Climate change and variability

Climate variations within a defined period (for example, 30 years) are not climate change but belong to the climate value, expressed as the periodic mean and its variance including statistics of extreme values. Human societies are highly adapted to the ordinary annual rhythms of climate, which we call the seasons. Moreover, almost all climates display interannual differences, which have hitherto appeared to be unpredictable (Hare 1985). Climate change is said to occur when the differences between successive averaging periods exceed what variance can account for, i.e.. 

This includes also catastrophic events such as volcanic eruptions and the impaet of celestial bodies. It is beyond the focus of this book to describe the physics of sueh alterations. However, with an understanding of the chemical evolution of the eli-mate system (Chapter 2), it is evident that different chronological processes are superposed and that the different causes are interlinked in the sense of climatic feedbacks which make it very difficult to quantify climate changes and variations. Temperature and precipitation, as the most important climatic factors, are interrelated, but they are also interrelated with atmospheric composition and surface characteristics which again are interrelated. 

Volcanism has long been implicated as a possible cause of weather and elimate variations Benjamin Franklin and William Jackson Humphrey were pioneers in their association of volcanic eruptions with climate change. Franklin (1784) put forward a theory linking volcanic dust to climatic change  

During several of the summer months of the year 1783, when the effect of the sun s rays to heat the earth in these northern regions should have been greater, there existed a constant fog over all Europe, and great part of North America. This fog was of a permanent nature it was dry, and the rays of the sun seemed 

Hann (1897) first addresses climate changes with a separate section in his handbook in the sense of periodic variations ( the distribution of climatic elements is not [an] absolute constant ) but also in the sense of continuous changes over the earth s evolution. A first systematic description of climate changes is found in Hann (1908). Bruckner (1890) first identified climatic cycles by analyzing meteorological records (the so-called Bruckner cycle of 35 years). 

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Other challenges facing water quality in Kenya include climate change and variability, industrial and municipal wastes, agricultural practices and deforestation. These have been highlighted to give the magnitude of the problem. 

Smit, B. et al., 2000 An Anatomy of Adaptation to Climate Change and Variability, Climatic Change 45, p 223-251. 

Climate Variability, Climate Change, and Climate Adaptation. 67... 

The area of California influenced by a Mediterranean climate is home to over 30 million people. Climate variability and human water demand make freshwater a very precious resource. Allocations of water to cities, agriculture, and the environment create continual tension as demands for this vital and over-allocated resource grow. This paper presents a brief overview of water resource science and policy in a Mediterranean climate with substantial challenges from climate variability, climate change, and increasing human need. 

Hulme M. Barrow E.M. Arnell N.W. Harrison P.A. Johns T.C. and Downing T.E. (1999). Relative impacts of human-induced climate change and climate variability. Nature, 397, 689-691. 

Because of the concern about climate change and global warming, it is important to have reliable data on the trends in various areas of the planet. Weather stations monitor the following variables over the noted typical ranges (for the errors in these measurements, refer to Table 3.179) ... 

Over the past few decades the Black Sea has been seriously perturbed by climatic change and intensive anthropogenic contamination. Some nutrients have increased (e.g., NO3 due to eutrophication) while others have decreased (e.g., Si due to Danube river dams construction) [22]. Organisms imported as part of international shipping (e.g., Mnemiopsis and Beroe) have contributed to modification of the natural ecosystem. Understanding the natural temporal variability of the hydrochemistry of the Black Sea is important when trying to determine the effects of these anthropogenic perturbations. 

Broecker W. S. (1981) Glacial to interglacial changes in ocean and atmospheric chemistry. In Climatic Variations and Variability Facts and Theory (ed. A. Berger). Kluwer, Boston, pp. 111-121. 

Reality lies somewhere between these extremes. Some paleoclimatic proxies are so clearly and directly related to paleoclimatic conditions that quantitative estimates of past climate changes and their uncertainties can be made with considerable although not total confidence. In other cases, the tie between proxy and climate is sufficiently complex that direct quantitative interpretation is risky. Such proxies can nonetheless be appropriate for generating hypotheses, for allowing quantitative estimates if used in multi-parameter reconstructions with independent assumptions, and for allowing quantitative hypothesistesting of models that directly compute proxy characteristics rather than the climate variables related to the proxies. The value of research on paleoclimate proxies thus extends well beyond possible direct quantitative reconstructions. 

High variability within glacial periods, associated with the recorded rapid climate changes and also showing considerable amplitude on interannual time scales. 

This high variability of earth s climate is the back-gronnd against which the discussions in the public and in expert groups on the current climate change (and the anthropogenic contribution) should be viewed. 

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