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Chemistry, 03.04.2020 06:37 huangjianhe135

Describe the investigations from the readings that are being conducted to learn more about how much water flows in major rivers around the world. Explain why the researchers think that data from the rivers is related to climate change. Cite facts from the texts in your response.

Need to make at least a 3 paragraph essay. 4 sentences in each paragraph pls.

Heres the article:

BOULDER, Colorado. A new study has revealed that the flow of water from Earth's largest rivers has declined over the past 50 years, due primarily to climate change.

A team of researchers at the National Center for Atmospheric Research (NCAR) in Boulder, Colorado, discovered the reduction in water flow after analyzing the discharge from 925 major rivers around the world between 1948 and 2004. Among Earth's dwindling rivers are Asia's Changjiang (or Yangtze), Mekong, Ganges, Irrawaddy, Amur, and Xijiang. Also included are Africa's Congo and Niger rivers and South America's Amazon River. North America's Mackenzie and Columbia rivers are also affected.

Researchers assessed the overall effect of the shrinking rivers on the various oceans into which they drain. They used cubic kilometers as their unit of measurement. The researchers found that the overall trend over the years was a decrease in the rates of discharge. Over the past half-century, they found, the yearly amount of fresh water flowing into the Indian Ocean fell by about 3 percent, or 140 cubic kilometers. The annual river discharge into the Pacific Ocean dropped about 6 percent, or 526 cubic kilometers. Researchers noted that in terms of quantity, the decline in streamflow into the Pacific is equal to shutting off the Mississippi River.

Meanwhile, researchers discovered only a negligible variation in the annual river flow into the Atlantic Ocean. There, decreases in the Amazon River were offset by increases in South America's Parana River and our own Mississippi River. Due to increased rainfall, the Mississippi saw an increase in its flow of more than 22 percent over the period studied.

Aiguo Dai was the study's lead researcher. According to Dai, the only ocean showing a significant increase in the freshwater flow it received was the Arctic Ocean. There, annual river streamflow rose about 10 percent, or 460 cubic kilometers.

According to Dai, the change in river flows is primarily a result of climate change. Earth's warming temperatures have caused flooding in some regions. Other areas have experienced reduced precipitation and droughts. Droughts place even greater demands on the already shrinking rivers. They increase the need for dams and other diversions of river water for agriculture and industry. For example, decreased precipitation and increased water diversion caused a 14 percent reduction in the flow in the northwestern U. S.'s Columbia River.

"Freshwater resources will likely decline in the coming decades...due to climate changes," Dai said.

In the Arctic, climate change is responsible for accelerating the melting of snow and ice. This accounts for the increased discharge into the Arctic Ocean.

"[Rapidly] disappearing mountain glaciers in [higher latitudes] will make matters worse," said Dai.

In some regions, the effects of climate change on Earth's rivers are compounded by regularly occurring weather phenomena. Take the El Niño phenomenon, for example. An El Niño is a periodic cooling of sea surface waters in the tropical Pacific. Researchers noted that the El Niño phenomenon led to lower flows in the Amazon River and higher ones in the Mississippi River when it was in effect.

Researchers are concerned about the reduction in rivers, particularly the Yellow River in northern China, the Ganges in India, the Niger in West Africa, and the Colorado in the southwestern U. S. These rivers flow through densely populated areas, where water is in greater demand than in areas with smaller populations.

"These changes will have impacts on humans and ecosystems," said Margaret A. Palmer. Palmer is director of the Chesapeake Biological Laboratory of the University of Maryland Center for Environmental Science. "Many of these regions have large populations and drought-stressed ecosystems."

There are other reasons to be concerned about the diminished streamflow. One is that rivers supply oceans with essential nutrients. Another is that changes in streamflows can induce changes in ocean temperatures and salt levels. These changes are known to affect global ocean circulation patterns.

NCAR scientist Kevin Trenberth is concerned about climate change and its effects on rivers—and ultimately humans. "As climate change inevitably continues in coming decades," Trenberth said, "we are likely to see greater impacts on many rivers and water resources that society has come to rely on."

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