The UK is at risk of losing the next generation of scientists, a new group of scientific organisations has warned.
Fewer pupils are studying A-level physics
Falling numbers of physics students and a shortage of specialist teachers spell troubled times, said the Royal Society, which set up umbrella group, Score.
In the next five years the decline in take-up must be stemmed, it added.
Score - Science Community Partnership Supporting Education - is made up of societies and teachers, and will advise the government on science education.
This year A-level entries in physics reached a new low with 37% fewer students choosing it than in 1991, said the Royal Society.
While figures out last month showed teacher training applications for science and maths were down on last year, it added.
Royal Society vice-president Professor Martin Taylor said: "We have a window of opportunity in the next five years to ensure that we stem the decline in the sciences.
"If we get this wrong, we risk losing a generation of scientists.
"We need young people to be inspired by the sciences and mathematics so that they choose these subjects in sufficient numbers to ensure that the UK's economy prospers and that we retain our place as a world leader in science and technology."
Under the current system, most pupils study for a "combined science" double GCSE - rather than chemistry, physics and biology separately.
From this September, students can take a GCSE in science for citizens - covering science-based issues including global warming and mobile phone technology.
Those seeking a deeper understanding with a focus on scientific explanations and models can opt for GCSE additional science.
A spokeswoman for the Royal Society said it was too early to comment on the new GCSEs on behalf of the newly-formed Score, but the Royal Society supported it in principle.
"These new GCSEs should inspire more students who will carry on their studies into A-levels," she said.
Other founding members of Score are the Institute of Physics, the Royal Society of Chemistry, the Institute of Biology, the Biosciences Federation, the Science Council and the Association for Science Education.
It aims to be a coherent voice for the scientific community.
The Department for Education and Skills in England said increasing the number of scientists was a priority.
The sciences remained popular at A-level and the most recent set of university applications figures showed applications for science subjects up by more than 10%.
"A renewed focus on the sciences - particularly physics - through our £30m science strategy will deliver 3,000 more specialist teachers, changes to the GCSE and the introduction of single science awards will attract and engage more young people with the sciences," a spokesperson said.
"Working closely with employers, schools and experts in the field to improve science uptake, not least by girls, will be key to ensuring that we secure the scientists for the future."