Estimation of Joint Uncertainties Due to Natural Climate Variability and Emission Scenarios in Climate Change Assessment on Precipitation and Temperature in Zanjan

In this paper climate change impacts on daily precipitation, daily maximum, and daily minimum temperature are estimated, while joint uncertainties due to natural climate variability and emission scenarios are estimated. By considering these uncertainties, the results incorporate a wide range of future possible situations which is a great importance in increasing the reliability of the results.

For downscaling of future GCM scenarios, Weather Generator method is used using LARS-WG model. CGCM3 outputs for based on three emissions scenarios, medium (A1B) and high (A2), low (B1), are downscaled for Zanjan. Uncertainty due to natural climate variability is estimated by comparison of 90% limits of 100 LARS-WG generated series for historic and for each future climate scenarios.

The results of this research show that the daily minimum and maximum temperature will increase in the future. Despite the Uncertainty due to natural climate variability, if is expected that the monthly means of daily minimum and maximum temperature will increase for the entire calendar months. Moreover, the uncertainty of emission scenarios is low in comparison with the future increase in temperature. It is expected that the average of monthly precipitation will decrease for the most of the calendar months; although, there is a little possibility for increase in precipitation due to natural climate variability.

In result of climate change, temperature and precipitation of the Zanjan will change in the future and uncertainties due to natural climate variability and emission scenarios are important in climate change impact assessment on precipitation and temperature.