DiscourseAugust 10, 2021 14:31:45 IST
You probably remember classroom science teachers explaining that energy cannot be created or destroyed. It is a basic feature of the universe.
However, the energy can be changed. When the sun’s rays reach the earth, they turn into random movements of molecules that you feel like heat. At the same time, the Earth and the atmosphere are sending radiation back into space. The balance between incoming and outgoing energy is known as the Earth’s energy budget.
Our climate determines these energy flows. When the amount of energy coming in is more than going out, the planet warms up.
This can happen in a few ways, such as when the sea ice that normally reflects the sun’s radiation disappears and the dark ocean absorbs its energy instead. It also occurs when greenhouse gases accumulate in the atmosphere, capturing some of the energy that would otherwise have been irradiated away.
Scientists like me has been measuring the earth’s energy budget Since the 1980s, using instruments in satellites, air and oceans, and on earth. It is an important part of the new UN climate assessment Report of the Intergovernmental Panel on Climate Change published August 9, 2021.
Here’s a closer look at how energy flows and what an energy budget tells us about how and why the planet is warming.
Balancing solar energy
Almost all of the energy in the Earth’s climate system comes from the sun. Only a small fraction led upwards from within the country.
Average the planet receives 340.4 watts of sunshine per square meter. All the sunshine sets during the day, and the numbers are much higher at local noon.
Of which 340.4 watts per square meter:
- 99.9 watts are reflected back into space through clouds, dust, snow and the earth’s surface.
- The remaining 240.5 watts will be absorbed – about a quarter of the atmosphere and the rest of the planet’s surface. This radiation is converted into thermal energy within the earth.
Almost all of the absorbed energy is equivalent to the energy released back into space. However, the residue accumulates as global warming. This residue has increased, just under 0.6 watts per square meter at the end of the last century, to 0.79 between 2006 and 2018. the latest information from the Intergovernmental Panel on Climate Change. Most of it now warms the oceans. While it may sound like a small number, it adds energy.
The atmosphere absorbs a lot of energy and sends it as radiation both to space and back to the surface of the planet. In fact, the Earth’s surface receives almost twice as much radiation from the atmosphere as it does from direct sunlight. This is mainly due to the fact that the sun only heats the surface during the day, while the warm atmosphere is there 24/7.
Together, the energy reaching the earth’s surface from the sun and the atmosphere is about 504 watts per square meter. About 79 percent of the planet leaves it back. The remaining surface energy goes into volatile water and heats the air, oceans and land.
The residue between the incoming sun and the outgoing infrared is due to it greenhouse gases than carbon dioxide in the air. These gases are transparent to sunlight but opaque to infrared rays – they absorb and emit a lot of infrared rays downwards.
The Earth’s surface temperature must rise in response until the balance between incoming and outgoing radiation is restored.
What does this mean for global temperatures?
Doubling carbon dioxide would increase 3.7 watts of heat per square meter from the ground. Imagine old-fashioned light bulbs placed every three meters around the world and left to burn forever.
At current emission levels, greenhouse gas concentrations will double from pre-industrial levels by the middle of the century.
Climate scientists calculate that this much heat is added to the world warms the Earth’s climate by about 5 degrees Celsius (3 C). Preventing this would require replacing the burning of fossil fuels, which is the leading source of greenhouse gas emissions, with other energy sources.
The country’s energy budget is at the heart of the new IPCC climate assessment, written by hundreds of scholars looking at the latest research. Knowing what is changing, everyone can make better choices to preserve the climate as we know it.