The prospects of the world staying within the 1.5C limit on global heating have brightened owing to the “staggering” growth of renewable energy and green investment in the past two years, the chief of the world’s energy watchdog has said. Fatih Birol, the executive director of the International Energy Agency, and the world’s foremost energy economist, said much more needed to be done but that the rapid uptake of solar power and electric vehicles were encouraging. “Despite the scale of the challenges, I feel more optimistic than I felt two years ago,” he said in an interview. “Solar photovoltaic installations and electric vehicle sales are perfectly in line with what we said they should be, to be on track to reach net zero by 2050, and thus stay within 1.5C. Clean energy investments in the last two years have seen a staggering 40% increase.” But Birol also noted that greenhouse gas emissions from the energy sector were “still stubbornly high”, and that the extreme weather seen around the world this year had shown the climate was already changing “at frightening speed”. The IEA, in a report entitled Net Zero Roadmap, published on Tuesday morning, also called on developed countries with 2050 net zero targets, including the UK, to bring them forward by several years. The report found “almost all countries must move forward their targeted net zero dates”, which for most developed countries are 2050. Some developed countries have earlier dates, such as Germany with 2045 and Austria and Iceland with 2040 and for many developing countries they are much later, 2060 in the case of China and 2070 for India. Cop28, the UN climate summit to be held in Dubai this November and December, offered a key opportunity for countries to set out tougher emissions-cutting plans, Birol said. He wants to see Cop28 agree a tripling of renewable energy by 2030, and a 75% cut in methane from the energy sector by the same date. The latter could be achieved at little cost, because high gas prices mean that plugging leaks from oil and gas wells can be profitable. But Birol warned that the geopolitical situation, with many nations at loggerheads over the war in Ukraine, and still frosty relations between the US and China, would make for a difficult summit. He said: “The most important challenge [to limiting temperature rises to 1.5C above pre-industrial levels] is the lack of international cooperation. Cop28 is a critical juncture, and should send a strong signal to energy markets that governments are taking the climate seriously. They should move to reduce the consumption of unabated fossil fuels.” He also called for Cop28 to agree a doubling of energy efficiency. “To reduce fossil fuel emissions, we need to reduce demand for fossil fuels. This is a golden condition, if we are to reach our climate goals,” he said. Birol stopped short of endorsing the call that some countries have made for a full phase-out of fossil fuels by 2050 to be agreed at Cop28, but he said all countries must work on reducing their fossil fuel use. Rishi Sunak, the UK’s prime minister, last week reaffirmed his commitment to net zero by 2050, but reversed and delayed some key policies that would help to attain the goal. Sunak is also planning a large new round of North Sea oil and gas licences, despite clear advice from the IEA that no new upstream oil or gas projects should be built on the road to net zero. Birol also refused to single out any countries, but made it clear that the richest countries should be moving much faster on renewable energy, energy efficiency, reducing fossil fuel use and bringing forward their net zero targets. Birol said: “Advanced economies have special responsibilities in fighting climate change. What I would expect advanced economies to do is to increase their ambition further, rather than reducing it. Clean energy would create lots of new jobs and employment, and build a modern industry [needed] to have a competitive position with other countries. Industry knows that the next chapter of global industry is based on clean energy technologies.” Tessa Khan, executive director at Uplift, a campaigning organisation, said: “This [IEA report] is yet more confirmation from the world’s energy experts that we can’t have new oil and gas projects if we’re going to stay within a safe climate, and that massively scaling up renewables is key to achieving that. “Yet the UK is part of a tiny club of wealthy countries that while professing to lead on climate is massively expanding oil and gas production. Just five nations – the US, Canada, Australia, Norway and the UK – are responsible for over half of all planned oil and gas field developments from now to 2050.”