UN forecasts are based entirely on climate models. These are systems of differential equations based on well-documented physical processes to simulate the transfer of energy through fluid motion and chemistry. The Earth is divided into a grid wherein the equations are solved for each segment of the planet taking into account variations in the Earth’s surface as to land, sea and elevation. Essentially, climate models are an extension of weather forecasting but, whereas weather models make predictions over specific areas and short timespans, climate models cover large areas and long timespans. They attempt to predict how average conditions will change in a region over decades.
Based on studies of past climates in the geologic record, efforts are made to determine which variables are most important. The most important aspects of mathematical models have always been and will always be testing the sensitivity of outcomes to different variable inputs. Therefore, the models are always instructional, helping us learn more and more about physical systems.
Unfortunately, we have no seriously accurate understanding of all the variables that impact Earth’s climate. So, we use only the few variables we are confident of. As surprising as it may seem, we have little understanding of the role of clouds, ocean currents, the reflectivity of ice or evaporation from the oceans. Clearly, the Earth’s changing orbit around the Sun, the variable tilt of Earth’s axis of rotation and even the wobble of its axis must play important roles. But we can’t confidently calculate those yet.
And we have yet to mention that our continents drift and the molten center of the Earth rotates differently than does its crust. This is not to say that we should not try to understand how these factors relate to one another and the long-term climate. However, the United Nations should not be dictating policies for the benefit or detriment of humanity based on almost unfathomable puzzles.
Evidence to support this perspective is the graph below compiled by University of Alabama at Huntsville climatologist Dr. John Christy of 102 climate models supported by the UN.
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During 40 years of known weather and climate, the average of these various mathematical models diverges greatly from the known measurement of Earth's temperature as derived from instrumentation in satellites and weather balloons. Existing data allows us to ‘hindcast’ temperature predictions. When projections are not accurate, looking backward when the facts are available, how can we seriously set economic policies based on future predictions using the same flawed models?
When one designs a structure or an aircraft, a model can be tested at miniature levels or with test pilots. No such opportunity exists with climate forecasting. It would seem wiser then to spend the vast sums of money currently focused on climate models on projects to adapt to whatever nature might send our way next.