Life rather than climate influences diversity at scales greater than 40 million years.

The diversity of life on Earth is controlled by hierarchical processes that interact over wide ranges of timescales1. Here, we consider the megaclimate regime2 at scales ≥1 million years (Myr). We focus on determining the domains of 'wandering' stochastic Earth system processes ('Court Jester'3) and stabilizing biotic interactions that induce diversity dependence of fluctuations in macroevolutionary rates ('Red Queen'4). Using state-of-the-art multiscale Haar and cross-Haar fluctuation analyses, we analysed the global genus-level Phanerozoic marine animal Paleobiology Database record of extinction rates (E), origination rates (O) and diversity (D) as well as sea water palaeotemperatures (T). Over the entire observed range from several million years to several hundred million years, we found that the fluctuations of T, E and O showed time-scaling behaviour. The megaclimate was characterized by positive scaling exponents-it is therefore apparently unstable. E and O are also scaling but with negative exponents-stable behaviour that is biotically mediated. For D, there were two regimes with a crossover at critical timescale [Formula: see text] ≈ 40 Myr. For shorter timescales, D exhibited nearly the same positive scaling as the megaclimate palaeotemperatures, whereas for longer timescales it tracks the scaling of macroevolutionary rates. At scales of at least [Formula: see text] there is onset of diversity dependence of E and O, probably enabled by mixing and synchronization (globalization) of the biota by geodispersal ('Geo-Red Queen').

An observation-based scaling model for climate sensitivity estimates and global projections to 2100.

We directly exploit the stochasticity of the internal variability, and the linearity of the forced response to make global temperature projections based on historical data and a Green's function, or Climate Response Function (CRF). To make the problem tractable, we take advantage of the temporal scaling symmetry to define a scaling CRF characterized by the scaling exponent H, which controls the long-range memory of the climate, i.e. how fast the system tends toward a steady-state, and an inner scale τ ≈ 2   years below which the higher-frequency response is smoothed out. An aerosol scaling factor and a non-linear volcanic damping exponent were introduced to account for the large uncertainty in these forcings. We estimate the model and forcing parameters by Bayesian inference which allows us to analytically calculate the transient climate response and the equilibrium climate sensitivity as: 1 . 7 - 0.2 + 0.3   K and 2 . 4 - 0.6 + 1.3   K respectively (likely range). Projections to 2100 according to the RCP 2.6, 4.5 and 8.5 scenarios yield warmings with respect to 1880-1910 of: 1 . 5 - 0.2 + 0.4 K , 2 . 3 - 0.5 + 0.7   K and 4 . 2 - 0.9 + 1.3   K. These projection estimates are lower than the ones based on a Coupled Model Intercomparison Project phase 5 multi-model ensemble; more importantly, their uncertainties are smaller and only depend on historical temperature and forcing series. The key uncertainty is due to aerosol forcings; we find a modern (2005) forcing value of [ - 1.0 , - 0.3 ] Wm - 2 (90 % confidence interval) with median at - 0.7 Wm - 2 . Projecting to 2100, we find that to keep the warming below 1.5 K, future emissions must undergo cuts similar to RCP 2.6 for which the probability to remain under 1.5 K is 48 %. RCP 4.5 and RCP 8.5-like futures overshoot with very high probability.

23/9 dimensional anisotropic scaling of passive admixtures using lidar data of aerosols.

In buoyancy-driven flows, another dimensional quantity appears in addition to the energy flux. Classically, this leads to the prediction that at large scales, isotropic Bolgiano-Obukhov (BO) scaling can dominate isotropic Kolmogorov scaling. We investigate this in the atmosphere by using state-of-the-art high-powered lidar data. We examine simultaneous horizontal and vertical sections of passive scalar surrogates over the ranges 100 m to 120 km and 3 m to 4.5 km , respectively. Overall, this spans the crucial "mesoscale" and involves nearly 1000 times more data than the largest relevant experiments to date. Rather than a transition from one isotropic regime to another, we find that the two regimes always coexist in an anisotropic Corrsin-Obukhov law with the Kolmogorov holding in the horizontal, and the BO holding in the vertical. The stratification is quantified by an elliptical dimension D(el) found to be equal to 2.55+/-0.02 . This anisotropic scaling is very close to that predicted by the 23/9 dimensional unified scaling model of the atmosphere and is consistent with observations of the horizontal wind.