1 . California has lost half its big trees since the 1930s, according to a study to be published Tuesday and climate change seems to be a major factor(因素).

The number of trees larger than two feet across has declined by 50 percent on more than 46, 000 square miles of California forests, the new study finds. No area was spared or unaffected, from the foggy northern coast to the Sierra Nevada Mountains to the San Gabriels above Los Angeles. In the Sierra high country, the number of big trees has fallen by more than 55 percent; in parts of southern California the decline was nearly 75 percent.

Many factors contributed to the decline, said Patrick McIntyre, an ecologist who was the lead author of the study. Woodcutters targeted big trees. Housing development pushed into the woods. Aggressive wildfire control has left California forests crowded with small trees that compete with big trees for resources(资源).

But in comparing a study of California forests done in the 1920s and 1930s with another one between 2001 and 2010, McIntyre and his colleagues documented a widespread death of big trees that was evident even in wildlands protected from woodcutting or development.

The loss of big trees was greatest in areas where trees had suffered the greatest water shortage. The researchers figured out water stress with a computer model that calculated how much water trees were getting in comparison with how much they needed, taking into account such things as rainfall, air temperature, dampness of soil, and the timing of snowmelt(融雪).

Since the 1930s, McIntyre said, the biggest factors driving up water stress in the state have been rising temperatures, which cause trees to lose more water to the air, and earlier snowmelt, which reduces the water supply available to trees during the dry season.

2 . By the end of the century, if not sooner, the world’s oceans will be bluer and greener thanks to a warming climate, according to a new study.

At the heart of the phenomenon lie tiny marine microorganisms(海洋微生物) called phytoplankton. Because of the way light reflects off the organisms, these phytoplankton create colourful patterns at the ocean surface. Ocean colour varies from green to blue, depending on the type and concentration of phytoplankton. Climate change will fuel the growth of phytoplankton in some areas, while reducing it in other spots, leading to changes in the ocean’s appearance.

Phytoplankton live at the ocean surface, where they pull carbon dioxide(二氧化碳) into the ocean while giving off oxygen. When these organisms die, they bury carbon in the deep ocean, an important process that helps to regulate the global climate. But phytoplankton are vulnerable to the ocean’s warming trend. Warming changes key characteristics of the ocean and can affect phytoplankton growth, since they need not only sunlight and carbon dioxide to grow, but also nutrients.

Stephanie Dutkiewicz, a scientist in MIT’s Center for Global Change Science, built a climate model that projects changes to the oceans throughout the century. In a world that warms up by 3℃, it found that multiple changes to the colour of the oceans would occur. The model projects that currently blue areas with little phytoplankton could become even bluer. But in some waters, such as those of the Arctic, a warming will make conditions riper for phytoplankton, and these areas will turn greener. “Not only are the quantities of phytoplankton in the ocean changing. ” she said, “but the type of phytoplankton is changing.”

And why does that matter? Phytoplankton are the base of the food web. If certain kinds begin to disappear from the ocean, Dutkiewicz said, “it will change the type of fish that will be able to survive.” Those kinds of changes could affect the food chain.

Whatever colour changes the ocean experiences in the coming decades will probably be too gradual and unnoticeable, but they could mean significant changes. “It’ll be a while before we can statistically show that the changes are happening because of climate change,” Dutkiewicz said, “but the change in the colour of the ocean will be one of the early warning signals that we really have changed our planet.”

6 . As our Earth’s temperature warms up because of climate change, it is having unexpected effects on our world’s forests. When temperatures rise, trees close their skins to ___________ the loss of water, and this, in turn, slows down the ___________ of photosynthesis(光合作用). As a result, these trees are shorter and grow slowly, as well as have a ___________ death rate.

Climate change also increases the ___________ of droughts and wildfires. After wildfires, it takes a while for the forest systems to ___________ , and in some cases, the forests are ___________ permanently. Trees that are stressed are also ___________ to attacks by bacteria(细菌). In tropical forests, vines that use the trees as ___________ can often choke the trees and rob them of nutrients. Finally, humans have ___________ the forest landscape through logging. When trees are replanted on the soil, they will never grow as large as the ____________ trees that were cut down.

As these forests disappear, species that once called them “home” are forced to change, ____________ the variety of those systems. ____________ , some endangered species are unable to ____________ and die. Old-growth forests are disappearing in all regions of our world. When forests die, younger forests that are reestablished in the same area grow back weaker and smaller ____________ poor vegetation. With trees dying increasingly and continuously, will future generations ____________ out on the wonders of forests?

Lightning is very common but one of the most powerful weather forces to hit the Earth.     1     (actual), every second about 100 lightning strikes hit     2    surface of the Earth. In some parts of the world, for example in India, summer lightning storms are very common. With the rainy season    3    (begin) there, storms often cover most of the country’s northern area. The last week in June, the Reuters News Agency     4    (report) lightning strikes killed more than 100 people in two areas of India.

If you are outside,     5     (expert) say you should take cover,     6    means finding a safe shelter for protection. During a lightning storm, no place outside is safe. If you hear-thunder, lightning is close enough to hit you. Most lightning victims are in open areas or near a tree.

If you are indoors during a lightning storm, you could still be     7    danger. Stay off wired phones, computers and other     8    (equip) that can put you in direct contact with electricity. Avoid any area with running water and stay away from windows and doors. Specialists at the United States Centers for Disease Control and Prevention say that helping lightning strike victims can save    9    (they) lives. It is safe     10     (touch) a lightning strike victim. People struck by lightning do not carry charge. est. Some nutrients are easily lost in cooking if they are cooked in different ways.

8 . The Amazon rainforest is as undisturbed a place as most people can imagine, but even there, the effects of a changing climate are playing out. Now, research suggests that many of the region’s most sensitive bird species are starting to evolve in response to warming.

Birds are often considered sentinel (哨兵) species — meaning that they indicate the overall health of an ecosystem — so scientists are particularly interested in how they’re responding to climate change. In general, the news has not been good. For instance, a 2019 report by the National Audubon Society found that more than two-thirds of North America’s bird species will be in danger of extinction by 2100 if warming trends continue on their current course.

For the new study, researchers collected the biggest database so far on the Amazon’s resident birds, representing 77 non-migratory species and lasting the 40 years from 1979 to 2019. During the study period, the average temperature in the region rose, while the amount of rainfall declined, making for a hotter, dryer climate overall. According to the report on November 12 in the journal Science Advances, 36 species have lost substantial weight, as much as 2 percent of their body weight per decade since 1980. Meanwhile, all the species showed some decrease in average body mass, while a third grew longer wings.

Because of the study’s long time series and large sample sizes, the authors were able to show the morphological (形态学的) effects of climate change on resident birds. However, the researchers themselves are unsure and wonder what advantage the wing length changes give the birds, but suppose smaller birds may have an easier time keeping cool. In general, smaller animals have a larger rate of surface area to body size, so they dissipate more heat faster than a bigger animal. Less available food, such as fruit or insects, in dryer weather might lead to smaller body size.

9 . Worried about the climate?    1    . Here are some examples to get you started.

•Count the birds and the bees

Get closer to nature by becoming a citizen scientist. You could be counting birds in your garden, butterflies, insects and flowers, or even reptiles and hedgehogs.    2    . It’s a fun group activity, and your data can help scientists better understand the impact of human behaviour on natural habitats.

•    3    

Media headlines can be alarming when it comes to the climate and nature crisis or ignoring the issues completely. Hosting a local discussion can allow space for reflection, debate, ideas and collaboration (合作) to take action on global issues at a local level.

•Set up a library of things

Internet shopping has made it too easy to buy new stuff at the click of a button.    4    ? First, it’ll clutter (凌乱地塞满) your house，then it’ll clutter the planet. Setting up a library of things can encourage local people to share everything from tools to instruments, cooking gadgets to toys.

•Start a climate emergency centre

    5    . That’s why more and more climate emergency centres are popping up in derelict (废弃地) shops on high streets and in shopping centres. A climate emergency centre can be a space for events such as an exhibition on plastic waste or a workshop to learn how to make eco-cleaning products. It can also be a way to motivate more people to take action.