niño, La Niñas and Indian Ocean Dipole events. At the same time, much higher air temperatures will both increase desiccation during droughts and contribute to more extreme precipitation during storms and cyclones.
To respond to these changes, we are striving to develop improved early warning systems.
Also at risk
My expertise is focused on southern and eastern Africa, so my concerns apply to many of those countries as well.
In southern Africa, we have experienced many recent poor rainy seasons in Zimbabwe. In East Africa, conditions improved by climate change contributed to droughts in 2016-2017 and 2020-2021.
We were able to anticipate these shocks several months in advance based, in part, on the unusually warm West Pacific Sea surface temperatures.
We are now very concerned about the potential for another streak of light rains in East Africa from 2021-2022. Current forecasts appear to be very similar to those of recent drought years. This could be of particular concern for Ethiopia, where very poor rains have led to poor agricultural production results. The poor rains, combined with rising food prices, conflict and political divisions, have led to critical levels of food insecurity.
We have also shown in recent articles that in parts of East Africa, the dry seasons are getting drier in already arid places. Rising surface temperatures in the Indo-Pacific Sea and increasing land air temperatures increase climate risk.
But, we are not helpless.
Vital efforts are made to build resilience. For example, the social enterprise Tatirano (“to collect water” in Malagasy) aims to increase the adoption of rainwater harvesting techniques by communities. I am excited about the possibility that observations and forecasts from the Climate Hazards Center can be integrated with local decision support tools, such as Tatirano’s data systems.
According to Tatirano, along the coast, more than four million people live without basic access to safe drinking water, despite living in areas that receive more than 1,500 mm of rain per year. In dry and arid areas, rainwater harvesting can increase water retention for agriculture by increasing the amount of rain absorbed by the soil. Larger-scale collection and storage of nature-based rainwater (e.g. natural rock reservoirs) can help mitigate more variable precipitation and take advantage of extreme precipitation events, which appear to be more frequent.
In addition, improvements in early warning and early action, water resource management, safety net and risk management systems, and agricultural development provide and will offer pathways to greater climate resilience. – The conversation
Chris Funk is Affiliate Research Professor in the Climate Hazards Group at the University of California at Santa Barbara