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NASA measurements show direct evidence that humans are causing climate change



Given the large amount of evidence linking humans to humans, this may be surprising climate change, The directly observed evidence about human impact on climate is still not accepted by science. That is, until now.

In similar studies, NASA has calculated the various driving forces of recent climate change through direct satellite observations. Consistent with decades of climate models, the greenhouse gases produced by the burning of fossil fuels and pollutant particles suspended in the atmosphere (called aerosols) constitute the main source of modern warming.

In other words, NASA has proven through direct observation that the factors driving climate change are the gold standard for scientific research.

“I think most people will be surprised that we have not eliminated the long list of evidence supporting human factors. [human-caused] Climate change,”

; said Brian Sorden, a professor of atmospheric sciences at the Rosenstiel School of Ocean and Atmospheric Sciences at the University of Miami, co-author of the study.

So far, as we all know Rapid temperature rise Last century unnatural. It is produced by the accumulation of heat-collecting greenhouse gases such as carbon dioxide (CO2) and methane, most of which come from greenhouse gases. Fossil fuel combustion.

The scientific basis for why the earth is warming

When sunlight enters the atmosphere, part of it will be reflected back to space without heating the earth. The rest is absorbed by the earth’s surface and atmosphere, and re-radiated in the form of heat. Some of this heat is radiated back to space, but the rest is captured by specific molecules (such as CO2, methane, and water vapor). In short, the more greenhouse gases there are in the atmosphere, the more heat is captured, and the more the temperature rises.

NASA_climate_animation.gif
This NASA animation is a simplified illustration of the energy balance of the Earth planet: the energy budget is balanced between incident (yellow) and emitted radiation (red). Natural and man-made processes affect the energy received and the energy released back into space.

NASA


Since the mid-1800s, carbon dioxide The carbon dioxide content in the atmosphere has increased from 280 parts per million to 415 parts per million (an increase of 50%), and is now the highest level in at least three million years. The carbon dioxide in the atmosphere is increasing at a rate 100 times faster than natural growth.

At the same time, suspended pollutants called aerosols cool the atmosphere by blocking sunlight. Practice has proved that this unintentional side effect of the industrial revolution is useful in covering up certain greenhouse effects.

Although these particles effectively helped offset global warming in the mid to late 20th century, their impact is waning because pollution has been gradually removed since the 1980s. Although this is good news for health, it masks more warming in the system.

Due to changes in greenhouse gases and aerosols, the changes in the amount of heat absorbed in our atmosphere are collectively called “radiative forcing.” These changes in radiative forcing make the earth’s energy balance out of control. This is because, in order to keep the average temperature of the earth stable, the “energy input” from the sun must be equal to the “energy output” from the earth into space.

When these numbers are equal, the earth remains in balance. However, when the greenhouse gas accumulates, the energy that flows out is less than the energy that enters the earth system, which will heat our oceans and atmosphere, which will cause an imbalance in the energy budget of the earth.

What NASA did in this study was to calculate or quantify the individual forcings measured from specialized satellite observations to determine how well each component heats or cools the atmosphere. Not surprisingly, they found that the radiant force that computer models had been showing for decades to warm the earth matched the changes they had measured in their observations.

New insights from NASA

Gavin Schmidt, director of NASA’s Goddard Institute for Space Research, said that for a long time, the scientific community has been obtaining a large amount of indirect evidence to prove the cause of global warming. It can be seen from decades of computer models that the predicted energy imbalance has been seen by all mankind. The disappearing glacier more Extreme weather disaster To Ocean warming.

Schmidt explained: “For a long time, we have ample evidence that, due to the increase in ocean heat, the projected energy imbalance is real. This strongly confirms that these models are predicting warming for the right reasons. He said that scientists also have direct evidence that changes in greenhouse gases have affected the transfer and absorption of heat in the atmosphere, but only in a local environment, not in a comprehensive assessment.

Sorden added that science does have conclusive observational evidence that carbon dioxide has increased due to the burning of greenhouse gases in the last century, and laboratory measurements have confirmed that carbon dioxide has absorbed heat. In theory, this should make the planet more than about The rate of warming observed in a century. century. However, Sorden said that observing heat capture from space is actually very difficult. This new research solves this challenge.

The first author of the paper, a researcher at NASA Goddard Space Flight Center in Greenbelt, Maryland, said: “This is the first calculation of the Earth’s total radiative forcing using global observation data, taking into account aerosols and greenhouses. The influence of gas.”. “This is direct evidence that human activities are changing the planet’s energy budget.”

Specifically, this research has been able to calculate the real number of changes in the amount of heat captured in the Earth system from 2003 to 2019 from various factors that affect heat transfer (such as radiation, clouds, and water vapor). Researchers analyze satellite observations and apply so-called “radiation nuclei” to unlock the various components that control the transfer, absorption and release of heat within the Earth system, and the transmission of it back to space. So far, satellite observations of the Earth’s radiation budget have only measured the sum of radiation changes, not the individual components.

Then, there will also be feedbacks in the climate system, which will lead to smaller warming, but still important. An example is the fact that as the atmosphere warms, it can hold more water vapor, which means it can capture more heat, which further allows more water vapor to accumulate. This is a positive feedback that continues to heat up.

The result: from 2003 to 2018, radiative forcing increased by 0.5 watts/m2 (W/m2), which is the cause of planetary imbalance, which is the excess heat trapped in the earth system. The researchers concluded that this increase is indeed due to a combination of rising greenhouse gas concentrations and recent (to a lesser extent) recent decline in aerosol emissions.

As a reference, Schmidt said that from 2003 to 2018, the 0.5 W/m2 increase in the earth system is approximately equivalent to using one Christmas tree bulb for every 5 square feet of the earth. This may not sound like much, but in just 16 years, there will be so much energy to warm the earth by more than half a degree Fahrenheit. In other words, the 0.5 W/m2 excess heat absorbed by the earth system is 10 times the total energy used by humans in a year, which means everything from cooking utensils to nuclear energy.

Sorden said: “In fact, the observations are the same as the theoretical predictions.” “The results are not surprising, but in terms of human factors, they are actually more embellished with’i’ and’t’. [human-caused] climate change. It closes the last link between rising carbon dioxide levels and global warming. “

However, this research not only provides concrete evidence of the link between humans and recent climate change. It also shows how far science has gone in revealing the secrets that control the operation of our physical universe.


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