A complete halt to Russian supplies “cannot be ruled out”, it said, as Russia weaponises gas supplies as its war on Ukraine intensifies.
Meanwhile, competition for shipments of liquified natural gas (LNG) from around the world is likely to be fierce.
It argues that EU storage levels need to be kept at at least 33pc of capacity until the weather warms up, for “a safe and secure winter”.
Depending on the level of LNG imports that are available, that could require demand cuts of up to 13pc. Much of this will come from cutting gas use in commercial buildings and power stations.
However, the IEA also warns: “A 13pc demand reduction would also necessitate gas savings from households and require responsible electricity and gas consumption behaviour.
“Our analysis indicates that behaviour change could reduce gas demand by 15 billion cubic metres during the 2022/23 heating season, equating to over 40pc of the 13pc demand reduction.”
It estimates that turning the heating down by one degree centigrade could cut demand by about seven billion cubic metres.
It comes as the European Centre for Medium Weather-Range Forecasts warned of high pressure over western Europe in November and December, meaning cold, dry spells which would increase demand for heating and also reduce the output of wind turbines and hydro-power stations.
“If we have this pattern then for the energy it is quite demanding,” Florence Rabier, director-general of the centre, told the Financial Times.
This week, National Grid is set to publish its outlook for both gas and electricity supplies this winter. The Telegraph revealed that National Grid is racing to secure extra reserves of gas amid concern it will not be able to get enough from Europe.
Meanwhile, damage to the Nord Stream 1 pipelines built to bring gas from Russia to Europe, caused by suspected sabotage, have scuppered any hope that one could be brought back into action.
Keisuke Sadamori, director of energy markets and security at the IEA, said: “Russia’s invasion of Ukraine and sharp reductions in natural gas supplies to Europe are causing significant harm to consumers, businesses and entire economies – not just in Europe but also in emerging and developing economies.
“The outlook for gas markets remains clouded, not least because of Russia’s reckless and unpredictable conduct, which has shattered its reputation as a reliable supplier. But all the signs point to markets remaining very tight well into 2023.”
