The correlation between climate and energy rests on known causal relationships between human population growth, rising energy consumption and land use and the resulting greenhouse gas emissions and climate change. The relationships between energy-resource depletion, climate change, health resources and the environment, and the effects that they have on each other, have been subject to numerous scientific studies and research efforts. Environmental harm was caused early on during the industrial revolution, with air pollution being caused by soot coming from factories, as well as the greenhouse gas carbon dioxide being emitted into the atmosphere due to the burning of coal. The concern for climate change control and mitigation has consequently spurred policy makers and scientists to treat energy use and global climate as an inextricable nexus with effects also going in reverse direction. These winds are now increasingly used as a source of energy. The world's climate determines the pattern of its winds. In the 21st century, the Earth's climate and its energy policy interact and their relationship is studied and governed by a variety of national and international institutions. As a result, a majority of governments see climate and energy as two of the most important policy goals of the twenty first century.