A recent study published in the journal Science investigated the remains of nuclear bomb tests conducted by the U.S. and the Soviet Union in the 1960s for use in climate models.
- The researchers used climate models (Coupled Model Intercomparison Project CMIP) to estimate the amount of carbon stored in vegetation around the planet in a year.
- The CMIP models used in the study included some of the latest versions (5 and 6).
Key Highlights of the Study
- The Study: The Researchers used climate models to track the change in the level of Carbon 14 between 1963 and 1967 and thereby estimate the amount of carbon stored in vegetation around the planet in a year.
- The Nuclear explosions during the Cold War period sprayed radioactive material around the planet’s atmosphere.
- Carbon-14: It is an isotope of carbon also called Radiocarbon. Its atom’s nucleus has two neutrons more than the most common Carbon-12. The nuclear bomb tests steadily deposited more than usual quantity in the atmosphere.
- Radiocarbon bonds with oxygen to form CO2
- Limited Test Ban Treaty (LTBT): With the signing of the LTBT treaty in 1963 prohibiting nuclear testing over land, air, and under water the atmospheric radiocarbon concentration stopped increasing beyond this year.
- Findings:
- The models suggested that the radiocarbon was moving into vegetation from the atmosphere as the vegetation absorbed this Radiocarbon converted CO2 during photosynthesis to produce food and energy.
- Carbon Hosted in Vegetation: Scientists have used satellite data to estimate how much carbon vegetation around the world hosts by using climate models to estimate the amount of carbon stored in vegetation around the planet in a year.
- The study estimates 80 billion tonnes of carbon being stored per year, most of them being stored in leaves and finer roots, i.e. the non-woody parts of the plant as opposed to the previous estimates of 43-76 billion tonnes per year
- Fast Carbon Recycling: The Carbon Cycling is moving at a speed greater than previously thought as the plants are absorbing more CO2 from the atmosphere and storing it for a shorter duration than expected, before releasing it into their surroundings.
- Carbon Cycle: Plants absorb CO2 from the atmosphere during photosynthesis and use it to make glucose. A plant consumes some of the glucose and some it stores as starch in its leaves. In this process, some carbon is also lost when the plant exhales CO2 as it respirates.
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Climate Models
- Climate models also known as general circulation models or GCMs are based on well-documented physical processes to simulate the transfer of energy and materials through the climate system.
- They can be used to recreate the past climate or predict the future climate.
- They use mathematical equations to characterise how energy and matter interact in different parts of the ocean, atmosphere, land and Ice.
- Process: It is a complex process of,
- Identifying and quantifying Earth system processes; Representing them with mathematical equations; Setting variables to represent initial conditions and subsequent changes in climate forcing; Repeatedly solving the equations using powerful supercomputers.
- Composition:
- 3D Grid based Model: Climate models separate Earth’s surface into a three-dimensional grid of cells. The smaller the size of the grid cells, the higher the level of detail in the model.
- Time Step: It also includes the element of time, called a Time Step which can be in minutes, hours, days, or years. Like grid cell size, the smaller the time step, the more detailed the results will be
- Testing: The model is initialised to known conditions at a time in the past and once a climate model is set up, it can be tested via a process known as “hind-casting.”
- Example:
- Coupled Model Intercomparison Project (CMIP): It was set up by the World Climate Research Program in 1995 preparing climate projections that inform the U.N.’s climate reports.
- Scientific institutions in several countries pool their individual climate models together to produce better projections.
- Community Earth System Model 2: It was developed by the U.S. University Corporation for Atmospheric Research, and is the only model which has accounted for radiocarbon in its simulations
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August 12, 2024
