Less than a week after the world's scientists warned there may be just eight years to act on greenhouse gas pollution to avoid the worst of global warming, the aviation industry has announced record increases in the number of flights worldwide.

Booming demand for domestic flights in China has helped nudge the number of global take-offs scheduled for this month to more than 2.5m for the first time. A surge in the popularity of low-cost airlines means more than 114,000 more flights are expected than during the same period last year - a 5% rise.

Announcing the figures for May, Duncan Alexander, managing director of aviation analyst firm OAG, said: "From an industry perspective this healthy growth bodes very well for the future."

Climate experts and environmental campaigners were less pleased. Kevin Anderson, a global warming researcher at Manchester University's Tyndall Centre for Climate Change Research, said the expansion was at odds with efforts to tackle emissions: "While this might be good news for the aviation industry and its shareholders, it's bad news for the climate and ultimately it's our children that will pay the price."

The UN's Intergovernmental Panel on Climate Change said on Friday that worldwide greenhouse gas emissions needed to peak by 2015 to keep the expected temperature rise this century to 2C, defined by scientists as dangerous. Unrestrained growth could see a 6C rise by 2100.

Although aviation contributes only about 2% of global emissions, campaigners have highlighted the industry's environmental impact because it is the fastest-growing source of greenhouse gases, and there is no technological fix.

New official forecasts to be published at an aviation conference in Barcelona next month predict international carbon dioxide pollution from aircraft will reach 1.2bn to 1.4bn tonnes by 2025, up from 610m tonnes now.

Aircraft emissions have a greater warming effect because they are released at altitude. The UK government says this exaggerated impact means that 1 tonne of carbon dioxide released from an aircraft does the same damage as 2.5 tonnes emitted from cars or power stations. And because most aviation is classed as an international activity, its emissions are rarely included in official figures and they are excluded from the Kyoto protocol, the international treaty to regulate greenhouse gases.

Peter Lockley, of the Aviation Environment Federation campaign group, said: "Even the most optimistic industry estimates have fuel efficiency only increasing by 1-2% each year. So if the number of flights goes up 5% a year, it's not very difficult maths to see their carbon emissions are going to rise, just as the scientists say they need to be reduced."

OAG's May figures are taken from its Quarterly Airline Traffic Statistics, based on data from 1,000 scheduled airlines. They show that 2.51m flights are timetabled worldwide this month, topping the previous high of 2.49m from August last year. That represents an additional 113,827 flights compared with May 2006, or 17.7m extra seats. Mr Alexander said: "This is great news from a travellers' viewpoint, with much more competition and choice."

The largest year-on-year rise is within China, with nearly 23,000 more domestic flights scheduled this month than in May 2006, a rise of 18%. US domestic flights have risen by some 19,000, though that represents just a 2% rise, to 838,000. Demand also soared within India, up 10,000 flights, or 25%, to 43,000 flights.

The figures show that the UK is now the most popular country for international flights, with 121,000 scheduled arrivals and departures this month, up 7%. Spain showed the single largest rise, up nearly 10,000 flights, or 16%. Overall, the low-cost sector showed a rise of some 70,000 flights, up 22% year-on-year.

OAG says: "In sheer size, the most noteworthy route showing a year-on-year increase is for flights between western Europe and Africa. This month, there are over 2,200 more flights scheduled between these two continents, up 13%, and over 360,000 more seats available." Transatlantic routes also showed a significant rise.

The report comes as Mark Ellingham, founder of the Rough Guide series, has called for stringent new taxes on flights to deter travellers and reduce environmental damage. He wants a £100 green tax on all flights to Europe and Africa, and £250 on flights to the rest of the world, as well as a moratorium on airport expansion.

He said there was no such thing as an ethical holiday. "The tobacco industry fouled up the world while denying it as much as possible for as long as they could.

"If the travel industry rosily goes ahead as it is doing, ignoring the effect that carbon emissions from flying are having on climate change, we are putting ourselves in a very similar position to the tobacco industry."