Cloud cooling effects of afforestation and reforestation at midlatitudes.

Because of the large carbon sequestration potential, reforestation and afforestation (R&A) are among the most prominent natural climate solutions. However, while their effectiveness is well established for wet tropics, it is often argued that R&A are less advantageous or even detrimental at higher latitudes, where the reduction of forest albedo (the amount of reflected solar radiation by a surface) tends to nullify or even overcome the carbon benefits. Here, we carefully analyze the situation for R&A at midlatitudes, where the warming effects due to vegetation albedo are regarded to be almost balanced by the cooling effects from an increased carbon storage. Using both satellite data and atmospheric boundary-layer models, we show that by including cloud-albedo effects due to land-atmosphere interactions, the R&A cooling at midlatitudes becomes prevalent. This points to a much greater potential of R&A for wet temperate regions than previously considered.

Spectral fingerprints of nonequilibrium dynamics: The case of a Brownian gyrator.

The same system can exhibit a completely different dynamical behavior when it evolves in equilibrium conditions or when it is driven out-of-equilibrium by, e.g., connecting some of its components to heat baths kept at different temperatures. Here we concentrate on an analytically solvable and experimentally relevant model of such a system-the so-called Brownian gyrator-a two-dimensional nanomachine that performs a systematic, on average, rotation around the origin under nonequilibrium conditions, while no net rotation takes place under equilibrium ones. On this example, we discuss a question whether it is possible to distinguish between two types of a behavior judging not upon the statistical properties of the trajectories of components but rather upon their respective spectral densities. The latter are widely used to characterize diverse dynamical systems and are routinely calculated from the data using standard built-in packages. From such a perspective, we inquire whether the power spectral densities possess some "fingerprint" properties specific to the behavior in nonequilibrium. We show that indeed one can conclusively distinguish between equilibrium and nonequilibrium dynamics by analyzing the cross-correlations between the spectral densities of both components in the short frequency limit, or from the spectral densities of both components evaluated at zero frequency. Our analytical predictions, corroborated by experimental and numerical results, open a new direction for the analysis of a nonequilibrium dynamics.