The potential impact of climate change by the year 2050 on intensive livest
ock systems in Britain is assessed through the use of simulation models of
farming systems. The submodels comprise livestock feeding, livestock therma
l balance and the thermal balance of controlled environment buildings and a
stochastic weather generator. These are integrated to form system models f
or growing pigs and broiler chickens. They are applied to scenarios typical
of SE England, which is the warmest region of the country and represents t
he worst case. For both species the frequency of severe heat stress is subs
tantially increased, with a consequent risk of mortality. To offset this, i
t would be necessary to reduce stocking densities considerably, or to inves
t in improved ventilation or cooling equipment. Other effects on production
are likely to be small.