The number of days of extreme heat per year, when temperatures reach 50 °C, have doubled since 1980, according to a BBC study. Those temperatures are also being recorded in more and more areas of the world, posing an unprecedented challenge to our health and the way we live.
The total number of days above 50 °C increased in each of the past 4 decades. Between 1980 and 2009, temperatures exceeded 50 °C about 14 days a year on average, a figure that increased to 26 days a year between 2010 and 2019. In the same period, temperatures of 45 °C or more were recorded on average an extra 2 weeks per year. “The increase can be attributed 100% to the burning of fossil fuels”, says Dr. Friederike Otto, a leading climate scientist.
What do you mean by “place”?
We refer to a place as an individual area of the globe of about 25 square kilometers. Climate data is typically presented in gridded templates that represent a large area. The squares in this data set are 0.25 degrees latitude by 0.25 degrees longitude. The locations shown on the map above are those where the maximum temperature in an area of the grid exceeded 50 °C on a given day in that year.
How do the circles represent days?
The size of the circle on the map is related to the number of days per year that 50 °C was exceeded at that specific location. The circles vary in size, from 1 to 25 days. When all years are plotted, the circles show the total number of days above 50 °C at each site. The scale stops at 25 days to make it legible.
Where does these data come from?
This analysis uses maximum daily temperatures from the ERA5 dataset, produced by the Copernicus Climate Change Service. Climate data is typically presented in a gridded template that constitutes a vast area. Although each grid can contain different topographies, the data treats each area of the grid uniformly.
The ERA5 combines meteorological observations from many sources, such as stations and satellites, with data from weather forecast models. This process fills in the gaps left by poor coverage due to the lack of weather stations in many parts of the world.
As the entire planet warms, extreme temperatures become more likely and more intense. High temperatures can be deadly to humans and nature, causing major problems in buildings, roads, and power systems.
Temperatures of 50 °C occur predominantly in the Middle East and Gulf regions. And after record temperatures of 48.8 °C were recorded in Italy and 49.6 °C in Canada this summer, scientists have warned that temperatures above 50 ° C will be experienced elsewhere unless we reduce emissions of fossil fuels.
“We need to act quickly. The faster we reduce our emissions, the better off we all are”, says climate researcher Sihan Li. “With continued emissions and inaction, these extreme heat events will not only become more severe and frequent, but the emergency response and recovery will be more demanding”, warns Dr. Li.
The BBC analysis also found that in the last decade, maximum temperatures increased 0.5 °C compared to the longer-term average recorded between 1980 and 2009. But these increases have not been felt equally around the world: in Eastern Europe, southern Africa and Brazil some maximum temperatures increased by more than 1 °C, and parts of the Arctic and the Middle East recorded increases of more than 2 °C.
The scientists called for urgent action on world leaders who will meet at the UN climate summit in November, in which governments will be asked to commit to further emissions cuts to limit the rise in global temperature.
Impact of extreme heat
This BBC analysis includes a documentary series called ‘Life at 50°C’ that investigates how extreme heat is affecting people around the world. Even below 50 °C, high temperatures and humidity can create serious health risks.
Up to 1.2 billion people worldwide could face heat stress conditions by the year 2100 if current levels of global warming continue, according to a Rutgers University study published last year. That is at least 4 times more than those affected today.
People also face difficult decisions as the landscape around them changes, as extreme heat increases the likelihood of droughts and wildfires. Sheikh Kazem Al Kaabi grows wheat from a village in central Iraq that experiences extreme temperatures almost every year. The land around him was once fertile enough to support him and his neighbors, but it has gradually become dry and barren.
“All this land was green, but all that is gone. Now it is a desert”. Almost all the people in his village have moved to look for work in other provinces. “I lost my brother, my dear friends and loyal neighbors. They shared everything with me, even my laughter. Now nobody shares anything with me; I am just face to face with this empty land”.
In my area it exceeded 50 ° C; why it does not show up?
Record temperature reports generally come from measurements taken at a particular weather station. But the data we have studied represents areas larger than those covered by a single station.
For example, Death Valley National Park in Southern California is one of the hottest places on Earth. Temperatures in certain parts of the park regularly exceed 50 °C in summer. But by creating an average of maximum temperatures for the wider area around it, using different sources, a figure is reached below 50 °C.
What do we analyze?
• Using the maximum temperature for every day from 1980 to 2020, we identified how often temperatures exceeded 50 °C.
• We count the number of days and locations with a maximum temperature of 50 °C or more for each year, to determine the trend over time.
• We also observe the change in maximum temperatures. We did this by calculating the difference between the average maximum temperature over land and sea during the most recent decade (2010-2019) compared to the previous 30 years (1980-2009).
• Averages for at least 30 consecutive years are known as climatologies. The 30-year climatologies are used to show how recent periods compare to a climatic average.