The formulation of robust policies for mitigation of, and adaptation to, climate change requires a quantitative understanding of how and why specific changes are unfolding in the Earth system, and what might happen in the future. A quantitative explanation of observed changes – through robust process-based detection and attribution – is also fundamental to confidence specification in climate assessments, predictions, and projections. However, the capacity to deliver these capabilities is very immature. The WCRP Lighthouse on Explaining and Predicting Earth System Change (EPESC) Lighthouse Activity will address this gap.
The overarching objective of this Lighthouse Activity is to:
Design, and take major steps toward delivery of, an integrated capability for quantitative observation, explanation, early warning, and prediction of Earth System change on global and regional scales, with a focus on multi-annual to decadal timescales.
This includes three main themes:
- Observing and modeling Earth system change
- Integrated attribution, prediction, and projection (including early warning and the potential for abrupt change)
- Assessment of current and future hazards
This corresponds to the structure of the Lighthouse Activity:
This Lighthouse Activity proposes an ambitious plan to:
- Assess and improve persistent errors in climate models and re-analyses of historical observations.
- Build an integrated operational capability to attribute and predict multi-annual to decadal changes in the climate system and provide quantitative attribution statements to support WMO forecasts and State of the Climate reports.
- Establish a methodology for assessing the adequacy of and recommending improvements to observational networks and modeling systems to capture early indicators and the full evolution of these changes in the climate system.
- Provide quantitative assessments of current and future hazards, underpinned by robust process understanding.
- Seek to maximize the value to users of the advances achieved, e.g. through the development of an international open-access multi-model archive of seasonal-to-decadal hindcasts and forecast data, and through case studies employing co-design of decision-relevant products.
A key component of (2) will be large ensemble single forcing simulations of the historical period. These do not currently exist and will require support from funding agencies.
For more information, please see the draft Explaining and Predicting Earth System Change Science Plan (2021).