New Delhi, Sept. 26 -- n the last three articles, we have detailed various types of ocean currents and their roles in absorbing excess heat. We also discussed how the acidity of the oceans is rising through anthropogenic means and how that is adversely impacting marine life. In this two-part article, in the first part, we will correlate this warming and acidification of the oceans with Earth's falling albedo and the EEI (Earth's Energy Imbalance), as well as the various experiments conducted by climate scientists. In the second part, we will look at the work of various leading climate scientists such as Stevens, Jansen, Loeb, Myrhe, Hodgenborg, Armour and Rugenstein.
Earth's Albedo and EEI
CERES (Clouds and the Earth's Radiant Energy System) is run by NASA's Langley Centre in Virginia, USA. This project studies and measures the light being received by the Earth and reflected by it, using radiometers fixed on satellites. The CERES project has been measuring this since 2001 and has found that the Earth's reflectivity is falling, i.e., the Earth is reflecting back less and less sunlight over the years in comparison to what it is receiving. In other words, the Earth's albedo (which is simply the sunlight reflected back into space by the Earth) is going down. This is mainly because large sheets and areas of ice are vanishing and cloud cover is receding, which means that less sunlight is reflected back.
From the laws of thermodynamics, we know that:
The first law says that energy can neither be created nor destroyed; it can only change forms. In other words, the Earth's energy balance has to be maintained under normal conditions. But when the Earth's albedo falls, there is an energy imbalance because the incoming energy is higher than what is re-emitted by the Earth. For the first law to hold, the extra energy shifts towards the oceans and the atmosphere, which get heated up more than they would have in the absence of a falling albedo.
The second law has to do with thermal radiation and entropy and says that hotter bodies will radiate heat towards colder ones. In the Earth's case, this heat will be radiated into outer space in the form of infrared waves. To radiate enough heat into outer space, the Earth's temperature has to rise. The Earth warms up enough to match its heat output to the raised solar input (because of a lower albedo).
While CERES has unambiguously demonstrated the Earth's falling albedo and rising temperatures on the Earth and in the oceans, this has been confirmed by direct measurements of the ocean's acidity and temperature. One such confirmation comes from the Argo floats (which are nothing but thousands of robotic floats in the oceans that measure temperature and other parameters up to a depth of 6 km). The Argo measurements (which were discussed and critiqued by David Stainforth in his book on climate and climate prediction) confirm the CERES findings: most of the excess energy ends up in the oceans, and the rate of warming of the oceans is accelerating. NASA's ECCO (Estimating the Circulation and Climate of the Ocean) has also confirmed that accelerated ocean warming in the top 200-metre layer is strongly correlated with the fall in the Earth's albedo recorded by CERES. Another metric measured by the Argo floats indirectly confirms CERES' findings: the acidity levels in the ocean have risen as a result of the excess carbon dioxide being taken up by the oceans.
Another factor that may be lowering the Earth's albedo is the reduction in sulphur dioxide from thermal power plants as well as shipping lines because of strict standards. This has led to fewer sulphur aerosols and reduced reflection by the Earth (sulphur aerosols have a shiny surface, which re-emits sunlight back into the atmosphere). In other words, the 'cooling effect' of the sulphur aerosols is now absent, leading to accelerated warming. The fall in sulphur aerosols may also have led to lower cloud formation and, again, reduced reflection of sunlight.
We must, however, guard against this line of reasoning leading to solutions such as solar radiation management, where sulphur aerosols are pumped into the upper atmosphere: this will only shift focus from the main target of reducing greenhouse gas emissions. At the same time, research for its own sake on the link between aerosols, cloud thinning and the albedo can continue.
Published by HT Digital Content Services with permission from Millennium Post.