This research aimed to investigate the relationship between climate policy uncertainty (CPU), clean energy (ENERGY), carbon emission allowance prices (CARBON), and Bitcoin returns (BTC) for the period from August 2012 to August 2022. The empirical analysis strategies utilized in this study included the Fourier Bootstrap ARDL long-term coefficient estimator, the Fourier Granger Causality, and the Fourier Toda–Yamamoto Causality methods. Following the confirmation of cointegration among the variables, we observed a positive relationship between BTC and CARBON, a positive relationship between BTC and CPU, and a negative relationship between BTC and ENERGY. In terms of causal associations, we identified one-way causality running from CARBON to BTC, BTC to CPU, and BTC to the ENERGY variable. The study underscores the potential benefits and revenue opportunities for investors seeking diversified investment strategies in light of climate change concerns. Furthermore, it suggests actionable strategies for policymakers, such as implementing carbon taxes and educational campaigns, to foster a transition towards clean energy sources within the cryptocurrency mining sector and thereby mitigate environmental impacts.

Price bubbles which can be expressed as the deviation of the price of an asset from its fundamental value, have significant impacts on markets. The effects of the financial crisis that started with the burst of the housing bubbles in the USA in 2008 have spread all over the world and turned into a global crisis. In this study, the price bubbles of gold, silver, platinum and palladium in the commodity markets for the period between 01.01.2010-19.02.2019 were investigated. RtADF, SADF and GSADF methods were used to determine the formation and burst periods of price bubbles. As a result of the analysis, price bubbles were found in gold, silver and platinum, whereas no bubbles were found in palladium prices. Due to the close formation dates of these bubbles, whether there was any return or volatility spillover between gold, silver and platinum markets was investigated with VAR-EGARCH method. As a result of the study, it was found that there was a multiple spillover between the gold, silver and platinum returns. Thus, it was concluded that the price bubbles formed in precious metals triggered each other. Findings regarding the presence of price bubbles in the precious metal markets are crucial for traders in terms of trading timing. However, the findings related to the volatility spillover among precious metals are also important in terms of considering the effect of this spillover for the investors who provide hedging by precious metals.

Financial bubbles are described as the deviation of the market values of financial assets from their core values. They are one of the main indicators for the financial crises by negatively affecting the markets due to the constant overvaluation of the assets. Therefore, investigating the presence of financial bubbles and determining the reasons are of great importance for investors, market regulators, and portfolio managers in terms of investment risk and price stability. In the study, the presence of bubbles in the foreign exchange market is investigated by considering the most traded currencies such as the US Dollar, Euro, Japanese Yen, British Pound, and Chinese Yuan. For this purpose, the daily price data for the period between 03.01.2005-20.11.2019 for the US Dollar/Turkish Lira, Euro/Turkish Lira, British Pound/Turkish Lira, and Chinese Yuan/Turkish Lira, and the daily price data belonging to 28.08.2013-20.11.2019 period for Japanese Yen/Turkish Lira are used. Supremum Augmented Dickey-Fuller (SADF) and Generalized Supremum Augmented Dickey-Fuller (GSADF) tests are used to determine the bubbles in aforementioned exchange rates. The results indicate findings regarding the formation of financial bubbles in the foreign exchange market in Turkey.

This paper investigates the relationship between geothermal energy consumption, economic growth, and foreign direct investments in countries where geothermal energy production is possible. Panel Fourier Granger causality and panel Fourier Toda–Yamamoto causality tests (2020–2021) were applied, which can take into account smooth transitional structural breaks with trigonometric functions using quarterly data for the period 2016 Q1–2020 Q3. Data were obtained from the International Energy Agency (IEA), Federal Reserve Economic Data (FRED), and the OECD official website. According to the results obtained based on panels, there is one-way causality from economic growth to geothermal energy and one-way causality from geothermal energy consumption to foreign direct investments. The results obtained based on individual countries indicate that one-way causality from foreign direct investment to geothermal energy consumption was found for Mexico and Portugal, and one-way causality from geothermal energy consumption to economic growth was found for Italy and Mexico. On the other hand, causality from economic growth to geothermal energy consumption was observed for Germany, Japan, and USA. No significant results were found for Turkey and New Zealand, and it is understood that the macroeconomic structures of these countries are not affected by geothermal energy. The difference in the results reveals that the application recommendations on this subject should also be different.

Purpose- In this study, the effect of global economic policy uncertainty on crude oil prices is investigated. Methodology- In the study, which considers the Global Economic Policy Uncertainty (GEPU) Index as an indicator of global economic policy uncertainty and the American WTI crude oil spot and forward prices for crude oil, the data set consists of monthly data for the period January 1997-April 2022. These data were analyzed by Breitung and Candelon's (2006) frequency causality test. Findings- According to the results of Breitung and Candelon's (2006) frequency causality test, only long-term causality relationship was found from GEPU to American WTI crude oil spot and futures prices. In addition, it is seen that there is no causality relationship from American WTI crude oil spot prices to GEPU in short-term, mid-term and long-term while there is only long-term causality from American WTI crude oil future prices to GEPU. Conclusion- It is thought that economic policy uncertainty tends to affect crude oil prices due to differences in demand. In line with these results, it becomes important for investors to consider the GEPU Index and the economic conditions affecting this index within the scope of their hedging strategies. Keywords: Economic policy uncertainty, crude oil, spot market, futures market, causality in frequency JEL Codes: G32, G15, C32

Foreign trade plays a key role in the development of a country's economy and international social relations. Accordingly, the increase and decrease in a country's trade openness directly and indirectly affects macroeconomic indicators. In short, it is important to know the expected relationship between trade openness and inflation for a country's economy. Investigating the relationship between trade openness and inflation is important in keeping inflation under control, along with foreign trade policy practices. On the other hand, the theoretical basis of the association between trade openness and inflation is known with the Romer (1993) Hypothesis. According to the Romer Hypothesis, it is argued that an increase in trade openness will negatively affect inflation. However, although there are findings supporting this theory for the studies done so far, there are empirical studies expressing the opposite. This study has investigated this relationship in MIKTA countries. Kónya (2006) panel causality test was used in the study using annual data between 1960 and 2020. In result of the paper, it is found that there is no causal linkage between trade openness and inflation in countries. These results do not coincide with the Romer (1993) Hypothesis.