The 5th SCAR AntClim21 workshop, called Past2Projections, will be held on 16-17 June in Davos, Switzerland.  There are limited places still available - apply via the online form.

SCAR AntClim21 Past2Projections workshop

Saturday 16th-Sunday 17th June
Venue: Congress Centre Davos, A Forum room

Rationale

Quantitative estimates of how Antarctic and Southern Ocean climate may change by the year 2100 are largely dependent on output from global climate and earth-system models (referred to collectively here as ESMs). ESMs participating in major inter-comparison projects, such as CMIP5, exhibit a wide range of skill in reproducing observed climate. Modern-era in-situ instrumentation and remote sensing technologies are core to the evaluation of ESMs and related goals of AntClim21. However, longer-term datasets and reconstructions of past climate are also potentially important for a number of reasons including:

1. Low-frequency (multi-decadal) climate variability is an important component in quantifying the range of possible future evolutions of Antarctic climate over the 21^st century, particularly on the smaller spatial scale of regions such as the Antarctic Peninsula. Longer-term observations and/or reconstructions are required in order to evaluate the extent to which climate models reproduce observed characteristics of low-frequency variability.
2. Longer-term datasets and reconstructions provide the possibility to test climate models across a range of different climatic conditions and help evaluate their sensitivities to external forcing.
3. Sea ice provides an example of the importance of a longer-term perspective, since there are questions over the degree to which recent trends might be externally forced or internally generated and whether sea ice has been significantly more or less extensive in the past climate regimes.

AntClim21 is nearing its conclusion (it will conclude in 2020), and the use of longer-term datasets for informing and improving projections for future climate is one of the key goals.

Key science questions

How can our knowledge of real-world longer-term past climate help to inform projections of 21^st century climate change?

• How large is real-world annual to multi-decadal climate system variability and how well is it represented in climate models?
  • What are the main mechanisms driving variability on annual-centennial timescales?
  • Which variables and regions are most promising in terms of model-data comparisons?
  • What are the best (or most promising) approaches for separating internal from forced (natural and anthropogenic) variability?

• When will/have the response of the climate system to external anthropogenic factors depart significantly from background internal variability?
  • The answer to this question is highly dependent on the choice of variable (i.e. parameter and/or region); which are most important / informative?
  • How stationary are modern (e.g. reanalysis-derived) relationships between large-scale climate indices and regional parameters (e.g. Amundsen Sea Low and West Antarctic temperature)?
  • What are the implications for broader impacts on ecosystems and ice sheets?

Outputs

1. A community consensus report on the current progress and challenges in answering the above questions. A skeleton document/manuscript for the first output will be circulated in advance of the workshop with the aim of developing this during the workshop.
2. A community-agreed set of ‘best practices’ and metrics for the evaluation of ESMs using long-term records.