Objectives/Concept

The multitude of climatic and environmental information stored in natural climate archives (such as temperature, precipitation, greenhouse gas and aerosol concentrations, sea level, biome composition, etc), together with climate model results, allow us to draw a comprehensive picture of how climate, the environment, biogeochemical cycles as well as atmospheric and ocean circulation change in warmer worlds. Accordingly, the Integrative Activity "Warmer worlds" will assess the knowledge on these changes and the existence of planetary boundaries associated with extreme warmth and rapid warming in the past. Moreover, it will identify gaps in current research and make suggestions for the future research agenda.

The following cross-cutting questions should be addressed (this is not an exhaustive list):

- Climate with its impacts and feedbacks in past warmer interglacials: analogues for a warmer future? Among others, how can long-term changes in the past under different boundary conditions be used to constrain the fast present warming?
- Relationship between climate change and greenhouse gas concentrations (cause, effect, and feedback).
- Dynamics of change associated with warming – are there limits to the speed of warming?
- Were there global environmental "Tipping Points" associated with warming in the past? And how can these past tipping points inform us about possible near-term future tipping points? For example, irreversible loss of polar ice, positive carbon feedbacks etc.
- Variability and Extreme Events associated with warmer worlds.

Approach

An array of PAGES working groups that individually address particular focal points regarding warming and its impacts (for instance QUIGSPlioVARPALSEAOC3DICEGlobal Paleofire and former Sea Ice and future Holocene working groups) provide comprehensive expertise on the various aspects of climate and environmental changes mentioned above. "Warmer worlds" will tap this expertise by actively engaging these (and other) PAGES working groups into a coordinated activity in order to draw a comprehensive picture of climate and environmental conditions associated with past global warmth. This comprises the synthesis of observational evidence, model-data comparison, and the analysis of simulated mechanisms and feedbacks to study the applicability of past analogues for future warming.

To accomplish its objectives, "Warmer worlds" will organize dedicated workshops where members of all PAGES working groups will be invited to participate, with the intent of sharing progress and steering the ensemble of groups toward a coordinated assessment outcome. In addition, external expertise from Future Earth and the World Climate Research Programme (WCRP) will be invited to complement the PAGES working groups, to insure that the view emerging from study of the geologic past remains focused on issues relevant to Earth and humanity’s future.

Structure and people

"Warmer worlds" will be organized by co-chairs, elected by a steering committee, which will include at least one member of the leadership of the associated working groups. The co-chairs of the integrative activity will be accountable to keep the integrative activity on track. This integrative activity will in turn provide impetus to keep the individual working groups moving forward at an appropriate pace.