Read the following passage and choose the correct word or phrase that best fits each of the numbered blanks.
Climate scientists from the University of Sydney in Australia say tourism causes over 8 percent of greenhouse gasses. They also say that this ___(1)___ will continue to increase because the tourism industry is growing. Their study looked at the carbon footprint of many different areas of tourism. It studied the CO2 emissions from transport, events, hotels, restaurants and shopping. It ___(2)___ researched the carbon emissions from producing souvenirs. The researchers spent 18 months conducting the research. They included the tourist activities of 189 countries. Researcher Dr Arunima Malik said her team analyzed the impact on the environment of over one million businesses involved in tourism.
The researchers said ___(3)___ travel was a bigger cause of CO2 emissions than international or business travel. Air travel was the largest part of tourism's footprint. The researchers said flying would continue to increase global emissions ___(4)___ more people in the world become richer. The countries causing the most harm were the biggest and richest nations. The USA, China, India and Germany had the largest tourism carbon footprints. Their carbon emissions will continue to increase as more of their citizens travel. The researchers encouraged holiday-makers and travelers to try and reduce their carbon footprint when on vacation so their travel causes less harm to ___(5)___ planet.
(Sources: https://www.independent.co.uk/environment/tourism-climate-change carbon-emissions-globalwarming-flying-cars-transport-a8338946.html)