NASA study shows human impact on global drought dates back 100 years

NASA study shows human impact on global drought dates back 100 years

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A study conducted by NASA's Goddard Institute for Space Research in New York City found that human-caused greenhouse gases and atmospheric particles that cause climate change are 20 times more common. he has shown that he has influenced our world since the turn of the century.

Published in the journal Nature, the study 20. he compared projected and real-world soil moisture data to look for human effects on global drought patterns over the century.

There is a growing possibility that what has been talked about for some time may be real

The climate model shows that the human “fingerprint” (as a climate response to greenhouse gases; a global model of arid and humid regions) has been visible since the early 1900s and increases over time as emissions increase.

Using observational data such as rainfall in tree rings and traces of reconstruction, the researchers found that real-world data could be used in the 20th century. they found that in the first half of the century they began flush with fingerprints.

The study is a first in terms of providing historical evidence that combines human-induced emissions and drought on a global scale, the team said. This also gave credibility to forward-looking models that predicted a similar link.

The fingerprint is predicted to grow stronger over the next few decades, potentially with serious consequences on human life, according to this new research.

After The Fingerprint

The key drought indicator of the study was the Palmer Drought Severity Index, or PDSI for short.

PDSI calculates soil moisture in summer using data such as precipitation, air temperature and flow. Today, NASA measures soil moisture from space, but these measurements only date back to 1980. PDSI was useful to researchers to investigate past climate change by calculating average soil moisture values over a long period of time.

The team also used drought atlases. Maps of where and when droughts occurred throughout history were calculated from tree rings. As the thickness of the tree rings indicated the wet and dry years during its lifetime; this provided an old archive to support the recorded data.

“These records go back centuries,” said lead author Kate Marvel, a research associate at GISS and Columbia University. “We have a comprehensive picture of global drought conditions that go back to history, and it's incredibly high quality.”

The world may in some ways be more delicate than we expected

Taken together, modern soil moisture measurements of the past and records based on tree rings have created a dataset that allows the team to compare with existing models.

They also calibrated their data against climate models that worked with atmospheric conditions, such as in 1850, before the Industrial Revolution caused increases in greenhouse gases and air pollution.

Ben Cook, who led the study with Marvel and is a climate scientist at the GISS and Columbia University Earth Observatory in New York, said: "this human fingerprint, this human climate change signal, is the 20th century. we were very surprised to see it come out in the first half of the century,” he said.

Although the results are not conclusive, the data is in this direction

The story changed briefly between 1950 and 1975, when the atmosphere cooled and dampened. The team believes this is due to aerosols or particles in the atmosphere.

Before the air quality legislation came into force, the industry released large amounts of smoke, soot, sulfur dioxide and other particles that block sunlight into the atmosphere. This, in turn, prevented the warming effect of greenhouse gases on the climate for those periods.

Modeling aerosols is more difficult than modeling greenhouse gases. But even if they are the most likely culprits in this case, the team pointed out that more research needs to be done to establish a definitive link.

After 1975, with the decline of pollution, global drought patterns began to fingerprint again. The team does not yet have enough statistical matches to say that fingerprint effects have reappeared. But they acknowledge that the data is in that direction.

Reaching a decision

What makes this work innovative, Marvel says, is to “see the big picture of global drought.” Local areas can exhibit significant natural variability from year to year, making it difficult to say whether the drought trend is due to human activity. Combining many regions in the global drought Atlas means there is a stronger signal if drought occurs in several places at once.

If you look at the fingerprint, Marvel says, “you can tell if the areas that need to be arid are getting arid, or if the areas that need to be arid are really getting moisture,” he says. "This is exactly the work of a climate detective looking for a unique, real fingerprint at the scene.”

Cook noted that previous assessments from national and international climate organizations do not directly link trends in drought patterns on a global scale to human activity. By showing human fingerprints on past droughts, he suggests and adds that this study is evidence that human activities may continue to affect droughts in the future:

“Part of our motivation was to ask, with all these advances in our understanding of natural and human-caused climate changes, climate modeling, and paleoclimate, have we advanced a science in which we can begin to detect human impact on drought.”

“The answer is absolutely yes.”

Is happening right now

Models predict droughts will become more frequent and severe as temperatures rise, potentially causing food and water shortages, human health problems, devastating wildfires and conflicts between people competing for resources.

“Climate change is not just a future problem,” Cook said.

"It shows that this affects global drought models, hiroiclime, trends and variability (this is happening now as well). And we expect these trends to continue as long as we keep warming the world.”

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