Kelp forests support biodiverse communities and contribute to many ecosystem services. However, some kelp are highly sensitive to increases in temperature, making them vulnerable to increasingly frequent marine heatwaves. Other local drivers, such as sediment pollution, may exacerbate the impacts of marine heatwaves on kelp. This presentation will summarise several laboratory studies which explored the responses of giant kelp (Macrocystis pyrifera) sporophytes to simulated marine heatwaves. M. pyrifera from the warm edge of their range (Wellington, New Zealand) survived heatwaves of up to 20 °C, despite reduced growth rates, and could recover rapidly afterwards. However, at higher temperatures, sporophytes experienced much more severe physiological impacts, including reduced chlorophyll content, photosynthetic impairment, and mortality. The adverse impacts of heatwaves were exacerbated under light-limited conditions, with 100% mortality in some treatments. Sporophyte organic carbon content and δ13C increased with heatwave temperature, indicating that heat-stressed individuals likely increased their uptake of bicarbonate, which could be utilised for compensatory growth after the heatwave. The presentation will also describe a more recent experiment which compared the responses of warm edge and cold-water M. pyrifera populations to heatwaves. It is hoped that these findings will inform restoration efforts for this ecologically and economically important species.