When you look at the big picture the weather and climate of the Earth is quite simple. Energy in the form of light comes from the Sun. When it arrives at the Earth sunlight is either reflected back to space or or absorbed by the oceans, land, and plants. All that absorbed energy eventually makes its way back to space. Because the absorbed and emitted energy varies over the surface of the earth there a places with an excess of energy and places with a deficit energy. Mother Nature doesn't like energy excesses or deficits and tries to balance out those differences by putting the atmosphere and ocean into motion. That is, we get weather and climate.
Over time the amount of energy the Earth receives should exactly balance the amount of energy the earth radiates. Researchers mostly at NASA's Goddard Institute for Space Studies (GISS), which is located above Tom's Restaurant, and Columbia University have recently calculated that the Earth is now absorbing 0.85 Watts per square meter more energy from the Sun than it is emitting to space. 0.85 Watts of energy is about what a small Christmas tree light gives off. That doesn't sound like much but there are lots of square meters to the Earth's surface and those lights are on 24/7/365 year after year.
Where is the excess of energy and what does it mean for us? Those answers, and the weekend forecast, after the jump
The amount of excess energy is huge by historical standards . For a comparison, the scientists mention that an imbalance of 1 Watt per sq. meter sustained for 10,000 years, which is the length of time since the last Ice Age, would raise upper-level ocean temperatures by more than 100 C. In other words, if the same heat imbalance that we have now had existed since the last Ice Age much of the ocean would have boiled away.
By looking at vertical ocean temperature profiles the researchers determined that much of the excess energy is caught up in the oceans which, unlike the land, warms up slowly. This energy is "in the pipeline", and will eventually warm the Earth by about 0.6 C (or 1.1 F) over the next century even if there is no further increase in the human-induced greenhouse gases that are the cause of the energy imbalance.
The "thermal inertia" of the oceans presents a gnarly problem. The delay gives us a chance to reduce the magnitude of human-induced climate change before that change fully takes place. On the other hand, if we decide to wait for even more evidence that the climate is warming before acting, the energy excess will continue to build-up and the climate change that will result will be that much greater and much more difficult to avoid. For more information you can find the complete paper here.
As we move into the late afternoon and the clouds thicken our excess of energy is played out today. There's a slight chance of rain later but don't sweat it. A cold front is passing through tomorrow. At this time of year a cold front means thunderstorms. The t-storms are most likely tomorrow afternoon. Whatever rain we do get should be out of here by midnight Saturday, setting the stage for a breezy, sunny Sunday.
