One of the best parts of my position is that it is my job to go to interesting meetings and meet bright people. On June 13th I went to a joint briefing by the UK Space Agency and the European Space Agency about what their satellite images show about climate change. It turns out that the European Centre for Space Applications and Telecommunications (ECSAT) is located right in the UK, in Harwell. They are using various satellites (including images from NASA) in time series going back years to make some remarkable observations. Their data will be used in a status report for the UNFCCC Conference of Parties in Paris in 2015.
They look at many issues on land, in the ocean and up in the atmosphere. Today’s meeting looked at sea ice and glaciers, including how ice melting can raise sea levels. Since Greenland’s ice sits on land, it is most impacted by atmospheric temperatures, and it melting faster than the Antarctica ice sheets, which are more impacted by ocean temperatures. Indeed, Greenland’s ice melt apparently contributes roughly twice as much to the sea level rise from ice melt than Antarctica. Sea levels are indeed rising, not just from ice melt, but also warmer water takes up more volume. This warm water expansion appears to contribute much more to sea rise than ice melt. By the way, the satellites are following over 170,000 glaciers world-wide, so we are learning more about this all the time, which would be impossible without the supercomputers that we have today.
Finally, we talked about an interesting issue, the so-called pause in the rise of surface ocean temperatures, which skeptics say refutes theories of global warming. The ECSAT scientists are using their satellite data, and like all science, this could lead to refining of the climate models, although the primary conclusions remain the same. The satellites measure ocean surface temperature, and they have found that the Atlantic Ocean temperature is rising, and water in the Western Pacific is warming too, but water in the Eastern pacific (close to the US) is cooling. One theory is that the surface warm water is being buried in the ocean. In this case, warm water is pushed away from the equatorial waters, so colder water from the deep rises up so that surface water is cooler, but the overall ocean surface temperature appears constant. There is some evidence supporting this idea, but nothing is confirmed yet.
However, several scientists said that a better measure of the impact of global warming would be the overall temperature of the ocean water, which has been rising significantly. Moreover, the best measure of global warming might be the total amount of heat in the energy system. This graph is taken from the 2013 IPCC report, Working Group 1. It shows that the heat trapped in the atmosphere and land is relatively trivial, while the amount of heat stored in the ocean is enormous and rising.