In Sweden, unusually warm temperatures have combined with little to no rainfall to stoke severe wildfires in several parts of the country. The fires have been raging since July 15. Some may have started naturally, but others are likely to have been caused by the use of disposable barbecues (link in Swedish).

It’s one of the the worst wildfire outbreaks Sweden has suffered, and the country’s authorities have called for help. France, Germany, Denmark, and Poland have sent in firefighters, while Italy, Portugal, Norway, and Lithuania have sent in aircraft and helicopters (paywall). Other Nordic countries have been suffering severe droughts that threaten crops.

Sweden is one among many victims of a global heatwave that has scorched the normally green terrain in the UK and Ireland, killed at least 50 people in Canada, and set the highest recorded temperature in Africa (51.3°C, or 124.3°F).

One of the chief causes of the heatwave is misbehaving jet streams—bands of strong winds blowing five miles above the Earth’s surface. Intensified jet streams bring storms, but currently these winds are weak, causing hot and dry weather to not change. These swings are more pronounced because of human-caused climate change, which is pushing weather events to greater extremes.

TT News Agency/Maja Suslin via Reuters An aerial view of the wildfire outside Ljusdal, Sweden, July 18, 2018.

TT News Agency/Robert Henriksson via Reuters A helicopter drops water at a wildfire next to the village Grotingen in Bracke municipality in central Sweden on July 22, 2018.

Maja Suslin/TT via AP In this photo taken on July 18, 2018, smoke billows from a fire outside Ljusdal, Sweden.

Mats Andersson/TT News Agency via Reuters French Bombardier 415 firefighting aircraft is seen landing as part of an international effort to battle a wildfire that has been raging for more than a week, Sveg, Sweden on July 21, 2018.

Mats Andersson/TT News Agency via Reuters General view of a forest after one of the major wildfires in Angra, Ljusdal municipality, Sweden on July 22, 2018.