Globally coherent water cycle response to temperature changes during the past two millennia

The response of the global water cycle to changes in global surface temperature remains an outstanding question in future climate projections and past climate reconstructions. The stable hydrogen and oxygen isotope compositions of precipitation (δprecip), meteoric water (δMW), and seawater (δSW) integrate processes from microphysical to global scales and thus are uniquely positioned to track global hydroclimate variations. Here, we evaluate global hydroclimate during the past 2,000 years using a globally distributed compilation of proxies for δprecip, δMW, and δSW. We show that global mean surface temperature exerted a coherent influence on global δprecip and δMW throughout the past two millennia, driven by global ocean evaporation and condensation processes, with lower values during the Little Ice Age (1450-1850) and higher values after the onset of anthropogenic warming (~1850). The Pacific Walker Circulation is a predominant source of regional variability, particularly since 1850. Our results demonstrate rapid adjustments in global precipitation and atmospheric circulation patterns – within decades – as the planet warms and cools

Globally coherent water cycle response to temperature changes during the past two millennia

International audienceThe response of the global water cycle to changes in global surface temperature remains an outstanding question in future climate projections and past climate reconstructions. The stable hydrogen and oxygen isotope compositions of precipitation (δprecip), meteoric water (δMW), and seawater (δSW) integrate processes from microphysical to global scales and thus are uniquely positioned to track global hydroclimate variations. Here, we evaluate global hydroclimate during the past 2,000 years using a globally distributed compilation of proxies for δprecip, δMW, and δSW. We show that global mean surface temperature exerted a coherent influence on global δprecip and δMW throughout the past two millennia, driven by global ocean evaporation and condensation processes, with lower values during the Little Ice Age (1450-1850) and higher values after the onset of anthropogenic warming (~1850). The Pacific Walker Circulation is a predominant source of regional variability, particularly since 1850. Our results demonstrate rapid adjustments in global precipitation and atmospheric circulation patterns – within decades – as the planet warms and cools

Globally coherent water cycle response to temperature changes during the past two millennia

The response of the global water cycle to changes in global surface temperature remains an outstanding question in future climate projections and past climate reconstructions. The stable hydrogen and oxygen isotope compositions of precipitation (δprecip), meteoric water (δMW), and seawater (δSW) integrate processes from microphysical to global scales and thus are uniquely positioned to track global hydroclimate variations. Here, we evaluate global hydroclimate during the past 2,000 years using a globally distributed compilation of proxies for δprecip, δMW, and δSW. We show that global mean surface temperature exerted a coherent influence on global δprecip and δMW throughout the past two millennia, driven by global ocean evaporation and condensation processes, with lower values during the Little Ice Age (1450-1850) and higher values after the onset of anthropogenic warming (~1850). The Pacific Walker Circulation is a predominant source of regional variability, particularly since 1850. Our results demonstrate rapid adjustments in global precipitation and atmospheric circulation patterns – within decades – as the planet warms and cools

Annual average Sr/Ca measurements from Porites lutea coral at Ha'afera Island, Tonga

In the South Pacific Convergence Zone (SPCZ), the variability in a sub-seasonally resolved microatoll Porites colony Sr/Ca record from Tonga and a previously published high-resolution record from Fiji are strongly influenced by sea surface temperature (SST) over the calibration period from 1981 to 2004 (R^2 = 0.67 - 0.68). However, the Sr/Ca-derived SST correlation to instrumental SST decreases back in time. The lower frequency secular trend (~1°C) and decadal-scale (~2 - 3°C) modes in Sr/Ca-derived SST are almost two times larger than that observed in instrumental SST. The coral Sr/Ca records suggest that local effects on SST generate larger amplitude variability than gridded SST products indicate. Reconstructed d18O of seawater (d18Osw) at these sites correlate with instrumental sea surface salinity (SSS; r = 0.64 - 0.67) but not local precipitation (r = -0.10 to - 0.22) demonstrating that the advection and mixing of different salinity water masses may be the predominant control on d18Osw in this region. The Sr/Ca records indicate SST warming over the last 100 years and appears to be related to the expansion of the western Pacific warm pool (WPWP) including an increasing rate of expansion in the last ~20 years. The reconstructed d18Osw over the last 100 years also shows surface water freshening across the SPCZ. The warming and freshening of the surface ocean in our study area suggests that the SPCZ has been shifting (expanding) southeast, possibly related to the southward shift and intensification of the South Pacific gyre over the last 50 years in response to strengthened westerly winds

Documentation of sediment cores during SONNE Expedition SO228 from the western tropical Pacific

The core descriptions (chapter 7) summarize the most important results of the analysis of each sediment core following procedures applied during ODP/IODP expeditions. All cores were opened, described, and color-scanned. In the core descriptions the first column displays the lithological data that are based on visual analysis of the core and are supplemented by information from binocular and smear slide analyses. The sediment classification largely follows ODP/IODP convention. Lithological names consist of a principal name based on composition, degree of lithification, and/or texture as determined from visual description and microscopic observations. In the structure column the intensity of bioturbation together with individual or special features (turbidites, volcanic ash layers, plant debris, shell fragments, etc.) is shown. The hue and chroma attributes of color were determined by comparison with the Munsell soil color charts and are given in the color column in the Munsell notation. A GretagMacbethTM Spectrolino spectrophotometer was used to measure percent reflectance values of sediment color at 36 wavelength channels over the visible light range (380-730 nm) on all of the cores. The digital reflectance data of the spectrophotometer readings were routinely obtained from the surface (measured in 1 cm steps) of the split cores (archive half). The Spectrolino is equipped with a measuring aperture with folding mechanism allowing an exact positioning on the split core and is connected to a portable computer. The data are directly displayed within the software package Excel and can be controlled simultaneously. From all the color measurements, for each core the red/blue ratio (700 nm/450 nm) and the lightness are shown together with the visual core description. The reflectance of individual wavelengths is often significantly affected by the presence of minor amounts of oxyhydroxides or sulphides. To eliminate these effects, we used the red/blue ratio and lightness