Heatwaves are on the rise in Algeria due to climate change, says specialist

While there has been a gradual drop in temperatures, this summer Algerians experienced a heatwave over 40 days. Is this normal?

It’s unusual if you live in the northern, coastal Algerian cities, where maximum temperatures never drop below 36C; that’s our average body temperature, so it’s all related. However, 40C would be a more ‘normal’ temperature if you live in central Algeria or in the south.

In the Sahara, temperatures can regularly climb above 40C. The habituation effect can differentiate one region or city from another. One study conducted in Algeria proved the threshold of 36C could be exceeded on average annually at least 14 times in Oran, 50 times in Saïda (in the north-west) and 90 times in Aïn Sefra (south).

A heatwave is a lasting meteorological phenomenon which can take place over a series of days, and sometimes even weeks. The definition of it varies according to the country and sometimes the differing climates inside the country itself (geographic position, altitude, proximity to water surfaces, ground-cover crops …) A heatwave generally lasts for more than three consecutive days with maximum temperatures of 30 to 35C.

In the past, Algeria usually experiences siroccos – hot blasts of wind from the Sahara – rather than heatwaves, and this is usually over the last 10 days of July. Today, we have heatwaves at any time of the year with variable intensities. We will experience more heatwaves thanks to climate change, and we need to learn how to adapt to them in the long term.

How does a heatwave affect our health, agriculture and water resources?

We know that hot air takes in more water so the air temperature is usually higher since evaporation is always more intense near water surfaces. This has an impact on water reservoirs and dams. The persistence of the heat also dries up any water in the soil, so it affects the crops, leading to a phenomenon known as scalding.

Humans are warm-blooded because our core temperature is constant, varying between 36 and 37C. We use a mechanism called thermoregulation to balance the differences in heat in external temperatures – the energy is transferred via conduction, convection and radiation. But without this process the body’s defence mechanism against the heat kicks in via sweating, which cools the body down.

If there is no wind – say if the air is calm – the air temperature matches the body temperature, eliminating the thermal gradient which allows the body to get rid of its accumulation and surcharge of body heat. Humidity is the only way of evacuating heat from body temperature as long as the air is not saturated with water.

If the air is humid and saturated, the human organism cannot get rid of the heat and so we experience unbearable discomfort which can lead to serious symptoms. For example, it can worsen chronic pain in those who suffer from cardiovascular or respitory illnesses, like asthma. The body adjusts its cardiac rhythm to assure the thermal equilibium of the human body – which slows in the winter (bradycardia) and quickens in the summer (tachycardia). The latter affects those who have cardiovascular symptoms more. We also know that one of the main functions of our lungs is to saturate the air breathed in to achieve a body temperature of 36C, and to allow the blood to flow.

When the temperature is higher than 36C there is no more pulmonary evaporation, which is essential to ensure that the lungs are balanced.

You said heatwaves will become more frequent thanks to climate change. What should we do in Algeria to preserve our planet and minimise the chances of these worrying meterological phenomenon?

Heatwaves are increasingly linked to extreme weather changes such as floods, tornadoes, droughts and ‘cold snaps’ that we tend to hide.

Algeria is not a big contributor to climate change since it does not release a high number of greenhouse gas emissions, which is the source of this phenomenon. The average gas emissions per citizen is less than the global average; however, our country stands on the frontline of climate change when it comes to impact.

We need to urgently define a strategy of adaptation to mitigate climate change.

Summer 2015 broke records with its July temperatures; is this a one-off?

There is a trend from year to year; for example you could discern a change over a 15-year period up until 2014. Thirteen of the 15 hottest years have occurred since 2000.

2014 has been the warmest, followed by records set in 2005 and 2010. We need to wait for the summer to end before we can come to an objective and measurable conclusion about 2015. But yes, this is a cycle which will undoubtedly continue.

Why does the national weather service, Météo Algérie, not provide exact data? They seem to minimise the phenomenon ...

Every time a dangerous meteorological phenomenon is announced, the weather services usually send a special bulletin (BMS) out. These are addressed to various ministers, governors of the Algerian regions and the health minister. Algeria’s problem is not that the information doesn’t exist, it’s how it is used and sent out.

Instead we should be asking how we should behave in case there is a heatwave – what should we do, how and where? Do we have a ‘heatwave plan’, like other countries do, which clearly outlines the responsibilities on every level, be it national, regional or local? How are the citizens informed? The question of how we organise ourselves is something that should be asked at every level of our society. The state has to first be aware of the situation and recognise its importance before the weather service can highlight how important a heatwave can be.

Hot summers, cold winters – is this still a norm?

A statistical analysis of the current situation, particularly in Algeria, shows that minimum temperatures have been rising faster than maximum temperatures over a number of decades. If you apply the latest global climate models (for the mid- and long-term: 2050 and 2100), then the lower temperatures are minimised even further in Algeria. The data we have shows higher figures than the ones which the models have provided.

On a global scale, the data shows that hot waves have occured much more than colder episodes over the last centur; so global warming really is evident. Today we have 90% more of a chance of an annual heatwave than a cold snap, almost as if the latter will disappear in near future. At the end of the nineteenth century, there was a 50% chance of either of those.

Mahi Tabet-Aoul is an Algerian author, researcher and atmospheric scientist