联合国称气候变化影响土地质量和粮食生产

UN: Climate Change to Affect Land Quality, Food Production

A new United Nations scientific report says that human-caused climate change is greatly reducing land quality worldwide. It also warns that the way humans use land is causing the Earth’s atmosphere to warm faster and could harm food production.

The Intergovernmental Panel on Climate Change (IPCC) published its latest report on Thursday. It examines the relationship between climate change and land use, agriculture and food security.

The report notes that the effects of climate change are already making food more costly¹ and less nutritious² and are worsening food shortages.

“The cycle is accelerating,” says NASA climate scientist Cynthia Rosenzweig. She was among the writers of the report. “The threat of climate change affecting people’s food on their dinner table is increasing.”

The scientists write that if humans change the way they eat, grow food and manage forests, it could help slow world temperature rise.

Land warming faster

About 30 percent of the Earth’s surface is land. But the report says that the land is warming two times faster than the planet as a whole. While heat-trapping gases are causing problems in the atmosphere, land has been less talked about as a part of climate change.

“The way we use land is both part of the problem and also part of the solution,” said Valerie Masson-Delmotte. She is a French climate scientist who was on one of the IPCC’s working groups. “Sustainable land management can help secure a future that is comfortable,” she added.

The report said climate change has worsened land degradation³. It has caused deserts to spread and permafrost to partly melt, and made forests more easily harmed by fire, disease and lack of water.

The future could be worse, the report said.

Agriculture and forestry⁴ together account for about 23 percent of the heat-trapping gases that are warming the Earth. That does not include energy costs, food transportation and packaging. With those activities added, the amount grows to 37 percent.

But scientists also note that land is a good carbon “sink.” In other words, it can suck heat-trapping gases out of the air. From 2007 to 2016, for example, agriculture and forestry each year put 5.2 billion metric tons of carbon dioxide into the air. But the land pulled 11.2 billion metric tons out of it. Carbon dioxide is a main heat-trapping gas.

But one of the writers of the report, Luis Verchot, noted⁵, “this additional gift from nature is limited.” He warned that the land will be less able to take in emissions⁷ in the future. Verchot is a scientist at the International Center for Tropical Agriculture in Colombia.

He said that total emissions from land are increasing, especially because of deforestation in places such as Brazil, Colombia and Peru.

Less-nutritious food

Scientists have long believed that one of the few good things about higher levels of carbon dioxide is that plants grow well in such conditions, NASA’s Rosenzweig said. But many studies show that the high levels of carbon dioxide reduce protein and nutrients⁸ in many crops.

For example, the studies show that high levels of carbon in the air cause wheat to have six to 13 percent less protein, four to seven percent less zinc⁹ and eight percent less iron, Rosenzweig said.

Food security

The IPCC also warned of more harmful effects to the global food supply as extreme weather becomes more common. It predicts an increase of 7.6 percent in cereal prices by 2050. Higher food prices, the report said, lead to an increased risk of hunger.

Changing farming, changing diets

The report noted that better, smarter farming methods could reduce carbon levels by up to 18 percent of current emission⁶ levels by 2050.

The report also suggested ways that carbon emissions could be reduced further. This could be done if humans reduce the amount of red meat they eat and instead eat more plant-based foods like fruits, vegetables and seeds. That would also make people healthier, Rosenzweig said.

More plant-based diets also would free up several million square kilometers of land by 2050.

“There are certain kinds of diets that have a lower carbon footprint and put less pressure on land,” said Jim Skea, a professor at London’s Imperial College. He spoke¹⁰ with Reuters reporters Thursday.

Reducing food waste

The report said that reducing food waste is an important part of fighting climate change. The report noted that almost one-third of food produced is lost or wasted. The causes of food loss and waste differ greatly between developed and developing countries.

Between 2010 and 2016, worldwide food waste accounted for eight to 10 percent of heat-trapping emissions. Reducing food waste would reduce emissions and improve food security, the report said.

However, the report urged that “the window for making these changes is closing fast.”

Stanford University’s environmental sciences chief, Chris Field, was not involved in the IPCC's report. But he told the Associated press that the report’s main message is that humans must “recognize that we have profound limits on the amount of land available.”

He added, “We have to be careful about how we utilize¹¹ it.”

I’m Mario Ritter.

And I’m Anne Ball.

Words in This Story

accelerate - v. to move faster : to gain speed

comfortable - adj. not causing any physically¹² unpleasant feelings : producing physical comfort

degradation - n. the act or process of damaging or ruining something

permafrost - n. ?a layer of soil that is always frozen in very cold regions of the world?

account for - phrasal verb. to be the cause of (something)

emissions - n. ? the act of producing or sending out something (such as energy or gas) from a source?

footprint - n. ?the area occupied or affected¹³ by something?

profound - adj. ?very great?; absolute or complete

utilize - v. ?to use (something) for a particular purpose

1 costly   

adj.昂贵的，价值高的，豪华的

参考例句：

• It must be very costly to keep up a house like this.维修这么一幢房子一定很昂贵。
• This dictionary is very useful,only it is a bit costly.这本词典很有用，左不过贵了些。

2 nutritious   

adj.有营养的，营养价值高的

参考例句：

• Fresh vegetables are very nutritious.新鲜蔬菜富于营养。
• Hummingbirds have discovered that nectar and pollen are very nutritious.蜂鸟发现花蜜和花粉是很有营养的。

3 degradation   

n.降级；低落；退化；陵削；降解；衰变

参考例句：

• There are serious problems of land degradation in some arid zones.在一些干旱地带存在严重的土地退化问题。
• Gambling is always coupled with degradation.赌博总是与堕落相联系。

4 forestry   

n.森林学；林业

参考例句：

• At present, the Chinese forestry is being at a significant transforming period. 当前, 我国的林业正处于一个重大的转折时期。
• Anhua is one of the key forestry counties in Hunan province. 安化县是湖南省重点林区县之一。

5 noted   

adj.著名的，知名的

参考例句：

• The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
• Jim is noted for arriving late for work.吉姆上班迟到出了名。

6 emission   

n.发出物，散发物；发出，散发

参考例句：

• Rigorous measures will be taken to reduce the total pollutant emission.采取严格有力措施，降低污染物排放总量。
• Finally,the way to effectively control particulate emission is pointed out.最后，指出有效降低颗粒排放的方向。

7 emissions   

排放物( emission的名词复数 )； 散发物（尤指气体）

参考例句：

• Most scientists accept that climate change is linked to carbon emissions. 大多数科学家都相信气候变化与排放的含碳气体有关。
• Dangerous emissions radiate from plutonium. 危险的辐射物从钚放散出来。

8 nutrients   

n.（食品或化学品）营养物，营养品( nutrient的名词复数 )

参考例句：

• a lack of essential nutrients 基本营养的缺乏
• Nutrients are absorbed into the bloodstream. 营养素被吸收进血液。 来自《简明英汉词典》

9 zinc   

n.锌；vt.在...上镀锌

参考例句：

• Brass is formed by the fusion of copper and zinc.黄铜是通过铜和锌的熔合而成的。
• Zinc is used to protect other metals from corrosion.锌被用来保护其他金属不受腐蚀。

10 spoke   

n.（车轮的）辐条；轮辐；破坏某人的计划；阻挠某人的行动 v.讲，谈（speak的过去式）；说；演说；从某种观点来说

参考例句：

• They sourced the spoke nuts from our company.他们的轮辐螺帽是从我们公司获得的。
• The spokes of a wheel are the bars that connect the outer ring to the centre.辐条是轮子上连接外圈与中心的条棒。

11 utilize   

vt.使用，利用

参考例句：

• The cook will utilize the leftover ham bone to make soup.厨师要用吃剩的猪腿骨做汤。
• You must utilize all available resources.你必须利用一切可以得到的资源。

12 physically   

adj.物质上，体格上，身体上，按自然规律

参考例句：

• He was out of sorts physically,as well as disordered mentally.他浑身不舒服，心绪也很乱。
• Every time I think about it I feel physically sick.一想起那件事我就感到极恶心。

13 affected   

adj.不自然的，假装的

参考例句：

• She showed an affected interest in our subject.她假装对我们的课题感到兴趣。
• His manners are affected.他的态度不自然。