(CNN) — Nearly 20 people remain unaccounted for after a wildfire swept through a tinder-dry area near Spain’s Mediterranean coast on Thursday, according to regional officials.

At least 12 people were killed in the rapidly spreading blaze near Almeria, while four others suffered severe burns.

The wildfire is the first in Europe this year to claim multiple lives, but it is one of several major fires that have scorched thousands of hectares in recent weeks as much of southern Europe experiences unprecedented heat.

This week has also seen two major wildfires in France, including one in the Pyrenees that forced the evacuation of 12,000 people, as well as a significant blaze in central Portugal. Satellite imagery showed smoke plumes drifting far into the Atlantic Ocean.

Researchers say summer wildfires in southern Europe are occurring earlier in the year and with increasing intensity.

An exceptionally wet winter across much of France and Spain produced abundant vegetation, which quickly dried out after three successive heatwaves pushed temperatures into the upper 30s Celsius.

According to the European Forest Fire Information System (EFFIS), the number of large wildfires has surged this year.

To date, European Union countries have recorded 314 fires exceeding 30 hectares, nearly double the 158 recorded at the same point last year and the second-highest total since 2016. By 8 July, the fires had consumed approximately 160,000 hectares, compared with the average of just under 100,000 hectares since 2006.

EFFIS said very extreme fire conditions currently dominate large parts of western and central Europe, particularly across France, Spain, northern Portugal, the Alpine region extending into northern Italy, southern England and southeast Ireland.

Beyond the immediate loss of life, wildfires also release large amounts of carbon dioxide and toxic smoke, creating additional public health risks.

Research by Spanish and American scientists found that wildfires in Spain and Portugal in August last year contributed to more than 2,000 premature deaths from smoke exposure and produced unprecedented levels of overnight fire activity.

The researchers said the total energy released by those fires was comparable to the annual energy production of a 1,000-megawatt nuclear reactor, adding that increasingly larger fires are a sign that wildfire intensity is rising. They also cited rural depopulation, which has left more land unmanaged, as a contributing factor.

Spanish officials said this may have played a role in the Almeria wildfire, where some victims became trapped after attempting to escape by car along a track that was quickly surrounded by flames.

The prolonged heat is also having widespread impacts beyond wildfires.

In France, more than 2,000 deaths during the last week of June were attributed to extreme heat. The country recorded its hottest day on record on 24 June, with deaths increasing by 29 per cent compared with the previous week, according to Health Minister Stéphanie Rist.

The demand for air conditioning is also rising. Around 24 per cent of French households now have air conditioning, up from 18 per cent two years ago, although the figure remains well below neighbouring Italy, where about half of households are equipped with cooling systems.

However, air conditioning units release heat into surrounding areas, contributing to the urban heat island effect, particularly overnight.

Higher river temperatures are also disrupting electricity generation. French energy company EDF said output at the Nogent nuclear power plant on the River Seine would be reduced for the second time this summer, while another reactor on the Garonne River suspended production after water temperatures reached 28 degrees Celsius.

The heatwaves have also damaged agricultural production.

Grain trade association Coceral has lowered its forecast for European Union and United Kingdom maize production to 52.7 million tonnes, down from 57.2 million tonnes forecast last month.

France’s maize harvest is expected to fall below 10 million tonnes, the lowest level in two decades. Coceral also reduced its forecasts for barley and wheat production across Europe.

Scientists are also warning that warmer conditions are contributing to the spread of mosquito-borne diseases.

A recent Italian study found that the risk of dengue fever outbreaks in Europe increased by 56 per cent between 2013 and 2022 compared with the period from 1951 to 1960.

The researchers warned that diseases such as malaria and dengue, once largely confined to tropical regions, are increasingly emerging in temperate and urban areas.