CLIMATE CHANGE REQUIRES THE WORLD’S ATTENTION

We have known about climate change for decades. There is little doubt that Earth is getting warmer and warmer (see the graph). A warming ocean and atmosphere along with melting ice and rising sea levels provide evidence of a dramatic change in the global climate.

In 2013, a lot of people were shocked by a news photo of a dead polar bear that was found on Norway’s Arctic island of Svalbard. According to the scientists who found its dead body, all that remained of the polar bear was “skin and bones”. An expert who has studied polar bears for many years said that from the position of its dead body, the bear appeared to have starved and died. Experts claimed that low sea-ice levels caused by climate change meant the bear could not hunt seals as before, so it had to travel greater distances in order to find food. This alarming case showed how the increase in temperature had an impact on Earth’s ecology.

Then what is causing the increase in the global average surface temperature? Climate scientists often mention a key climate process called the “greenhouse effect”, which has two common meanings: the “natural” greenhouse effect and the “man-made” greenhouse effect. The “natural” greenhouse effect refers to the fact that heat from the sun enters the atmosphere and warms Earth’s surface as short-wave radiation. The heat is released back into space at longer wave lengths. Greenhouse gases in the atmosphere, such as methane and carbon dioxide, trap some of the heat, keeping Earth’s climate warm and habitable. Without this process, Earth could not sustain life. However, the “man-made” greenhouse effect has now become a big problem. When people produce huge amounts of extra greenhouse gases by burning fossil fuels, more heat energy is trapped in the atmosphere and causes Earth’s surface temperature to rise quickly.

There is strong and comprehensive evidence that the rise in temperature has led to an increase in extreme weather and natural disasters worldwide, not only causing serious damage, but also costing human lives. Climate scientists have warned that if we do not take appropriate actions, this warming trend will probably continue and there will be a higher price to pay. In fact, news reports are frequently broadcast about extreme rainstorms and heatwaves causing deaths and economic losses.

Continued greenhouse gas emissions will result in further warming and long-lasting changes to the global climate. This requires the attention of people all over the world. Governments need to consider making policies and taking appropriate actions and measures to reduce greenhouse gas emissions. We as individuals can also reduce our “carbon footprint” by restricting the amount of carbon dioxide our lifestyles produce. It is our responsibility to seize every opportunity to educate everyone about global warming, along with its causes and impacts, because this is the most serious issue affecting all of us on this planet. So what will you do to help?

【推荐3】The green, natural forest absorbs carbon dioxide from the air through photo- synthesis (光合作用). There is another way of dealing with the climate crisis. That is setting up fields of dark-colored solar panels (太阳能电池板), also known as “solar forests”, which replace power stations that use fossil fuels such as coal and gas to make electricity, thus mitigating harmful emissions (排放) of greenhouse gases.

But since they are both relatively dark, they absorb a lot of solar radiation. Some of the energy is used for photosynthesis in natural forests or to produce electricity in “solar forests”, but most returns to the atmosphere, heating it up. Then what would be the more effective land use option in terms of the climate crisis: planting a forest, or building solar panels? This issue has long been debated by decision-makers around the world. Now, we may have an answer, thanks to a new study.

First, the researchers compared the impact of a forest on the climate crisis in a dry area to that of a solar farm in a similar environment. The researchers found that the albedo effect (反射效应) of both of these “forests” was similar, but that the absorption or prevention of carbon emissions was very different. It turns out that it takes 2.5 years for the heat emitted by solar farms to be balanced by the carbon emissions that are avoided, thanks to the energy they produce. In the case of a natural forest of similar size, it would take more than 100 years of photosynthesis to balance its heating effect.

The researchers also studied how the heating-cooling relationship changed in other climates and found that in more humid environments, the heating effect of planting large numbers of trees is smaller. And the break-even point is reached within 15 to 18 years.

“In dry places, building solar forests seems far more effective in addressing the climate crisis. Meanwhile, forests absorb about a third of annual carbon emissions and play a vital role in the global rain cycle, in maintaining biodiversity and in many other environmental and social contexts. Preventing them from being cut down and planting more trees in humid areas are of great significance,” explains one of the researchers in the study.