Abstract:To date, international efforts to mitigate climate change have focussed on reducing emissions of greenhouse gases in the energy, transportation and agriculture sectors, and on sequestering atmospheric carbon dioxide in forests. Here, the potential to complement these efforts by actions to enhance the reflectance of solar insolation by the human settlement and grassland components of the Earth's terrestrial surface is explored. Preliminary estimates derived using a static two dimensional radiative transfer model indicate that such efforts could amplify the overall planetary albedo enough to offset the current global annual average level of radiative forcing caused by anthropogenic greenhouse gases by as much as 30% or 0.76 Wm -2 .Terrestrial albedo amplification may thus extend, by about 25 years, the time available to advance the development and use of low-emission energy conversion technologies which ultimately remain essential to mitigate long-term climate change. While a scoping analysis indicates the technical feasibility of sufficiently enhancing human settlement and grassland albedos to levels needed to achieve reductions in radiative forcing projected here, additional study is required on two fronts. Firstly, the modelled radiative forcing reductions are static estimates. As they would generate climate feedbacks, more detailed dynamic climate modelling would be needed to confirm the stationary value of the radiative forcing reduction that would result from land surface albedo amplification. Secondly, land surface albedo amplification schemes may have important economic and environmental impacts. Accurate ex ante impact assessments would be required to validate global implementation of related measures as a viable mitigation strategy.

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Intensities (I) and rotational temperatures (T) of the OH(8, 3) and (6, 2) bands were derived from spectrophotometric observations of airglow emissions, over Longyearbyen in Spitsbergen, made in December 1984. The high latitude of the Spitsbergen Observatory (78°15′N) permitted 24‐hour coverage of the wintertime polar airglow. These measurements yielded the following results: (1) T derived from P1 rotational lines of OH depend on the choice of A values (T (Honl‐London, A) > T (Mies, A) > T (Espy, A)); (2) P =,213= 2072 K 207 implying a 3‐ to 5‐K/km temperature gradient in the atmosphere around 85 km height; (3) Ī(8, 3) = 314 ± 30 R and Ī (6, 2) = 1025 ± 110 R; the corresponding OH(υ′) columnar abundances are (5.5 ± 0.6) × 108 cm−2 and (8.0 ± 0.8) × 108 cm−2 for υ′ = 8 and υ′ = 6 vibrational levels. These results are compared with the predictions of a one‐dimensional oxygen‐hydrogen model which shows that (1) the reaction rate of OH H + O 2 may be much higher than the laboratory‐measured k6 value for OH(υ′ = 0); (2) the higher k6 value accounts for the separation of OH layers for different υ′ levels observed in various rocket measurements of OH*(υ′) profiles and implies a positive temperature gradient in the atmosphere around 85 km; (3) Llewellyn et al.’s (1978) rate for quenching of OH* by M(N2 and O2) is required in the model to match the calculated column abundance of OH* in υ′ = 8 to the value derived from the observed intensities of the airglow OH(8, 3) band; and (4) a perhydroxyl source must be invoked for the model to yield a column abundance of OH* in υ′ = 6 consistent with the intensity of the airglow OH(6, 2) band observed in Spitsbergen.

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As countries transition to a green economy, they will need to identify profitable entry points in which they can favorably compete with other nations in emerging green markets. Identifying and building supply capacity for commercially viable, competitive green product exports can be seen as a fundamental part of supporting green growth and sustainable development. Building on the product space model initially advanced by Hidalgo and Hausmann in 2009, this article proposes a green product space methodology to map the export strengths of countries for a specified set of green products. The methodology does so by identifying green products for which a country is likely to be competitive in the world market based on export performance of related products. Results for Brazil are presented to illustrate the green product space methodology followed by a discussion of its limitations and potential contribution to industrial policy formulation to support emerging green sectors.

Temporal variations in the absolute intensity (I) and the rotational temperature (T) of the polar winter airglow OH(8, 3) bands were observed over Longyearbyen, Spitsbergen (78.2°N), in December 1984. The high latitude of the observatory places it in a continuous polar night around the winter solstice period, thereby permitting 24‐hour optical measurements. Spectral analyses of the I and T time series reveal a dominant semidiurnal component and a wave with a period of 3.7 hours. Other waves with shorter periods may be present for part of the total observing period, but the signal‐to‐noise ratios of their amplitudes averaged over a 24‐hour interval are too low to permit definitive identification. The ratio η of the correlated Fourier components of (I − Ī)/Ī to that of (an overbar signifies time average) has amplitude 3.2 ± 0.9 and 4.3 ± 1.3 for the 12‐ and 3.7‐hour waves, respectively, while the phase ϕ of η for these periods is 6° ± 16° and −12° ± 12°. The value of η for the 3.7‐hour wave can be compared with the theoretical prediction of η for gravity wave modulation of the OH emission. For an emission height of 87 km and an atomic oxygen scale height ℋ(O) of −2 km, theory gives |η| = 4.2 and ϕ = 0° for the 3.7‐hour wave, in good agreement with the observation. The theoretical interpretation of η at the 12‐hour period is complicated by the likelihood that the observed semidiurnal oscillation is not a simple tide. For tidal modulation of the OH nightglow, theory gives |η| between 2.6 and 0.9 and ϕ between 0° and 10° for high‐order semidiurnal modes and for the same values of emission height and ℋ(O) as above.

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