Human-induced climate change compounded by socio-economic water stressors increased severity of 5-year drought in Iran and Euphrates and Tigris basin

From boreal winter 2020/21 onwards, a large region in West Asia, encompassing the Fertile Crescent around the rivers Euphrates and Tigris as well as Iran has suffered from exceptionally low rains and elevated temperatures. This five-year-long drought has led to severe water scarcity across the region. In Iraq, 2025 has become the driest year on record since 1933, with water levels in the Tigris and Euphrates dropping by up to 27 percent due to poor rainfall and upstream restrictions. In neighbouring Syria, rainfall has fallen by nearly 70 percent, crippling 75 percent of the country’s rain-fed farmland and leaving an estimated wheat shortfall of 2.73 million tonnes. The impacts have been similarly severe in Iran, including in Teheran, the capital of Iran, home to more than 10 million people, who, at the time of writing in November 2025, may need to evacuate if no rain arrives by December (Reuters, 2025). Five years of drought have meant that the dams serving the city have not been replenished, and with 2025 receiving even less rain than the already dry five years previous the water crisis has become extremely severe (Al Jazeera, 2025)

In 2023, World Weather Attribution undertook a rapid attribution study of the drought conditions as they were in mid-2023 and had already led to severe impacts on agriculture and access to potable water and caused a famine in Syria affecting 12 million people.  By combining a detailed assessment of exposure and vulnerability in the three affected countries: Syria, Iraq and Iran with a probabilistic attribution of the change in likelihood and intensity of the drought hazard with anthropogenic climate change the study found that there is strong evidence that human-induced climate change has increased the risk of drought by more than a factor of 10 and that this change has rolled-back development gains after the conflicts in the region. 

Here, we perform a super-rapid attribution study, updating the observational analysis from 2023 to include the additional dry years up until October 2025, and highlighting additional insights on vulnerability and exposure that emerged over the last two years.