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NASA has just released the first direct evidence that humans are causing climate change



Simplified animation of the energy balance of the Earth planet: The planet’s energy budget is balanced between incident radiation (yellow) and outgoing radiation (red). Image source: NASA.

By now, it is not surprising to know that the earth is warming rapidly. More than 99% of scientists said that most of this warming is not a natural phenomenon, but the result of greenhouse gas heat released by human activities (such as burning fossil fuels).

However, in thousands of studies on climate change and its links with human activities, until recently, NASA researchers have made direct observations of the driving forces of climate change.

Since the Industrial Revolution first aroused people̵

7;s appetite for coal and other fossil fuels in the mid-19th century, the concentration of CO2 in the atmosphere has soared from 280 parts per million to more than 415 ppm today.

There is no doubt that we know that greenhouse gases such as carbon dioxide, methane or water vapor trap heat into the atmosphere, thereby raising the surface temperature. We also know that carbon dioxide in the atmosphere is increasing at a rate 100 times faster than the natural rate of increase.

At the same time, human activities also cause air pollution. For example, we all know particulate matter that is harmful to our health and the health of wildlife. But some of this air pollution comes in the form of aerosols, which are tiny particles suspended in the atmosphere that reflect incoming sunlight back into space. In other words, this pollution has a global cooling effect.

Therefore, aerosol is a cooling force, and greenhouse gases generate heat. The difference between the energy absorbed by the atmosphere (mainly greenhouse gases) and the energy radiated back to space through factors such as aerosols is called “radiative forcing.”

When the radiative forcing is zero, it means that the planet’s energy system is in equilibrium, so the atmosphere should neither warm nor cool. When the radiative forcing is positive, it means that the earth system is out of balance and warming.

What NASA has done in recent research is to use satellite observations to quantify individual radiative forcing in order to accurately determine how much each component heats or cools the earth.

For decades, scientists have designed climate change models to predict how temperature will change in response to changes in greenhouse gases in the atmosphere. Not surprisingly, NASA’s new research has found that after combining data from NASA’s cloud and Earth Radiant Energy System (CERES), the radiation force is matched with these models, which study the radiant flow at the top of the Earth’s atmosphere and oceans. Other data sources. Calorie measurement.

“This is the first calculation of the Earth’s total radiative forcing using global observation data, taking into account the effects of aerosols and greenhouse gases,” the first author of the paper and a researcher at NASA’s Goddard Space Flight Center in Greenbelt, Maryland Said Ryan Kramer, and the University of Maryland in Baltimore County. “There is direct evidence that human activities are changing the planet’s energy budget.”

Another nail on the coffin

Scientists agree that human activities are the only reason for the sharp rise in the average temperature of the earth. Since 1880, the average global temperature has risen by 1 degree Celsius (2 degrees Fahrenheit). Two-thirds of the warming that has occurred since 1975 has changed at a rate of approximately 0.15-0.20°C every ten years.

Although there are numerous evidences about man-made global warming, this is actually the first study to provide direct rather than indirect evidence to support the explanation of the warming we are currently experiencing. So far, only local areas can obtain direct evidence that changes in greenhouse gases will affect the heat transfer capacity of the atmosphere.

According to this study, the radiative forcing on the earth caused by human activities increased by about 0.5 watts per square meter between 2003 and 2018.

Gavin Schmidt, director of NASA’s Goddard Institute for Space Studies (GISS), said: “Creating a direct record of radiative forcing from observations will allow us to assess how climate models simulate these Forced.” “This will enable us to make more confident predictions of future climate change.”

The research results are published in the journal Geophysical Research Letters.


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