What should be closely monitored to understand future climate changes?

Monitoring the levels of greenhouse gases and solar activity is crucial for understanding future climate changes because both directly influence Earth's climate system. Greenhouse gases, such as carbon dioxide and methane, trap heat in the atmosphere and contribute to the greenhouse effect, resulting in global warming. An increase in these gas concentrations correlates strongly with rising global temperatures.

Solar activity, including solar irradiance and sunspot cycles, also plays a significant role in climate. Variations in solar energy can affect weather patterns and climate over various time scales, from short-term fluctuations to long-term trends.

While the frequency of volcanic eruptions can impact climate temporarily through ash and gas emissions, their effects are often short-lived compared to the persistent influence of greenhouse gases. Monitoring ocean current changes is also important, but it primarily reflects the impacts of climate change rather than the driving factors. The rate of deforestation is a critical environmental concern, given its implications for carbon storage and biodiversity, but it does not encompass the comprehensive understanding needed of atmospheric conditions like greenhouse gases and solar activity do. Thus, evaluating greenhouse gas levels alongside solar activity provides a more complete picture to anticipate future climate changes.