Whenever I read the latest scientific research on climate, I marvel at how much we don’t know. Meteorology is kind of a Johnny-come-lately sort of science. Sure there are big wheels of climate science like Gilbert Walker who in the 1920’s came up with what is now called the Walker Oscillation. I suspect most people have never heard of the Walker Oscillation, but meteorologists blame El Nino on the reversal of the Walker Oscillation and I’m pretty sure everyone is familiar with El Nino. (Here’s a great link to a blogger at the National Oceanic and Atmospheric Administration who explains the connection between the Walker Oscillation and El Nino: http://www.climate.gov/news-features/blogs/enso/walker-circulation-ensos-atmospheric-buddy). If you look at other sciences, their foundations are based on centuries of work. Everybody knows of Galileo and Isaac Newton. Chemistry has its Antoine Lavoisier and geology has its Charles Lyell. I suppose you could name a few founding meteorologist from the 19th century, like Luke Howard. Luke who? Well he gave the names to the cloud formations which we still use today. Remember cumulus, stratus, and cirrus? I’m sure you memorized those names in school at some point. But really the greats of meteorology are probably alive today. The people cited by textbooks in a hundred years as the scientific founders and inventors of modern meteorology are writing papers and publishing now.
Peer review journals are often good at winnowing out papers of questionable scientific merit, but it is even better when you have a board of scientists who are engaged in examining all of the scientific literature on a subject in order to determine its significance; especially when dealing with a global issue like climate change. Or you will end up with a lot of debatable science, like the “hollow earth” theory of the 19th century touted by such luminaries as John Leslie, who by the way did some of the early work (strangely enough) on heat transfer. Yes there was quite a debate in the early 19th century on the “hollow earth” theory and it captured the imagination of writers like Jules Verne who in his famous 1864 novel “Journey to the Center of the Earth” sent a German team of explorers down through a volcanic crater into a supposed vast subterranean interior. So a panel of super cautious scientists is what I like to depend on in looking at climate change data. The Intergovernmental Panel on Climate Change (IPCC) sponsored by the United Nations is just such a group. I took the time to read the IPCC report on Climate Change: The Physical Science Basis, which was published by the Cambridge University Press in 2013.
I hope it doesn’t come as a surprise to anyone that heat transfers from the atmosphere to the ocean and vice versa. So as the atmosphere has warmed, so have the oceans. Not by much, you don’t have to worry about burning your toes when walking in the surf. The IPCC estimates there has been about a 0.2 degree Fahrenheit increase per decade in the upper 250 feet of the ocean since 1971. That’s kind of a global average. Temperature increases are variable depending at what latitude and in which ocean you are. And just as heat is transferred from the atmosphere to the ocean, the warmer surface ocean transfers heat to the colder deeper ocean. The IPCC estimates during the same time period, the global average increase in temperature down to 2300 feet has been about 0.03 degrees Fahrenheit per decade.
The IPCC was not confident in using temperature data collected prior to 1971 to make any sort of interpretation of long term ocean temperature changes, because the mix of instruments and the sparcity and variability of sampling didn’t provide consistent enough data to sort out long term temperature changes from the regular variable temperature changes found over seasons, years, decades and centuries. As interest in climate change has increased, so has the extent and quality of temperature measurements in the ocean. The IPCC also reported on the variability in warming among the oceans. Data shows a greater warming in the Northern Hemisphere than elsewhere on the globe.
Climate scientists like to talk about energy inventories, energy storage and energy transfer. Where is all that energy trapped by the greenhouse gases in the atmosphere going? After all, it normally would be reflected back out into space. Now all this heat and energy is trapped in the earth’s atmosphere. These days, there are actually reported inventories of greenhouse gas emissions. So scientists can calculate the total amount of various greenhouse gases, produced in power plants and by other human activities, in the atmosphere on an annual basis.
Climate scientists also can calculate how much energy would be needed to raise the upper ocean temperatures by the 0.14 degrees Fahrenheit the IPCC estimates has occurred over the 40 year period between 1971 and 2010. However methodologies are variable and therefore estimates are variable. I would say, it is a lot of additional energy that must have been transferred to the oceans to raise the temperature in the upper ocean by that much. The IPCC report cites numerous calculations found in the scientific literature. These calculations show an increased heating rate, somewhere between 74 and 137 Terawatts, would have been needed to raise the temperature of the oceans by the amount observed between 1971 and 2010. Most people are familiar with watts. You know if you have a 40 watt or a 60 watt light bulb. The watt is a measurement of energy transfer. A terawatt is one trillion watts. If you turn on your 40 watt bulb in your lamp it is using 40 watts per hour. If you use a 60 watt bulb it is using 60 watts per hour. If you turn on your 137 Terawatt bulb, it is using 137 trillion watts per hour. (Yes I’m just kidding, there are no terawatt bulbs.) But remember this is over 40 years, so the amount of energy transferred to increase the oceans’ temperature to the amount observed would be 137 Terawatts per 40 years.
The IPCC also goes on to calculate the amount of increased energy storage on the Earth between 1971 and 2010 based on annual inventories of greenhouse gas emissions. From the energy storage, they further calculate the resulting increased heating rate for the earth’s total surface and then just for the oceans. Now as far as I’m concerned we’re getting into the realm of science factoid versus science fact with these kinds of calculations. So I’m going to paraphrase what the IPCC states: based on increased energy storage due to greenhouse gas emission, 0.55 watts per square meter of additional heat were applied continuously (24 hours a day, 7 days a week, 365 days a year) over the entire ocean surface between 1971 and 2010.That’s a lot of extra energy going into the oceans of the world.
The ocean is a warmer place. Warmer water has a lot of consequences: changes in ocean chemistry, including oxygen content; impacts on the creatures that live in the oceans; and potential changes in ocean circulation, wind and weather.