Lessons on climate sensitivity

As part of an effort of the Netherlands Earth System Science Centre (NESSC), IMAU climate scientists, together with (inter-)national colleagues, have published a new paper on climate sensitivity. The article “Lessons on climate sensitivity from past climate changes” appeared in the new journal Current Climate Change Reports.

By combining evidence from the past with theoretical approaches – a major research topic of NESSC- the review paper highlights a number of ways to improve our understanding of ongoing climate change. The new publication is a tangible result of the NESSC workshop “Mathematical approaches to (palaeo-)climate sensitivity”, organized by IMAU-researchers Anna von der Heydt, Henk Dijkstra and Roderik van de Wal in November 2015. A particular focus of this paper is the impact of tipping points in the climate system.

Climate sensitivity is a key indicator to quantify the effect of greenhouse gas emissions on climate. It is usually defined as the long-term global mean near-surface temperature change that follows from doubling the atmospheric CO₂ content. Many palaeoclimate studies have reconstructed natural climate changes in the past to calculate the climate sensitivity, but a lack of consistent methodologies produced a wide range of estimates.

Because of its importance (understanding how the Earth’s climate changed in the past can help estimating the response of the climate system to future changes in greenhouse gas concentrations), a more consistent definition of climate sensitivity in prehistoric times was suggested by the PALAEOSENS project. This project, which also involved IMAU researchers, helped improve existing estimates based on palaeoclimate data with those derived from climate projections developed by the Intergovernmental Panel on Climate Change (IPCC).

However, the scientific debate around climate sensitivity derived from palaeo-records continues: how can the large uncertainty of this indicator be reduced? How can theoretical approaches and observations or reconstructions of past climates be combined? Do we need to change the definition of climate sensitivity to make progress? These fundamental questions were discussed during the 2015 NESSC workshop, which ultimately led to this new publication.

Publication:
Lessons on climate sensitivity from past climate changes

Current Climate Change Reports (2016)