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"What these examples have in common is that they illustrate two of the key tasks of the social sciences: to measure important social variables over time and space, and to identify the social mechanisms that lead to variation in these variables. There are large problems of methodology and conceptual clarification that need to be addressed in both parts of this agenda. On the side of measurement, we have the problems of arriving at consistent and revealing definitions of economic wellbeing, using incomplete historical sources to reconstruct estimates of prices and wages, and using a range of statistical methods to validate and interpret the results. And on the explanatory side, we are faced with the difficult task of reconstructing social processes and forces in the past that may have powered the changes we are able to document, and with the task of validating the hypotheses we have put forward on the basis of historical evidence."

In more than 1,000 years, the Atlantic Meridional Overturning Circulation (AMOC), also known as Gulf Stream System, has not been as weak as in recent decades. This is the result of a new study by scientists from Ireland, Britain and Germany. The researchers compiled so-called proxy data, taken mainly from natural archives like ocean sediments or ice cores, reaching back many hundreds of years to reconstruct the flow history of the AMOC. They found consistent evidence that its slowdown in the 20th century is unprecedented in the past millennium; it is likely linked to human-caused climate change. The giant ocean circulation system is relevant for weather patterns in Europe and regional sea levels in the U.S.; its slowdown is also associated with an observed cold blob in the northern Atlantic.

If you want to understand an ecosystem, look at what the species within it eat. In studying food webs-how animals and plants in a community are connected through their dietary preferences-ecologists can piece together how energy flows through an ecosystem and how stable it is to climate change and other disturbances. Studying ancient food webs can help scientists reconstruct communities of species, many long extinct, and even use those insights to figure out how modern-day communities might change in the future. There's just one problem: only some species left enough of a trace for scientists to find eons later, leaving large gaps in the fossil record-and researchers' ability to piece together the food webs from the past.