1.    Breeding systems in which group members help to raise the offspring of co-members are associated with arid, unpredictable environments. Cooperative rearing may mitigate the effects of adverse environmental conditions on pup growth and survival. However, few studies have explored the relationship between environmental variation and breeding success, and the role of helpers. 
2.    Here we show that increases in daily maximum air temperatures (T_max) in the southern Kalahari over the last twenty years have been associated with reductions in the growth and survival of meerkat (Suricata suricatta) pups. 
3.    On days when T_max was high, meerkat pups gained less body mass than on cooler days. Reductions in the diurnal body mass gain (ΔM_b) of pups on hotter days were not a consequence of reductions in the frequency with which pups were fed by adults as feeding rate increased with T_max, suggesting that the reductions in ΔM_b by pups on hot days reflected a decrease in water content of the food items or an increased water and energy cost of thermoregulation. 
4.    Reductions in pup ΔM_b on hot days were smaller in larger groups, in which helper-to-pup ratios were relatively high.
5.    As further increases in air temperature are predicted with climate change, further reductions in meerkat pup growth and survival seem inevitable.