Introduction
In the last 100 years (1906-2005) a 0.56 0.92 °C (best estimate: 0.74 °C) Earth's surface’s temperature increase has occured: polar and continental glaciers melting, ocean level increase (1.8 mm/year in the period of 1961 to 2003), frequency and intensity high rate of extreme weather phenomena (hurricanes, floods, drought, etc) are a direct consquence of this occurance.
In agreement with IV Report of IPCC (Intergovernmental Panel on Climate Change) the observed recent global warming is caused, with a probability of around 90%, by anthropic activities which introduce greenhouse gases (mainly CO₂) in the atmosphere due to fossil fuel burning processes. Today the 1997 Kyoto Protocol is the only significant instrument to control CO₂ emissions. It requires the 38 signatory states to reduce their emissions to 5% below 1990 levels during the 2008 2012 commitment period.
Recent studies show that global warming reduction would be very low (3-10% in a century) even if all involved countries fulfilled the Kyoto’s goals. Moreover many nations, including the United States (responsible for 36.1% of the total CO₂ emissions) have refused to ratify the agreement and no precautionary measures have been taken for developing countries (that contribute to half of the world's total greenhouse gas emissions). Thus, the Protocol is clearly not adequate to effectively control global warming.
On the other hand the same greenhouse gas emission control policies adopted by industrialized countries, could have negative consequences in developing countries in terms of growth.
The rapid and continuous increase in concentration of greenhouse gases and the lack of policies and technical instruments to oppose the phenomenon made it necessary to find environmentally friendly, technically simple and cheap solutions to be applied in countries with limited economic resources to control the global average temperature increase.

An effective solution to reduce global warming and compensate the effect produced by the emission of greenhouse gases into the atmosphere could be to artificially modify the Earth's surface reflectance increasing the Solar energy reflected to space and reducing the amount of energy that contributes to the Earth's warming.

Proposed technology
The proposed solution to compensate for the increase in Earth's temperature is the development of surfaces with an higher reflection coefficient than the earth's surface’s one, for the solar spectrum wavelengths (wavelengths range: 0.2 4 ?m) and with an higher emissivity in the infrared zone (wavelengths range:4 25 ?m).
The proposed solution contributes towards the reduction of the absorbed energy thus increasing Earth's surface reflectance and at the same time increasing Earth's emissivity factor in the infrared zone for the global cooling.
Two italian patents have been registered, proposing methodologies, materials and technologies.

The reflecting surfaces can be laid both on land and on sea; both artificial and natural surfaces can be used (roofs of houses, sport facilities and industrial plants, roads, pedestrian areas, city squares, car parking lots, gardens, parks, etc).
Alternatively the growing of trees, shrubs or flowers with appropriate colour characteristics and high average reflection coefficients can be utilized.
Floating or semi-floating islands could be laid on ocean surfaces.
In land applications the reflective surface can be obtained by laying paints, films, plates or any type of coating with a high reflection coefficient and a high infrared emissivity.
The use of titanium dioxide paints and films is particularly interesting for the construction of the reflecting surfaces. This chemical compound has a great sunlight reflection (its high refractive index is second only to diamond) and it’s an excellent catalyst that can degrade through oxidation several volatile organic compounds in polluted air.
Paints made with titanium dioxide pigment could constitute a solution to make surfaces with high reflection coefficients and good cleaning and depolluting properties.
Other cheaper materials, such calcium carbonate powder, grain patterns for flower beds or gardens, lime hydrate, could be used for many applications.?
Vertical or arbitrarily oriented surfaces can give their contribution (lower than horizontal orientated surface).
The effectiveness of laid reflective materials is closely related to latitude and meteorological and morphological characteristics of the installation area and the original value of the reflectance of the spot where these materials are placed.
Effectiveness of reflecting materials is higher if they are used to coat surfaces with a natural high absorptivity (low albedo) due to a major reduction of absorbed solar radiation. Solutions which modify sea surfaces albedo would be particularly effective.

A grid of trusted surfaces (10 m² each), both horizontally and vertically arranged, will guarantee the requested accuracy in the measure of albedo through satellite differential spectrophotometry: their albedo will be precisely measured on ground by integration sphere spectrophotometers. Trusted surfaces can lead to a very accurate technology for the satellite differential spectrophotometry, based both on direct measurement of the reflected radiation and the differences between values of albedo.