The goal of this International Team is to develop a clear physics-based understanding of long-term changes in heliosphere, solar irradiance, and space weather conditions near Earth. This project will employ newly developed maps of magnetic field for modeling the space weather effect on Earth and solar irradiance (TSI) over the last century. We will also use community-accepted models such as PFSS, WSA-Enlil etc to model the amount of open flux from the Sun, the location of coronal holes, the electron density, temperature and speed of solar wind in the heliosphere and at 1 AU. We will compare and constrain the results of our modeling with historical observations of geomagnetic activity.