This paper presents an overview of results obtained during the CAWSES-II period on the short-term variability of the
Sun and how it affects the near-Earth space environment. CAWSES-II was planned to examine the behavior of the
solar-terrestrial system as the solar activity climbed to its maximum phase in solar cycle 24. After a deep minimum
following cycle 23, the Sun climbed to a very weak maximum in terms of the sunspot number in cycle 24 (MiniMax24),
so many of the results presented here refer to this weak activity in comparison with cycle 23. The short-term variability
that has immediate consequence to Earth and geospace manifests as solar eruptions from closed-field regions
and high-speed streams from coronal holes. Both electromagnetic (flares) and mass emissions (coronal mass
ejections - CMEs) are involved in solar eruptions, while coronal holes result in high-speed streams that collide
with slow wind forming the so-called corotating interaction regions (CIRs). Fast CMEs affect Earth via leading
shocks accelerating energetic particles and creating large geomagnetic storms. CIRs and their trailing high-speed
streams (HSSs), on the other hand, are responsible for recurrent small geomagnetic storms and extended days of
auroral zone activity, respectively. The latter leads to the acceleration of relativistic magnetospheric ‘killer’ electrons.
One of the major consequences of the weak solar activity is the altered physical state of the heliosphere that has
serious implications for the shock-driving and storm-causing properties of CMEs. Finally, a discussion is presented on
extreme space weather events prompted by the 23 July 2012 super storm event that occurred on the backside of the
Sun. Many of these studies were enabled by the simultaneous availability of remote sensing and in situ observations
from multiple vantage points with respect to the Sun-Earth line.