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Li Hua

2 . Against the supposition that forest fires in Alaska, Canada and Siberia warm the climate, scientists have discovered that cooling may occur in areas where burnt trees allow more snow to mirror more sunlight into space.

This finding suggests that taking steps to prevent northern forest fires to limit the release of greenhouse gases may warm the climate in northern regions. Usually large fires destroyed forests in these areas over the past decade. Scientists predict that with climate warming, fires may occur more frequently over next several centuries as a result of a longer fire season. Sunlight taken in by the earth tends to cause warming, while heat mirrored back into space tends to give rise to cooling.

This is the first study to analyze all aspects of how northern fires influence climate. Earlier studies by other scientists have suggested that fires in northern regions speed up climate warming because greenhouse gases from burning trees and plants are released into the atmosphere and thus trap heat.

Scientists found that right after the fire, large amounts of greenhouse gases entered the atmosphere and caused warming. Ozone(臭氧) levels increased, and ash from the fire fell on far-off sea ice, darkening the surface and causing more radiation from the sun to be taken in. The following spring, however, the land within the area of the fire was brighter than before the fire, because fewer trees covered the ground. Snow on the ground mirrored more sunlight back into space, leading to cooling.

“We need to find out all possible ways to reduce the growth of greenhouse gases in the atmosphere.” Scientists tracked the change in amount of radiation entering and leaving the climate system as a consequence of the fire, and found a measurement closely related to the global air temperature. Typically, fire in northern regions occurs in the same area every 80 to 150 years. Scientists, however, found that when fire occurs more frequently, more radiation is lost from the earth and cooling results. Specifically, they determined when fire returns 20 years earlier than predicated, 0.5 watts per square meter of area burned are soaked up by the earth from greenhouse gases, but 0.9 watts per square meter will be sent back into space. The net effect is cooling. Watts are used to measure the rate at which energy is gained or lost from the earth.

Our Environment in the Future

Melati and Isabel deeply love their home on the island, which    1    (surround) by rain forests, green fields, and a vast ocean. Enjoying a swim at their local beach was once a daily pleasure for them. But when Melati was fifteen, and Isabel just ten, the sisters started to lose their     2    (interesting) in swimming in the waters near their home. Plastic bags would be around them as they swam and some were scattered (散落) on the beach. They got     3     (extreme) upset about that.

Melati didn’t think much about it until one day her teacher gave a lesson on some world heroes,     4     had sparked (引发) movements of positive changes in the world. After school, Melati walked home slowly in silence,     5    (concern) about the large amount of plastic rubbish on the beach. The heroes crossed her mind. Then    6     idea lit her up. She couldn’t wait to share what she thought with Isabel. Isabel also had a strong desire to do something. Picturing a    7    (fascinate) beach as before in mind, the pair jumped with joy.

They made a list     8     things they needed and reached out to the community for support. Melati and Isabel’s small idea attracted many volunteers to help clean up the beach,     9    (make) it start to become cleaner and more beautiful again. The sisters were overjoyed to see the impact they had made and continued to inspire others to take action against plastic pollution. They knew that even small actions like theirs could create significant positive change in     10    (they) community and the world.

Without the usual smoggy days, local     1    (resident) have been happy with the air quality since the heating season started. They open the window to air their homes. On social media, pictures of blue skies and white clouds     2     (frequent) appear,     3    (show) people’s excitement about the clear days.

In Shanxi,     4     major coal production province, burning coarse coal (粗煤) for heating used to be a main source of air     5    (pollute). The government has been striving to change all this. It has launched a campaign to replace coarse coal     6     clean fuels for heating since 2017.

More than 38 percent of the heating companies in Shanxi had applied advanced equipment with higher efficiency and     7    (low) emission (排放) by the end of 2019,     8    (compare) with 25.5 percent at the end of 2017. It     9     (believe) that the number can reach 50 percent by the end of this year,     10     is the goal of the government.

Thank you for your concern about our efforts in environmental protection. As too many use of plastic bags has caused serious white pollution, our government encourages us use environment-friendly shopping bags. These bags were made from a variety of materials that can be easy treated when they become rubbish. Beside, they can be reused. More and more Chinese have been realized the advantages of such bags and started to use it. What is believed is whether the wide use of these shopping bags can greatly improve our environment. This is one of the steps taking to make our country a even cleaner place.