Bending the curve of terrestrial biodiversity needs an integrated strategy Summary paragraph Increased efforts are required to prevent further losses of terrestrial biodiversity and the ecosystem services it provides 1,2. Ambitious targets have been proposed, such as reversing the declining trends in biodiversity 3-yet, just feeding the growing human population will make this a challenge 4. We use an ensemble of land-use and biodiversity models to assess whether (and if so, how) humanity can reverse terrestrial biodiversity declines due to habitat conversion, a major threat to biodiversity 5. We show that immediate efforts, consistent with the broader sustainability agenda but of unprecedented ambition and coordination, may allow to feed the growing human population while reversing global terrestrial biodiversity trends from habitat conversion. If we decide to increase the extent of land under conservation management, restore degraded land, and generalize landscapelevel conservation planning, biodiversity trends from habitat conversion could become positive by mid-century on average across models (confidence interval: 2042-2061), but not for all models. Food prices could increase and, on average across models, almost half (confidence interval: 34-50%) of future biodiversity losses could not be avoided. However, additionally tackling the drivers of landuse change may avoid conflict with affordable food provision and reduces the food system's environmental impacts. Through further sustainable intensification and trade, reduced food waste, and healthier human diets, more than two thirds of future biodiversity losses are avoided and the biodiversity trends from habitat conversion are reversed by 2050 for almost all models. Although limiting further loss will remain challenging in several biodiversity-rich regions, and other threats, such as climate change, must be addressed to truly reverse biodiversity declines, our results show that bold conservation efforts and food system transformation are central to an effective post-2020 biodiversity strategy. Reversing biodiversity trends by 2050 Without further efforts to counteract habitat loss and degradation, we projected that global biodiversity will continue to decline (BASE scenario; Fig. 1). Rates of loss over time for all nine BDIs in 2010-2050 were close to or greater than those estimated for 1970-2010 (Extended data Extended Data Table 1). For various biodiversity aspects, on average across IAM and BDI combinations, peak losses over the 2010-2100 period were: 13% (range: 1-26%) for the extent of suitable habitat, 54% (range: 45-63%) for wildlife population density, 5% (range: 2-9%) for local compositional intactness , 4% (range: 1-12%) for global extinctions, and 4% (range: 2-8%) for regional extinctions (Extended Data Table 1). Percentage losses were greatest in biodiversity-rich regions (Sub-Saharan Africa, South Asia, South East Asia, the Caribbean and Latin America; Extended Data Fig. 2). The projected future trends for habitat loss and degradation and its driv...

Herein, we provide an account of the activation strain model of chemical reactivity and its recent applications. In this model, the potential energy surface DeltaE(zeta) along the reaction coordinate zeta is decomposed into the strain DeltaE(strain)(zeta) of the increasingly deformed reactants plus the interaction DeltaE(int)(zeta) between these deformed reactants, i.e., DeltaE(zeta) = DeltaE(strain)(zeta) + DeltaE(int)(zeta). The purpose of this fragment-based approach is to arrive at a qualitative understanding, based on accurate calculations, of the trends in activation barriers and transition-state geometries (e.g., early or late along the reaction coordinate) in terms of the reactants' properties. The usage of the activation strain model is illustrated by a number of concrete applications, by us and others, in the fields of catalysis and organic chemistry.

Land use is at the core of various sustainable development goals. Long-term climate foresight studies have structured their recent analyses around five socio-economic pathways (SSPs), with consistent storylines of future macroeconomic and societal developments; however, model quantification of these scenarios shows substantial heterogeneity in land-use projections. Here we build on a recently developed sensitivity approach to identify how future land use depends on six distinct socio-economic drivers (population, wealth, consumption preferences, agricultural productivity, land-use regulation, and trade) and their interactions. Spread across models arises mostly from diverging sensitivities to long-term drivers and from various representations of land-use regulation and trade, calling for reconciliation efforts and more empirical research. Most influential determinants for future cropland and pasture extent are population and agricultural efficiency. Furthermore, land-use regulation and consumption changes can play a key role in reducing both land use and food-security risks, and need to be central elements in sustainable development strategies.

Systematic model inter-comparison helps to narrow discrepancies in the analysis of the future impact of climate change on agricultural production. This paper presents a set of alternative scenarios by five global climate and agro-economic models. Covering integrated assessment (IMAGE), partial equilibrium (CAPRI, GLOBIOM, MAgPIE) and computable general equilibrium (MAGNET) models ensures a good coverage of biophysical and economic agricultural features. These models are harmonized with respect to basic model drivers, to assess the range of potential impacts of climate change on the agricultural sector by 2050. Moreover, they quantify the economic consequences of stringent global emission mitigation efforts, such as non-CO 2 emission taxes and land-based mitigation options, to stabilize global warming at 2 • C by the end of the century under different Shared Socioeconomic Pathways. A key contribution of the paper is a vis-à-vis comparison of climate change impacts relative to the impact of mitigation measures. In addition, our scenario design allows assessing the impact of the residual climate change on the mitigation challenge. From a global perspective, the impact of climate change on agricultural production by mid-century is negative but small. A larger negative effect on agricultural production, most pronounced for ruminant meat production, is observed when emission mitigation measures compliant with a 2 • C target are put in place. Our results indicate that a mitigation strategy that embeds residual climate change effects (RCP2.6) has a negative impact on global agricultural production relative to a no-mitigation strategy with stronger climate impacts (RCP6.0). However, this is partially due to the limited impact of the climate change scenarios by 2050. The magnitude of price changes is different amongst models due to methodological differences. Further research to achieve a better harmonization is needed, especially regarding endogenous food and feed demand, including substitution across individual commodities, and endogenous technological change.

Catalytic activity is known to depend on the ligandmetal-ligand angle, the so-called bite angle (see Scheme 1).[1] Many pioneering studies have been undertaken in order to understand how exactly reaction barriers are affected by this and related structural parameters of the catalytically active complex. [2, 3] It is commonly accepted that the effect of the bite angle on the reaction barrier of, for example, C À X bond activation [Eq. (1)], originates from an electronic factor.According to this electronic model, the transition state (TS) is stabilized by donor-acceptor orbital interactions from metal d orbitals to the substrate s* CÀX , which become more stabilizing as the metal-ligand d hybrid orbital is pushed up at smaller bite angles.[3]Here, we provide evidence that the mechanism through which the bite angle affects barrier heights (and also the twist angle in the TS, see Scheme 1) [4] is steric in nature, rather than electronic. This insight is of direct relevance for developing correct, rational design principles for catalysts. Our evidence is based on relativistic density functional theory (DFT) analyses with the ADF program [5] at ZORA-BLYP/TZ2P (see reference [6] for benchmark studies) of a series of oxidative insertion (OxIn) reactions of model cata-) with n = 1-6 and model substrates H 3 CÀX with X = H, CH 3 , and Cl.To obtain a qualitative, physical understanding of how trends in catalytic activity (i.e., OxIn barrier height) are determined by the ligand and catalyst structure, we have carried out an analysis of the reaction profiles using the activation-strain model of chemical reactivity. In this model, the potential-energy surface DE(z) is decomposed, along the reaction coordinate z (obtained from intrinsic reaction coordinate (IRC) calculations), into the strain associated with deforming the substrate, DE strain A C H T U N G T R E N N U N G [substr](z), and the catalyst, DE strain A C H T U N G T R E N N U N G [cat](z), plus the actual interaction DE int (z) between these two deformed reactants [Eq. (2)]: [7][8][9] DEðzÞ ¼ DE strain ½substrðzÞ þ DE strain ½catðzÞ þ DE int ðzÞ ð2ÞKey results are collected in Table 1 and Figure 1; for details, see Tables S1 and S2 and Figure S1 in the Supporting Information.A number of general trends can be observed in Tables 1 and S1. Both, the endothermicity and barrier height increase from Pd, along the seriesThis is, in part, caused by a weakening of the catalyst-substrate interaction from bare to coordinated palladium, as suggested by the concomitant loss of stability of the reactant complexes and confirmed by our activation-strain analyses (vide infra). Furthermore, barrier heights increase from C À Cl to C À H to C À C activation, as discussed in detail already previously, for the insertion of uncoordinated Pd atoms.[7a] The highly strained PdA C H T U N G T R E N N U N G [P1P], a four-membered ring, slightly expands (for insertion into CÀH) or even fully dissociates (for insertion into CÀC and CÀCl) one PdÀP bond in the reactant complexes and transitio...