EXPLORING GRANGER CAUSALITY OF GLOBAL CARBON DIOXIDE CONCENTRATION AND THE URBANIZATION EFFECT FOR TEMPERATURE TRENDS IN HONG KONG OVER THE PERIOD 1886-2012
YU Qi-wei
Alexis K.H.LAU
Jimmy C.H.FUNG
DENG Xue-jiao
MAI Bo-ru
LI Fei
ZOU Yu
Abstract：Causality is an important question across many scientific fields.In climate change research,a crucial issue is whether and to what extent the change of weather and extreme events can be attributed to anthropogenic warming.Attribution analysis is predominantly using climate models,which have inherent limitations in describing the non-linear systems.We investigate this problem using an alternative approach on long-term observational data.More specifically,we examine the cause effect of global CO2 concentration and urbanization effect on Hong Kong temperature evolution using Granger causality test.Based on temperature data for Hong Kong from 1886 to 2012,we first illustrate the increasing trend of summer mean,maximum and minimum temperatures and the change in the number of very hot days and hot nights.A distributional change of daily temperatures can also be detected.The results of the Granger causality analysis suggest that both the global CO2 concentration and an urbanization effect are driving the evolution of Hong Kong's temperature,and the effect holds with different time lags.By comparing with a non-urban site,we find that the urbanization effect is likely to contribute about 40％ of the summer temperature increase.The preliminary results indicate that the approach can offer a useful alternative way to assess the cause of local temperature rises.Our analysis could be expanded to investigate on the causal effect of other greenhouse gases on extreme weather events,as well as the link between climate change and societal impacts.
Keywords：Climate changeGranger causality testextreme temperaturesurbanization effecttime series models
Publication Date：2016-01-01
Pages：9( 855-863 )