NASA’s advanced computing model shows how greenhouse gases such as carbon dioxide (CO2) – the main driver of global warming – change in the Earth’s atmosphere all year round. Higher densities are shown in red. Credits: NASA Scientific Image Studio / NASA Office of Global Modeling and Communications
The Earth is on a budget – an energy budget. Our planet is constantly trying to balance energy in and out of the Earth system. But human activity throws that off balance, causing our planet to warm up in response.
Radiant energy enters the Earth’s system from the sunlight shining on our planet. Some of this energy reflects the Earth’s surface or atmosphere back into space. The rest gets in, heats the planet, and then emits it as thermal radiation energy in the same way that black asphalt gets hot and radiates heat on a sunny day. Eventually, this energy also goes to space, but some of it is re-absorbed by clouds and greenhouse gases in the atmosphere. The captured energy can also be sent back to Earth, where it warmed the surface even more.
Adding more components that absorb radiation – such as greenhouse gases – or removing those that expose it – such as aerosolas – throws the Earth’s energy balance, and causes absorb more energy with the Earth instead of escaping into space. This is called radiation penetration, and is the strongest way human actions affect the climate.
Simplified animation of the planet’s energy balance: A planet’s energy budget is balanced between incoming radiation (yellow) and outgoing radiation (red). On Earth, natural and human processes cause an impact on the amount of energy received as well as released into space. This study filters out changes in the Earth’s energy budget as a result of feedback processes, highlighting the energy changes caused by aerosols and greenhouse gas emissions. Reputation: NASA Goddard Space Center Contemplative Image Center
Climate modeling predicts that human activity causes the release of greenhouse gases and aerosols that affect the Earth’s energy budget. Now, a NASA study has confirmed these predictions with direct observations for the first time: radiation forcings are increasing as a result of human actions, affecting the energy balance of the planet and ultimately causing change climate. The paper was published online on March 25, 2021, in the journal Geophysical Research Letters.
“This is the first calculation of the Earth’s total radical propulsion using global observations, describing the effects of aerosols and greenhouse gases,” said Ryan Kramer, the paper’s first author and researcher at NASA’s Space Flight Center in Greenbelt, Maryland, and the University of Maryland, Baltimore County. “It is direct evidence that human activity is causing changes in the Earth’s energy budget.”
NASA’s Clouds and the Earth’s Radiant Energy System (CERES) project studies the flow of radiation at the Earth’s atmospheric surface. A series of CERES instruments have been flying continuously on satellites since 1997. Each one measures the amount of energy entering and leaving the Earth’s system, giving the total total change in radiation. These data, in combination with other data sources such as ocean heat measurements, show that there is an energy imbalance on our planet.
“But it doesn’t tell us what factors are causing changes in energy balance,” Kramer said.
NASA’s CERES instruments monitor Earth’s energy balance. This image shows how the difference between incoming short-wave energy and regenerative energy – locked solar energy – can be compared with scattered long-wave radiation to the Earth’s net change. in energy to prove. Credit: NASA Scientific Image Studio
This study used a new method to find out what rate of total energy change people are causing. The researchers worked out the extent of the imbalance caused by variations in factors that often occur naturally, such as water valves, clouds, temperature and surface albedo (indeed brightness or the shadow of the Earth’s surface). For example, the Atmospheric Infrared Sounder (AIRS) instrument on NASA’s Aqua satellite measures water valves in Earth’s atmosphere. Water vapor absorbs energy in the form of heat, so changes in water vapor ultimately affect the amount of energy leaving the Earth’s system. The researchers worked out the energy change caused by each of these natural factors, and then subtracted the values from the total. The remaining portion is the radiation thrust.
The team found that human activity has caused the radiation emissions on Earth to rise by about 0.5 Watts per square meter from 2003 to 2018. The increase is mainly from greenhouse gas emissions from things like power generation, transportation and industrial manufacturing. Lower reflective aerosol also contributes to the imbalance.
The new method is computationally faster than previous model-based methods, allowing researchers to monitor radiation exposure in near real time. The method can be used to track how human emissions affect the climate, monitor how well different mitigation efforts are working, and evaluate models to predict make changes in the weather in the future.
“Creating a direct record of radiation exposure measured from observation will allow us to assess how well climate models can simulate these forcings,” said Gavin Schmidt, director of the Institute of Studies NASA Space Agency (GISS) in New York City. “This will allow us to make more confident predictions about how the weather will change in the future. ”
Fact: “Observing evidence of growing global radiation” by Ryan J. Kramer, Haozhe He, Brian J. Soden, Lazaros Oreopoulos, Gunnar Myhre, Piers M. Forster and Christopher J. Smith, March 25, 2021, Geophysical Research Letters.
DOI: 10.1029 / 2020GL091585