Changes in water vapor and clouds are amplifying global warming

The Guardian reports: A very new paper currently in press shines light on climate feedbacks and the balance of energy flows to and from the Earth. The paper was published by Kevin Trenberth, Yongxin Zhang, John Fasullo, and Shoichi Taguchi. In this study, the authors ask and answer a number of challenging questions. Their findings move us a big step forward in understanding what is happening to the planet now, and how the climate will evolve into the future.

So, what did the scientists do? First, they used measurements at the top of the Earth atmosphere to count the energy coming into the Earth system and the energy leaving the planet. The measurements were made by satellites as part of the Clouds and Earth’s Radiant Energy System project (CERES for short). By subtracting one energy flow from the other, they found what is called the Earth’s energy imbalance. Most studies show that the energy imbalance is in the range of 0.5 to 1 Watt per square meter of surface area, which is causing ongoing global warming.

What the authors then asked is, how does this imbalance change? It turns out, the imbalance changes a lot over time. On a monthly basis the balance might change 1 Watt per square meter of surface area. The changes are caused principally by changes to clouds and water vapor, and other short-term weather patterns. Clouds have the ability to reflect sunlight back to space; however, clouds also have the ability to trap more heat within the Earth’s atmosphere. So, short-term fluctuations in clouds have large impacts on the net rate of heat gain by the Earth. [Continue reading…]

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