The Quantifying and Understanding the Earth System (QUEST) programme assimilated scientists' knowledge of the Earth as an integrated system. Its aim was to substantially improve predictions of global environmental change.

Human activities are altering the atmosphere and oceans, transforming ecosystems, and changing the climate over and above natural variation. To predict how the complex interactions and feedbacks between different components of the Earth System will respond to our growing influence, they need to be considered together.

The programme had three main themes:

-The contemporary carbon cycle and its interactions with climate and atmospheric chemistry.
-The natural regulation of atmospheric composition on glacial-interglacial and longer time scales.
-The implications of global environmental changes for the sustainable use of resources.

QUEST helped to accelerate development of the next generation of environmental-change models, and provided a focal point for UK work, forging collaborations and synergies between worldwide experts in Earth System research and modelling.