Guest essay by Dr. Tim Ball
Lack of temperature data is a problem, but measures of water and precipitation are much worse. Temperature changes, especially cooling, are important to a degree over the long term. Precipitation changes are much more important for short, medium and long periods. Droughts are much more devastating to flora, fauna and the human condition. Irrigation was one of the earliest technologies developed 9000 years ago to offset droughts in the Fertile Crescent, triggered by onset of Holocene warming.
McKitrick et al. and others identified the problems of determining global temperature. Instruments changed over time, but continuous records are limited to the accuracy of early measures ±0.5°C. There are the problems of the recording sites as Anthony Watt’s identified. Only 7.8 percent of the US record is accurate to less than 1°C. What does that say about the rest of the world?
Measuring precipitation accurately is the most challenging of all weather elements. It’s easy if precipitation falls straight down and is only liquid, but it doesn’t and isn’t. Measuring variable snowfall and water content is even more difficult. All precipitation amounts are much more variable than temperature. Some are not considered precipitation. Condensation is overlooked and unmeasured, yet very important.
One year in the late 1980s in Western Canada crop experts predicted a below average harvest because of low precipitation. Actual yield was average or higher in most regions. A combination of high daytime temperatures, close to 30°C, and low nighttime temperatures, close to 0°C, which was well below the Dew Point temperature, produced considerable condensation. Over a couple of weeks this provided sufficient moisture to “fill out” the crop. The moisture was more widespread and evenly spread than rainfall. Deposited at the surface at night meant reduced evaporative loss. More was available to replenish soil moisture in the root zone. All this occurs below the Stevenson screen where conditions are markedly different than at the surface. Read Geiger’s brilliant 1965 Climate Near the Ground to learn the difference.
For most areas the number of precipitation measuring stations is a fraction of the WMO recommended density. For example, two computer model predictions of monsoon rains for Africa showed completely opposite results. In Waiting for the Monsoon, (4 August 2006 VOL 313 Science) Columbia University climate scientist Alessandra Giannini says “The issue of where Sahel climate is going is contentious,” “Some models predict a wetter future; others, a drier one. “They cannot all be right.” They concluded,
“One obvious problem is a lack of data. Africa’s network of 1152 weather watch stations, which provide real-time data and supply international climate archives, is just one-eighth the minimum density recommended by the World Meteorological Organization (WMO). Furthermore, the stations that do exist often fail to report.”
It’s not surprising because the IPCC note in Chapter 8 of the 2007 Report,
In short, most AOGCMs do not simulate the spatial or intra-seasonal variation of monsoon precipitation accurately.
Precipitation events are extremely variable spatially. Most rainfall comes as showers of varying intensity so amount differ within short distances. The models gloss over limited temperature data with parameterization, but they can’t do that with precipitation. The grid is too coarse for even the massive systems of thunderstorms and midsize cyclones.
The Water Cycle is a more critical mechanism than the Carbon Cycle and knowledge of its mechanisms challenged meteorology and climatology even before the IPCC bias. For example, there are four different measures of water content of air.
Absolute Humidity: Ratio of mass or weight of water vapor per unit volume of air – grams per cubic meter.
Specific Humidity: Ratio of the mass or weight of water vapor in the air to a unit of air including the water vapor – grams of water vapor per kilogram of wet air.
Mixing Ratio: Ratio of the mass of water vapor to the mass of dry air -grams per gram or grams per kilogram.
Relative Humidity: Ratio of amount of water vapor in the air as a percentage of what it could hold.
The last is best known, most used, but most useless. It’s a function of temperature, so, for example, the same 70 percent relative humidity results from different amounts of water in the air.
Water movement is one part of the Cycle, but transport of latent heat energy is another major function. A very large part of the evaporation, transport and release of water and energy from the surplus region to the deficit region (Figure) is through the Hadley Cell and tropical cyclones.
The IPCC say,
The spatial resolution of the coupled ocean-atmosphere models used in the IPCC assessment is generally not high enough to resolve tropical cyclones, and especially to simulate their intensity.
The IPCC underplay the role of CO2 in plant growth, but there’s less focus on water because it requires discussion of natural cycles and patterns. In addition, their definition limits them to human causes of climate change. As a result there is limited funding or support for such research. Fortunately, there is a commercial and humane demand. Irrigation is the single largest use of fresh water by humans, especially in the developing world: India has more land under irrigation than any other country.
Vladimir Koppen did early work on water balance. His “B” climate group identified arid climates and recognized the “effectiveness” of precipitation on plant types and growth. More recently Charles Thornthwaite who also produced a classification system pioneered water balance. W.C. Palmer produced a drought severity index in 1965, but it only relates to meteorological droughts. The fact there are three types, meteorological, hydrological and agricultural, underscores the importance of water balance on climate and life.
All this addresses water and limitations on data and understanding of mechanism at the surface. It is even worse in the atmosphere. We know from the IPCC inability to deal with clouds of the challenge. Water exists as a gas, liquid and solid at the same temperature and can exist in a single cloud at different levels. Here are comments about measuring just water vapor.
It is very hard to quantify water vapor in the atmosphere. Its concentration changes continually with time, location and altitude. To measure it at the same location every day, you would need a hygrometer, which in earlier days made use of the moisture-sensitivity of a hair, and by now of for instance condensators. A vertical profile is obtained with a weather balloon. To get a global overview, only satellite measurements are suitable. From a satellite, the absorption of the reflecting sunlight due to water vapor molecules is measured. The results are pictures of global water vapor distributions and their changes. The measurement error, however, is still about 30 to 40%.
This was in 1996, but it was no better in 2002 as NASA noted,
Finally, water vapor plays a key role in the Earth’s hydrologic cycle. Therefore, a better understanding of its role will require long-term observations of both small and large scale water vapor features, a major goal of the National Aeronautics and Space and Administration’s (NASA’s) Mission to Planet Earth (MTPE) program.
The bottom line is we don’t know how much water vapour is in the troposphere and stratosphere. It is ignored in most assessments of atmospheric gases; they record only dry air at sea level. Why? It is the only gas with a wide variability from almost zero to 4 percent. It is by far the most important greenhouse gas, but that is something else the IPCC doesn’t want the public to know.
Here is what the IPCC say about water related issues in the computer models in Chapter 8 of the 2007 Physical Science Basis Report.
Unfortunately, the total surface heat and water fluxes are not well observed.
The evaluation of the hydrological component of climate models has mainly been conducted uncoupled from AOGCMs (Bowling et al., 2003; Nijssen et al., 2003; Boone et al., 2004). This is due in part to the difficulties of evaluating runoff simulations across a range of climate models due to variations in rainfall, snowmelt and net radiation.
For models to simulate accurately the seasonally varying pattern of precipitation, they must correctly simulate a number of processes (e.g., evapotranspiration, condensation, transport) that are difficult to evaluate at a global scale.
Since the TAR, there have been few assessments of the capacity of climate models to simulate observed soil moisture. Despite the tremendous effort to collect and homogenize soil moisture measurements at global scales (Robock et al., 2000), discrepancies between large-scale estimates of observed soil moisture remain.
Glaciers and ice caps, due to their relatively small scales and low likelihood of significant climate feedback at large scales, are not currently included interactively in any AOGCMs.
The MOC (meridional overturning circulation) is an important component of present-day climate and many models indicate that it will change in the future (Chapter 10). Unfortunately, many aspects of this circulation are not well observed.
Sun et al. (2006) investigated the intensity of daily precipitation simulated by 18 AOGCMs, including several used in this report. They found that most of the models produce light precipitation (<10 mm day–1) more often than observed, too few heavy precipitation events and too little precipitation in heavy events (>10 mm day–1). The errors tend to cancel, so that the seasonal mean precipitation is fairly realistic.
The last comment is remarkable and laughable if it was not so pathetic. They are saying the extremes are wrong, but because the average of them is close to the average it makes it correct. Beyond illogical, it assumes the average is correct, which is not possible because of totally inadequate data.
There is no justification for the IPCC claim of 95-percept certainty that human CO2 is the cause of warming and latterly climate change.