Solar variability and climate change during the first half of the 20th century (SOVAC)

• Research unit: COST
• Project number: C11.0124

Key words (English)

Climate; solar irradiance; modeling; atmopsheric chemsitry; energetic particles

Research programs (English)

COST-Action ES1005 - Towards a more complete assessment of the impact of solar variability on the Earth’s climate

Short description (English)

Most of the models that participated in the IPCC AR4 experiment failed to reproduce statistically significant the global warming as well as typical features of its space pattern like e.g.,the warming over the continental US and over the Arctic. This problem remains important and should be reinvestigated given the noticeable recent progress in modeling and understanding of climate forcings. In the proposed project we intend to elucidate the causes of climate warming during the first half of 20th century. To addres this question we simulate the climate evolution from 1880 to 1950 using the state-of-the-art atmosphere-ocean-chemistry-climate model and the latest reconstructions of the climate forcings. The experiments will be performed with a series of multi-year ensemble runs driven by all known anthropogenic and natural forcings taken in different combinations to elucidate the effects of solar spectral irradiance, energetic particle precipitation and volcanic aerosol variability. The seasonal and geographical patterns of the climate change during the considered period will be compared against the observation data and reanalysis products to establish the robustness of the obtained climate behavior. The analysis of the sensitivity runs will allow disentangling the contribution of different forcing mechanisms to the climate change. The results will have implications for the forecast of future climate change due to combined effects of anthropogenic and natural factors.

Further information (English)

Full name of research-institution/enterprise: Physikalisch-Meteorologisches Observatorium Davos Weltstrahlungszentrum PMOD/WRC

Partners and International Organizations (English)

AT; BE; BG; HR; CZ; DK; FI; FR; DE; EL; HU; IL; IT; NO; RO; ES; UK; RU

Abstract (English)

The project is aimed at the understanding the causes of climate warming during the first half of the 20th century. To address this question we have simulated the climate evolution from 1900 to 1950 using the state-of-the-art atmosphere-ocean-chemistry-climate model (AOCCM) SOCOL-MPIOM driven by the most recent compilation of all relevant climate forcing data. We performed the comparison of the seasonal and geographical patterns of the climate change during the considered period with the observation data, reanalysis products and other model simulations in order to establish the robustness of the obtained climate behavior. We analyzed the results of additional sensitivity runs and established the contribution of different forcing agents to the simulated climate change. The results have implications for the forecast of future climate change due to combined effects of anthropogenic and natural factors. During the last phase of the project we have continued extensive comparison of the simulated results with observations and other models using different statistical approaches. We analyzed the climate and ozone responses to the decadal scale solar irradiance variability simulated with models participating in IPCC CMIP5 activity and established the subset of models, which are able to mimic available observations. The analysis showed that AOCCM SOCOL-MPIOM is able to reproduce the observed pattern of the climate warming during the first half of the 20th century only if we apply large solar irradiance changes during this period. We also found that the increase of tropospheric ozone can substantially contribute to the warming trend. Other models from CMIP-5 subset with sufficient number of ensemble members did not show robust climate warming most likely because of the internally generated multi-decadal variability. The comparison of AOCCM SOCOL-MPIOM simulations with CMIP-5 models and observation results will be described in the paper that now in preparation for submission to EGU 'Climate of the Past' journal.

References in databases (English)

Swiss Database: COST-DB of the State Secretariat for Education and Research Hallwylstrasse 4 CH-3003 Berne, Switzerland Tel. [phone] Swiss Project-Number: C11.0124