How Clouds Affect Climate Change

By David L. Brown

A story from BBC News reports the launching of two new satellites by NASA to study the Earth’s atmosphere. Here’s an excerpt.

Some of the gaping holes that exist in our understanding of the Earth’s atmosphere will be answered by two new satellites launched on Friday.

The Cloudsat and Calipso missions will study how clouds and aerosols (fine particles) form, evolve and affect our climate, the weather and air quality.

Scientists say knowledge gaps in such areas severely hamper their ability to forecast future climate change.

Different types of cloud, for example, can help cool or warm the planet.

“We will be making the key observations that address this problem,” said Dr Graeme Stephens, the Cloudsat principal investigator from Colorado State University, US.

The US space agency (Nasa) satellites were launched from the Vandenberg Air Force Base in California at 1002 GMT, after a week of delays due to technical problems and unfavourable wind conditions.

They have been put in a 705km (438 miles) circular, sun-synchronous polar orbit, where they will fly in formation just 15 seconds apart. The spacecraft are part of an Earth-observation constellation Nasa calls the “A-Train”. Read the whole story.

The satellites, called Calypso and CloudSat, travel together in polar orbits oriented to the Sun, just 15 seconds apart.

As the article says, the amount of cloud cover (or particulate matter) in the atmosphere has a significant effect on global temperatures. This was demonstrated in the days after 9/11/01 when all non-military jet flights over the U.S. were banned. Those days recorded higher-than-normal temperatures. On the other hand, after the eruption of the Phillipine volcano Mount Pinatubo, which ejected many square kilometers of ash into the upper atmosphere, the Earth grew cooler for several years.

It is apparent that we need to learn more about the effect of cloud cover or particles in our atmosphere. The continued burning of fossil fuels puts more than just CO2 into the air, and it may be that a balance has been created between the greenhouse gases with their warming effects and human- or nature-induced cloud cover and particulate matter that may offset the warming. This raises an interesting question: Should humankind succeed in replacing fossil fuels with “clean” energy, would that create a new spike in global temperatures? That is a question that these new satellites may help to answer.

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