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Previous phases of the Coupled Model Intercomparison Project (CMIP) have primarily focused on simulations driven by atmospheric concentrations of greenhouse gases (GHGs), both for idealized model experiments, and for climate projections of different emissions scenarios. We argue that although this approach was pragmatic to allow parallel development of Earth System Model simulations and detailed socioeconomic futures, carbon cycle uncertainty as represented by diverse, process-resolving Earth System Models (ESMs) is not manifested in the scenario outcomes, thus omitting a dominant source of uncertainty in meeting the Paris Agreement. Mitigation policy is defined in terms of human activity (including emissions), with strategies varying in their timing of net-zero emissions, the balance of mitigation effort between short-lived and long-lived climate forcers, their reliance on land use strategy and the extent and timing of carbon removals. To explore the response to these drivers, ESMs need to explicitly represent complete cycles of major GHGs, including natural processes and anthropogenic influences. Carbon removal and sequestration strategies, which rely on proposed human management of natural systems, are currently represented upstream of ESMs in an idealized fashion during scenario development. However, proper accounting of the coupled system impacts of and feedback on such interventions requires explicit process representation in ESMs to build self-consistent physical representations of their potential effectiveness and risks under climate change. We propose that CMIP7 efforts prioritize simulations driven by CO2 emissions from fossil fuel use, projected deployment of carbon dioxide removal technologies, as well as land use and management, using the process resolution allowed by state-of-the-art ESMs to resolve carbon-climate feedbacks. Post-CMIP7 ambitions should aim to incorporate modeling of non-CO2 GHGs (in particular sources and sinks of methane) and process

New delta13C, delta18O, and delta34S data from the Karakaene Ndi skarn, Au occurrences along the western margin of the Kofi series, and zircons within plutonic rocks of the Faleme batholith are combined with existing data from the Loulo Au deposits to model the contribution of magmatic volatiles to Au mineralisation. Comparison of the C and O isotope data with water-rock reaction models indicates the Loulo Au deposits formed primarily through unmixing of an aqueous carbonic fluid derived from the devolatilisation of sedimentary rocks with an organic carbon component. Isotopic data suggest the presence of a hypersaline brine that enhanced this phase separation including components derived from both Kofi series evaporite horizons interlayered with the dolostones and a magmatic-hydrothermal brine. This magmatic-hydrothermal component is particularly apparent in O, C, and S isotope data from the Gara deposit and Au prospects immediately adjacent to the Faleme batholith. It is concluded that there was a critical role for magmatism in the development of early alteration assemblages in the Loulo district, in the genesis of the Faleme iron skarns, and in those Au deposits that formed in response to fluid mixing., New delta13C, delta18O, and delta34S data from the Karakaene Ndi skarn, Au occurrences along the western margin of the Kofi series, and zircons within plutonic rocks of the Faleme batholith are combined with existing data from the Loulo Au deposits to model the contribution of magmatic volatiles to Au mineralisation. Comparison of the C and O isotope data with water-rock reaction models indicates the Loulo Au deposits formed primarily through unmixing of an aqueous carbonic fluid derived from the devolatilisation of sedimentary rocks with an organic carbon component. Isotopic data suggest the presence of a hypersaline brine that enhanced this phase separation including components derived from both Kofi series evaporite horizons interlayered with the dolostones and a magmatic-hydrothermal brine. This magmatic-hydrothermal component is particularly apparent in O, C, and S isotope data from the Gara deposit and Au prospects immediately adjacent to the Faleme batholith. It is concluded that there was a critical role for magmatism in the development of early alteration assemblages in the Loulo district, in the genesis of the Faleme iron skarns, and in those Au deposits that formed in response to fluid mixing.

Heat uptake is a key variable for understanding the Earth system response to greenhouse gas forcing. Despite the importance of this heat budget, heat uptake by inland waters has so far not been quantified. Here we use a unique combination of global-scale lake models, global hydrological models and Earth system models to quantify global heat uptake by natural lakes, reservoirs, and rivers. The total net heat uptake by inland waters amounts to 2.6 ± 3.2 ×1020 J over the period 1900–2020, corresponding to 3.6% of the energy stored on land. The overall uptake is dominated by natural lakes (111.7%), followed by reservoir warming (2.3%). Rivers contribute negatively (-14%) due to a decreasing water volume. The thermal energy of water stored in artificial reservoirs exceeds inland water heat uptake by a factor ∼10.4. This first quantification underlines that the heat uptake by inland waters is relatively small, but non-negligible.

The Land Surface, Snow and Soil Moisture Model Intercomparison Project (LS3MIP) is designed to provide a comprehensive assessment of land surface, snow and soil moisture feedbacks on climate variability and climate change, and to diagnose systematic biases in the land modules of current Earth system models (ESMs). The solid and liquid water stored at the land surface has a large influence on the regional climate, its variability and predictability, including effects on the energy, water and carbon cycles. Notably, snow and soil moisture affect surface radiation and flux partitioning properties, moisture storage and land surface memory. They both strongly affect atmospheric conditions, in particular surface air temperature and precipitation, but also large-scale circulation patterns. However, models show divergent responses and representations of these feedbacks as well as systematic biases in the underlying processes. LS3MIP will provide the means to quantify the associated uncertainties and better constrain climate change projections, which is of particular interest for highly vulnerable regions (densely populated areas, agricultural regions, the Arctic, semi-arid and other sensitive terrestrial ecosystems). The experiments are subdivided in two components, the first addressing systematic land biases in offline mode (“LMIP”, building upon the 3rd phase of Global Soil Wetness Project; GSWP3) and the second addressing land feedbacks attributed to soil moisture and snow in an integrated framework (“LFMIP”, building upon the GLACE-CMIP blueprint).

Desert dust perturbs climate by directly and indirectly interacting with incoming solar and outgoing long wave radiation, thereby changing precipitation and temperature, in addition to modifying ocean and land biogeochemistry. While we know that desert dust is sensitive to perturbations in climate and human land use, previous studies have been unable to determine whether humans were increasing or decreasing desert dust in the global average. Here we present observational estimates of desert dust based on paleodata proxies showing a doubling of desert dust during the 20th century over much, but not all the globe. Large uncertainties remain in estimates of desert dust variability over 20th century due to limited data. Using these observational estimates of desert dust change in combination with ocean, atmosphere and land models, we calculate the net radiative effect of these observed changes (top of atmosphere) over the 20th century to be −0.14 ± 0.11 W/m2 (1990–1999 vs. 1905–1914). The estimated radiative change due to dust is especially strong between the heavily loaded 1980–1989 and the less heavily loaded 1955–1964 time periods (−0.57 ± 0.46 W/m2), which model simulations suggest may have reduced the rate of temperature increase between these time periods by 0.11 °C. Model simulations also indicate strong regional shifts in precipitation and temperature from desert dust changes, causing 6 ppm (12 PgC) reduction in model carbon uptake by the terrestrial biosphere over the 20th century. Desert dust carries iron, an important micronutrient for ocean biogeochemistry that can modulate ocean carbon storage; here we show that dust deposition trends increase ocean productivity by an estimated 6% over the 20th century, drawing down an additional 4 ppm (8 PgC) of carbon dioxide into the oceans. Thus, perturbations to desert dust over the 20th century inferred from observations are potentially important for climate and biogeochemistry, and our understanding of these changes

The Tongon deposit in northern Côte d’Ivoire is the first reported occurrence of Au skarn mineralisation hosted in Palaeoproterozoic greenstone rocks of the West African craton. Tongon is an unusually large skarn (3.8 Moz at 2.5 g/t Au) replacing noncarbonate host rocks. The deposit is hosted exclusively in basaltic-andesitic crystal tuffs of the Senoufo greenstone belt. The alteration haloes surrounding the deposit formed during three main stages. Stage 2 garnets contain high Al and Ti, and the skarns have elevated Ni and Cr, reflecting the mafic composition of the host rocks. Proximal to peripheral mineral zonation patterns are defined by decreases in the ratio of garnet to pyroxene, increasing Fe in pyroxene, higher Au concentrations, and an increase in the intensity of retrograde alteration, seen as a change from white-to green-coloured skarn. Spatially, gold-rich stage 3 alteration coincides with stage 2 intermediate diopside-rich skarn and distal hedenbergite-ferroactinolite skarn, whereas the proximal garnet-bearing skarn typically has much lower Au grades. U-Pb dating of hydrothermal titanite indicates the Au skarn formed between 2 139 ± 21 and 2 128 ± 21 Ma, 20 to 70 m.y. before the major episode of orogenic Au mineralisation in southwest Ghana and western Mali. Dating provides further evidence that Au mineralisation within the Palaeoproterozoic rocks of West Africa craton occurred over several tens of millions of years through a variety of different processes., The Tongon deposit in northern Côte d’Ivoire is the first reported occurrence of Au skarn mineralisation hosted in Palaeoproterozoic greenstone rocks of the West African craton. Tongon is an unusually large skarn (3.8 Moz at 2.5 g/t Au) replacing noncarbonate host rocks. The deposit is hosted exclusively in basaltic-andesitic crystal tuffs of the Senoufo greenstone belt. The alteration haloes surrounding the deposit formed during three main stages. Stage 2 garnets contain high Al and Ti, and the skarns have elevated Ni and Cr, reflecting the mafic composition of the host rocks. Proximal to peripheral mineral zonation patterns are defined by decreases in the ratio of garnet to pyroxene, increasing Fe in pyroxene, higher Au concentrations, and an increase in the intensity of retrograde alteration, seen as a change from white-to green-coloured skarn. Spatially, gold-rich stage 3 alteration coincides with stage 2 intermediate diopside-rich skarn and distal hedenbergite-ferroactinolite skarn, whereas the proximal garnet-bearing skarn typically has much lower Au grades. U-Pb dating of hydrothermal titanite indicates the Au skarn formed between 2 139 ± 21 and 2 128 ± 21 Ma, 20 to 70 m.y. before the major episode of orogenic Au mineralisation in southwest Ghana and western Mali. Dating provides further evidence that Au mineralisation within the Palaeoproterozoic rocks of West Africa craton occurred over several tens of millions of years through a variety of different processes.

Loulo is a world-class orogenic gold mining district in the Birimian terrane of western Mali. Orebodies are located along second- or higher-order shears associated with the Senegal-Mali shear zone, with gold mineralisation largely linked to a transtensional event. Two distinct styles of gold deposit on the basis of their differing geological characteristics are the Gara deposit and the Yalea deposit, both hosted by similar rock types, calcareous graywackes and calcitic-dolomitic marbles. Gara-style orebodies occur as sulphide disseminations or ankerite-rich shear vein stockworks, hosted in folded tourmalinised sandstones and breccias. Gold lodes are Fe-rich, dominated by nickeloan pyrite, contain Cu-Ni +/-Co minor and trace sulphides, and show consistently high levels of P-REE-W-bearing phases apatite, monazite, xenotime and scheelite. Base metal concentrations show a marked increase in marble host rocks, with the formation of nickeloan pyrite-cobaltite-clausthalite ores. In contrast, Yalea-style deposits are associated with quartz +/-ankerite vein lodes and disseminated sulphide stringer zones. Ore paragenesis is enriched in As, mainly as multistage growth of arsenopyrite and arsenian pyrite. Base metal sulphides, scheelite and (REE-)phosphates are extremely rare. The diversity in the ore paragenesis is controlled by a dynamic hydrothermal system that sourced fluids and metals from different reservoirs within the region., Loulo is a world-class orogenic gold mining district in the Birimian terrane of western Mali. Orebodies are located along second- or higher-order shears associated with the Senegal-Mali shear zone, with gold mineralisation largely linked to a transtensional event. Two distinct styles of gold deposit on the basis of their differing geological characteristics are the Gara deposit and the Yalea deposit, both hosted by similar rock types, calcareous graywackes and calcitic-dolomitic marbles. Gara-style orebodies occur as sulphide disseminations or ankerite-rich shear vein stockworks, hosted in folded tourmalinised sandstones and breccias. Gold lodes are Fe-rich, dominated by nickeloan pyrite, contain Cu-Ni +/-Co minor and trace sulphides, and show consistently high levels of P-REE-W-bearing phases apatite, monazite, xenotime and scheelite. Base metal concentrations show a marked increase in marble host rocks, with the formation of nickeloan pyrite-cobaltite-clausthalite ores. In contrast, Yalea-style deposits are associated with quartz +/-ankerite vein lodes and disseminated sulphide stringer zones. Ore paragenesis is enriched in As, mainly as multistage growth of arsenopyrite and arsenian pyrite. Base metal sulphides, scheelite and (REE-)phosphates are extremely rare. The diversity in the ore paragenesis is controlled by a dynamic hydrothermal system that sourced fluids and metals from different reservoirs within the region.

The Loulo mining district (15 500 000 oz Au resource), in the Birimian terrane of western Mali, contains diverse styles of orogenic gold mineralisation, distinguished by As-rich orebodies as at Yalea as well as tourmaline-bearing Fe-rich orebodies as at Gara. New fluid inclusion and stable isotope data presented here point towards the role of multifluid sources, both metamorphic and magmatic, in the formation of orogenic gold deposits. Microthermometric and laser Raman studies from Yalea Main and two other similar orebodies (Loulo-3 and Baboto) reveal inclusions showing evidence of fluid unmixing from reduced, low-salinity, CO2-rich H2O-NaCl-N2 +/-CH4 primary ore fluids. The P-T-X state of the Yalea-style mineralising fluids, along with the 18-O(fluid) compositions, is consistent with the derivation of auriferous fluids during greenschist-facies regional metamorphism of the host terrane. Precipitation of gold from the H2S-rich metamorphic fluid was primarily linked to phase separation of the ore fluid. Composition of the brines, along with carbon isotope data, suggests a magmatic Gara-style hydrothermal system. The coexistence in the fluid inclusion assemblages of the magmatic brines with Yalea-style, CO2-rich metamorphic fluids and the positive correlation between salinity and homogenisation temperatures suggest mineralisation was locally controlled by fluid mixing. Gold deposition in the Gara-style system was related to physical and chemical changes of the two fluids during mixing., The Loulo mining district (15 500 000 oz Au resource), in the Birimian terrane of western Mali, contains diverse styles of orogenic gold mineralisation, distinguished by As-rich orebodies as at Yalea as well as tourmaline-bearing Fe-rich orebodies as at Gara. New fluid inclusion and stable isotope data presented here point towards the role of multifluid sources, both metamorphic and magmatic, in the formation of orogenic gold deposits. Microthermometric and laser Raman studies from Yalea Main and two other similar orebodies (Loulo-3 and Baboto) reveal inclusions showing evidence of fluid unmixing from reduced, low-salinity, CO2-rich H2O-NaCl-N2 +/-CH4 primary ore fluids. The P-T-X state of the Yalea-style mineralising fluids, along with the 18-O(fluid) compositions, is consistent with the derivation of auriferous fluids during greenschist-facies regional metamorphism of the host terrane. Precipitation of gold from the H2S-rich metamorphic fluid was primarily linked to phase separation of the ore fluid. Composition of the brines, along with carbon isotope data, suggests a magmatic Gara-style hydrothermal system. The coexistence in the fluid inclusion assemblages of the magmatic brines with Yalea-style, CO2-rich metamorphic fluids and the positive correlation between salinity and homogenisation temperatures suggest mineralisation was locally controlled by fluid mixing. Gold deposition in the Gara-style system was related to physical and chemical changes of the two fluids during mixing.

The Kibali deposit, with a current resource estimate of 18 600 000 oz Au and first production expected in 2014, is a series of stacked dipping lodes divided into mineralised corridors hosted within volcano-sedimentary conglomerates in one of the last unexplored Archaean greenstone belts in the world; gold is texturally associated with finely disseminated pyrite. Its structural setting within a thrust stack differs from orogenic deposits linked to a major, steeply dipping strike-slip fault: the preliminary model is that ore-forming fluids produced by metamorphic devolatilisation under upper greenschist facies, deep within the thrust wedge, migrated upward and southward along dipping thrust faults where mineralisation occurred in dilational sites at the intersections with lateral ramps., The Kibali deposit, with a current resource estimate of 18 600 000 oz Au and first production expected in 2014, is a series of stacked dipping lodes divided into mineralised corridors hosted within volcano-sedimentary conglomerates in one of the last unexplored Archaean greenstone belts in the world; gold is texturally associated with finely disseminated pyrite. Its structural setting within a thrust stack differs from orogenic deposits linked to a major, steeply dipping strike-slip fault: the preliminary model is that ore-forming fluids produced by metamorphic devolatilisation under upper greenschist facies, deep within the thrust wedge, migrated upward and southward along dipping thrust faults where mineralisation occurred in dilational sites at the intersections with lateral ramps.