Concerning heatwaves and northern hemisphere ag

Concerning heatwaves and northern hemisphere ag

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Concerning heatwaves and northern hemisphere ag

European summers have become unbearably hot. Record-breaking heatwaves in the last couple years have brought consequences not only on people's livelihood, but also on the agricultural sector, especially on fruit and vegetable crops. High temperatures affect the biochemical processes related to the optimal functioning of crops, causing severe repercussions on their production and development.

High-temperature climate conditions generate droughts and instability in food security, says a June 28 World Health Organization (WHO) report focused on Europe. Temperatures have been increasing twice as fast as the world average since the 1980s and according to a report by the European Union and the World Meteorological Organization, 2023 is expected to be "unusually warm".

This organization stresses that it is urgent to reduce greenhouse gas emissions into the atmosphere because they are responsible for increasing global temperatures, which in turn increase the frequency of heatwaves.

Widespread drought and production declines

Drought warnings are in effect in much of Western Europe and no significant rainfall is expected soon. As for the United States, it will face its third consecutive year of drought and great water stress, the country’s largest reservoirs Lake Mead and Powel in Arizona are at their lowest levels, less than 30% of their capacity according to the U.S. Drought Monitor.

Climate change intensified the heatwave in southern Europe by 36°F and made the heatwave that affected parts of China 50 times more likely, according to a new study by the World Weather Attribution (WWA). Scientists also warn that if global temperature rise reaches 35.6°F, these events will occur every two to five years.

In temperatures above 109°F, Mediterranean crops suffer heat stress and may lose their flowers, leaves and fruits, says agroclimatology and Stormchaser administrator, Serge Zaka.

Faced with this problem, the expert and international agricultural advisor, Carlos Castillo, notes that "I have been in close contact with European technicians and doctors in nutrition and plant physiology. In terms of citrus, since February and March this year there have been abortions in flower, less presence of flowering, which has resulted in production curves falling in oranges, grapefruit, lemons and tangerines. Valencia and Almeria are having big problems due to high temperatures, as well as northern Italy.”

In the case of Mexico, Castillo points out, weather conditions and the presence of El Niño currently bring higher temperatures. He recalls, for example, that in February unexpected rains fell in the Trujillo area, causing flooding, which stressed avocados and blueberries. 

Then, at the height of harvest, the temperature was around 80°F when it should have been between 64°F and 70°F, causing fruit abortion in avocados and a very marked stress in blueberries.

"The flowering curves were delayed in blueberries which caused a reduction in exports at the beginning of the season, mainly in varieties such as Ventura. In the case of avocado, a lot of fruit was lost due to the stress of excess rain in February which causes saturation and soil compaction causing root asphyxia and this caused the fruit not to grow and fix more dry matter increasing the caliber, also causing the abortion of growing fruit," he concludes.

In February, California went through a similar climate scenario which affected citrus production. Areas such as Sacramento, San Francisco, Los Angeles, were affected by rains and the cultivars were flooded generating stress.

Copa Cogeca, representing farmers and agricultural cooperatives in the European Union, reports that cereal and grain harvest forecasts for drought conditions have been reduced across the continent.

In May, only Spain, Italy and Portugal were expecting large losses, however, with the droughts in May and June, parts of Romania, Lithuania, Finland and Poland are also expecting less production and lower-quality fruit.

With this, the worst harvest since 2007 is expected, with a production of about 256 metric tons. In addition,  high energy prices, inflation, fertilizers and low sales prices, mean farmers face a very difficult campaign.


In the case of China, the heat has also been accompanied by rains, which could affect rice harvests.

These weather conditions cause complex agricultural production work, low yields, which could stress prices and generate rises in international markets. 

El Niño phenomenon

"In the face of El Niño, governments around the world must prepare to limit the effects it may have on our health, our ecosystems and our economies. Early warnings and preventive measures to cope with extreme weather events associated with this major climate phenomenon are of utmost importance to save lives and livelihoods," says the Secretary-General of the World Meteorological Organization, WMO, Professor Petteri Taala.

El Niño occurs on average every two to seven years, with episodes typically lasting nine to twelve months. It is a natural weather pattern associated with warming of ocean surface waters in the central and eastern parts of the tropical Pacific Ocean, although it occurs under circumstances of anthropogenic climate change; which is a change caused by mankind..

In anticipation of a repeat El Niño event, a May 2023 WMO report predicted that there was a 98% chance that at least one of the next five years and the five-year period as a whole would be the warmest on record, surpassing the record set in 2016, when an exceptionally strong El Niño occurred.

The report, which the UK Met Office produced in conjunction with partners around the world, also stated that there was a 66% chance that the annual average global near-surface temperature between 2023 and 2027 would temporarily exceed pre-industrial levels by 34°F for at least one year.

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